JP2000009673A - Capacity-type sensor device - Google Patents
Capacity-type sensor deviceInfo
- Publication number
- JP2000009673A JP2000009673A JP10192508A JP19250898A JP2000009673A JP 2000009673 A JP2000009673 A JP 2000009673A JP 10192508 A JP10192508 A JP 10192508A JP 19250898 A JP19250898 A JP 19250898A JP 2000009673 A JP2000009673 A JP 2000009673A
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- Japan
- Prior art keywords
- capacitor
- fluid
- sensor device
- detected
- capacitance
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、混合液の成分混合
比等を計測する容量式センサ装置に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a capacitive sensor device for measuring the mixing ratio of components of a mixed solution.
【０００２】[0002]
【従来の技術】容量式センサ装置は、液体等の被検出流
体の比誘電率が、成分混合比等の物理量に応じて変化す
ることに着目した装置で、被検出流体中に電極を配設し
て電極を被検出流体の比誘電率に応じて静電容量が変化
するキャパシタとなし、キャパシタの静電容量に基づい
て上記物理量を測定する。静電容量は、例えば、このキ
ャパシタを有するＣＲ発振回路を構成し、キャパシタの
充放電によりキャパシタの静電容量に比例した周期の発
振出力を得ることで知られるようになっている。この場
合、発振信号の周期はＣＲ発振回路の時定数に比例し、
原理的には、静電容量に比例する比誘電率は上記時定数
に比例することになる。したがって、発振信号から一定
数の振動がカウントされるまでの時間を測定すれば、そ
の時間が比誘電率に比例することになり、計測時間から
比誘電率が簡単に演算できる。2. Description of the Related Art A capacitive sensor device focuses on the fact that the relative permittivity of a fluid to be detected, such as a liquid, changes in accordance with a physical quantity such as a component mixing ratio. An electrode is arranged in the fluid to be detected. The electrode is formed as a capacitor whose capacitance changes in accordance with the relative dielectric constant of the fluid to be detected, and the physical quantity is measured based on the capacitance of the capacitor. The capacitance is known, for example, by forming a CR oscillation circuit having this capacitor and obtaining an oscillation output having a period proportional to the capacitance of the capacitor by charging and discharging the capacitor. In this case, the cycle of the oscillation signal is proportional to the time constant of the CR oscillation circuit,
In principle, the relative permittivity proportional to the capacitance is proportional to the time constant. Therefore, if the time until a certain number of vibrations are counted from the oscillation signal is measured, the time is proportional to the relative permittivity, and the relative permittivity can be easily calculated from the measurement time.
【０００３】[0003]
【発明が解決しようとする課題】かかる容量式センサ装
置において、高精度化を阻害するものに、電極と接地等
間に生じる寄生容量の影響がある。例えば、キャパシタ
を被検出流体が流通するハウジング内に格納した構成の
容量式センサ装置では、ハウジングは堅牢さや外部から
のノイズの影響の防止の観点から金属で作られるため、
図７に示すように、電極９１とハウジング９３の間に寄
生容量９２が発生する。この寄生容量は、電極９１とハ
ウジング９３間の距離や被検出流体の比誘電率によって
大きさが変化するから、被検出流体の比誘電率と計測時
間の間の線形性がずれ、複雑な計算式や補正マップが必
要になり、装置が複雑化する。なお、このように電極を
格納するハウジングを有する装置では、ハウジングの形
状を大きくしてハウジングと電極との距離をとることに
より、寄生容量をある程度抑えることができるが、この
ような寄生容量防止策は、近年の装置の小型化の要請か
らは到底容認できるものではない。In such a capacitive sensor device, the one that hinders improvement in accuracy is the influence of a parasitic capacitance generated between an electrode and ground. For example, in a capacitive sensor device in which a capacitor is stored in a housing through which a fluid to be detected flows, the housing is made of metal from the viewpoint of robustness and prevention of the influence of external noise.
As shown in FIG. 7, a parasitic capacitance 92 is generated between the electrode 91 and the housing 93. This parasitic capacitance varies in size depending on the distance between the electrode 91 and the housing 93 and the relative permittivity of the fluid to be detected, so that the linearity between the relative permittivity of the fluid to be detected and the measurement time deviates, resulting in complicated calculations. Formulas and correction maps are required, which complicates the device. In the device having the housing for storing the electrodes as described above, the parasitic capacitance can be suppressed to some extent by increasing the shape of the housing and increasing the distance between the housing and the electrodes. However, the recent demand for downsizing of the device is not at all acceptable.
【０００４】本発明は上記実情に鑑みなされたもので、
寄生容量を低減して簡単な構成で高い測定精度が得られ
る容量式センサ装置を提供することを目的とする。[0004] The present invention has been made in view of the above circumstances,
It is an object of the present invention to provide a capacitive sensor device capable of reducing parasitic capacitance and obtaining high measurement accuracy with a simple configuration.
