阅读说明：本技术 微粒数检测器 (Particle number detector ) 是由 菅野京一 奥村英正 水野和幸 于 2018-05-15 设计创作，主要内容包括：微粒数检测器10具备：电荷产生元件、捕集装置、以及个数测定装置。电荷产生元件向被导入至通气管12内的气体中的微粒附加通过放电而产生的电荷,使其成为带电微粒。捕集装置利用通过电场产生部42而产生的电场,将带电微粒捕集于捕集电极48。个数测定装置基于根据捕集电极48所捕集到的带电微粒的数量而发生变化的捕集电极48的物理量,来检测带电微粒的数量。此处,通气管12具备：由陶瓷材料构成的致密质的骨架形成部13(13a～13d)、以及由杨氏模量比陶瓷材料的杨氏模量低的材料构成且与骨架形成部13接触的致密质的应力缓和部14(14a～14d)。(The number of fine particles detector 10 includes: a charge generating element, a trapping device, and a number measuring device. The charge generating element adds electric charge generated by the discharge to the fine particles in the gas introduced into the breather pipe 12, and turns the fine particles into charged fine particles. The trapping device traps the charged fine particles at the trapping electrode 48 by the electric field generated by the electric field generating unit 42. The number measuring device detects the number of charged fine particles based on the physical quantity of the collecting electrode 48 that changes according to the number of charged fine particles collected by the collecting electrode 48. Here, the breather pipe 12 includes: dense skeleton-forming portions 13(13a to 13d) made of a ceramic material, and dense stress relaxation portions 14(14a to 14d) made of a material having a lower young's modulus than that of the ceramic material and in contact with the skeleton-forming portions 13.)

1. A particle count detector is provided with:

a charge generation element for adding charges generated by the discharge to the fine particles in the gas introduced into the gas duct to form charged fine particles;

a charged particle collecting unit that is provided on the downstream side of the charge generating element with respect to the gas flow and collects the charged particles; and

a number detection unit that detects the number of the charged fine particles based on a physical quantity of the charged fine particle trapping unit that changes in accordance with the number of the charged fine particles trapped by the charged fine particle trapping unit,

the breather pipe is provided with: the piezoelectric element includes a dense skeleton-forming portion made of a ceramic material, and a dense stress relaxation portion made of a material having a Young's modulus lower than that of the ceramic material and in contact with the skeleton-forming portion.

2. A particle count detector is provided with:

a charge generation element for adding charges generated by the discharge to the fine particles in the gas introduced into the gas duct to form charged fine particles;

a residual charge trapping portion that is provided on a downstream side of the charge generating element with respect to the gas flow, and traps residual charges that are not added to the microparticles; and

a number detection unit that detects the number of the charged microparticles based on a physical quantity of the residual charge trapping unit that changes in accordance with the number of the residual charges trapped by the residual charge trapping unit,

the breather pipe is provided with: the piezoelectric element includes a dense skeleton-forming portion made of a ceramic material, and a dense stress relaxation portion made of a material having a Young's modulus lower than that of the ceramic material and in contact with the skeleton-forming portion.

3. The particle count detector according to claim 1 or 2, wherein,

the frame forming portion is a split member obtained by dividing the ventilation pipe into a plurality of pieces, and the stress relaxing portion is a joining layer joining the split members.

4. The particle count detector according to claim 3,

the ventilation pipe is a square tube, and the split type component is a component obtained by dividing the ventilation pipe into 4 pieces according to each surface.

5. The particle count detector according to claim 1 or 2, wherein,

the framework forming part is a pipe body with the same shape as the vent pipe,

the stress relaxation portion is provided in a layered manner at least at 1 position among the outer surface, the inner surface, and the inside of the pipe body.

6. The particle count detector according to any one of claims 1 to 5, wherein,

the stress relaxation section has a Young's modulus of 0.7 times or less that of the ceramic material constituting the skeleton-forming section.

7. The particle count detector according to any one of claims 1 to 6, wherein,

the skeleton-forming portion is composed of at least 1 kind of ceramic material selected from the group consisting of alumina, silicon nitride, mullite, cordierite, and magnesia.

8. The particle count detector according to any one of claims 1 to 7, wherein,

the stress relaxation portion is made of crystallized glass.

Technical Field

The present invention relates to particle number detectors.

Background

As the number of fine particles detector, there is known a number of fine particles detector in which a charge generating element generates ions by corona discharge, the ions are added to fine particles in a gas introduced into a ceramic vent tube, a collecting electrode collects the charged fine particles, and a number measuring device measures the number of fine particles based on the charge amount of the collected fine particles (see, for example, patent document 1).

