JP2020165743A

JP2020165743A - Electric conductivity cell

Info

Publication number: JP2020165743A
Application number: JP2019065146A
Authority: JP
Inventors: 諒介水村; Ryosuke Mizumura; 修司菅原; Shuji Sugawara; わかな橋本; Wakana Hashimoto; 芳晴伊藤; Yoshiharu Ito
Original assignee: DKK TOA Corp
Current assignee: DKK TOA Corp
Priority date: 2019-03-28
Filing date: 2019-03-28
Publication date: 2020-10-08
Anticipated expiration: 2039-03-28
Also published as: JP7277724B2

Abstract

To provide an electric conductivity cell from which bubbles can be easily discharged outside from an inner side of an outer cylinder through an open hole of the outer cylinder.SOLUTION: In an electric conductivity cell 1 comprising a substantially columnar electrode part 2 including a plurality of electrodes 3 and a substantially columnar outer cylinder 5 on which a plurality of open holes 6 are formed, the open hole 6 is configured so that each of two corners 6d on a side of a bottom end 2b in an axial direction V has a substantially square shape and each of two corners 6e on a side of a top end 2a in the axial direction V has an R shape or there is an arcuate side on the side of the top end 2a in the axial direction V.SELECTED DRAWING: Figure 1

Description

本発明は、液体の電気伝導率を測定するための電気伝導率セルに関するものである。 The present invention relates to an electrical conductivity cell for measuring the electrical conductivity of a liquid.

従来、河川水などの環境水、飲料水、産業などで使用される水溶液などの液体の電気伝導率を測定するために電気伝導率セルが用いられている（特許文献１）。図７は、従来の電気伝導率セル２０１の概略断面側面図である。電気伝導率セル２０１は、複数の電極２０３が設けられた略円柱状の電極部２０２と、電極部２０２を囲むように設けられた略円筒状の外筒２０５と、を有する。電極部２０２は、例えば略円柱状（又は円板状）の電極２０３と、電気絶縁体２０４と、が交互に繋げられて構成されている。外筒２０５は、電気絶縁体で形成され、電極部２０２の軸線方向（以下「電極軸線方向」ともいう。）における電極部２０２の先端部（以下「電極先端部」ともいう。）２０２ａ側の端部に開口部２０５ｃが設けられている。電気伝導率セル２０１を用いて電気伝導率を測定するには、電気伝導率セル２０１を被検液中に浸漬することで、電極部２０２と外筒２０５との間の略円筒状の空間（測定空間）Ｔに被検液を導入する。そして、電極部２０２の電極２０３を用いて測定空間Ｔ内の被検液に電流を流し、被検液の電気抵抗を測定することで、被検液の電気伝導率を測定する。電気伝導率セル２０１には、２極式、３極式、４極式、５極式などが知られているが、図７では３極式の例を示している。また、一般に、電気伝導率の測定には交流電流が用いられてインピーダンス（交流抵抗）が測定される。 Conventionally, an electric conductivity cell has been used for measuring the electric conductivity of a liquid such as an environmental water such as river water, drinking water, or an aqueous solution used in industry (Patent Document 1). FIG. 7 is a schematic cross-sectional side view of the conventional electrical conductivity cell 201. The electric conductivity cell 201 has a substantially cylindrical electrode portion 202 provided with a plurality of electrodes 203, and a substantially cylindrical outer cylinder 205 provided so as to surround the electrode portion 202. The electrode portion 202 is configured by, for example, a substantially columnar (or disc-shaped) electrode 203 and an electrical insulator 204 being alternately connected. The outer cylinder 205 is formed of an electric insulator and is on the side of the tip end portion (hereinafter also referred to as “electrode tip portion”) 202a of the electrode portion 202 in the axial direction of the electrode portion 202 (hereinafter, also referred to as “electrode axial direction”). An opening 205c is provided at the end. To measure the electrical conductivity using the electrical conductivity cell 201, the electrical conductivity cell 201 is immersed in the test solution to form a substantially cylindrical space between the electrode portion 202 and the outer cylinder 205 ( Measurement space) Introduce the test solution into T. Then, the electric conductivity of the test solution is measured by passing a current through the test solution in the measurement space T using the electrode 203 of the electrode portion 202 and measuring the electric resistance of the test solution. Two-pole type, three-pole type, four-pole type, five-pole type and the like are known as the electric conductivity cell 201, and FIG. 7 shows an example of the three-pole type. Further, in general, an alternating current is used for measuring the electric conductivity, and the impedance (AC resistance) is measured.

外筒２０５は、例えば電気伝導率セル２０１が被検液を収容した容器の壁面付近で用いられた場合に壁面の材料や壁面と電極２０３との間の距離などによって測定値が変動することなどを抑制するために設けられる。しかし、例えば電気伝導率セル２０１を被検液に浸漬する際などに、測定空間Ｔ内に気泡を巻き込んでしまうことがある。測定空間Ｔ内に気泡があると、例えば電極２０３と外筒２０５との間に気泡が挟まるなどして、測定空間Ｔ内の被検液のインピーダンスが本来よりも大きく（電気伝導率が本来よりも小さく）測定されてしまう。 For example, when the electric conductivity cell 201 is used near the wall surface of the container containing the test solution, the measured value of the outer cylinder 205 fluctuates depending on the material of the wall surface and the distance between the wall surface and the electrode 203. It is provided to suppress. However, for example, when the electric conductivity cell 201 is immersed in the test solution, air bubbles may be involved in the measurement space T. If there are air bubbles in the measurement space T, for example, air bubbles are sandwiched between the electrode 203 and the outer cylinder 205, and the impedance of the test solution in the measurement space T is larger than it should be (electrical conductivity is higher than it should be). Is also small).

そこで、従来、外筒２０５には、測定空間Ｔ内の気泡を外筒２０５の外部へと排出するために、電極軸線方向における電極部２０２の基端部（以下「電極基端部」ともいう。）２０２ｂよりに、貫通孔（気泡抜き孔）２０６が設けられている。つまり、通常、電気伝導率セル２０１は、電極先端部２０２ａ側を下方、電極基端部２０２ｂ側を上方に向けて被検液に浸漬されて用いられる。そのため、電気伝導率セル２０１を被検液に浸漬する際などに測定空間Ｔに入った気泡が上方へ移動し、上方に配置された貫通孔２０６を通して外筒２０５の外部に排出されることが企図されている。 Therefore, conventionally, in the outer cylinder 205, in order to discharge the air bubbles in the measurement space T to the outside of the outer cylinder 205, the base end portion of the electrode portion 202 in the electrode axis direction (hereinafter, also referred to as “electrode base end portion”). A through hole (air bubble vent hole) 206 is provided from 202b. That is, usually, the electric conductivity cell 201 is used by being immersed in the test solution with the electrode tip portion 202a side facing downward and the electrode base end portion 202b side facing upward. Therefore, when the electric conductivity cell 201 is immersed in the test solution, the bubbles entering the measurement space T may move upward and be discharged to the outside of the outer cylinder 205 through the through hole 206 arranged above. It is intended.

特開平１−２５９２４９号公報Japanese Patent Application Laid-Open No. 1-259249

しかしながら、従来の電気伝導率セル２０１の構成では、測定空間Ｔ内の気泡を十分に外筒２０５の外部に排出できないことがあった。 However, in the conventional configuration of the electric conductivity cell 201, the bubbles in the measurement space T may not be sufficiently discharged to the outside of the outer cylinder 205.

外筒２０５の貫通孔２０６は、従来一般に、円形（真円や楕円）とされている。貫通孔２０６を通した気泡の排出（気泡抜き）をしやすくするために、単純に貫通孔２０６の大きさ（直径）を大きくすることが考えられる。しかし、貫通孔２０６の大きさを単純に大きくすると、気泡の排出はしやすくなるものの、測定空間Ｔ内の被検液のインピーダンスを正しく測定できなくなることがある。つまり、本来は図８（ａ）中の実線で示す電流による測定空間Ｔ内の被検液のインピーダンスが測定目的である。しかし、貫通孔２０６の大きさを単純に大きくすると、電極先端部２０２ａ側の外筒２０５の開口部２０５ｃと貫通孔２０６との間での、外筒２０５の外側の液体などを通る回路（図５（ａ）中の破線）のインピーダンスが小さくなる。その結果、外筒２０５の外側のインピーダンスの影響（外来の影響）が大きくなって、測定空間Ｔ内の被検液のインピーダンスを正しく測定できなくなることがある。 The through hole 206 of the outer cylinder 205 is generally circular (perfect circle or ellipse). It is conceivable to simply increase the size (diameter) of the through hole 206 in order to facilitate the discharge (bleeding of air bubbles) of the air bubbles through the through hole 206. However, if the size of the through hole 206 is simply increased, air bubbles can be easily discharged, but the impedance of the test solution in the measurement space T may not be measured correctly. That is, originally, the impedance of the test solution in the measurement space T due to the current shown by the solid line in FIG. 8A is the measurement purpose. However, if the size of the through hole 206 is simply increased, a circuit through which a liquid or the like outside the outer cylinder 205 passes between the opening 205c of the outer cylinder 205 on the electrode tip 202a side and the through hole 206 (FIG. The impedance (broken line in 5 (a)) becomes smaller. As a result, the influence of the impedance on the outside of the outer cylinder 205 (the influence of the foreign body) becomes large, and the impedance of the test solution in the measurement space T may not be measured correctly.