【０００５】[0005]
【課題を解決するための手段】請求項１記載の発明で
は、容量式センサ装置は、被検出流体中に電極を配設し
て、被検出流体の測定しようとする物理量に応じて比誘
電率が変化することにより静電容量が変化するキャパシ
タとする。キャパシタの静電容量に基づいて上記物理量
を測定する。電極の周囲に低誘電性の絶縁材料で構成し
た包囲部材を設け、該包囲部材には被検出流体が流通す
る開口部を形成する。According to the first aspect of the present invention, in the capacitive sensor device, an electrode is disposed in a fluid to be detected, and a relative permittivity according to a physical quantity to be measured of the fluid to be detected. Is changed, the capacitance is changed. The physical quantity is measured based on the capacitance of the capacitor. A surrounding member made of a low dielectric insulating material is provided around the electrode, and an opening through which the fluid to be detected flows is formed in the surrounding member.
【０００６】電極を囲む包囲部材により、電極と例えば
接地間の寄生容量が小さく抑えられ、寄生容量による物
理量の測定誤差を補正する必要がなくなる。また、本発
明を、ハウジングを有する構成の容量式センサ装置に適
用すると、寄生容量が小さく抑えられることで、ハウジ
ングを大型にしたのと同じ効果を得ることができ、形状
の小型化と寄生容量の低減とを両立せしめることができ
る。[0006] By the surrounding member surrounding the electrode, the parasitic capacitance between the electrode and, for example, the ground is kept small, and it is not necessary to correct the measurement error of the physical quantity due to the parasitic capacitance. In addition, when the present invention is applied to a capacitive sensor device having a housing, the parasitic capacitance can be suppressed to be small, and the same effect as that obtained when the housing is enlarged can be obtained. Can be achieved at the same time.
【０００７】請求項２記載の発明では、上記キャパシタ
の充放電によりキャパシタの容量に応じた周波数で発振
する発振回路を具備せしめて発振信号の周期変化に基づ
いて被検出流体の物理量を測定する構成とし、かつ発振
回路を上記電極の電圧が接地電位に対して正負に交番す
る構成とする。According to a second aspect of the present invention, there is provided an oscillation circuit which oscillates at a frequency corresponding to the capacitance of the capacitor by charging and discharging the capacitor, and measures a physical quantity of the fluid to be detected based on a period change of the oscillation signal. And the oscillation circuit is configured such that the voltage of the electrode alternates between positive and negative with respect to the ground potential.
【０００８】上記電極の電圧が正負に交番するので、被
検出流体の導電率によって電極と被検出流体間に電流が
流れても、その電流は絶えず向きを反転させることにな
る。しかして、電極表面における電気腐食を防止するこ
とができる。Since the voltage of the electrode alternates between positive and negative, even if a current flows between the electrode and the fluid to be detected due to the conductivity of the fluid to be detected, the current constantly reverses its direction. Thus, electric corrosion on the electrode surface can be prevented.
【０００９】[0009]
【発明の実施の形態】（第１実施形態）図１に燃料電池
システムに適用した本発明の容量式センサ装置の実施形
態を示す。容量式センサ装置１は、水とメタノールの混
合器から被検出流体たる水／メタノール混合液をメタノ
ール改質器に送出する管路の途中に設けられ、水とメタ
ノールの混合比が水／メタノール混合液の比誘電率の関
数であることを利用して上記混合比を計測するものであ
る。燃料電池システムでは、容量式センサ装置１の計測
結果は水およびメタノールの供給量を調整するバルブ制
御に用いられ、水／メタノール混合液の混合比が管理さ
れる。(First Embodiment) FIG. 1 shows an embodiment of a capacitive sensor device according to the present invention applied to a fuel cell system. The capacitive sensor device 1 is provided in the middle of a pipe for sending a water / methanol mixed liquid, which is a fluid to be detected, from a water / methanol mixer to a methanol reformer, and the mixing ratio of water / methanol is water / methanol mixed. The mixing ratio is measured using the function of the relative dielectric constant of the liquid. In the fuel cell system, the measurement result of the capacitive sensor device 1 is used for valve control for adjusting the supply amounts of water and methanol, and the mixing ratio of the water / methanol mixture is managed.
【００１０】容量式センサ装置１は、ハウジング２を有
し、ハウジング２は５つのハウジングユニット２１，２
２，２３，２４，２５から構成されている。ハウジング
ユニット２１，２４，２５はステンレススティール等の
金属製で、ハウジングユニット２２，２３は、ポリエー
テルケトン（ＰＥＥＫ）材を成形したものである。第１
のハウジングユニット２１は、厚肉のブロック状部材に
凹部２１ａが形成されたもので、凹部２１ａを横切る横
穴８が形成してある。The capacitive sensor device 1 has a housing 2, and the housing 2 has five housing units 21,
2, 23, 24 and 25. The housing units 21, 24, 25 are made of metal such as stainless steel, and the housing units 22, 23 are formed by molding a polyetherketone (PEEK) material. First
The housing unit 21 is formed by forming a concave portion 21a in a thick block-shaped member, and has a lateral hole 8 formed across the concave portion 21a.
【００１１】第１のハウジングユニット２１の凹部２１
ａには、これを埋めるように、包囲部材たる第２、第３
のハウジングユニット２２，２３が配設してある。The recess 21 of the first housing unit 21
a, the second and third surrounding members,
Are provided.
【００１２】第２、第３のハウジングユニット２２，２
３には、第２のハウジングユニット２２の凹部２２ａを
第３のハウジングユニット２３が上方より閉鎖すること
で、空間２ａが形成してある。また、第２、第３のハウ
ジングユニット２２，２３には、図の左右に開口部２０
１，２０２が形成され、空間２ａと上記横穴８とを連通
せしめている。Second and third housing units 22, 2
3, a space 2a is formed by the third housing unit 23 closing the recess 22a of the second housing unit 22 from above. The second and third housing units 22 and 23 have openings 20 on the left and right in the figure.