Disclosure of Invention

However, when the number of particles in the high-temperature gas is measured by using the particle number detector, if water adheres to the ceramic breather pipe, cracks may occur due to thermal shock. The case where the crack penetrates the wall surface of the vent pipe inevitably leads to a decrease in measurement accuracy, and even if the crack does not penetrate the wall surface of the vent pipe, the measurement accuracy may be decreased. That is, when a crack that does not penetrate through the wall surface of the breather pipe occurs, the stress released by the crack causes: the wall surface of the breather pipe is deformed, and the charge generating element arranged on the wall surface is dislocated. In the uneven electric field required for generating corona discharge, the distribution of electric field lines is concentrated at the end portion, and therefore, the electric field distribution is largely changed by slight deformation. As a result, the spatial distribution of the ion density also changes, and the amount of ions attached to each microparticle deviates from the design value, resulting in a decrease in measurement accuracy.

The present invention has been made to solve the above problems, and a main object thereof is to prevent the charge generating element from being misaligned.

The number of fine particles detector of the present invention comprises:

a charge generation element for adding charges generated by the discharge to the fine particles in the gas introduced into the gas duct to form charged fine particles;

a charged particle collecting unit that is provided on the downstream side of the charge generating element with respect to the gas flow and collects the charged particles; and

a number detection unit that detects the number of the charged fine particles based on a physical quantity of the charged fine particle trapping unit that changes in accordance with the number of the charged fine particles trapped by the charged fine particle trapping unit,

the breather pipe is provided with: the piezoelectric element includes a dense skeleton-forming portion made of a ceramic material, and a dense stress relaxation portion made of a material having a Young's modulus lower than that of the ceramic material and in contact with the skeleton-forming portion.

Alternatively, the first and second electrodes may be,

the number of fine particles detector of the present invention comprises:

a charge generation element for adding charges generated by the discharge to the fine particles in the gas introduced into the gas duct to form charged fine particles;

a residual charge trapping portion that is provided on a downstream side of the charge generating element with respect to the gas flow, and traps residual charges that are not added to the microparticles; and

a number detection unit that detects the number of the charged microparticles based on a physical quantity of the residual charge trapping unit that changes in accordance with the number of the residual charges trapped by the residual charge trapping unit,

the breather pipe is provided with: the piezoelectric element includes a dense skeleton-forming portion made of a ceramic material, and a dense stress relaxation portion made of a material having a Young's modulus lower than that of the ceramic material and in contact with the skeleton-forming portion.

In the particle count detector, the charge generating element adds charges generated by the discharge to particles in the gas introduced into the gas pipe, thereby forming charged particles. The number detection unit detects the number of the microparticles in the gas based on a physical quantity of the charged microparticle trapping unit that changes in accordance with the number of the charged microparticles trapped by the charged microparticle trapping unit. Alternatively, the residual charge trapping portion traps residual charges, and the number detection portion detects the number of the charged microparticles based on a physical quantity of the residual charge trapping portion that changes in accordance with the number of the residual charges trapped by the residual charge trapping portion. Here, the breather pipe includes: the piezoelectric element includes a dense skeleton-forming portion made of a ceramic material, and a dense stress relaxation portion made of a material having a Young's modulus lower than that of the ceramic material constituting the skeleton-forming portion and in contact with the skeleton-forming portion. Thus, since the entire breather pipe is dense, the gas containing the fine particles does not pass through the wall surface of the breather pipe. In addition, when the number of fine particles in the high-temperature gas is measured, when water adheres to the vent pipe, the portion to which the water adheres is rapidly cooled, and energy due to thermal shock is generated. This prevents the charge generating element from being displaced by a crack, and the measurement accuracy can be maintained at a high level.

In the present specification, the term "charge" includes ions in addition to positive and negative charges. The "number of detected particles" includes not only the case of measuring the number of particles but also the case of determining whether or not the number of particles falls within a predetermined numerical range (for example, whether or not the number exceeds a predetermined threshold). The "physical quantity" is a parameter that changes depending on the number of charged fine particles (charge amount), and examples thereof include a current. The term "dense" means that the open porosity is 5% or less (preferably 3% or less, more preferably 1% or less).

In the particle count detector according to the present invention, the skeleton-forming portion may be a split member obtained by dividing the ventilation pipe into a plurality of pieces, and the stress relaxing portion may be a joining layer joining the plurality of split members. Accordingly, the plurality of split members are joined by the joining layer to produce the vent pipe, and therefore, the production of the vent pipe is facilitated. The ventilation pipe may be a square tube, and the split member may be a member obtained by dividing the ventilation pipe into 4 pieces for each surface. Accordingly, the split member is a planar member, and the joining layer serving as the stress relaxation portion is allowed to expand and contract in the planar direction, so that the occurrence of cracks in the breather pipe can be further suppressed.

