JP2007093570A - Capacitance particulate measuring device - Google Patents
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Abstract
Description
本発明は粉体を静電容量の変化として測定する静電容量型粉体計測装置に関し、特に粉体の測定を高感度、高精度化して、同時に製造方法を簡単化する構造に関するものである。 The present invention relates to a capacitance-type powder measuring apparatus that measures powder as a change in capacitance, and more particularly to a structure that simplifies the manufacturing method by increasing the sensitivity and accuracy of powder measurement. .
粉体を静電容量の変化として測定する静電容量型粉体計測装置は円筒形状の静電容量センサーに粉体を通過させるだけで測定できる。この為、搬送パイプの経路に簡単取り付ける事ができるので用途の拡大が期待されている。
従来の静電容量センサーは円筒パイプの中心軸に対称に形成された並行半円筒形状電極及び螺旋形状電極の構造のものが多く用いられている。これらの電極は粉体の流れを挟むように静電容量が形成されていて、平行平面板コンデンサーに近似して、その中を通過する粉体による静電容量の変化で動作が説明される。
しかし、これらの形状の電極内は粉体が通過する静電容量を形成する円筒全体で電界強度が一様ではない。従って、静電容量センサーの電極内のどの場所を粉体が通過するかによって静電容量の変化が異なり、測定値が場所によって変動を受ける。
粉体が移動する時、円筒パイプ内をランダムにその場所を変化しながら通過するので、静電容量の変化は平均化されて、静電容量センサーの場所による変動は低減される。しかし、確率的に必ず平均化されるのではないので測定誤差を生じる事がある。
このような粉体のランダム移動による確率的な測定誤差の低減でなく、電極内の場所に依存する大きな測定誤差を低減する要求が高まってきている。Capacitance-type powder measuring devices that measure powder as a change in capacitance can be measured simply by passing the powder through a cylindrical capacitance sensor. For this reason, since it can be easily attached to the path of the transport pipe, the use is expected to be expanded.
Many conventional electrostatic capacitance sensors have a structure of parallel semi-cylindrical electrodes and spiral electrodes formed symmetrically with the central axis of a cylindrical pipe. These electrodes are formed with a capacitance so as to sandwich the flow of the powder, and the operation is explained by a change in the capacitance due to the powder passing through it, similar to a parallel flat plate capacitor.
However, the electric field strength is not uniform throughout the cylinder that forms the capacitance through which the powder passes in the electrodes of these shapes. Accordingly, the change in capacitance differs depending on the location in the electrode of the capacitance sensor through which the powder passes, and the measured value varies depending on the location.
As the powder moves, it passes through the cylindrical pipe while changing its location at random, so that the change in capacitance is averaged and variation due to the location of the capacitance sensor is reduced. However, since it is not always averaged stochastically, measurement errors may occur.
There is an increasing demand for reducing a large measurement error depending on the location in the electrode, instead of reducing the probabilistic measurement error due to such random movement of the powder.