1, 202 are formed to connect the space 2a with the lateral hole 8.
【００１３】横穴８の両端部８１，８２は上記混合器お
よびメタノール改質器と接続するための接続部８１，８
２としてあり、ハウジングユニット２２，２３の空間２
ａを、水／メタノール混合液Ｌが流通するようになって
いる。Both ends 81 and 82 of the horizontal hole 8 are connected to the mixers and the methanol reformer.
2 and the space 2 of the housing units 22 and 23
a, a water / methanol mixed liquid L flows.
【００１４】ハウジングユニット２２，２３の空間２ａ
には、キャパシタたる検出キャパシタ４１Ａ、温度セン
サ７が配設してある。Space 2a of housing units 22, 23
Is provided with a detection capacitor 41A, which is a capacitor, and a temperature sensor 7.
【００１５】このように、ハウジング２は、ハウジング
ユニット２１，２４とで形成される外側のハウジング部
とハウジングユニット２２，２３とで形成される内側の
ハウジング部とからなり、ハウジングユニット２２，２
３は検出キャパシタ４１Ａ、温度センサ７を包囲してい
る。As described above, the housing 2 includes the outer housing formed by the housing units 21 and 24 and the inner housing formed by the housing units 22 and 23.
Reference numeral 3 surrounds the detection capacitor 41A and the temperature sensor 7.
【００１６】第４、第５のハウジングユニット２４，２
５は第３のハウジングユニット２３の上方に設けられ
る。第４のハウジングユニット２４は円形の箱状に成形
されたもので、これを蓋となる第５のハウジングユニッ
ト２５が上方より螺着されて閉鎖し、空間２ｂが形成し
てある。空間２ｂには回路基板３１，３２が配設してあ
る。回路基板３１，３２は第４のハウジングユニット２
４に保持されている。Fourth and fifth housing units 24, 2
5 is provided above the third housing unit 23. The fourth housing unit 24 is formed in the shape of a circular box, and a fifth housing unit 25 serving as a lid is screwed from above and closed to form a space 2b. Circuit boards 31 and 32 are provided in the space 2b. The circuit boards 31 and 32 are connected to the fourth housing unit 2.
4 is held.
【００１７】また第４、第５のハウジングユニット２
４，２５は、図略のボルトにより第１のハウジングユニ
ット２１に固定され、第２，第３のハウジングユニット
２２，２３が第１のハウジングユニット２１と、第４、
第５のハウジングユニット２４，２５の間に挟持され
る。しかしてハウジング２はそのハウジングユニット２
１〜２５が互いに密着して一体化する。Fourth and fifth housing units 2
4 and 25 are fixed to the first housing unit 21 by bolts (not shown), and the second and third housing units 22 and 23 are connected to the first housing unit 21 and the fourth and fourth housing units.
It is sandwiched between the fifth housing units 24 and 25. Thus, the housing 2 has its housing unit 2
1 to 25 are tightly integrated with each other.
【００１８】検出キャパシタ４１Ａは、所定の間隔をお
いて上下方向に積層する多数の電極たる電極板４１１，
４１２により構成され、電極板４１１，４１２は、空間
２ａの上壁である第３のハウジングユニット２３から垂
下する支柱３３、リード支柱３４により保持されてい
る。リード支柱３４は、図示されないものが奥側にもう
１つ設けてあり、いずれも第３、第４のハウジングユニ
ット２３，２４を貫通して空間２ｂに進出している。２
つのリード支柱３４はキャパシタ４１Ａの正負のリード
部をなしている。電極板４１１，４１２は交互にいずれ
かのリード支柱３４を介して回路基板３１，３２と接続
されており、交互に水／メタノール混合液を挟んで対向
する正側電極４１１群と負側電極４１２群とを形成す
る。検出キャパシタ４１Ａの静電容量は空間２ａの水／
メタノール混合液Ｌの比誘電率に応じて変化する。The detection capacitor 41A has a large number of electrode plates 411 and 471 vertically stacked at predetermined intervals.
The electrode plates 411 and 412 are held by columns 33 and lead columns 34 that hang from the third housing unit 23 that is the upper wall of the space 2a. One of the lead posts 34, not shown, is provided on the back side, and each of them extends through the third and fourth housing units 23 and 24 into the space 2b. 2
The two lead posts 34 form the positive and negative lead portions of the capacitor 41A. The electrode plates 411 and 412 are alternately connected to the circuit boards 31 and 32 via one of the lead posts 34, and alternately face the positive electrode 411 and the negative electrode 412 with the water / methanol mixture interposed therebetween. Form a group. The capacitance of the detection capacitor 41A is equal to the water /
It changes according to the relative dielectric constant of the methanol mixture L.
【００１９】温度センサ７は抵抗温度計等で構成され、
第３のハウジングユニット２３から垂下するケース３５
内に収容してある。温度センサ７のリード３６は回路基
板３１，３２と接続されている。The temperature sensor 7 comprises a resistance thermometer or the like,
Case 35 depending from third housing unit 23
Housed inside. The lead 36 of the temperature sensor 7 is connected to the circuit boards 31 and 32.