In the particle count detector according to the present invention, the skeleton-forming portion may be a pipe body having the same shape as the vent pipe, and the stress relaxing portion may be provided in a layer shape at least at 1 position among an outer surface, an inner surface, and an inner portion of the pipe body. When the number of particles in the high-temperature gas is measured, the energy of thermal shock is generated when water adheres to the vent pipe, but at least a part of the energy density can be reduced by the stress relaxation section. In addition, when the stress relaxation section is provided in a layered manner on the outer surface of the pipe body, the stress relaxation section also plays a role of protecting the breather pipe. In the case where the stress relaxation portion is provided in a layered form inside the pipe body, the stress relaxation portion is particularly less likely to peel off from the pipe body.

In the particle count detector of the present invention, the young's modulus of the stress relaxation portion may be 0.7 times or less the young's modulus of the ceramic material constituting the skeleton-forming portion. Accordingly, thermal stress generated when water adheres to the breather pipe can be sufficiently reduced.

In the particle count detector according to the present invention, the skeleton-forming portion is preferably made of at least 1 kind of ceramic material selected from the group consisting of alumina, silicon nitride, mullite, cordierite, and magnesia. Preferably, the stress relaxing section is made of crystallized glass. Since the particle count detector of the present invention is usually mounted on an exhaust pipe made of a metal material, thermal stress can be reduced if the skeleton-forming portion is made of a material close to the CTE (10 ppm/c or higher) of the metal material. In this regard, magnesium oxide is suitable as a material of the skeleton-forming portion. In the particle count detector of the present invention, the charge generating element and the charged particle trap section (or the excess charge trap section) are provided with electrodes having conductivity. The material of the electrode may be, for example, a conductive material containing Pt. The CTE of Pt is 10.5 ppm/DEG C, which is also low in the metallic material. Therefore, in the case where a conductive material containing Pt is used as a material of the electrode, alumina can be used as a material of the skeleton-forming portion.

The particle number detector of the present invention may be: the charged particle collecting section is disposed between a pair of collecting electric field generating electrodes, and collects charged particles when a collecting voltage is applied between the pair of collecting electric field generating electrodes. In addition, the number of fine particles detector of the present invention may further include an excess charge removing portion that removes excess charge between the charge generating element and the charged fine particle trapping portion. The remaining charge removing portion may be: and a pair of removing electric field generating electrodes arranged between the pair of removing electric field generating electrodes, wherein if a removing voltage lower than a trapping voltage is applied between the pair of removing electric field generating electrodes, excess charges not added to the microparticles are trapped.

The particle count detector of the present invention is used for, for example, atmospheric environment surveys, indoor environment surveys, pollution surveys, combustion particle metering for automobiles and the like, particle generation environment monitoring, particle synthesis environment monitoring, and the like.

Drawings

Fig. 1 is a cross-sectional view showing a schematic configuration of a particle count detector 10.

Fig. 2 is a sectional view a-a of fig. 1.

FIG. 3 is a graph showing the relationship between the Young's modulus ratio and the safety factor ratio.

Fig. 4 is a cross-sectional view of the breather pipe 112.

Fig. 5 is a cross-sectional view of the vent tube 212.

Fig. 6 is a cross-sectional view of a modification of the breather pipe 12.

Fig. 7 is a perspective view of the charge generation element 120.

Fig. 8 is a sectional view showing a schematic configuration of the particle number detector 310.

Detailed Description

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. Fig. 1 is a sectional view showing a schematic configuration of a particle number detector 10, and fig. 2 is a sectional view a-a of fig. 1.

The particle number detector 10 measures the number of particles contained in a gas (for example, an exhaust gas of an automobile). The particle count detector 10 includes, in a ceramic vent pipe 12: a charge generating element 20, a trapping device 40, a residual charge removing device 50, a number measuring device 60, and a heater device 70.