従来の静電容量センサーの構造を、図８に並行半円筒形状電極、図１０に螺旋形状電極の例を示す。これらの電極は粉体の流れを挟むように静電容量が形成されている。
並行半円筒形状電極内を粉体が通過する様子を図９に示す。（イ）電極が円周上に狭く形成された場合、（ロ）電極が円周上に広く形成された場合、（ハ）電極の外側を覆うガード・シールドの影響を考慮した場合を示す。
（イ）の例では、電極の端の効果が無視できなくなり、円筒の中心部を粉体が通過する時と電極から外れた円周部を粉体が通過する時では斜線部に示す部分が局部的に静電容量の変化が非常に小さくなり、中心部と円周部とでは静電容量の変化は大きく異なる。但し、ガード・シールドを考慮しない。
（ロ）の例では、局部的に静電容量の変化が非常に小さくなる領域は少なくなるが、円筒の中心部と円周部に近い場所では電極間距離が大きく異なり、静電容量の変化は異なる。
但し、ガード・シールドを考慮しない。
（ハ）の例では、外側に同じ円筒状の遮蔽板で覆われる為に静電容量電極の端の部分からの電気力線が対向電極間ではなく遮蔽板へと結ばれる事になり、対向電極間で静電容量を形成しない領域が部分的にできる。この場合も静電容量の変化は大きく異なる。
螺旋形電極構造は前記並行半円筒形状の電極を円周上に回転させて形成し、静電容量が部分的に大きくなる、または小さくなる問題を改良している。
しかし、粉体が円筒パイプの中心部を通過する場合、粉体は対向電極の間にあり、対向電極の間からは外れない。一方、円周部に近いところを通過する場合は対向電極の間から外れるところがあり、粉体の通過する場所により静電容量の変化は異なる事になる。図１１にその様子を示す。但し、ガード・シールドを考慮しない。
従来の螺旋形状電極は螺旋を円周上に多く回転させて形成する方が誤差は低減するが、粉体の搬送路に沿ってより長くなってしまう。静電容量センサーの電極を長くすると計測装置が大きくなり、また、その応答速度も低下する。
この為、粉体計測用静電容量センサーとして高精度、高感度、高速応答速度で小型化による性能向上という課題があった。FIG. 8 shows an example of a conventional electrostatic capacitance sensor, and FIG. 10 shows an example of a spiral electrode. These electrodes have a capacitance so as to sandwich the flow of the powder.
FIG. 9 shows how the powder passes through the parallel semi-cylindrical electrodes. (A) The case where the electrode is narrowly formed on the circumference, (b) the case where the electrode is formed widely on the circumference, and (c) the case where the influence of the guard shield covering the outside of the electrode is considered.
In the example of (a), the effect of the end of the electrode cannot be ignored, and when the powder passes through the central part of the cylinder and when the powder passes through the circumferential part off the electrode, the part indicated by the hatched part is The change in capacitance is extremely small locally, and the change in capacitance is greatly different between the central portion and the circumferential portion. However, guard shield is not considered.
In the example of (b), the area where the change in capacitance is very small locally decreases, but the distance between the electrodes is greatly different at locations close to the center and the circumference of the cylinder, and the change in capacitance Is different.
However, guard shield is not considered.
In the case of (c), since the outer side is covered with the same cylindrical shielding plate, the electric lines of force from the end portion of the capacitance electrode are connected to the shielding plate instead of between the opposing electrodes. A region where no capacitance is formed between the electrodes is partially formed. Also in this case, the change in capacitance is greatly different.
The spiral electrode structure is formed by rotating the parallel semi-cylindrical electrodes on the circumference, thereby improving the problem that the capacitance is partially increased or decreased.
However, when the powder passes through the center of the cylindrical pipe, the powder is between the counter electrodes and does not come off between the counter electrodes. On the other hand, when passing through a place close to the circumference, there is a place where it is out of between the counter electrodes, and the change in capacitance varies depending on the place where the powder passes. This is shown in FIG. However, guard shield is not considered.
The conventional spiral electrode is formed by rotating the spiral many times on the circumference, but the error is reduced, but it becomes longer along the powder conveyance path. If the electrode of the capacitance sensor is lengthened, the measuring device becomes large, and the response speed thereof also decreases.
For this reason, there has been a problem of improving performance by miniaturization with high accuracy, high sensitivity, and high response speed as a capacitance sensor for powder measurement.