これに対して、次のような方法で、測定空間Ｔ内の被検液のインピーダンスに対する外筒２０５の外側の液体などを通る回路のインピーダンスを大きくし、外筒２０５の外側のインピーダンスの影響を低減することが考えられる。つまり、図８（ｂ）に示すように最も電極先端部２０２ａ側の電極２０３よりもさらに電極先端部２０２ａ側に絶縁部を設けたり、図８（ｃ）に示すように最も電極基端部２０２ｂ側の電極２０３と貫通孔２０６との間の距離を大きくしたり、図８（ｄ）に示すように電極先端部２０２ａ側の外筒２０５の長さを延長したりすることである。しかし、これらの方法で十分な効果を得ようとすると、電気伝導率セル２０１が大きくなるため、電気伝導率セル２０１の小型化を妨げる要因となる。 On the other hand, by the following method, the impedance of the circuit passing through the liquid outside the outer cylinder 205 is increased with respect to the impedance of the test liquid in the measurement space T, and the influence of the impedance on the outside of the outer cylinder 205 is affected. It is possible to reduce it. That is, as shown in FIG. 8B, an insulating portion is provided on the electrode tip portion 202a side more than the electrode 203 on the electrode tip portion 202a side, or as shown in FIG. 8C, the electrode base end portion 202b is provided. The distance between the electrode 203 on the side and the through hole 206 is increased, and the length of the outer cylinder 205 on the side of the electrode tip 202a is extended as shown in FIG. 8D. However, if a sufficient effect is to be obtained by these methods, the electric conductivity cell 201 becomes large, which is a factor that hinders the miniaturization of the electric conductivity cell 201.

また、上述のように、貫通孔２０６は、従来一般に円形とされ、外筒２０５の周方向に相互に間隔をあけて複数（例えば２〜４個）設けられている。この貫通孔２０６は、電極基端部２０２ｂ側、すなわち、上方に円弧形状の辺を有するため、隣接する貫通孔２０６の境界部分の特に上方に気泡が溜まりやすい（図４（ｄ））。このように気泡が溜まると、更に気泡が溜まって電極２０３と外筒２０５との間に気泡が挟まったり、電極２０３と外筒２０５との間に気泡が挟まらない場合でも気泡の溜まり方が異なっていたりすることで、測定空間Ｔ内の被検液の本来のインピーダンスが測定されなくなることがある。 Further, as described above, the through holes 206 are generally circular in the past, and a plurality (for example, 2 to 4) through holes 206 are provided at intervals in the circumferential direction of the outer cylinder 205. Since the through hole 206 has an arc-shaped side on the electrode base end portion 202b side, that is, upward, air bubbles are likely to accumulate particularly above the boundary portion of the adjacent through hole 206 (FIG. 4 (d)). When air bubbles are accumulated in this way, the air bubbles are further accumulated and the air bubbles are trapped between the electrode 203 and the outer cylinder 205, or even if the air bubbles are not sandwiched between the electrode 203 and the outer cylinder 205, the air bubbles are accumulated. If they are different, the original impedance of the test solution in the measurement space T may not be measured.

したがって、本発明の目的は、外筒の貫通孔を通した外筒の内部から外部への気泡の排出がしやすい電気伝導率セルを提供することである。 Therefore, an object of the present invention is to provide an electric conductivity cell in which air bubbles can be easily discharged from the inside to the outside of the outer cylinder through the through hole of the outer cylinder.

上記目的は本発明に係る電気伝導率セルにて達成される。要約すれば、本発明は、略円柱状の電極部であって、前記電極部の軸線方向に沿って相互に間隔をあけて複数の電極が設けられた電極部と、略円筒状の外筒であって、前記外筒の内周面と前記電極部の外周面との間に間隔をあけて前記電極部との間に略円筒状の空間を形成するように配置され、前記軸線方向における前記電極部の先端部側の端部が開口しており、前記軸線方向における前記電極部の基端部側の端部よりに前記外筒の周方向に沿って相互に間隔をあけて複数の貫通孔が形成されている外筒と、を有する電気伝導率セルにおいて、前記貫通孔は、前記軸線方向における前記基端部側の２つの隅部がそれぞれ略角形状を有し、前記軸線方向における前記先端部側の２つの隅部がそれぞれＲ形状を有するか又は前記軸線方向における前記先端部側に円弧形状の辺を有することを特徴とする電気伝導率セルである。 The above object is achieved by the electric conductivity cell according to the present invention. In summary, the present invention is a substantially cylindrical electrode portion, the electrode portion in which a plurality of electrodes are provided at intervals along the axial direction of the electrode portion, and a substantially cylindrical outer cylinder. It is arranged so as to form a substantially cylindrical space between the inner peripheral surface of the outer cylinder and the outer peripheral surface of the electrode portion at a distance from the electrode portion, and is arranged in the axial direction. A plurality of ends of the electrode portion on the tip end side are open, and a plurality of electrodes are spaced apart from each other along the circumferential direction of the outer cylinder from the end portion on the base end side of the electrode portion in the axial direction. In an electric conductivity cell having an outer cylinder having a through hole formed therein, the through hole has a substantially angular shape at each of two corners on the base end side in the axial direction, and the axial direction thereof. It is an electric conductivity cell characterized in that each of the two corners on the tip end side of the above has an R shape or has an arc-shaped side on the tip end side in the axial direction.

本発明によれば、外筒の貫通孔を通した外筒の内部から外部への気泡の排出をしやすくすることができる。 According to the present invention, it is possible to facilitate the discharge of air bubbles from the inside to the outside of the outer cylinder through the through hole of the outer cylinder.

電気伝導率測定用プローブの断面図である。It is sectional drawing of the probe for electric conductivity measurement. 電気伝導率測定用プローブ及びセンサユニット（電気伝導率セル）の側面図である。It is a side view of the probe for electric conductivity measurement and a sensor unit (electrical conductivity cell). 電極部及び外筒の近傍の断面側面図である。It is sectional drawing side view in the vicinity of an electrode part and an outer cylinder. 外筒の貫通孔の構成及び作用を説明するための模式図である。It is a schematic diagram for demonstrating the structure and operation of the through hole of an outer cylinder. 電極部の根本の近傍の断面図である。It is sectional drawing in the vicinity of the root of an electrode part. 外筒の貫通孔の配置を説明するための模式図である。It is a schematic diagram for demonstrating the arrangement of the through hole of an outer cylinder. 従来の電気伝導率セルの概略断面側面図である。It is a schematic cross-sectional side view of the conventional electric conductivity cell. 従来の課題を説明するための模式図である。It is a schematic diagram for demonstrating a conventional problem.

以下、本発明に係る電気伝導率セルを図面に則して更に詳しく説明する。 Hereinafter, the electric conductivity cell according to the present invention will be described in more detail with reference to the drawings.

［実施例１］
１．電気伝導率測定用プローブの全体構成
図１は、本発明を適用した電気伝導率測定用プローブ（以下「ＥＣプローブ」ともいう。）１００の断面図である。また、図２（ａ）は、ＥＣプローブ１００の側面図であり、図２（ｂ）は電気伝導率セルで構成された後述するセンサユニット１の側面図である。なお、図１は、図２（ａ）中のＡ−Ａ線断面を示している。ここでは、上下は重力方向の上下であり、ＥＣプローブ１００は、通常、後述する電極先端部２ａ側を下方、電極基端部２ｂ側を上方に向けて用いられるものとする。 [Example 1]
1. 1. Overall Configuration of Probe for Electrical Conductivity Measurement FIG. 1 is a cross-sectional view of a probe for electrical conductivity measurement (hereinafter, also referred to as “EC probe”) 100 to which the present invention is applied. 2 (a) is a side view of the EC probe 100, and FIG. 2 (b) is a side view of the sensor unit 1 described later, which is composed of an electric conductivity cell. Note that FIG. 1 shows a cross section taken along line AA in FIG. 2 (a). Here, the top and bottom are up and down in the direction of gravity, and the EC probe 100 is usually used with the electrode tip portion 2a side, which will be described later, facing downward and the electrode base end portion 2b side facing upward.