The breather pipe 12 has: a gas inlet 12a for introducing gas into the breather pipe 12, a gas outlet 12b for discharging gas passing through the breather pipe 12, and a hollow portion 12c which is a space between the gas inlet 12a and the gas outlet 12 b. As shown in fig. 2, the vent pipe 12 is a square tube, i.e., a tube having a quadrangular cross section. The breather pipe 12 includes: a dense skeleton-forming portion 13 made of a ceramic material, and a dense stress relaxation portion 14 made of a material having a young's modulus lower than that of the ceramic material constituting the skeleton-forming portion 13 and in contact with the skeleton-forming portion 13. The skeleton-forming portion 13 includes: the ventilation pipe 12 is divided into 4 parts for each surface. Specifically, the skeleton-forming portion 13 includes: upper surface member 13a, lower surface member 13b, and 2 wall surface members 13c, 13 d. The ceramic material constituting the 4 members 13a to 13d is not particularly limited, and examples thereof include: alumina (Young's modulus: 280GPa, CTE: 8.0 ppm/DEG C), silicon nitride (Young's modulus: 270GPa, CTE: 3.5 ppm/DEG C), mullite (Young's modulus: 210GPa, CTE: 5.8 ppm/DEG C), cordierite (Young's modulus: 145GPa, CTE: 0.1 ppm/DEG C or less), magnesia (Young's modulus: 245GPa, CTE: 12.9 ppm/DEG C), etc. The CTE is a coefficient of thermal expansion (40 to 850 ℃ C.) (the same applies hereinafter). The 4 members 13a to 13d are dense, and have an open porosity of 5% or less, preferably 3% or less, and more preferably 1% or less. The stress relaxation portion 14 is a bonding layer 14a to 14d for bonding 4 members 13a to 13 d. Specifically, the stress relaxing section 14 includes: a bonding layer 14a for bonding the upper surface member 13a and the wall surface member 13c, a bonding layer 14b for bonding the upper surface member 13a and the wall surface member 13d, a bonding layer 14c for bonding the lower surface member 13b and the wall surface member 13c, and a bonding layer 14d for bonding the lower surface member 13b and the wall surface member 13 d. As the material constituting the 4 bonding layers 14a to 14d, a metal or a normal glass having no crystal phase precipitated can be used, but a crystallized glass is preferable in that it has shape-following properties at the time of softening, is advantageous for sealing, and does not soften after crystallization. The crystallized glass is not particularly limited, and examples thereof include: neoceram (Young's modulus: 100GPa, CTE: 0.1 ppm/DEG C), and crystallized glass for SOFC (Young's modulus: 50-150 GPa, CTE: 9.5-13.0 ppm/DEG C). The crystallized glass is also referred to as glass ceramic. The 4 bonding layers 14a to 14d are dense and have an open porosity of 5% or less, preferably 3% or less, and more preferably 1% or less. The difference in thermal expansion coefficient between the skeleton-forming portion 13 and the stress relaxation portion 14 is preferably ± 1 ppm/deg.C or less, and more preferably ± 0.5 ppm/deg.C or less.

A method of manufacturing the vent pipe 12 is described below. First, the members 13a to 13d are produced. That is, the raw material powder is molded into a molded body having a predetermined shape, and the molded body is fired to obtain the members 13a to 13d made of dense ceramic material. Various electrodes and the like are embedded during molding. Next, a glass powder paste (a mixture of a glass powder, a binder, and a solvent) is applied to the bonding portion to integrate the members 13a to 13d, and the integrated members are heated to pass through a glass softening point (e.g., 500 ℃) and a thermal decomposition temperature of carbon (e.g., 600 ℃) and then maintained at a high temperature (e.g., 800 ℃) to grow a crystal phase, thereby forming bonding layers 14a to 14d made of crystallized glass. Instead of the glass powder paste, a green sheet or a glass sheet of glass powder (obtained by filling a mold with glass powder, pressing the glass powder, and if necessary, heating the glass powder to cure the glass powder) may be used. Since the green sheet and the glass sheet of the glass powder are solid, handling is easier than that of a paste, which is preferable. Further, since carbon is not present in the glass sheet, pinholes and the like are less likely to occur after heating, which is preferable.

The thermal stress was calculated using an 1/4 model of the vent pipe 12 (the portion surrounded by the one-dot chain line in fig. 2). Specifically, the safety factor was obtained when water adhered to a region including the boundary between the skeleton-forming portion 13 (here, alumina) and the stress relaxation portion 14 so that the region reached 100 ℃ at an ambient temperature of 600 ℃ for young's modulus ratios of 0.9, 0.7, and 0.3, respectively. The results are shown in FIG. 3. The young's modulus ratio is young's modulus of the stress relaxation portion/young's modulus of alumina, the safety factor is allowable stress/maximum stress of alumina, and the allowable stress of alumina is 2160 MPa. The maximum stresses at Young's modulus ratios of 0.9, 0.7 and 0.3 were 700MPa, 500MPa and 300MPa, respectively. As can be seen from fig. 3: when the Young's modulus ratio is 0.7 or less, the safety factor is preferably 5 or more.