静電容量センサーを構成する静電容量電極を粉体が通過する流路を輪切りするようにして円筒電極を形成し、円筒電極の間で粉体が流れる方向に静電容量を形成させる。
円筒電極間で形成させた静電容量は従来の対向電極のような電極板の端の影響を生じない。電気力線の長さは静電容量に逆比例するので、円筒電極間の部分的な静電容量は電気力線が長い円筒軸の中心部が小さく、電気力線が短い円周部が大きい。従って、円筒電極の径を短くして電極間距離を長くすると静電容量の差が少なくなる。
円周部の電気力線はガード・シールドと結ぶ事になる。ガード・シールドの径が円筒電極の径に近くなると円周部とガード・シールドを結ぶ電気力線の数は多くなり、部分的な静電容量は逆に円周部より中心部の方が大きくなる。
円筒電極の径、電極間距離及び円筒電極の外側を覆うガード・シールドの径を適当な寸法にする事で電極間距離を長くするだけでなく、粉体が通過する場所による変化を従来の電極構造より少なくできる。
また、円筒電極間の距離を短くすると、その静電容量も大きくなり、粉体による静電容量の変化も増大する。
この為、従来の静電容量センサーとは逆に小型化、短小化する事により高感度化が実現できる。また、この発明による静電容量センサーの外形寸法を短くする事により粉体の流れの変化分をより高速に検出できるようになる。Cylindrical electrodes are formed so as to cut the flow path through which the powder passes through the capacitive electrodes constituting the capacitive sensor, and electrostatic capacitance is formed in the direction in which the powder flows between the cylindrical electrodes.
The capacitance formed between the cylindrical electrodes does not cause the influence of the end of the electrode plate as in the conventional counter electrode. Since the length of the electric force line is inversely proportional to the electrostatic capacity, the partial electrostatic capacity between the cylindrical electrodes is small at the center of the cylindrical shaft having a long electric force line and large at the circumference having a short electric force line. . Therefore, when the diameter of the cylindrical electrode is shortened and the distance between the electrodes is lengthened, the difference in capacitance is reduced.
The electric field lines around the circumference will be connected to the guard shield. When the diameter of the guard shield is close to the diameter of the cylindrical electrode, the number of electric lines of force connecting the circumference and the guard shield increases, and the partial capacitance is conversely larger at the center than at the circumference. Become.
By changing the diameter of the cylindrical electrode, the distance between the electrodes, and the diameter of the guard shield covering the outside of the cylindrical electrode to an appropriate dimension, the distance between the electrodes can be lengthened, and changes depending on the place where the powder passes can be changed. Can be less than structure.
Further, when the distance between the cylindrical electrodes is shortened, the capacitance increases, and the change in capacitance due to the powder also increases.
For this reason, high sensitivity can be realized by downsizing and shortening, contrary to the conventional capacitance sensor. Further, the change in the flow of the powder can be detected at higher speed by shortening the outer dimension of the capacitance sensor according to the present invention.
この発明によれば、静電容量センサーを通過する粉体の位置による誤差を低減する。さらに微小な粉体流でも静電容量センサーの変化分が大きくなり、より高速に測定できるようになる。また、小型化ができて、製造方法を簡単にする事ができる。 According to this invention, the error due to the position of the powder passing through the capacitance sensor is reduced. Furthermore, even with a fine powder flow, the amount of change in the capacitance sensor becomes large, and measurement can be performed at a higher speed. Further, the size can be reduced and the manufacturing method can be simplified.