本実施例では、ＥＣプローブ１００は、電気伝導率セルで構成されたセンサユニット１と、測定ユニット１１０と、を有する。測定ユニット１１０は、センサユニット１から取得したアナログ信号をセンサユニット１の測定結果を示すデジタル信号に変換する測定回路１１１ａを有している。本実施例では、測定ユニット１１０は、ケーブル１２０を介して計測装置本体（図示せず）に接続され、測定回路１１１ａで変換したデジタル信号を計測装置本体に送信する。計測装置本体は、測定ユニット１１０から取得したデジタル信号を処理して測定結果の表示などを行う。また、本実施例では、計測装置本体に対してＥＣプローブ１００が着脱可能であると共に、測定ユニット１１０に対してセンサユニット１が着脱可能とされている。ＥＣプローブ１００と計測装置本体とによって電気伝導率計測装置が構成される。 In this embodiment, the EC probe 100 has a sensor unit 1 composed of an electric conductivity cell and a measurement unit 110. The measurement unit 110 has a measurement circuit 111a that converts an analog signal acquired from the sensor unit 1 into a digital signal indicating a measurement result of the sensor unit 1. In this embodiment, the measuring unit 110 is connected to the measuring device main body (not shown) via the cable 120, and transmits the digital signal converted by the measuring circuit 111a to the measuring device main body. The measuring device main body processes the digital signal acquired from the measuring unit 110 and displays the measurement result. Further, in this embodiment, the EC probe 100 is detachable from the measuring device main body, and the sensor unit 1 is detachable from the measuring unit 110. The electric conductivity measuring device is composed of the EC probe 100 and the measuring device main body.

センサユニット１は、略円柱状の電極部２と、電極部２を囲むように設けられた略円筒状の外筒５と、を有する。電極部２には、電極部２の軸線方向（「電極軸線方向」）Ｖに沿って相互に間隔をあけて複数の電極３（３ａ、３ｂ、３ｃ）が設けられている。外筒５は、外筒５の内周面５ａと電極部２の外周面２ｃとの間に間隔をあけて電極部２との間に略円筒状の空間（測定空間）Ｔを形成するように配置されている。また、外筒５は、電極軸線方向Ｖにおける電極部２の先端部（「電極先端部」）２ａ側の端部が開口している。すなわち、外筒５は、電極先端部２ａ側の端部に開口部５ｃを有する。さらに、外筒５は、電極軸線方向Ｖにおける電極部２の基端部（「電極基端部」）２ｂ側の端部よりに、外筒５の周方向に沿って相互に間隔をあけて複数の貫通孔６が形成されている。本実施例では、センサユニット１は、３極式の電気伝導率セルで構成されている。 The sensor unit 1 has a substantially cylindrical electrode portion 2 and a substantially cylindrical outer cylinder 5 provided so as to surround the electrode portion 2. The electrode portion 2 is provided with a plurality of electrodes 3 (3a, 3b, 3c) at intervals along the axial direction (“electrode axial direction”) V of the electrode portion 2. The outer cylinder 5 forms a substantially cylindrical space (measurement space) T between the inner peripheral surface 5a of the outer cylinder 5 and the outer peripheral surface 2c of the electrode portion 2 with a gap between the outer cylinder 5 and the electrode portion 2. Is located in. Further, the outer cylinder 5 has an open end portion on the tip portion (“electrode tip portion”) 2a side of the electrode portion 2 in the electrode axial direction V. That is, the outer cylinder 5 has an opening 5c at the end on the electrode tip 2a side. Further, the outer cylinder 5 is spaced apart from the end portion on the 2b side of the base end portion (“electrode base end portion”) 2b side of the electrode portion 2 in the electrode axial direction V along the circumferential direction of the outer cylinder 5. A plurality of through holes 6 are formed. In this embodiment, the sensor unit 1 is composed of a three-pole electric conductivity cell.

更に説明すると、センサユニット１は、支持部材１０及び電極棒１１を備えたセンサ本体１Ａと、外筒５と、を有して構成される。支持部材１０は、略円筒状とされ、電極軸線方向Ｖの電極先端部２ａ側の端部に、他の部分よりも小径とされた支持部１０ａが設けられている。また、電極棒１１は、略円柱状とされ、電極軸線方向Ｖの電極基端部２ｂ側の端部に、他の部分よりも小径とされた接続部１１ａが設けられている。そして、支持部材１０の支持部１０ａに形成された開口部に電極棒１１の接続部１１ａが嵌合されて、センサ本体１Ａが構成される。センサユニット１は、全体として略細長円柱状とされている。支持部材１０の支持部１０ａと、電極棒１１の接続部１１ａ以外の部分の外径と、は略同一とされている。本実施例では、電極棒１１と、支持部材１０の支持部（外筒５との接合部７よりも電極先端部２ａ側の部分）１０ａと、によって、略円柱状の電極部２が構成されるものとする。 More specifically, the sensor unit 1 includes a sensor body 1A provided with a support member 10 and an electrode rod 11, and an outer cylinder 5. The support member 10 has a substantially cylindrical shape, and a support portion 10a having a diameter smaller than that of other portions is provided at an end portion on the electrode tip portion 2a side in the electrode axis direction V. Further, the electrode rod 11 has a substantially cylindrical shape, and a connecting portion 11a having a diameter smaller than that of other portions is provided at an end portion on the electrode base end portion 2b side in the electrode axis direction V. Then, the connection portion 11a of the electrode rod 11 is fitted into the opening formed in the support portion 10a of the support member 10, and the sensor body 1A is configured. The sensor unit 1 has a substantially elongated columnar shape as a whole. The support portion 10a of the support member 10 and the outer diameter of the portion of the electrode rod 11 other than the connection portion 11a are substantially the same. In this embodiment, the electrode rod 11 and the support portion 10a of the support member 10 (the portion on the electrode tip portion 2a side of the joint portion 7 with the outer cylinder 5) 10a form a substantially cylindrical electrode portion 2. Shall be.

電極棒１１は、略円柱状（又は円板状）の電極３と、電気絶縁体で形成された略円筒状のセパレータ４と、が交互に繋げられて構成されている。３個の電極３のうち最も電極先端部２ａ側の第１電極３ａは、円板状とされ、円形の端面が電極先端部２ａに露出し、環状の周面が電極部２の外周面２ｃから露出するように形成されて、セパレータ４に取り付けられている。また、３個の電極のうち中央の第２電極３ｂ、及び最も電極基端部２ｂ側の第３電極３ｃは、それぞれ環状の周面が電極部２の外周面２ｃから露出するように形成されて、セパレータ４に固定されている。各電極３は、電極棒１１の内部でリード線８に接続され、このリード線８は、支持部材１０へと引き出され、支持部材１０の内部を通って、支持部材１０に設けられた回路基板１２に接続されている。本実施例では、各電極３は、チタンで形成されている。ただし、これに限定されるものではなく、電気伝導率セルの電極として適した、典型的には導電性材料で形成されていればよく、例えばＳＵＳ（ステンレス鋼）、ハステロイ（ニッケル基合金の商品名）、白金、グラッシーカーボンなどであってもよい。また、本実施例では、セパレータ４は、ＰＰ（ポリプロピレン）で形成されている。ただし、これに限定されるものではなく、典型的に樹脂材料とされる電気絶縁性材料で形成されていればよい。 The electrode rod 11 is configured by alternately connecting a substantially cylindrical (or disc-shaped) electrode 3 and a substantially cylindrical separator 4 formed of an electric insulator. Of the three electrodes 3, the first electrode 3a on the electrode tip 2a side is in the shape of a disk, the circular end face is exposed to the electrode tip 2a, and the annular peripheral surface is the outer peripheral surface 2c of the electrode 2. It is formed so as to be exposed from the separator 4 and attached to the separator 4. Further, of the three electrodes, the central second electrode 3b and the third electrode 3c closest to the electrode base end portion 2b are formed so that the annular peripheral surface is exposed from the outer peripheral surface 2c of the electrode portion 2, respectively. It is fixed to the separator 4. Each electrode 3 is connected to a lead wire 8 inside the electrode rod 11, and the lead wire 8 is pulled out to the support member 10, passes through the inside of the support member 10, and is provided on the support member 10. It is connected to 12. In this embodiment, each electrode 3 is made of titanium. However, the present invention is not limited to this, and it is sufficient that the electrode is typically made of a conductive material suitable as an electrode of an electric conductivity cell. For example, SUS (stainless steel) and Hastelloy (nickel-based alloy products) Name), platinum, glassy carbon, etc. may be used. Further, in this embodiment, the separator 4 is made of PP (polypropylene). However, the present invention is not limited to this, and it may be formed of an electrically insulating material typically used as a resin material.

外筒５は、電極基端部２ｂ側の端部の内周面に設けられたネジ部が、支持部材１０の外周面に設けられたネジ部に螺合されることで、センサ本体１Ａに固定される。外筒５は電極部２と略同軸的に配置される。外筒５の構成、及び外筒５と電極部２との位置関係などについては後述して更に詳しく説明する。 The outer cylinder 5 has a screw portion provided on the inner peripheral surface of the end portion on the electrode base end portion 2b side, which is screwed into the screw portion provided on the outer peripheral surface of the support member 10 to form a sensor body 1A. It is fixed. The outer cylinder 5 is arranged substantially coaxially with the electrode portion 2. The configuration of the outer cylinder 5 and the positional relationship between the outer cylinder 5 and the electrode portion 2 will be described in more detail later.