The charge generation element 20 is provided on the side of the breather pipe 12 close to the gas introduction port 12 a. The charge generation element 20 includes: a needle electrode 22, and a counter electrode 24 provided to face the needle electrode 22. The needle electrode 22 and the counter electrode 24 are connected to a discharge power source 26 to which a voltage Vp (for example, a pulse voltage) is applied. The counter electrode 24 is a ground electrode. When a voltage Vp is applied between the needle electrode 22 and the counter electrode 24, a gas discharge occurs due to a potential difference between the electrodes. The gas passes through the gas discharge, and the particles 16 in the gas are charged 18 to become charged particles P.

The trap device 40 is a device that traps the charged fine particles P, and is provided in a hollow portion 12c (on the downstream side of the flow of the exhaust gas with respect to the charge generation element 20) in the breather pipe 12. The trap device 40 includes: an electric field generating section 42 and a collecting electrode 48. The electric field generating section 42 includes: a negative electrode 44 embedded in a wall of the hollow portion 12c, and a positive electrode 46 embedded in a wall facing the negative electrode 44. The collecting electrode 48 is exposed to the wall of the hollow portion 12c in which the positive electrode 46 is embedded. A negative potential-V1 is applied to the negative electrode 44 of the electric field generating unit 42, and a ground potential Vss is applied to the positive electrode 46. The level of negative potential-V1 ranges from-mV to-tens of V. Thereby, an electric field is generated from the positive electrode 46 toward the negative electrode 44 in the hollow portion 12 c. Therefore, the charged fine particles P that have entered the hollow portion 12c are attracted to the positive electrode 46 by the generated electric field, and are collected by the collecting electrode 48 provided midway.

The residual charge removing device 50 is a device for removing the charges 18 that are not added to the particulates 16, and is provided in the hollow portion 12c at a position upstream of the trapping device 40 in the flow of the exhaust gas (between the charge generating element 20 and the trapping device 40). The residual charge removing device 50 includes an electric field generating section 52 and a removing electrode 58. The electric field generating unit 52 includes: a negative electrode 54 embedded in a wall of the hollow portion 12c, and a positive electrode 56 embedded in a wall facing the negative electrode 54. The removal electrode 58 is exposed to the wall of the hollow portion 12c in which the positive electrode 56 is embedded. A negative potential-V2 is applied to the negative electrode 54 of the electric field generating unit 52, and a ground potential Vss is applied to the positive electrode 56. The level of negative potential-V2 ranges from-mV to-tens of V. The absolute value of the negative potential-V2 is smaller than the absolute value of the negative potential-V1 applied to the negative electrode 44 of the trapping device 40 by 1 order of magnitude or more. This generates a weak electric field from the positive electrode 56 toward the negative electrode 54. Therefore, the electric charges 18 not added to the fine particles 16 among the electric charges 18 generated by the gas discharge in the electric charge generating element 20 are attracted to the positive electrode 56 by the weak electric field, and are thrown to GND via the removing electrode 58 provided in the middle thereof.

The number measuring device 60 is a device for measuring the number of the microparticles 16 based on the amount of the charges 18 of the charged microparticles P trapped by the trapping electrode 48, and includes a current measuring section 62 and a number calculating section 64. Between the current measuring unit 62 and the collecting electrode 48, there are connected in series from the collecting electrode 48 side: capacitor 66, resistor 67, and switch 68. The switch 68 is preferably a semiconductor switch. When the switch 68 is turned on to electrically connect the collecting electrode 48 and the current measuring section 62, the current based on the electric charge 18 added to the charged fine particles P attached to the collecting electrode 48 is transmitted to the current measuring section 62 as a transient response via the series circuit composed of the capacitor 66 and the resistor 67. The current measuring unit 62 may use a normal ammeter. The number calculating unit 64 calculates the number of microparticles 16 based on the current value from the current measuring unit 62.

The heater device 70 has: heater electrodes 72, and a heater power supply 74. The heater electrode 72 is embedded in the wall on which the collecting electrode 48 is provided. The heater power supply 74 applies a voltage between terminals provided at both ends of the heater electrode 72 and causes a current to flow through the heater electrode 72, thereby generating heat in the heater electrode 72. The heater device 70 is also used to measure the number of fine particles in a state where the influence of a high molecular hydrocarbon called SOF (soluble organic Fraction) is eliminated.

Next, an example of use of the particle number detector 10 will be described. When measuring fine particles contained in exhaust gas of an automobile, the number-of-fine particles detector 10 is installed in an exhaust pipe of an engine. At this time, the particulate number detector 10 is installed so that the exhaust gas is introduced into the breather pipe 12 from the gas inlet 12a of the particulate number detector 10 and is discharged from the gas outlet 12 b.