【００２０】図２に、キャパシタ４１Ａ、温度センサ
７、回路基板３１，３２により形成される検出回路を示
す。キャパシタ４１Ａ、温度センサ７以外の部分は回路
基板３１，３２上に実装される。FIG. 2 shows a detection circuit formed by the capacitor 41A, the temperature sensor 7, and the circuit boards 31 and 32. Portions other than the capacitor 41A and the temperature sensor 7 are mounted on the circuit boards 31 and 32.
【００２１】検出器側発振回路４Ａと基準側発振回路４
Ｂとは、インバータ４３を直列に接続した等価な回路構
成のＣＲ発振回路で、発振信号は、「Ｌ」レベルと
「Ｈ」レベルを繰り返すパルス信号となる。検出器側発
振回路４Ａの充放電回路は、検出キャパシタ４１Ａと抵
抗４２Ａとで構成され、検出器側発振回路４Ａの発振周
波数（検出器側発振周波数）は水／メタノール混合液Ｌ
の比誘電率に応じて変化する。一方、基準側発振回路４
Ｂの充放電回路は、基準キャパシタ４１Ｂと抵抗４２Ｂ
とで構成され、基準側発振回路４Ｂの発振周波数（基準
側発振周波数）は設置環境が一定していれば一定値をと
る。検出器側発振回路４Ａの発振出力（検出器側発振出
力）はカウンタ５Ａに入力し、基準側発振回路４Ｂの発
振出力（基準側発振出力）はカウンタ５Ｂに入力する。Detector side oscillation circuit 4A and reference side oscillation circuit 4
B is a CR oscillation circuit having an equivalent circuit configuration in which the inverters 43 are connected in series, and the oscillation signal is a pulse signal that repeats “L” level and “H” level. The charge / discharge circuit of the detector-side oscillation circuit 4A includes a detection capacitor 41A and a resistor 42A, and the oscillation frequency (detector-side oscillation frequency) of the detector-side oscillation circuit 4A is a water / methanol mixture L.
Changes according to the relative permittivity of On the other hand, the reference side oscillation circuit 4
B includes a reference capacitor 41B and a resistor 42B.
The oscillation frequency (reference oscillation frequency) of the reference oscillation circuit 4B takes a constant value if the installation environment is constant. The oscillation output of the detector-side oscillation circuit 4A (detector-side oscillation output) is input to the counter 5A, and the oscillation output of the reference-side oscillation circuit 4B (reference-side oscillation output) is input to the counter 5B.
【００２２】各カウンタ５Ａ，５Ｂには、また、マイク
ロコンピュータ６から同時にリセット信号が入力し、各
カウンタ５Ａ，５Ｂは、リセット信号が入力すると、そ
の時点から発振出力のパルスをカウントし、規定数のパ
ルスをカウントすると規定パルス到達信号をマイクロコ
ンピュータ６に返送するようになっている。Each of the counters 5A and 5B receives a reset signal from the microcomputer 6 at the same time. When the reset signal is input, each of the counters 5A and 5B counts the pulse of the oscillation output from that time and sets a prescribed number. Is counted, the specified pulse arrival signal is returned to the microcomputer 6.
【００２３】マイクロコンピュータ６はＣＰＵ、メモリ
等よりなる一般的な構成のもので、両カウンタ５Ａ，５
Ｂから規定パルス到達信号を受け取るとその時間差から
後述するように水／メタノール混合液Ｌの混合比を演算
するようになっている。The microcomputer 6 has a general configuration including a CPU, a memory, and the like.
When the prescribed pulse arrival signal is received from B, the mixing ratio of the water / methanol mixture L is calculated from the time difference as described later.
【００２４】マイクロコンピュータ６にはまた、温度セ
ンサ７から検出信号が入力し、マイクロコンピュータ６
は、後述するように上記混合比の演算において温度セン
サ７による検出温度に応じて補正演算をするようになっ
ている。A detection signal is input from the temperature sensor 7 to the microcomputer 6 and the microcomputer 6
Is configured to perform a correction calculation according to the temperature detected by the temperature sensor 7 in the calculation of the mixture ratio as described later.
【００２５】本容量式センサ装置１の作動を説明する。
図３にマイクロコンピュータ６で実行される制御フロー
を示す。ステップＳ１０１では、温度センサ７の検出信
号を読み込み、水／メタノール混合液Ｌの温度を得る。The operation of the present capacitive sensor device 1 will be described.
FIG. 3 shows a control flow executed by the microcomputer 6. In step S101, the detection signal of the temperature sensor 7 is read, and the temperature of the water / methanol mixture L is obtained.
【００２６】ステップＳ１０２では、カウンタ５Ａ，５
Ｂにリセット信号を出力し、検出器側発振回路４Ａと基
準側発振回路４Ｂの規定パルス到達時間の差を計測す
る。In step S102, the counters 5A, 5
A reset signal is output to B, and the difference between the specified pulse arrival times of the detector-side oscillation circuit 4A and the reference-side oscillation circuit 4B is measured.