支持部材１０の、電極軸線方向Ｖにおける電極棒１１が取り付けられる側とは反対側の端部近傍には、回路基板１２が設けられており、上述のようにこの回路基板１２に電極棒１１から引き出されたリード線８が接続されている。また、この回路基板１２には、センサユニット側コネクタ１３が設けられており、後述する測定ユニット１１０の回路基板１１１に設けられた測定ユニット側コネクタ１１２と接続可能とされている。本実施例では、支持部材１０は、ＰＰ（ポリプロピレン）で形成されているが、これに限定されるものではなく、上記セパレータ４の場合と同様の電気絶縁性材料で形成されることが好ましい。 A circuit board 12 is provided in the vicinity of the end of the support member 10 on the side opposite to the side on which the electrode rod 11 is attached in the electrode axis direction V, and as described above, the circuit board 12 is connected to the electrode rod 11 from the electrode rod 11. The lead wire 8 drawn out is connected. Further, the circuit board 12 is provided with a sensor unit side connector 13, and can be connected to the measurement unit side connector 112 provided on the circuit board 111 of the measurement unit 110, which will be described later. In this embodiment, the support member 10 is made of PP (polypropylene), but is not limited to this, and is preferably formed of the same electrically insulating material as in the case of the separator 4.

測定ユニット１１０には、測定回路１１１ａを備えた回路基板１１１が設けられている。また、この回路基板１１１には、測定ユニット側コネクタ１１２が設けられており、上述のセンサユニット１の回路基板１２に設けられたセンサユニット側コネクタ１３と接続可能とされている。また、測定ユニット１１０は、センサユニット１の電極軸線方向Ｖにおける電極先端部２ａ側とは反対側の端部が挿入されて嵌合される凹部１１３を有する。そして、センサユニット１が測定ユニット１１０の凹部１１３に挿入され、センサユニット側コネクタ１３と測定ユニット側コネクタ１１２とが着脱可能に接続されることで、センサユニット１と測定ユニット１１０とが一体化されて、ＥＣプローブ１００が構成される。 The measurement unit 110 is provided with a circuit board 111 provided with the measurement circuit 111a. Further, the circuit board 111 is provided with a measurement unit side connector 112, and can be connected to the sensor unit side connector 13 provided on the circuit board 12 of the sensor unit 1 described above. Further, the measurement unit 110 has a recess 113 in which an end portion of the sensor unit 1 opposite to the electrode tip portion 2a side in the electrode axial direction V is inserted and fitted. Then, the sensor unit 1 is inserted into the recess 113 of the measurement unit 110, and the sensor unit side connector 13 and the measurement unit side connector 112 are detachably connected so that the sensor unit 1 and the measurement unit 110 are integrated. The EC probe 100 is configured.

なお、本実施例では、支持部材１０の電極軸線方向Ｖにおける電極棒１１が取り付けられる側とは反対側の端部近傍の外周面と、測定ユニット１１０の凹部１１３の内周面と、の間に、封止部材としてのＯリング１４が配置されて、センサユニット１の内部が液密に保たれている。また、本実施例では、センサユニット１は、スライド移動させられて測定ユニット１１０の凹部１１３に嵌合される。そして、センサユニット１の外周を取り巻くように配置された固定部材としての袋ナット１５が、測定ユニット１１０のセンサユニット１側の端部に螺合されることで、センサユニット１は測定ユニット１１０に対して固定されるようになっている。 In this embodiment, between the outer peripheral surface near the end of the support member 10 on the side opposite to the side on which the electrode rod 11 is attached in the electrode axis direction V and the inner peripheral surface of the recess 113 of the measuring unit 110. An O-ring 14 as a sealing member is arranged therein, and the inside of the sensor unit 1 is kept liquidtight. Further, in this embodiment, the sensor unit 1 is slid and fitted into the recess 113 of the measurement unit 110. Then, the bag nut 15 as a fixing member arranged so as to surround the outer circumference of the sensor unit 1 is screwed into the end portion of the measurement unit 110 on the sensor unit 1 side, so that the sensor unit 1 becomes the measurement unit 110. On the other hand, it is fixed.

また、センサユニット１は、上記とは逆に測定ユニット１１０から取り外されて、交換することが可能とされている。また、測定ユニット１１０の回路基板１１１から引き出された配線は、ケーブル１２０としてまとめられて計測装置本体に接続される。本実施例では、測定ユニット１１０は、上記ケーブル１２０の端部に設けられたプローブ側コネクタ（図示せず）と、計測装置本体に設けられた本体側コネクタ（図示せず）と、によって、計測装置本体に対して着脱可能に接続される。 Further, the sensor unit 1 can be removed from the measuring unit 110 and replaced, contrary to the above. Further, the wiring drawn from the circuit board 111 of the measuring unit 110 is bundled as a cable 120 and connected to the measuring device main body. In this embodiment, the measurement unit 110 is measured by a probe-side connector (not shown) provided at the end of the cable 120 and a main body-side connector (not shown) provided in the measuring device main body. It is detachably connected to the main body of the device.

ＥＣプローブ１００を用いて電気伝導率を測定するには、センサユニット１の電極先端部２ａ側を下方に向けて被検液中に浸漬することで、電極部２と外筒５との間の略円筒状の測定空間Ｔに被検液を導入する。そして、センサユニット１の電極３を用いて測定空間Ｔ内の被検液に交流電流を流し、被検液のインピーダンスを測定することで、被検液の電気伝導率を測定する。本実施例では、センサユニット１は、概略、第２電極３ｂと第１電極３ａとの間、及び第２電極３ｂと第３電極３ｃとの間に交流電圧を印加して、測定空間Ｔ内の被検液に交流電流を流し、測定空間Ｔ内の被検液のインピーダンスを測定することで、測定空間Ｔ内の被検液の電気伝導率を測定する。 In order to measure the electric conductivity using the EC probe 100, the electrode tip portion 2a side of the sensor unit 1 is directed downward and immersed in the test solution, so that the electrode portion 2 and the outer cylinder 5 are separated from each other. The test solution is introduced into the substantially cylindrical measurement space T. Then, an alternating current is passed through the test solution in the measurement space T using the electrode 3 of the sensor unit 1, and the impedance of the test solution is measured to measure the electrical conductivity of the test solution. In this embodiment, the sensor unit 1 roughly applies an AC voltage between the second electrode 3b and the first electrode 3a and between the second electrode 3b and the third electrode 3c in the measurement space T. The electrical conductivity of the test solution in the measurement space T is measured by passing an alternating current through the test solution and measuring the impedance of the test solution in the measurement space T.

２．外筒の構成、及び外筒と電極部との位置関係
次に、本実施例における外筒５について更に詳しく説明する。図３は、センサユニット（以下「電気伝導率セル」という。）１の電極部２及び外筒５の近傍を拡大して示す断面側面図である。 2. Configuration of the outer cylinder and positional relationship between the outer cylinder and the electrode portion Next, the outer cylinder 5 in this embodiment will be described in more detail. FIG. 3 is an enlarged cross-sectional side view showing the vicinity of the electrode portion 2 and the outer cylinder 5 of the sensor unit (hereinafter referred to as “electrical conductivity cell”) 1.

電極部２には、上述のように、第１、第２、第３電極３ａ、３ｂ、３ｃが設けられている。本実施例では、第１電極３ａが、電極軸線方向Ｖにおいて複数の電極３のうち最も電極先端部２ａ側に配置された「先端電極」であり、第３電極３ｃが、最も電極基端部２ｂ側に配置された「基端電極」であり、第２電極３ｂが、中央に配置された「中央電極」である。本実施例では、第１、第２、第３電極３ａ、３ｂ、３ｃの電極軸線方向Ｖにおける幅Ｗは、略同一であり、３ｍｍである。また、本実施例では、電極軸線方向Ｖにおける少なくとも電極先端部２ａから貫通孔６に隣接する位置までの領域の電極部２の直径Ｄ１は、略同一であり、１０ｍｍである。また、本実施例では、第１、第２、第３電極３ａ、３ｂ、３ｃの直径もこの直径Ｄ１と略同一であり、１０ｍｍである。また、本実施例では、第１、第２、第３電極３ａ、３ｂ、３ｃは、電極軸線方向Ｖにおいて略等間隔に設けられている。なお、各電極３の位置は、電極軸線方向Ｖにおける各電極３の中央位置で代表するものとする。本実施例では、第１電極３ａの位置と第２電極３ｂの位置との間の距離Ｌ１、第２電極３ｂの位置と第３電極３ｃの位置との間の距離Ｌ２は、それぞれ３３ｍｍである。 As described above, the electrode portion 2 is provided with the first, second, and third electrodes 3a, 3b, and 3c. In this embodiment, the first electrode 3a is the "tip electrode" arranged on the most electrode tip portion 2a side of the plurality of electrodes 3 in the electrode axial direction V, and the third electrode 3c is the most electrode base end portion. It is the "base end electrode" arranged on the 2b side, and the second electrode 3b is the "center electrode" arranged in the center. In this embodiment, the widths W of the first, second, and third electrodes 3a, 3b, and 3c in the electrode axial direction V are substantially the same, and are 3 mm. Further, in this embodiment, the diameter D1 of the electrode portion 2 in the region from at least the electrode tip portion 2a to the position adjacent to the through hole 6 in the electrode axial direction V is substantially the same, and is 10 mm. Further, in this embodiment, the diameters of the first, second, and third electrodes 3a, 3b, and 3c are also substantially the same as the diameter D1 and are 10 mm. Further, in this embodiment, the first, second, and third electrodes 3a, 3b, and 3c are provided at substantially equal intervals in the electrode axis direction V. The position of each electrode 3 is represented by the central position of each electrode 3 in the electrode axial direction V. In this embodiment, the distance L1 between the position of the first electrode 3a and the position of the second electrode 3b and the distance L2 between the position of the second electrode 3b and the position of the third electrode 3c are 33 mm, respectively. ..