When the particles 16 included in the exhaust gas introduced into the breather pipe 12 from the gas inlet 12a pass through the charge generating element 20, the particles are charged 18 (electrons) to become charged particles P, and then enter the hollow portion 12 c. The charged fine particles P directly pass through the residual charge removing device 50 and reach the trapping device 40, wherein the residual charge removing device 50 has a weak electric field, and the length of the removing electrode 58 is short relative to the length of the hollow portion 12c and is 1/20-1/10. In addition, the electric charges 18 that are not attached to the microparticles 16 also enter the hollow portion 12 c. Even if the electric field is weak, the electric charges 18 are attracted to the positive electrode 56 of the residual charge removing device 50 and are thrown to GND via the removing electrode 58 provided in the middle thereof. Thus, the undesired electric charges 18 that are not attached to the microparticles 16 hardly reach the trapping device 40.

When the charged fine particles P reach the trapping device 40, they are attracted to the positive electrode 46 and trapped by the trapping electrode 48 provided in the middle thereof. The current based on the charges 18 of the charged fine particles P attached to the collecting electrode 48 is transmitted to the current measuring section 62 of the number measuring device 60 as a transient response via a series circuit including a capacitor 66 and a resistor 67.

The relationship between the current I and the charge amount q is I ═ dq/(dt), q ═ Idt. Therefore, the number calculating unit 64 integrates (integrates) the current value from the current measuring unit 62 during the period in which the switch 68 is turned on (switch-on period) to obtain the integrated value (accumulated charge amount) of the current value. After the switch on period has elapsed, the total number of charges (the number of trapped charges) is determined by dividing the accumulated charge amount by the basic charge, and the number of microparticles 16 adhering to the trapping electrode 48 within a certain time (for example, 5 to 15 seconds) can be determined by dividing the number of trapped charges by the average value of the number of charges adhering to 1 microparticle 16. The number calculating unit 64 repeats, for a predetermined period (for example, 1 to 5 minutes): the following can be calculated by calculating the number of fine particles 16 in a fixed time and integrating the number of fine particles: the number of fine particles 16 adhering to the collecting electrode 48 in a predetermined period. Further, by using the transient response by the capacitor 66 and the resistor 67, measurement can be performed even with a small current, and the number of fine particles 16 can be detected with high accuracy. If the current is a minute current at pA (pico ampere) level or nA (nano ampere), the minute current can be measured by increasing the time constant using the resistor 67 having a large resistance value, for example.

In the case of measuring the number of the fine particles 16, the measurement accuracy is lowered if the exhaust gas containing the fine particles 16 passes through the wall surface of the flue pipe 12 and passes through the inside and outside of the flue pipe 12, but in the present embodiment, the whole flue pipe 12 is dense and the exhaust gas containing the fine particles 16 does not pass through the wall surface of the flue pipe 12, so the measurement accuracy can be maintained at a high level. In the case of measuring the number of particulates in the high-temperature exhaust gas, if water adheres to the breather pipe 12, energy due to thermal shock is generated in the portion where the water adheres, but the stress relaxation section 14 (the junction layers 14a to 14d) in the breather pipe 12 reduces at least a part of the energy density, and therefore, the occurrence of cracks in the breather pipe 12 can be suppressed. This prevents the charge generating element 20 from being displaced by the crack (particularly, the tip of the needle electrode 22 from being displaced), and the measurement accuracy can be maintained at a high level. Since the spatial distribution of the ion density also changes if the tip of the needle electrode 22 is displaced, the average value of the number of electric charges added to 1 particle 16 (a parameter for calculating the number of particles 16) may deviate from the design value, and the measurement accuracy may be degraded.

After the number of fine particles is measured, the fine particles and the like may be deposited on the collecting electrode 48. In this case, the heater power supply 74 is controlled so that a predetermined regenerative voltage is applied between the pair of terminals of the heater electrode 72. The heater electrode 72 to which a predetermined regeneration voltage is applied reaches a temperature at which the charged fine particles P trapped by the trapping electrode 48 can be burned off. This enables the collection electrode 48 to be regenerated.

Here, the correspondence relationship between the components of the particle number detector 10 of the present embodiment and the components of the particle number detector of the present invention is clarified. The breather pipe 12 of the present embodiment corresponds to the breather pipe of the present invention, the charge generating element 20 corresponds to the charge generating element, the trapping device 40 corresponds to the charged fine particle trapping unit, and the number measuring device 60 corresponds to the number detecting unit.