図１に本発明の概略を示す。図１の静電容量センサーは静電容量電極の外側にガード電極とシールド電極を構成した実際に近い静電容量センサーの概略を示す。図２は静電容量センサーを構成する対向する円筒電極の部分を示す。
円筒電極間の中心軸に沿ってａ−ａ断面の２次元電位係数分布の概略を図３に示す。
円筒電極間の二等分した断面の電位は平面となる。この断面に平行に近い電位分布とこの断面に対して直角な円筒電極に向かう電位分布とに分ける事にする。このように近似した静電容量の等価回路を図６（イ）、（ロ）に示す。図２の円筒の直径と電極幅及び円筒電極間の距離等の関係にもよるが、Ｃ１及びＣ２は図３に示すように電位係数が小さくなっているので静電容量の値はＣ０に比べて大きな値である。
全体の静電容量は各々が直列接続なので
となる。静電容量電極は対称な構造なのでＣ１＝Ｃ２とすると
ここで、Ｃ０≪Ｃ１と仮定すると
と近似できる。
図２の静電容量を上式のように近似すると図７のような円形電極の平行平面板コンデンサーとして見る事ができる。この場合の円筒の半径をｒ、仮定した円形電極間の平均距離をｄ′とすると静電容量は
と表す事ができる。
ｄ′は実際の電極間距離に対して、図３に示す電位が円筒電極に入り込んだところに仮想電極が形成されたものとする事ができる。上記、円筒電極間距離ｄとその仮定平均距離ｄ′と
と表され、図７で表すような円形電極の平行平面板コンデンサーとして見る事ができる。
図４は電位係数分布に対応した電気力線の概略を表したものである。電気力線は円筒の円周部より中心部が長いので、円筒形状電極の部分的な静電容量は円筒の円周部より中心部の方が相対的に小さい。この為、粉体が中心部を通過する場合と円周部を通過する場合で静電容量の変化が異なり誤差を生じる。
円筒電極型静電容量センサーの外側はガード・シールドで覆われて、センサー内に外部から雑音が混入しないようにする必要がある。このガード・シールドの影響を考慮した場合の電気力線の様子を図５に示す。
図５の場合、円周部の一部の電気力線はガード・シールドと結ぶ。この電気力線は円筒電極の径と電極間の距離及びガード・シールドの円筒パイプの径との相対的な寸法により様子が異なる。
ガード・シールドの径が円筒電極の径に近いと円筒電極とガード・シールドと結ぶ電気力線が多くなり、部分的な静電容量は円筒の円周部より中心部の方が相対的に大きくなる。つまり、本発明の静電容量センサーにおいて、計測に関与する領域の円周部と中心部の電気力線の長さを整える事になる。
円筒の径、ガード・シールドの径、一対の円筒電極間隔等の寸法を適切に選ぶ事により、円筒の中心部と円周部の部分的な静電容量の変化の差を小さくする事ができる。
相対する円筒電極の間隔を短くすると電極間の静電容量は増加する。これは粉体が微小量でも静電容量の変化が大きくなり、感度が向上する。また、同時に静電容量センサーの寸法が短く構成できる事になる。
図１２に本発明による静電容量センサーの各電極の接続例を示す。この回路接続で、従来のように図１３に示す交流ブリッジ回路を構成して、その出力を交流増幅、検波して直流電圧として取り出す事ができる。FIG. 1 shows an outline of the present invention. The capacitance sensor of FIG. 1 shows an outline of a capacitance sensor close to actuality in which a guard electrode and a shield electrode are formed outside the capacitance electrode. FIG. 2 shows the portion of the opposing cylindrical electrodes that make up the capacitive sensor.
FIG. 3 shows an outline of the two-dimensional potential coefficient distribution of the aa cross section along the central axis between the cylindrical electrodes.
The potential of the bisected cross section between the cylindrical electrodes is a plane. It is divided into a potential distribution that is almost parallel to the cross section and a potential distribution that is directed to the cylindrical electrode perpendicular to the cross section. An equivalent circuit of the capacitance approximated in this way is shown in FIGS. Although it depends on the relationship between the diameter of the cylinder, the electrode width, the distance between the cylindrical electrodes, etc. in FIG. 2 , the potential coefficient of C 1 and C 2 is small because the potential coefficient is small as shown in FIG. It is a larger value than 0 .
The total capacitance is connected in series
It becomes. Since the capacitance electrode has a symmetrical structure, if C 1 = C 2
Here, assuming that C 0 << C 1
Can be approximated.
When the capacitance of FIG. 2 is approximated by the above equation, it can be seen as a parallel plane plate capacitor of circular electrodes as shown in FIG. In this case, if the radius of the cylinder is r and the average distance between the assumed circular electrodes is d ′, the capacitance is
Can be expressed.
It can be assumed that a virtual electrode is formed where d ′ is a potential where the potential shown in FIG. The cylindrical electrode distance d and its assumed average distance d ′
And can be viewed as a circular electrode parallel plane plate capacitor as shown in FIG.