外筒５は、電極部２を取り囲むように配置され、電極軸線方向Ｖにおける電極基端部２ｂ側の端部が、支持部材１０に螺合されて接合される。本実施例では、この外筒５と支持部材１０との螺合による接合部が、電極部２と外筒５との接合部７である。本実施例では、この接合部７に隣接して、外筒５の周方向に相互に間隔をあけて複数の貫通孔６が設けられている。本実施例では、外筒５には、複数の貫通孔６として、外筒５の周方向に沿って略等間隔に４つの貫通孔６が設けられている。つまり、外筒５の周方向において互いに対向する位置に配置された２つの貫通孔６の組が２組設けられている。なお、貫通孔６の数は４個に限定されるものではなく、典型的には２〜４個である。 The outer cylinder 5 is arranged so as to surround the electrode portion 2, and the end portion on the electrode base end portion 2b side in the electrode axial direction V is screwed and joined to the support member 10. In this embodiment, the joint portion between the outer cylinder 5 and the support member 10 by screwing is the joint portion 7 between the electrode portion 2 and the outer cylinder 5. In this embodiment, a plurality of through holes 6 are provided adjacent to the joint portion 7 at intervals in the circumferential direction of the outer cylinder 5. In this embodiment, the outer cylinder 5 is provided with four through holes 6 as a plurality of through holes 6 at substantially equal intervals along the circumferential direction of the outer cylinder 5. That is, two sets of two through holes 6 arranged at positions facing each other in the circumferential direction of the outer cylinder 5 are provided. The number of through holes 6 is not limited to 4, but is typically 2 to 4.

なお、各電極３と外筒５の内周面５ａとの間の距離Ｌ３は、１ｍｍ以上、３ｍｍ以下であることが好ましい。この距離Ｌ３が１ｍｍより小さいと、気泡を排出しにくくなる。また、この距離Ｌ３が３ｍｍより大きいと、測定値の直線性が低下しやすくなることがある。本実施例では、この距離Ｌ３は１．７ｍｍである。また、本実施例では、外筒５の内径Ｄ２は、少なくとも第１電極３ａと対向する位置から第３電極３ｃと対向する位置までの領域の内径は略同一であり、１３．４ｍｍである。また、本実施例では、電極軸線方向Ｖにおける第１電極３ａの電極先端部２ａ側の端部（すなわち、電極先端部２ａ）から外筒５の電極先端部２ａ側の端部までの距離Ｌ４は０．５ｍｍ程度である。 The distance L3 between each electrode 3 and the inner peripheral surface 5a of the outer cylinder 5 is preferably 1 mm or more and 3 mm or less. If this distance L3 is smaller than 1 mm, it becomes difficult to discharge air bubbles. Further, if this distance L3 is larger than 3 mm, the linearity of the measured value may easily decrease. In this embodiment, this distance L3 is 1.7 mm. Further, in this embodiment, the inner diameter D2 of the outer cylinder 5 has substantially the same inner diameter in the region from at least the position facing the first electrode 3a to the position facing the third electrode 3c, and is 13.4 mm. Further, in this embodiment, the distance L4 from the end portion of the first electrode 3a on the electrode tip portion 2a side (that is, the electrode tip portion 2a) to the end portion of the outer cylinder 5 on the electrode tip portion 2a side in the electrode axial direction V. Is about 0.5 mm.

そして、貫通孔６は、電極軸線方向Ｖにおける電極基端部２ｂ側の２つの隅部がそれぞれ略角形状を有し、電極軸線方向Ｖにおける電極先端部２ａ側の２つの隅部がそれぞれＲ形状（円弧形状）を有するか（図４（ａ））又は電極軸線方向Ｖにおける電極先端部２ａ側に円弧形状の辺を有する（図４（ｂ））形状とされる。本実施例では、上述のように、貫通孔６は、外筒５の周方向に沿って略等間隔に４つ設けられている。 In the through hole 6, the two corners on the electrode base end 2b side in the electrode axial direction V each have a substantially angular shape, and the two corners on the electrode tip 2a side in the electrode axial direction V are R. It has a shape (arc shape) (FIG. 4 (a)) or has an arc-shaped side on the electrode tip portion 2a side in the electrode axis direction V (FIG. 4 (b)). In this embodiment, as described above, four through holes 6 are provided at substantially equal intervals along the circumferential direction of the outer cylinder 5.

なお、略角形状とは、２辺が完全に直交する形状のみを意味するものではなく、製造上の理由などにより、９０°に対して±５°程度の範囲の角度を有して交差する形状、あるいは十分に小さい曲率半径（典型的には０．５ｍｍ以下）の円弧形状とされている場合も含むものである。また、Ｒ形状、円弧形状とは、完全に円弧形状であることのみを意味するものではなく、製造上の理由などにより斯界にて一般に許容される程度に円弧形状からずれている場合も含むものである。 The substantially angular shape does not mean only a shape in which the two sides are completely orthogonal to each other, but intersects with an angle in the range of ± 5 ° with respect to 90 ° due to manufacturing reasons. It also includes the case where the shape is an arc shape with a sufficiently small radius of curvature (typically 0.5 mm or less). Further, the R shape and the arc shape do not only mean that they are completely arc shapes, but also include cases where they deviate from the arc shape to a extent generally accepted in the field due to manufacturing reasons or the like. ..

更に説明すると、図４（ａ）は、本実施例における各貫通孔６を示す模式図である。本実施例では、４つの貫通孔６の形状は実質的に同一である。本実施例では、貫通孔６の、電極軸線方向Ｖにおける電極基端部２ｂ側の辺（上辺）６ａ、及び電極先端部２ａ側の辺（下辺）６ｂは、それぞれ平面視において電極軸線方向Ｖと略直交する方向に延びる。そして、これら上辺６ａと下辺６ｂとが、平面視において電極軸線方向Ｖと略平行に延びる２つの辺（縦辺）６ｃで連結されている。ただし、図４（ｂ）に示すように、貫通孔６の電極軸線方向Ｖにおける電極先端部２ａ側の辺（下辺）６ｂを円弧形状の辺としてもよい。 More specifically, FIG. 4A is a schematic view showing each through hole 6 in this embodiment. In this embodiment, the shapes of the four through holes 6 are substantially the same. In this embodiment, the side (upper side) 6a of the through hole 6 on the electrode base end portion 2b side and the side (lower side) 6b on the electrode tip portion 2a side in the electrode axial direction V are respectively the electrode axial direction V in a plan view. Extends in a direction approximately orthogonal to. The upper side 6a and the lower side 6b are connected by two sides (vertical sides) 6c extending substantially parallel to the electrode axis direction V in a plan view. However, as shown in FIG. 4B, the side (lower side) 6b of the through hole 6 on the electrode tip portion 2a side in the electrode axial direction V may be an arc-shaped side.