【００２７】規定パルス到達時間は規定パルス数を発振
周波数で除した時間であるから、規定パルス到達時間差
は、検出器側発振回路４Ａと基準側発振回路４Ｂとの充
放電回路の時定数偏差に比例し、時定数はキャパシタ４
１Ａ，４１Ｂの静電容量に比例する。Since the specified pulse arrival time is the time obtained by dividing the specified pulse number by the oscillation frequency, the specified pulse arrival time difference is determined by the time constant deviation of the charge / discharge circuit between the detector-side oscillation circuit 4A and the reference-side oscillation circuit 4B. Proportional to the time constant of the capacitor 4
It is proportional to the capacitance of 1A, 41B.
【００２８】ここで、従来の装置ではキャパシタ４１Ａ
の静電容量が上記のごとく寄生容量の影響を受ける。し
かし、本容量式センサ装置１では、電極４１１，４１２
を第２、第３のハウジングユニット２２，２３が包囲し
ているから、電極４１１，４１２と金属製の第１、第４
のハウジングユニット２１，２４の間に生じる寄生容量
は、ＰＥＥＫ材を誘電体とするものである。ＰＥＥＫ材
は、比誘電率が、水の約８０、メタノールの約３０に対
して２程度と、極めて低い値を示す。したがって、寄生
容量の静電容量は、ハウジングユニット２２，２３がな
い場合よりも大幅に抑えられ、その結果、水／メタノー
ル混合液Ｌの混合比が変化しても寄生容量は実質的に一
定とみなせる小さなレベルとなる。Here, in the conventional device, the capacitor 41A
Is affected by the parasitic capacitance as described above. However, in the present capacitive sensor device 1, the electrodes 411, 412
Are surrounded by the second and third housing units 22 and 23, so that the electrodes 411 and 412 and the first and fourth metal
The parasitic capacitance generated between the housing units 21 and 24 is made of a PEEK material as a dielectric. The PEEK material has an extremely low relative dielectric constant of about 2 with respect to about 80 for water and about 30 for methanol. Therefore, the capacitance of the parasitic capacitance is significantly suppressed as compared with the case where the housing units 22 and 23 are not provided. As a result, even when the mixing ratio of the water / methanol mixture L changes, the parasitic capacitance is substantially constant. It is a small level that can be considered.
【００２９】したがって、被検出流体の比誘電率を、計
測時間との直線的な対応関係に基づき演算しても計測誤
差はごくわずかである。Therefore, even if the relative permittivity of the fluid to be detected is calculated based on the linear correspondence with the measurement time, the measurement error is very small.
【００３０】さらに、検出器側発振回路４Ａとともに、
これと等価な基準側発振回路４Ｂを設けることで、装置
の設置環境による外乱の発振回路に与える影響を相殺
し、測定誤差の低減を図っている。Further, together with the detector-side oscillation circuit 4A,
By providing an equivalent reference-side oscillation circuit 4B, the influence of the disturbance on the oscillation circuit due to the installation environment of the device is canceled, and the measurement error is reduced.
【００３１】さて、検出器側発振回路４Ａと基準側発振
回路４Ｂとで、充放電回路を構成するキャパシタ４１
Ａ，４１Ｂの容量や抵抗４２Ａ，４２Ｂの抵抗値が等し
いと仮定すると、検出器側発振周波数と基準側発振周波
数とは等しい。するとカウンタ５Ａ，５Ｂからの規定パ
ルス到達信号は同時にマイクロコンピュータ６に返送さ
れ、規定パルス到達時間差は０である。The capacitor 41 constituting the charge / discharge circuit is composed of the detector side oscillation circuit 4A and the reference side oscillation circuit 4B.
Assuming that the capacitances of A and 41B and the resistances of resistors 42A and 42B are equal, the oscillation frequency on the detector side is equal to the oscillation frequency on the reference side. Then, the prescribed pulse arrival signals from the counters 5A and 5B are simultaneously returned to the microcomputer 6, and the prescribed pulse arrival time difference is zero.
【００３２】水／メタノール混合液Ｌの混合比が変化し
て水／メタノール混合液Ｌの比誘電率が変化すると、水
／メタノール混合液Ｌの比誘電率に応じて、規定パルス
到達時間差が直線的に変化する。When the mixing ratio of the water / methanol mixture L changes and the relative permittivity of the water / methanol mixture L changes, the prescribed pulse arrival time difference varies linearly according to the relative permittivity of the water / methanol mixture L. Change.
【００３３】このように規定パルス到達時間差は水／メ
タノール混合液Ｌの混合比に応じて変化するが、比誘電
率が、水／メタノール混合液Ｌの混合比に加えてその温
度の関数でもあるため、水／メタノール混合液Ｌの混合
比は規定パルス到達時間差および水／メタノール混合液
Ｌの温度で特定される。ステップＳ１０３では、ステッ
プＳ１０１にて検出した水／メタノール混合液Ｌの温度
に基づく補正を加味して、規定パルス到達時間差から水
／メタノール混合液Ｌの混合比を演算する。すなわち、
マイクロコンピュータ６のメモリ（ＲＯＭ）には、予
め、水／メタノール混合液Ｌの規定パルス到達時間差と
混合比の関係式を記憶しており、水／メタノール混合液
Ｌの検出温度に対応した関係式により、混合比を演算す
る。As described above, the prescribed pulse arrival time difference changes according to the mixing ratio of the water / methanol mixture L, and the relative dielectric constant is a function of the temperature in addition to the mixing ratio of the water / methanol mixture L. Therefore, the mixing ratio of the water / methanol mixture L is specified by the prescribed pulse arrival time difference and the temperature of the water / methanol mixture L. In step S103, the mixing ratio of the water / methanol mixture L is calculated from the specified pulse arrival time difference, taking into account the correction based on the temperature of the water / methanol mixture L detected in step S101. That is,
The relational expression between the prescribed pulse arrival time difference and the mixing ratio of the water / methanol mixture L is stored in the memory (ROM) of the microcomputer 6 in advance, and the relational expression corresponding to the detected temperature of the water / methanol mixture L To calculate the mixing ratio.