In the particulate count detector 10 described in detail above, the entire flue pipe 12 is dense, and the exhaust gas containing particulates does not pass through the wall surface of the flue pipe 12. In addition, even if water adheres to the vent pipe 12, the stress relaxing section 14 in the vent pipe 12 suppresses the occurrence of cracks, and therefore, the electric charge generating element 20 can be prevented from being displaced due to cracks. Therefore, the measurement accuracy can be maintained at a high level by the particle number detector 10.

Further, since the vent pipe 12 is manufactured by bonding the plurality of members 13a to 13d with the bonding layers 14a to 14d, the vent pipe 12 can be easily manufactured.

Further, since the plurality of members 13a to 13d are planar members and the junction layers 14a to 14d are allowed to expand and contract in the planar direction, the occurrence of cracks in the breather pipe 12 can be further suppressed.

The present invention is not limited to the above embodiments, and may be implemented in various forms as long as the technical scope of the present invention is achieved.

In the above embodiment, the ventilation pipe 12 including the skeleton-forming portion 13 and the stress relaxation portion 14 is used, but instead, the ventilation pipes 112 and 212 shown in fig. 4 or 5 may be used. Fig. 4 is a cross-sectional view of the vent pipe 112, and fig. 5 is a cross-sectional view of the vent pipe 212. They are drawings corresponding to the sectional view a-a of fig. 1. Reference numerals 42, 44, 46, 48, and 72 denote the same components as those of the above embodiment, and therefore, their description will be omitted.

The breather pipe 112 shown in fig. 4 includes: a frame forming portion 113 which is a pipe body having the same shape as the air pipe 112, and a layer-shaped stress relaxing portion 114 which covers the outer surface of the frame forming portion 113. The skeleton-forming portion 113 is made of a ceramic material. Specific examples of the ceramic material are described in the above embodiments. The stress relaxing portion 114 is made of a material (e.g., crystallized glass) having a young's modulus lower than that of the ceramic material constituting the skeleton-forming portion 113. When the number of particles in the high-temperature gas is measured, the energy of thermal shock is generated when water adheres to the vent pipe 112, but at least a part of the energy density can be reduced by the stress relaxing section 114. Therefore, the occurrence of cracks in the breather pipe 112 can be suppressed. The stress relaxing unit 114 also functions to protect the breather pipe 112. Instead of the stress relaxation portion 114, a layer-shaped stress relaxation portion may be provided that covers the inner surface of the skeleton-forming portion 113 (except for the electrodes 22, 24, 48, and 58), or a layer-shaped stress relaxation portion may be provided that covers the inner surface of the skeleton-forming portion 113 (except for the electrodes 22, 24, 48, and 58) in addition to the stress relaxation portion 114. As a result of examining the relationship between the young's modulus ratio and the safety factor in the same manner as in the above-described embodiment, the safety factor is 5 or more when the young's modulus ratio is 0.7 or less.

The breather pipe 212 shown in fig. 5 includes: a frame forming portion 213, which is a pipe body having the same shape as the air pipe 212, and a layer-shaped (thin cylindrical) stress relaxing portion 214 embedded in the frame forming portion 213. The skeleton-forming portion 213 is made of a ceramic material. Specific examples of the ceramic material are described in the above embodiments. The stress relaxing section 214 is made of a material (e.g., crystallized glass) having a young's modulus lower than that of the ceramic material constituting the skeleton-forming section 213. When the number of particles in the high-temperature gas is measured, the energy of thermal shock is generated when water adheres to the vent pipe 212, but at least a part of the energy density can be reduced by the stress relaxation section 214. Therefore, the occurrence of cracks in the breather pipe 212 can be suppressed. Further, the stress relaxing portion 214 is less likely to be separated from the skeleton-forming portion 213. In addition to the stress relaxation portion 214, the stress relaxation portion 114 shown in fig. 4 may be provided, or a layer-shaped stress relaxation portion covering the inner surface of the skeleton-forming portion 213 (except for the electrodes 22, 24, 48, and 58) may be provided.

In the above embodiment, the joint layers 14a to 14d of the vent pipe 12 are used as the stress relaxation section 14, but in addition, a layer-shaped stress relaxation section may be provided at least 1 position in the outer surface, the inner surface, and the inner portion of the vent pipe 12.

In the above embodiment, the ventilation pipe 12 is divided into 4 pieces, but as shown in fig. 6, the split members 13e and 13f (skeleton-forming portion 13) obtained by dividing the ventilation pipe 12 into 2 pieces in the upper and lower direction may be joined by the joining layers 14e and 14f (stress relaxation portion 14). In fig. 6, reference numerals 42, 44, 46, 48, and 72 denote the same components as those of the above embodiment, and therefore, their description is omitted.