このように、貫通孔６を、従来の円形から、四角形と円形とを組み合わせた形状とすることで、貫通孔６を通した気泡の排出をしやすくして、測定空間Ｔの上方に気泡が溜まる可能性を低減させると共に、必要以上に貫通孔６を大きくすることで電気伝導率の測定値に対する外筒５の外側のインピーダンスの影響が大きくなることを抑制することができる。つまり、図４（ｄ）に示すように、貫通孔６が従来の円形の場合は、隣接する貫通孔６の境界部分の特に上方に気泡がたまりやすい。これに対して、図４（ｃ）に示すように、貫通孔６の上方の２か所の隅部を略角形状とすることで、特に気泡が溜まりやすい隣接する貫通孔６の境界部分の上方において貫通孔６の開口面積を大きくして（すなわち、隣接する貫通孔６の境界部分を小さくして）、気泡の排出をしやすくすることができる。一方、貫通孔６の下方の２か所の隅部をＲ形状とする（又は下方の辺を円弧形状とする）ことで、貫通孔６の電極３（第３電極３ｃ）に近い側を必要以上に大きくしてしまうことで測定値に対する外筒５の外側のインピーダンスの影響が大きくなることを抑制することができる。また、貫通孔６を必要以上に大きくしなくてよいため、外筒５の外側のインピーダンスの影響を低減するために図８（ｂ）〜（ｄ）を参照して説明したような方法による対策が必要なくなり、電気伝導率セル１の小型化を図ることができる。 In this way, by changing the shape of the through hole 6 from the conventional circular shape to a combination of a quadrangle and a circular shape, it is easy to discharge the air bubbles through the through hole 6, and the air bubbles are generated above the measurement space T. By reducing the possibility of accumulation and making the through hole 6 larger than necessary, it is possible to suppress the influence of the impedance on the outside of the outer cylinder 5 on the measured value of the electric conductivity. That is, as shown in FIG. 4D, when the through hole 6 is a conventional circular shape, air bubbles are likely to accumulate particularly above the boundary portion of the adjacent through hole 6. On the other hand, as shown in FIG. 4C, by forming the two upper corners of the through hole 6 into a substantially angular shape, the boundary portion of the adjacent through hole 6 in which air bubbles are particularly likely to accumulate is formed. The opening area of the through hole 6 can be increased above (that is, the boundary portion of the adjacent through hole 6 can be reduced) to facilitate the discharge of air bubbles. On the other hand, by forming the two lower corners of the through hole 6 into an R shape (or forming the lower side into an arc shape), a side of the through hole 6 close to the electrode 3 (third electrode 3c) is required. By making it larger than this, it is possible to suppress that the influence of the impedance on the outside of the outer cylinder 5 on the measured value becomes large. Further, since the through hole 6 does not have to be made larger than necessary, measures are taken by the method as described with reference to FIGS. 8 (b) to 8 (d) in order to reduce the influence of the impedance on the outside of the outer cylinder 5. Is no longer necessary, and the electric conductivity cell 1 can be miniaturized.

本実施例では、貫通孔６の、平面視における電極軸線方向Ｖと略直交する方向の幅Ｗ１は８ｍｍであり、平面視における電極軸線方向Ｖと略平行な方向の幅Ｗ２は８ｍｍである。そして、本実施例では、上辺６ａと縦辺６ｃとで形成される２つの隅部６ｄはそれぞれ略角形状とされている。貫通孔６は、これに限定されるものではないが、電極軸線方向Ｖと略直交する方向及び電極軸線方向Ｖの幅Ｗ１、Ｗ２が、それぞれ６ｍｍ以上、８ｍｍ以下であることが好ましい。この幅Ｗ１、Ｗ２が６ｍｍより小さいと、気泡の排出がしにくくなる。また、この幅Ｗ１、Ｗ２が８ｍｍより大きくなると、測定値に対する外筒５の外側のインピーダンスの影響が大きくなる傾向がある。なお、この幅Ｗ１、Ｗ２は、外筒５の内周面側の貫通孔６の開口部の幅で代表するものとする。また、換言すると、この幅Ｗ１、Ｗ２は、外筒５の円周長さに対して１０％以上、１５％以下であることが好ましい。なお、この場合の外筒５の円周長さは、電極軸線方向Ｖにおける貫通孔６の略中央における外筒の内周の周長で代表するものとする。また、貫通孔６の下辺６ｂ側の２つの隅部６ｅのＲ形状の曲率半径は、少なくとも貫通孔６の対向する２辺に内接する円の半径の１２．５％以上、１００％以下であることが好ましい。本実施例では、上記対向する２辺とは、上辺６ａと下辺６ｂ、又は２つの縦辺６ｃである。このＲ形状の曲率半径が上記範囲より小さい場合には、上述した隣接する貫通孔６の境界部分の特に上方に溜まりやすい気泡の排出をしやすくしつつ、測定値に対する外筒５の外側のインピーダンスの影響を抑制する効果が得にくくなる。より具体的には、これに限定されるものではないが、このＲ形状の曲率半径は、１ｍｍ以上、４ｍｍ以下が好ましい。 In this embodiment, the width W1 of the through hole 6 in the direction substantially orthogonal to the electrode axis direction V in the plan view is 8 mm, and the width W2 in the direction substantially parallel to the electrode axis direction V in the plan view is 8 mm. In this embodiment, the two corners 6d formed by the upper side 6a and the vertical side 6c each have a substantially angular shape. The through hole 6 is not limited to this, but it is preferable that the widths W1 and W2 of the direction substantially orthogonal to the electrode axial direction V and the electrode axial direction V are 6 mm or more and 8 mm or less, respectively. If the widths W1 and W2 are smaller than 6 mm, it becomes difficult to discharge air bubbles. Further, when the widths W1 and W2 are larger than 8 mm, the influence of the impedance on the outside of the outer cylinder 5 on the measured value tends to be large. The widths W1 and W2 are represented by the width of the opening of the through hole 6 on the inner peripheral surface side of the outer cylinder 5. In other words, the widths W1 and W2 are preferably 10% or more and 15% or less with respect to the circumferential length of the outer cylinder 5. In this case, the circumference of the outer cylinder 5 is represented by the circumference of the inner circumference of the outer cylinder at substantially the center of the through hole 6 in the electrode axis direction V. Further, the radius of curvature of the R shape of the two corners 6e on the lower side 6b side of the through hole 6 is at least 12.5% or more and 100% or less of the radius of the circle inscribed in the two opposite sides of the through hole 6. Is preferable. In this embodiment, the two opposing sides are an upper side 6a and a lower side 6b, or two vertical sides 6c. When the radius of curvature of this R shape is smaller than the above range, the impedance on the outside of the outer cylinder 5 with respect to the measured value is facilitated while facilitating the discharge of air bubbles that tend to accumulate particularly above the boundary portion of the adjacent through hole 6 described above. It becomes difficult to obtain the effect of suppressing the influence of. More specifically, although not limited to this, the radius of curvature of this R shape is preferably 1 mm or more and 4 mm or less.

また、本実施例における電気伝導率セル１は、以下に示すような追加の特徴を有している。 In addition, the electrical conductivity cell 1 in this embodiment has the following additional features.

本実施例では、図５（ａ）に示すように、貫通孔６を形成する縁部のうち、電極軸線方向Ｖにおける電極基端部２ｂ側の一辺（上辺）６ａの縁部６ｆは、外筒５の内周面５ａ側から外周面５ｂ側に向かうにつれて貫通孔６の開口が広がるようにテーパーが設けられている。このように貫通孔６の上辺６ａの縁部６ｆにテーパーを設けることで、貫通孔６を通した気泡の排出のしやすさを更に向上させることができる。気泡の排出のしやすさを更に向上させる観点から、この貫通孔６の縁部のテーパーは、５°以上、４５°以下の角度αで形成されていることが好ましい。なお、この角度αは、電極軸線方向Ｖと略直交する方向に対してなす角度である。本実施例では、この角度αは３０°である。 In this embodiment, as shown in FIG. 5A, of the edges forming the through hole 6, the edge 6f of one side (upper side) 6a on the electrode base end portion 2b side in the electrode axial direction V is outside. A taper is provided so that the opening of the through hole 6 widens from the inner peripheral surface 5a side to the outer peripheral surface 5b side of the cylinder 5. By providing the edge portion 6f of the upper side 6a of the through hole 6 in this way, the ease of discharging air bubbles through the through hole 6 can be further improved. From the viewpoint of further improving the ease of discharging air bubbles, the taper of the edge portion of the through hole 6 is preferably formed at an angle α of 5 ° or more and 45 ° or less. Note that this angle α is an angle formed with respect to a direction substantially orthogonal to the electrode axis direction V. In this embodiment, this angle α is 30 °.

また、本実施例では、図５（ｂ）に示すように、電極軸線方向Ｖにおける、電極部２と外筒５との接合部７に隣接し、少なくとも一部が貫通孔６と対向する領域（これを電極部２の「根本」ともいう。）９の電極部２の外周面２ｃに、電極軸線方向Ｖに沿って電極先端部２ａ側から電極基端部２ｂ側に向かうにつれて外径が大きくなるようにテーパーが設けられている。このように電極部２の根本９にテーパーを設けることで、測定空間Ｔ内の気泡を貫通孔６に向けて導きやすくなり、貫通孔６を通した気泡の排出のしやすさを更に向上させることができる。気泡の排出のしやすさを更に向上させる観点から、この電極部２の根本９のテーパーは、５°以上、６０°以下の角度βで形成されていることが好ましい。なお、この角度βは、電極軸線方向Ｖと略直交する方向に対してなす角度である。本実施例では、この角度βは４５°である。 Further, in this embodiment, as shown in FIG. 5B, a region adjacent to the joint portion 7 between the electrode portion 2 and the outer cylinder 5 in the electrode axial direction V and at least a part facing the through hole 6. (This is also referred to as the "root" of the electrode portion 2.) The outer diameter of the outer peripheral surface 2c of the electrode portion 2 of 9 increases from the electrode tip portion 2a side to the electrode base end portion 2b side along the electrode axial direction V. A taper is provided so as to be large. By providing the taper at the root 9 of the electrode portion 2 in this way, it becomes easier to guide the air bubbles in the measurement space T toward the through hole 6, and the ease of discharging the air bubbles through the through hole 6 is further improved. be able to. From the viewpoint of further improving the ease of discharging air bubbles, the taper of the root 9 of the electrode portion 2 is preferably formed at an angle β of 5 ° or more and 60 ° or less. Note that this angle β is an angle formed with respect to a direction substantially orthogonal to the electrode axis direction V. In this embodiment, this angle β is 45 °.