【００３４】規定パルス到達時間差と温度センサ７の検
出温度とに基づいて、上記のごとく水／メタノール混合
液Ｌの混合比が求められ、上記バルブの制御用の制御装
置に出力される（ステップＳ１０４）。Based on the specified pulse arrival time difference and the temperature detected by the temperature sensor 7, the mixing ratio of the water / methanol mixture L is obtained as described above, and is output to the control device for controlling the valve (step S104). ).
【００３５】図４は、規定パルス到達時間差の特性を示
すグラフで、水／メタノール混合液Ｌの水の割合を変化
させたときのものである。図中、本実施形態になる容量
センサ式センサ装置（絶縁体あり）とともに、包囲部材
（２２，２３）を有しない従来型の装置（絶縁体なし）
のものを併せて示している。FIG. 4 is a graph showing the characteristics of the prescribed pulse arrival time difference when the ratio of water in the water / methanol mixture L is changed. In the figure, together with the capacitance sensor type sensor device (with insulator) according to the present embodiment, a conventional device without surrounding members (22, 23) (without insulator)
Are also shown.
【００３６】規定パルス到達時間差の計測値は、その回
帰直線からのずれが、いずれも水の割合が９０％のとき
に最も大きく、従来例（絶縁体なし）では２６．４μｓ
であったのに対し、本発明（絶縁体あり）では２１．６
μｓであり、直線性が１８％も向上した。The measured value of the specified pulse arrival time difference has the largest deviation from the regression line when the percentage of water is 90%, and 26.4 μs in the conventional example (without insulator).
Whereas, in the present invention (with insulator), 21.6
μs, and the linearity was improved by 18%.
【００３７】このように、本発明によれば、簡単な構成
で、寄生容量の発生を抑え、測定精度を向上させること
ができる。しかも、本実施形態のごとく電極を格納する
金属製のハウジングを有する場合には、ハウジングを大
型化することなく、寄生容量を抑えることができ、装置
の小型化と寄生容量の低減との両立を実現できる。As described above, according to the present invention, the occurrence of parasitic capacitance can be suppressed with a simple configuration, and the measurement accuracy can be improved. In addition, when a metal housing for storing the electrodes is provided as in the present embodiment, the parasitic capacitance can be suppressed without increasing the size of the housing, and both the miniaturization of the device and the reduction of the parasitic capacitance can be achieved. realizable.
【００３８】なお、本発明は、検出器側発振回路ととも
に基準側発振回路を設けて発振回路の温度特性を相殺す
る構成の装置に適用したが、検出器側発振回路単体の構
成の装置にも適用し得る。Although the present invention has been applied to an apparatus having a configuration in which a reference-side oscillation circuit is provided together with a detector-side oscillation circuit to offset the temperature characteristics of the oscillation circuit, the present invention is also applicable to an apparatus having a single-unit configuration of the detector-side oscillation circuit. Applicable.
【００３９】（第２実施形態）第１実施形態の構成で
は、イオン化傾向の高い成分が含まれる場合等、被検出
流体の導電率が高いと、電極表面において電気腐食が生
じるおそれがある。本実施形態はかかる電気腐食を防止
する構成を提供するもので、第１実施形態の構成におい
て、検出器側発振回路を別の構成に代えたものである。
図５に、この発振回路の構成を示す。(Second Embodiment) In the configuration of the first embodiment, when the conductivity of the fluid to be detected is high, such as when a component having a high ionization tendency is contained, there is a possibility that electric corrosion may occur on the electrode surface. The present embodiment provides a configuration for preventing such electrical corrosion, and is obtained by replacing the detector-side oscillation circuit with another configuration in the configuration of the first embodiment.
FIG. 5 shows the configuration of this oscillation circuit.
【００４０】この発振回路４ＡＡでは、インバータ４３
は東芝ＴＣ７４ＨＣＵ０４等のインバータＩＣで構成さ
れ、その電源として、インバータＩＣのＶDD端子には正
電圧を印加し（例えば＋２．５Ｖ）、ＶSS端子には負電
圧を印加する（例えば−２．５Ｖ）。図６は、各電極４
１１，４１２の電位を示すもので、Ａ点（一方の電極
側）およびＢ点（他方の電極側）は、電源の電位が負側
にシフトすることにより、接地電位に対して正負に振れ
る波形となる。しかして、被検出流体の導通率が高く被
検出流体と電極４１１，４１２間に電流が流れる場合で
あっても、電流の向きが交互に変わるから、電極４１
１，４１２表面における電気腐食を防止することができ
る。In the oscillation circuit 4AA, the inverter 43
Is composed of an inverter IC such as Toshiba TC74HCU04, and applies a positive voltage to the VDD terminal of the inverter IC (for example, +2.5 V) and a negative voltage to the VSS terminal (for example, -2.5 V). . FIG. 6 shows each electrode 4
11A and 11B show potentials at points A (one electrode side) and B (the other electrode side), which are positive and negative with respect to the ground potential due to the shift of the potential of the power supply to the negative side. Becomes Therefore, even when the conductivity of the fluid to be detected is high and a current flows between the fluid to be detected and the electrodes 411 and 412, the direction of the current alternates.