FIG. 4 shows an outline of the lines of electric force corresponding to the potential coefficient distribution. Since the electric lines of force are longer in the center than the circumference of the cylinder, the partial capacitance of the cylindrical electrode is relatively smaller in the center than in the circumference of the cylinder. For this reason, when the powder passes through the central portion and when it passes through the circumferential portion, the change in capacitance differs and an error occurs.
It is necessary to cover the outside of the cylindrical electrode type capacitive sensor with a guard shield so that noise is not mixed into the sensor from the outside. FIG. 5 shows the lines of electric force when the influence of the guard shield is taken into consideration.
In the case of FIG. 5, some electric lines of force on the circumference are connected to the guard shield. The lines of electric force differ depending on the relative dimensions of the diameter of the cylindrical electrodes, the distance between the electrodes, and the diameter of the cylindrical pipe of the guard shield.
When the diameter of the guard shield is close to the diameter of the cylindrical electrode, the electric lines of force connecting the cylindrical electrode and the guard shield increase, and the partial capacitance is relatively larger at the center than at the circumference of the cylinder. Become. That is, in the capacitance sensor of the present invention, the lengths of the electric lines of force at the circumference and the center of the region involved in the measurement are adjusted.
By appropriately selecting dimensions such as the diameter of the cylinder, the diameter of the guard shield, the distance between the pair of cylinder electrodes, etc., it is possible to reduce the difference in partial capacitance change between the center and the circumference of the cylinder. .
When the interval between the opposed cylindrical electrodes is shortened, the capacitance between the electrodes increases. This increases the change in capacitance even when the amount of powder is very small, thereby improving the sensitivity. At the same time, the size of the capacitance sensor can be shortened.
FIG. 12 shows a connection example of each electrode of the capacitance sensor according to the present invention. With this circuit connection, the AC bridge circuit shown in FIG. 13 can be configured as in the prior art, and the output can be extracted as a DC voltage by AC amplification and detection.
以上、図を参照して実施例を説明したところから明らかのように、本発明によれば、粉体が静電容量センサー内を通過する位置が変わっても、静電容量の変化が大きく変わらなくする事ができる。さらに粉体量が微小になっても、静電容量の変化量を増加させ、応答速度の速い計測が可能になる。また、従来の螺旋構造電極に比べて非常に簡単な構造となり、小型で製造コストを大幅に低減する事ができる。 As described above, as apparent from the description of the embodiments with reference to the drawings, according to the present invention, even if the position where the powder passes through the capacitance sensor is changed, the change in the capacitance is greatly changed. Can be eliminated. Furthermore, even if the amount of powder becomes minute, the amount of change in capacitance is increased, and measurement with a fast response speed becomes possible. In addition, the structure is much simpler than that of the conventional spiral structure electrode, and the manufacturing cost can be greatly reduced with a small size.
１ 静電容量センサー
１ａ 円筒電極
１ｂ 円筒電極
２、３、４ ガード・シールド電極
２０ 測定電極
２１ 基準電極
２２、２３ 抵抗
２４ 交流発振器
３０、３２ 交流ブリッジ出力DESCRIPTION OF SYMBOLS 1 Capacitance sensor 1a Cylindrical electrode 1b Cylindrical electrode 2, 3, 4 Guard shield electrode 20 Measuring electrode 21 Reference electrode 22, 23 Resistance 24 AC oscillator 30, 32 AC bridge output
Claims (5)
一対の電極を持ち、
一対の電極は粉体の流れる方向に静電容量を形成することを特徴とする粉体計測用静電容量センサー。In a powder measurement capacitance sensor that measures the amount of powder in the measurement object,
Have a pair of electrodes,
A capacitance sensor for powder measurement, wherein the pair of electrodes forms a capacitance in a direction in which the powder flows.