また、電極軸線方向Ｖにおいて、電極基端部２ｂ側の貫通孔６の端部（上端）の位置は、電極部２と外筒５との接合部７と略同じ位置、又はこの接合部７に対して電極先端部２ａとは反対側であることが好ましい。つまり、図６に示す距離Ｌ５が０ｍｍ以上であることが好ましい。このような位置関係とすることで、貫通孔６より上方に気泡が溜まるデッドスペースが形成されないようにすることができる。本実施例では、図３に示すように、貫通孔６の上端の位置を、電極部２と外筒５との接合部７と略同じ位置とした。なお、貫通孔６の上端の位置は、外筒５の内周面側の貫通孔６の開口部における上端の位置で代表するものとする。 Further, in the electrode axial direction V, the position of the end portion (upper end) of the through hole 6 on the electrode base end portion 2b side is substantially the same as the joint portion 7 between the electrode portion 2 and the outer cylinder 5, or this joint portion 7. It is preferable that the side is opposite to the electrode tip portion 2a. That is, it is preferable that the distance L5 shown in FIG. 6 is 0 mm or more. With such a positional relationship, it is possible to prevent the formation of a dead space in which air bubbles accumulate above the through hole 6. In this embodiment, as shown in FIG. 3, the position of the upper end of the through hole 6 is set to substantially the same position as the joint portion 7 between the electrode portion 2 and the outer cylinder 5. The position of the upper end of the through hole 6 is represented by the position of the upper end in the opening of the through hole 6 on the inner peripheral surface side of the outer cylinder 5.

また、図６に示すように、電極軸線方向Ｖにおいて、最も電極基端部２ｂ側に配置された第３電極（基端電極）３ｃの電極基端部２ｂ側の端部から、電極先端部２ａ側の貫通孔６の端部（下端）までの距離Ｌ６は、０ｍｍ以上、２ｍｍ以下（貫通孔６の端部（下端）の方が電極基端部２ｂ側）であることが好ましい。このような位置関係とすることで、電気伝導率セル１の小型化を図ることができる。本実施例では、貫通孔６の上方の隅部６ｄを略角形状、下方の隅部６ｅをＲ形状とすることで、貫通孔６の電極３（第３電極）に近い側を必要以上に大きくすることなく気泡の排出を良好に行うことができる。そのため、外筒５の外側のインピーダンスの影響による測定値の誤差を抑制しつつ、貫通孔６と電極３（第３電極３ｃ）との間の距離を可及的に小さくすることができる。本実施例では、上記距離Ｌ６は０ｍｍである。なお、貫通孔６の下端の位置は、外筒５の内周面側の貫通孔６の開口部における下端の位置で代表するものとする。 Further, as shown in FIG. 6, in the electrode axial direction V, from the end portion of the third electrode (base end electrode) 3c arranged on the electrode base end portion 2b side to the electrode base end portion 2b side, the electrode tip portion The distance L6 to the end (lower end) of the through hole 6 on the 2a side is preferably 0 mm or more and 2 mm or less (the end (lower end) of the through hole 6 is on the electrode base end 2b side). With such a positional relationship, the electric conductivity cell 1 can be miniaturized. In this embodiment, the upper corner 6d of the through hole 6 has a substantially angular shape, and the lower corner 6e has an R shape, so that the side of the through hole 6 close to the electrode 3 (third electrode) is unnecessarily formed. Bubbles can be discharged satisfactorily without increasing the size. Therefore, the distance between the through hole 6 and the electrode 3 (third electrode 3c) can be made as small as possible while suppressing the error of the measured value due to the influence of the impedance on the outside of the outer cylinder 5. In this embodiment, the distance L6 is 0 mm. The position of the lower end of the through hole 6 is represented by the position of the lower end in the opening of the through hole 6 on the inner peripheral surface side of the outer cylinder 5.

３．セル定数に対する影響など
例えば、従来の電気伝導率セル１の外筒５に代えて本発明に従う外筒５を適用し、本発明に係る電気伝導率セル１を構成する場合、外筒５の違いにより測定値（セル定数）が大幅に変化することを避けることが望ましい。なお、電極間の抵抗をＲ、電極間の距離をＬ（ｍ）、電極の面積をＳ（ｍ^２）、電気伝導率をκ（Ｓ／ｍ）とすると、次の関係が成り立つ。
Ｒ＝Ｌ／Ｓ×１／κ
κ＝Ｌ／Ｓ×１／Ｒ
上記式中のＬ／Ｓは電気伝導率セル１に固有の値でセル定数と呼ばれる。セル定数が大きければ大きいほど、同じ溶液でもインピーダンスの測定結果は大きくなる。電極間の距離Ｌ及び電極の面積Ｓが変わっていない場合に、セル定数Ｌ／Ｓが変われば、外筒５の外側のインピーダンスの影響を受けていることになる。そのため、所定の電気伝導率の被検液を用いてセル定数を測定する（あるいはセル定数を固定して所定の電気伝導率の被検液の電気伝導率を測定する）ことで、外筒５の外部のインピーダンスの影響の有無、程度を判断することができる。 3. 3. Effect on cell constant, etc. For example, when the outer cylinder 5 according to the present invention is applied instead of the outer cylinder 5 of the conventional electric conductivity cell 1 to form the electric conductivity cell 1 according to the present invention, the difference between the outer cylinders 5 and the like. It is desirable to avoid a large change in the measured value (cell constant). If the resistance between the electrodes is R, the distance between the electrodes is L (m), the area of the electrodes is S (m ² ), and the electrical conductivity is κ (S / m), the following relationship holds.
R = L / S × 1 / κ
κ = L / S × 1 / R
The L / S in the above formula is a value peculiar to the electric conductivity cell 1 and is called a cell constant. The larger the cell constant, the larger the impedance measurement result for the same solution. If the cell constant L / S changes when the distance L between the electrodes and the area S of the electrodes do not change, it means that the impedance on the outside of the outer cylinder 5 is affected. Therefore, by measuring the cell constant using a test solution having a predetermined electrical conductivity (or fixing the cell constant and measuring the electric conductivity of the test solution having a predetermined electrical conductivity), the outer cylinder 5 It is possible to judge the presence or absence and degree of influence of the external impedance of.

ここで、貫通孔６の形状が異なる外筒５について、測定値に対する影響について調べた。ここでは、比較例、本実施例の外筒５について調べた。比較例の外筒５では、本実施例の外筒５の貫通孔６に代えて、本実施例の外筒５の貫通孔６と実質的に同じ位置に、直径８ｍｍの円形の貫通孔６が４つ設けられている。そして、比較例、本実施例の外筒５を同じ電気伝導率セル（東亜ディーケーケー株式会社製、ＣＴ−２７１１２Ｂ）１に装着し、セル定数として同じ値である２５０ｍ^−１を用いて被検液としての標準液の電気伝導率の測定を行った。標準液としては、２５℃に温調したＫＣｌ水溶液（０．０１ｍｏｌ／Ｌ（旧ＪＩＳ標準液Ｃ）、０．１ｍｏｌ／Ｌ（旧ＪＩＳ標準液Ｂ）、１ｍｏｌ／Ｌ（旧ＪＩＳ標準液Ａ））を用いた。また、これら各標準液を用いて各例の電気伝導率セルを校正し、それぞれの標準液でのセル定数を求めた。 Here, the influence of the outer cylinder 5 having a different shape of the through hole 6 on the measured value was investigated. Here, the outer cylinder 5 of the comparative example and the present embodiment was examined. In the outer cylinder 5 of the comparative example, instead of the through hole 6 of the outer cylinder 5 of the present embodiment, the circular through hole 6 having a diameter of 8 mm is substantially the same as the through hole 6 of the outer cylinder 5 of the present embodiment. Are provided in four. Then, the outer cylinder 5 of the comparative example and the present embodiment is mounted on the same electrical conductivity cell (CT-27112B, manufactured by DKK-TOA CORPORATION) 1, and the test solution is used as the cell constant of 250 m ^-1. The electrical conductivity of the standard solution was measured. As the standard solution, a KCl aqueous solution whose temperature was adjusted to 25 ° C. (0.01 mol / L (former JIS standard solution C), 0.1 mol / L (former JIS standard solution B), 1 mol / L (former JIS standard solution A)). ) Was used. In addition, the electrical conductivity cells of each example were calibrated using each of these standard solutions, and the cell constants of each standard solution were determined.