Electric corrosion on the surface of 1,412 can be prevented.
【００４１】なお、電気腐食を防止するには、各電極４
１１，４１２の電位が接地電位を中心に正負に同じ大き
さで振れるのが理想的である。したがって、上記のごと
く、｜ＶDD｜＝｜−ＶSS｜とするのが望ましい。In order to prevent electric corrosion, each electrode 4
Ideally, the potentials of 11, 412 fluctuate in the same magnitude in the positive and negative directions around the ground potential. Therefore, as described above, it is desirable that | VDD | = | -VSS |.
【００４２】なお、電極とハウジング間の寄生容量の
他、電極とリード支柱間にも寄生容量が生じるから、さ
らに寄生容量の影響による測定誤差を抑えるには、リー
ド支柱を上記ＰＥＥＫ等の絶縁材料により被覆するのが
よい。In addition to the parasitic capacitance between the electrode and the housing, the parasitic capacitance is also generated between the electrode and the lead post. In order to further suppress the measurement error due to the influence of the parasitic capacitance, the lead post must be formed of an insulating material such as PEEK. It is good to coat with.
【００４３】また、包囲部材は、ポリエーテルケトンに
限定されるものではなく、例えば、ポリアセタールやポ
リイミド等の低誘電性の絶縁材料が好適に用いられ得
る。この場合、寄生容量の影響を抑えるには、比誘電率
が被検出流体の比誘電率に比して十分に小さな絶縁材料
が望ましいが、要求される測定精度や、絶縁材料の被検
出流体に対する耐薬品性に応じて適宜選択する。Further, the surrounding member is not limited to polyetherketone, and for example, a low dielectric insulating material such as polyacetal or polyimide can be suitably used. In this case, in order to suppress the influence of the parasitic capacitance, an insulating material whose relative permittivity is sufficiently smaller than the relative permittivity of the fluid to be detected is desirable. It is appropriately selected according to the chemical resistance.
【００４４】また、温度変動等があまり大きくない場合
等、比誘電率の測定値の温度の影響を無視してよけれ
ば、温度センサによる補正は省略した構成でもよい。Further, when the influence of the temperature on the measured value of the relative permittivity can be ignored, for example, when the temperature fluctuation is not so large, the correction by the temperature sensor may be omitted.
【００４５】また、本発明は燃料電池システムにおける
水／メタノール混合液濃度の計測用だけではなく、他の
液体等の物理量の計測に適用することができる。The present invention can be applied not only to the measurement of the concentration of a water / methanol mixture in a fuel cell system, but also to the measurement of physical quantities of other liquids and the like.
【図１】本発明の容量式センサ装置の断面図である。FIG. 1 is a sectional view of a capacitive sensor device according to the present invention.
【図２】本発明の容量式センサ装置の回路図である。FIG. 2 is a circuit diagram of a capacitive sensor device according to the present invention.
【図３】本発明の容量式センサ装置の作動を説明するフ
ローチャートである。FIG. 3 is a flowchart illustrating the operation of the capacitive sensor device according to the present invention.
【図４】本発明の容量式センサ装置の作動を説明するグ
ラフである。FIG. 4 is a graph illustrating the operation of the capacitive sensor device of the present invention.
【図５】本発明の別の容量式センサ装置の要部回路図で
ある。FIG. 5 is a main part circuit diagram of another capacitive sensor device of the present invention.
【図６】本発明の別の容量式センサ装置の作動を説明す
るタイムチャートである。FIG. 6 is a time chart illustrating the operation of another capacitive sensor device according to the present invention.
【図７】従来の容量式センサ装置の課題を説明する回路
図である。FIG. 7 is a circuit diagram illustrating a problem of a conventional capacitive sensor device.