In the above embodiment, the ventilation pipe 12 is a square tube, but is not particularly limited to a square tube, and may be a cylinder or a tube having a polygonal cross section. The outline shape of the cross section of the vent pipe 12 may be circular, and the hollow portion 12c of the cross section of the vent pipe 12 may be quadrangular. This is the same in fig. 4 to 6.

In the above-described embodiment, the charge generation element 20 including the needle electrode 22 and the counter electrode 24 is used, but instead, the charge generation element 120 shown in fig. 7 may be used. The charge generation element 120 is provided with a discharge electrode 122 and an induction electrode 124 on the front surface and the back surface of a dielectric layer 126, respectively. The discharge electrode 122 has a plurality of triangular fine protrusions 122a on a long side facing the rectangular thin metal plate. The inductive electrodes 124 are rectangular electrodes, and 2 inductive electrodes are provided parallel to the longitudinal direction of the discharge electrodes 122. When a high-frequency high voltage is applied between both electrodes of the charge generating element 120, discharge occurs to generate ions (electric charges).

In the above-described embodiment, the number of fine particles is measured, but instead, it is possible to determine whether or not the number of fine particles falls within a predetermined numerical range (for example, whether or not it exceeds a predetermined threshold).

In the above-described embodiment, the current is exemplified as the parameter that changes in accordance with the number (charge amount) of the charged fine particles, but the current is not particularly limited thereto, and any parameter may be used as long as it changes in accordance with the number (charge amount) of the charged fine particles.

Although the residual charge removing device 50 is provided in the above embodiment, the residual charge removing device 50 may be omitted.

In the above-described embodiment, the number of charged microparticles P is determined based on the current flowing through the collecting electrode 48 of the collecting device 40, but like the microparticle number detector 310 shown in fig. 8, the collecting device 40 (the electric field generating unit 42 and the collecting electrode 48) may be omitted, the number measuring device 360 may determine the number of residual charges based on the current flowing through the removing electrode 58 of the residual charge removing device 50, and the number of residual charges may be subtracted from the total number of charges generated by the charge generating element 20 to determine the number of charged microparticles P. In this case, as shown in fig. 2, the breather pipe 12 includes: dense skeleton-forming portions 13(13a to 13d) made of a ceramic material, and dense stress relaxation portions 14(14a to 14d) made of a material having a lower young's modulus than that of the ceramic material and in contact with the skeleton-forming portions 13. Accordingly, in the particle count detector 310, the entire flue pipe 12 is dense, and the exhaust gas containing particles does not pass through the wall surface of the flue pipe 12. In addition, even if water adheres to the vent pipe 12, the stress relaxing section 14 in the vent pipe 12 suppresses the occurrence of cracks, and therefore, the electric charge generating element 20 can be prevented from being displaced due to cracks. Therefore, the measurement accuracy can be maintained at a high level. Instead of the vent pipe 12 shown in fig. 2, the vent pipe 112 shown in fig. 4, the vent pipe 212 shown in fig. 5, and the vent pipe 12 shown in fig. 6 may be used.

The present application takes japanese patent application No. 2017-96234, filed 5, 15, 2017 as the basis for claiming priority, the entire contents of which are incorporated by reference in the present specification.

Industrial applicability

The present invention can be used for: the amount of particles in the gas is detected.

Description of the symbols

A 10 fine particle number detector, a 12a gas inlet, a 12b gas outlet, a 12c hollow portion, a 13 skeleton-forming portion, a 13a upper surface member, a 13b lower surface member, 13c, 13d wall surface members, 13e, 13f split members, a 14 stress relaxation portion, bonding layers 14a to 14f, 16 fine particles, 18 charges, 20 charge-generating elements, 22 needle electrodes, 24 opposed electrodes, 26 discharge power sources, 40 trap devices, 42 electric field-generating portions, 44 negative electrodes, 46 positive electrodes, 48 trap electrodes, 50 remaining charge-removing devices, 52 electric field-generating portions, 54 negative electrodes, 56 positive electrodes, 58-removing electrodes, 60 number measuring devices, 62 current-measuring portions, 64 number calculating portions, 66 capacitors, 67 resistors, 68 switches, 70 heater devices, 72 heater electrodes, 74 heater power sources, 112, 113 skeleton-forming portions, 114 stress relaxation portions, 120 charge generating elements, 122 discharge electrodes, 122a fine protrusions, 124 induction electrodes, 126 dielectric layers, 212 vent pipes, 213 skeleton forming parts, 214 stress relieving parts, 310 particle count detectors, and 360 measuring devices.