なお、上述のように異なる構成の外筒５を用いた他は、比較例及び本実施例の電気伝導率セル１の構成は実質的に同じであり、同一の計測装置を用いて、実質的に同じ環境で測定を行った。また、いずれの測定も外筒５の内部には気泡が実質的に無い状態で行った。実験に用いた電気伝導率セル１の主要部（電極部２の電極の構成や配置など）は、前述の本実施例の電気伝導率セル１と同等のものである。 In addition, except that the outer cylinders 5 having different configurations are used as described above, the configurations of the electric conductivity cells 1 of the comparative example and the present embodiment are substantially the same, and substantially the same measuring device is used. The measurement was performed in the same environment. In addition, all the measurements were performed in a state where there were substantially no bubbles inside the outer cylinder 5. The main part of the electric conductivity cell 1 used in the experiment (such as the configuration and arrangement of the electrodes of the electrode part 2) is the same as that of the above-mentioned electric conductivity cell 1 of the present embodiment.

結果を表１、表２に示す。表１（ａ）は、各例について電気伝導率の測定値と、各標準液の電気伝導率の理論値と、を示す。また、表１（ｂ）は、表１（ａ）の結果に基づく、比較例の電気伝導率の測定値に対する本実施例の電気伝導率の測定値の差（相対値（％）：比較例の測定値を１００％とした場合の本実施例の測定値の１００分率）を示す。表２（ａ）は、各例の電気伝導率セルを各標準液で校正した場合のセル定数を示す。また、表２（ｂ）は、表２（ａ）の結果に基づく、比較例の電気伝導率セルのセル定数に対する本実施例の電気伝導率セルのセル定数の差（相対値（％）：比較例のセル定数を１００％とした場合の本実施例のセル定数の１００分率）を示す。 The results are shown in Tables 1 and 2. Table 1 (a) shows the measured value of the electric conductivity for each example and the theoretical value of the electric conductivity of each standard solution. Further, Table 1 (b) shows the difference between the measured value of the electric conductivity of the comparative example and the measured value of the electric conductivity of the present embodiment based on the result of Table 1 (a) (relative value (%): comparative example. (100% of the measured value of this example) is shown when the measured value of is 100%. Table 2 (a) shows the cell constants when the electric conductivity cells of each example are calibrated with each standard solution. Further, Table 2 (b) shows the difference (relative value (%)) of the cell constant of the electric conductivity cell of this example with respect to the cell constant of the electric conductivity cell of the comparative example based on the result of Table 2 (a). The cell constant of this example is 100%) when the cell constant of the comparative example is 100%.

表１、表２からわかるように、いずれの標準液についても、比較例の外筒５を用いた場合と本実施例の外筒５を用いた場合とで測定値、セル定数のずれは１％未満である。このように、外筒５の貫通孔６を従来の円形から本実施例の形状に変更したことによる電気伝導率の測定値に対する影響はないことがわかった。 As can be seen from Tables 1 and 2, for each of the standard solutions, the deviation of the measured value and the cell constant is 1 between the case where the outer cylinder 5 of the comparative example is used and the case where the outer cylinder 5 of this example is used. Less than%. As described above, it was found that changing the through hole 6 of the outer cylinder 5 from the conventional circular shape to the shape of the present embodiment has no effect on the measured value of the electric conductivity.

４．効果
本実施例の電気伝導率セル１を様々な条件で被検液に浸漬して確認したところ、従来の円形の貫通孔６を備えた外筒５を有する電気伝導率セル１よりも気泡を排出しやすいことがわかった。 4. Effect When the electrical conductivity cell 1 of this example was immersed in the test solution under various conditions and confirmed, bubbles were generated more than the conventional electrical conductivity cell 1 having an outer cylinder 5 having a circular through hole 6. It turned out to be easy to discharge.

以上説明したように、本実施例によれば、貫通孔６の上方の隅部６ｄを略角形状、下方の隅部６ｅをＲ形状（あるいは円弧形状の辺）とすることで、隣接する貫通孔６の境界部分の特に上方に気泡が溜まりやすくなることを抑制することができる。これにより、貫通孔６を必要以上に大きくすることで外筒５の外側のインピーダンスが測定値に影響することを抑制しつつ、外筒５の貫通孔６を通した外筒５の内部から外部への気泡の排出をしやすくすることができる。 As described above, according to the present embodiment, the upper corner portion 6d of the through hole 6 has a substantially angular shape, and the lower corner portion 6e has an R shape (or an arc-shaped side), whereby the adjacent penetrations are made. It is possible to prevent air bubbles from easily accumulating particularly above the boundary portion of the hole 6. As a result, by making the through hole 6 larger than necessary, the impedance on the outside of the outer cylinder 5 is suppressed from affecting the measured value, and the inside to the outside of the outer cylinder 5 through the through hole 6 of the outer cylinder 5 is suppressed. It is possible to facilitate the discharge of air bubbles to.

［その他の実施例］
以上、本発明を具体的な実施例に即して説明したが、本発明は上述の実施例に限定されるものではない。 [Other Examples]
Although the present invention has been described above with reference to specific examples, the present invention is not limited to the above-mentioned examples.

上述の実施例では、電気伝導率セルは測定回路を備えた電気伝導率測定用プローブのセンサユニットとして構成されていたが、実質的に電気伝導率セルからなり、アナログ信号を計測装置本体に送り、計測装置本体が備えた測定回路によって電気伝導率が求められるものであってもよい。 In the above-described embodiment, the electric conductivity cell is configured as a sensor unit of a probe for measuring electric conductivity having a measuring circuit, but it is substantially composed of an electric conductivity cell and sends an analog signal to the measuring device main body. , The electric conductivity may be obtained by the measuring circuit provided in the measuring device main body.

また、上述の実施例では電気伝導率セルは３極式のものであったが、２極式、４極式、５極式などのものであってもよい。 Further, in the above-described embodiment, the electric conductivity cell is of a 3-pole type, but may be a 2-pole type, a 4-pole type, a 5-pole type, or the like.

１電気伝導率セル（センサユニット）
２電極部
３電極
５外筒
１００電気伝導率測定用プローブ
１１０測定ユニット 1 Electrical conductivity cell (sensor unit)
2 Electrode 3 Electrode 5 Outer cylinder 100 Electrical conductivity measurement probe 110 Measuring unit

Claims

An electrode portion that is a substantially columnar electrode portion and is provided with a plurality of electrodes at intervals along the axial direction of the electrode portion.
It is a substantially cylindrical outer cylinder, and is arranged so as to form a substantially cylindrical space between the inner peripheral surface of the outer cylinder and the outer peripheral surface of the electrode portion at a distance from the electrode portion. The end portion of the electrode portion on the tip end side in the axial direction is open, and the end portion of the electrode portion on the proximal end side in the axial direction is mutually oriented along the circumferential direction of the outer cylinder. An outer cylinder with multiple through holes formed at intervals,
In an electrical conductivity cell with
In the through hole, the two corners on the base end side in the axial direction each have a substantially angular shape, and the two corners on the tip side in the axial direction each have an R shape. An electric conductivity cell characterized by having an arc-shaped side on the tip end side in the axial direction.

The electric conductivity cell according to claim 1, wherein the radius of curvature of the R shape is at least 12.5% or more and 100% or less of the radius of the circle inscribed in the two opposite sides of the through hole. ..

The electric conductivity cell according to claim 1 or 2, wherein the radius of curvature of the R shape is 1 mm or more and 4 mm or less.

Among the edges forming the through hole, the edge of one side of the base end side in the axial direction is such that the opening of the through hole widens from the inner peripheral surface side to the outer peripheral surface side of the outer cylinder. The electric conductivity cell according to any one of claims 1 to 3, wherein the taper is provided on the surface.

On the outer peripheral surface of the electrode portion in a region adjacent to the joint portion between the electrode portion and the outer cylinder in the axial direction and at least a part facing the through hole, the tip portion side along the axial direction. The electric conductivity cell according to any one of claims 1 to 4, wherein a taper is provided so that the outer diameter becomes larger toward the base end portion side.

In the axial direction, the position of the end portion of the through hole on the base end portion side is substantially the same as the joint portion between the electrode portion and the outer cylinder, or is opposite to the tip portion with respect to the joint portion. The electrical conductivity cell according to any one of claims 1 to 5, characterized in that it is on the side.

The claim is characterized in that, in the axial direction, the distance from the end of the proximal electrode on the proximal end side to the end of the through hole on the distal end side is 0 mm or more and 2 mm or less. The electrical conductivity cell according to any one of 1 to 6.