１ 容量式センサ装置 ２ ハウジング ２２，２３ ハウンジングユニット（包囲部材） ２０１，２０２ 開口部 ４Ａ 検出器側発振回路（発振回路） ４１Ａ 検出キャパシタ（キャパシタ） ４１１，４１２ 電極 ４２Ａ 抵抗 ４Ｂ 基準側発振回路 ４１Ｂ 基準キャパシタ ４２Ｂ 抵抗 ５Ａ，５Ｂ カウンタ ６ マイクロコンピュータ ７ 温度センサ Ｌ 水／メタノール混合液（被検出流体） REFERENCE SIGNS LIST 1 capacitive sensor device 2 housing 22, 23 housing unit (surrounding member) 201, 202 opening 4A detector-side oscillation circuit (oscillation circuit) 41A detection capacitor (capacitor) 411,412 electrode 42A resistance 4B reference-side oscillation circuit 41B Reference capacitor 42B Resistance 5A, 5B Counter 6 Microcomputer 7 Temperature sensor L Water / methanol mixture (fluid to be detected)
───────────────────────────────────────────────────── フロントページの続き (72)発明者 森次 通泰 愛知県西尾市下羽角町岩谷14番地 株式会 社日本自動車部品総合研究所内 (72)発明者 河津 成之 愛知県豊田市トヨタ町１番地 トヨタ自動 車株式会社内 Ｆターム(参考） 2G060 AA06 AE17 AF04 AF10 AG08 AG11 FA01 FA15 FB02 HA03 HA08 HC02 HC08 HC13 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Michiyasu Moritsuji 14 Iwatani, Shimowakaku-cho, Nishio-shi, Aichi Prefecture Inside Japan Automotive Parts Research Institute Co., Ltd. (72) Inventor Shizuyuki Kawazu 1st Toyota Town, Toyota-shi, Aichi Prefecture Toyota F-term (reference) in Automobile Co., Ltd. 2G060 AA06 AE17 AF04 AF10 AG08 AG11 FA01 FA15 FB02 HA03 HA08 HC02 HC08 HC13
Claims (2)
パシタであって被検出流体の測定しようとする物理量に
応じて比誘電率が変化することにより静電容量が変化す
るキャパシタを設け、キャパシタの静電容量に基づいて
上記物理量を測定するようになした容量式センサ装置に
おいて、電極の周囲に低誘電性の絶縁材料で構成した包
囲部材を設け、該包囲部材には被検出流体が流通する開
口部を形成したことを特徴とする容量式センサ装置。1. A capacitor comprising an electrode disposed in a fluid to be detected, the capacitor having a capacitance that changes due to a change in relative permittivity according to a physical quantity of the fluid to be measured. In a capacitive sensor device configured to measure the physical quantity based on the capacitance of a capacitor, an enclosing member made of a low-dielectric insulating material is provided around the electrode, and the enclosing member has a fluid to be detected. A capacitive sensor device, wherein an opening through which the gas flows is formed.
て、上記キャパシタの充放電によりキャパシタの容量に
応じた周波数で発振する発振回路を具備せしめて発振信
号に基づいて上記被検出流体の物理量を測定する構成と
し、かつ発振回路を上記電極の電圧が接地電位に対して
正負に交番する構成とした容量式センサ装置。2. The capacitive sensor device according to claim 1, further comprising an oscillation circuit that oscillates at a frequency corresponding to the capacitance of the capacitor by charging and discharging the capacitor, and wherein the physical quantity of the fluid to be detected is determined based on the oscillation signal. A capacitive sensor device having a configuration for measuring, and an oscillation circuit configured so that the voltage of the electrode alternates between positive and negative with respect to the ground potential.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP19250898A JP3895048B2 (en) | 1998-06-23 | 1998-06-23 | Capacitive sensor device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP19250898A JP3895048B2 (en) | 1998-06-23 | 1998-06-23 | Capacitive sensor device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2000009673A true JP2000009673A (en) | 2000-01-14 |
| JP3895048B2 JP3895048B2 (en) | 2007-03-22 |
Family
ID=16292463
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP19250898A Expired - Fee Related JP3895048B2 (en) | 1998-06-23 | 1998-06-23 | Capacitive sensor device |
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| Country | Link |
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2003302300A (en) * | 2001-11-20 | 2003-10-24 | Saginomiya Seisakusho Inc | Pressure sensor |
| JP2004012406A (en) * | 2002-06-11 | 2004-01-15 | Saginomiya Seisakusho Inc | Pressure sensor |
| JP2010145279A (en) * | 2008-12-19 | 2010-07-01 | Denso Corp | Fuel property sensor |
| JP2011164085A (en) * | 2010-01-12 | 2011-08-25 | Denso Corp | Fuel alcohol concentration detector |
| JP2016090300A (en) * | 2014-10-31 | 2016-05-23 | 株式会社鷺宮製作所 | Liquid detector, compressor and air conditioner |
| JP2016090302A (en) * | 2014-10-31 | 2016-05-23 | 株式会社鷺宮製作所 | Liquid detection unit, compressor and air conditioner |
| JP2019179041A (en) * | 2019-06-27 | 2019-10-17 | 株式会社鷺宮製作所 | Liquid detection unit, compressor and air conditioner |
-
1998
- 1998-06-23 JP JP19250898A patent/JP3895048B2/en not_active Expired - Fee Related
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2003302300A (en) * | 2001-11-20 | 2003-10-24 | Saginomiya Seisakusho Inc | Pressure sensor |
| JP2004012406A (en) * | 2002-06-11 | 2004-01-15 | Saginomiya Seisakusho Inc | Pressure sensor |
| JP2010145279A (en) * | 2008-12-19 | 2010-07-01 | Denso Corp | Fuel property sensor |
| US8593162B2 (en) | 2008-12-19 | 2013-11-26 | Denso Corporation | Fuel-aspect sensor |
| JP2011164085A (en) * | 2010-01-12 | 2011-08-25 | Denso Corp | Fuel alcohol concentration detector |
| JP2016090300A (en) * | 2014-10-31 | 2016-05-23 | 株式会社鷺宮製作所 | Liquid detector, compressor and air conditioner |
| JP2016090302A (en) * | 2014-10-31 | 2016-05-23 | 株式会社鷺宮製作所 | Liquid detection unit, compressor and air conditioner |
| JP2019179041A (en) * | 2019-06-27 | 2019-10-17 | 株式会社鷺宮製作所 | Liquid detection unit, compressor and air conditioner |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3895048B2 (en) | 2007-03-22 |
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