一対の電極は円筒形状を有し、
さらに前記一対の電極を離して配置し、
前記一対の電極はそれぞれの円筒の中心軸を合わせたことを特徴とする粉体計測用静電容量センサー。The electrostatic capacity sensor for powder measurement according to claim 1,
The pair of electrodes has a cylindrical shape,
Further, the pair of electrodes are arranged apart from each other,
The capacitance sensor for powder measurement, wherein the pair of electrodes are aligned with a central axis of each cylinder.
前記円筒形状の一対の電極は筒形の多角形であることを特徴とする粉体計測用静電容量センサー。The capacitance sensor for powder measurement according to claim 2,
The capacitance measuring sensor for powder measurement, wherein the pair of cylindrical electrodes are cylindrical polygons.
一対の電極を最適な間隔に調整できることを特徴とする粉体計測用静電容量センサー。In the electrostatic capacitance sensor for powder measurement according to claim 1 to claim 3,
A capacitance sensor for powder measurement, characterized in that a pair of electrodes can be adjusted to an optimum interval.
前記一対の電極はガード電極とシールド電極を持ち、
前記電極の一部または全部を覆うガード電極で構成することが出来ることを特徴とする粉体計測用静電容量センサー。In the electrostatic capacitance sensor for powder measurement according to claim 1 to claim 4,
The pair of electrodes has a guard electrode and a shield electrode,
A capacitance measuring sensor for powder measurement, characterized in that it can be constituted by a guard electrode that covers part or all of the electrode.
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|---|---|---|---|
| JP2005313454A JP2007093570A (en) | 2005-09-29 | 2005-09-29 | Capacitance particulate measuring device |
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|---|---|---|---|
| JP2005313454A JP2007093570A (en) | 2005-09-29 | 2005-09-29 | Capacitance particulate measuring device |
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| JP (1) | JP2007093570A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20130091733A (en) * | 2010-07-06 | 2013-08-19 | 브리-에어 프로콘 에스에이지엘 | Capacitance electrode structure for measuring moisture |
| JP2015141074A (en) * | 2014-01-28 | 2015-08-03 | 九州エレクトロン株式会社 | Particulate detector |
| CN109839412A (en) * | 2019-01-21 | 2019-06-04 | 东南大学 | The synchronous measuring device and method for obtaining capacitor and electrostatic signal in Dual-Phrase Distribution of Gas olid |
| WO2020207211A1 (en) * | 2019-04-09 | 2020-10-15 | 厦门大学 | Coaxial capacitive sensor and online monitoring and diagnosis method for engine lubricating oil abrasive particles |
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2005
- 2005-09-29 JP JP2005313454A patent/JP2007093570A/en active Pending
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20130091733A (en) * | 2010-07-06 | 2013-08-19 | 브리-에어 프로콘 에스에이지엘 | Capacitance electrode structure for measuring moisture |
| JP2013533971A (en) * | 2010-07-06 | 2013-08-29 | ブリ−エア・プロコン・エスアーゲーエル | Capacitive electrode structure for measuring moisture |
| KR101659065B1 (en) * | 2010-07-06 | 2016-09-23 | 브리-에어 프로콘 에스에이지엘 | Capacitance electrode structure for measuring moisture |
| JP2015141074A (en) * | 2014-01-28 | 2015-08-03 | 九州エレクトロン株式会社 | Particulate detector |
| CN109839412A (en) * | 2019-01-21 | 2019-06-04 | 东南大学 | The synchronous measuring device and method for obtaining capacitor and electrostatic signal in Dual-Phrase Distribution of Gas olid |
| CN109839412B (en) * | 2019-01-21 | 2021-07-09 | 东南大学 | Measuring device and method for synchronously acquiring capacitance and electrostatic signals in gas-solid two-phase flow |
| WO2020207211A1 (en) * | 2019-04-09 | 2020-10-15 | 厦门大学 | Coaxial capacitive sensor and online monitoring and diagnosis method for engine lubricating oil abrasive particles |
| US11061010B2 (en) | 2019-04-09 | 2021-07-13 | Xiamen University | Coaxial capacitive sensor and a method for on-line monitoring and diagnosing engine lubricating oil abrasive particles |
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