JP5829351B1

JP5829351B1 - Wetted electromagnetic flow meter

Info

Publication number: JP5829351B1
Application number: JP2015149693A
Authority: JP
Inventors: 保小林; 長興嘉山; 慶野元
Original assignee: Tokyo Keiso Co Ltd
Current assignee: Tokyo Keiso Co Ltd
Priority date: 2015-07-29
Filing date: 2015-07-29
Publication date: 2015-12-09
Anticipated expiration: 2035-07-29
Also published as: JP2017032304A

Abstract

【課題】流量分布の影響を受けることなく、大きな口径の管路に対しても良好な測定精度を得る。【解決手段】金属管１１の内周には絶縁材１２がライニングされており、一対の接液電極板１３ａ、１３ｂが絶縁材１２の内周面に貼り付けられている。接液電極板１３ａ、１３ｂはそれぞれ、同形の２枚の金属板である表面板１５と裏面板１６とから成り、これらは溶接等の手段により貼り合わせにより結合されている。裏面板１６の背面には、後方に突出するＬ字片状、鉤状の突起から成る多数の係止部１７が設けられており、これらの係止部１７は絶縁材１２中において固定され、接液電極板１３ａ、１３ｂの脱落を防止している。【選択図】図７An object of the present invention is to obtain good measurement accuracy even for a pipe having a large diameter without being affected by a flow rate distribution. An insulating material is lined on an inner periphery of a metal tube, and a pair of liquid contact electrode plates is bonded to an inner peripheral surface of the insulating material. Each of the wetted electrode plates 13a and 13b includes a front plate 15 and a back plate 16 which are two metal plates having the same shape, and these are bonded together by means such as welding. On the back surface of the back plate 16, there are provided a large number of locking portions 17 made of L-shaped and hook-shaped protrusions protruding backward, and these locking portions 17 are fixed in the insulating material 12. The liquid contact electrode plates 13a and 13b are prevented from falling off. [Selection] Figure 7

Description

本発明は、測定流体の流速分布の影響を受けず、特に口径の大きな管路に好適な接液式電磁流量計に関するものである。 The present invention relates to a wetted electromagnetic flow meter that is not affected by the flow velocity distribution of a measurement fluid and that is particularly suitable for a pipe having a large diameter.

一般に、管路中に配置した流量計では、その測定精度を向上させるために、流量計の前後の配管中に直管部を十分にとることにより、流速分布が安定した状態で測定することが望まれている。 In general, in a flow meter placed in a pipeline, in order to improve the measurement accuracy, it is possible to measure in a state where the flow velocity distribution is stable by taking sufficient straight pipe parts in the piping before and after the flow meter. It is desired.

なかでも、電磁流量計は比較的に直管部が少なくて済むが、更にその改善を図るために、直管部が殆どなくとも流速分布の影響をあまり受けない容量式電磁流量計として、特許文献１が知られている。 Among them, the electromagnetic flow meter requires a relatively small number of straight pipe parts, but in order to further improve it, as a capacitive electromagnetic flow meter that is hardly affected by the flow velocity distribution even if there is almost no straight pipe part, it is patented. Document 1 is known.

特許文献１はＭＩＴのクリストファ・Ｃ・スミス氏の論文：「電磁流量計の理論的考察」における積分型電磁流量計の基本式を背景としてなされた発明である。 Patent Document 1 is an invention made in the background of the basic formula of an integral electromagnetic flow meter in MIT's Christopher C. Smith's paper: "Theoretical Consideration of an Electromagnetic Flow Meter".

この特許文献１の主たる特徴点は、「検出電極の管軸方向の電極長を、前記管路の管壁に立つ法線方向と前記管軸及び前記磁界に直交する軸とでなす角度の余弦に比例するようにした容量式電磁流量計」である。角度の余弦に比例した形状を持つ一対のリーフ形状の検出電極を、測定流体とは電気的に絶縁して管路の外周面に配置することにより、流量分布に依存せずに流量を測定することができる。 The main feature of this patent document 1 is that “the cosine of the angle formed by the normal direction standing on the tube wall of the pipe and the axis perpendicular to the tube axis and the magnetic field is the electrode length of the detection electrode in the tube axis direction. It is a capacitive electromagnetic flow meter that is proportional to A pair of leaf-shaped detection electrodes having a shape proportional to the cosine of the angle is electrically insulated from the measurement fluid and arranged on the outer peripheral surface of the pipe, thereby measuring the flow rate without depending on the flow distribution. be able to.

特許文献１の容量式電磁流量計は、図９や特許文献１の段落００５６に示すように、絶縁性の円形管路の外周面に導電性材料により電極幅を余弦であるｃｏｓθとする一対の面電極２ａ、２ｂを形成し、測定流体の流量を電磁誘導により発生した誘導起電力を容量結合により検出している。 As shown in FIG. 9 and Paragraph 0056 of Patent Document 1, the capacitive electromagnetic flow meter of Patent Document 1 is a pair of electrodes having a cosine of cosine that is a cosine by an electrically conductive material on the outer peripheral surface of an insulating circular pipe. The surface electrodes 2a and 2b are formed, and the induced electromotive force generated by electromagnetic induction is detected by capacitive coupling for the flow rate of the measurement fluid.

このように、絶縁性の円形管路の外周面に電極２ａ、２ｂを配置する場合では、円形管路は温度変化等に強く、誘電容量の安定性を維持するアルミナ等の絶縁性セラミック材料で成型された管体１を使用することが必要である。 As described above, when the electrodes 2a and 2b are arranged on the outer peripheral surface of the insulating circular pipe, the circular pipe is made of an insulating ceramic material such as alumina which is resistant to temperature change and maintains the stability of the dielectric capacitance. It is necessary to use a molded tube 1.

図１０により特許文献１の基本原理を説明する。面電極２ａ、２ｂの管軸方向の長さつまり電極幅は、管体１の中央断面を横切る線ｙ−ｙ’の管軸ｚ−ｚ’と交差する点であって、各面電極２ａ、２ｂの中央を結ぶ線ｘ−ｘ’を基準として、管路の内周面とのなす角θの余弦、つまりｃｏｓθに比例するように形成されている。 The basic principle of Patent Document 1 will be described with reference to FIG. The length of the surface electrodes 2a, 2b in the tube axis direction, that is, the electrode width, is a point intersecting the tube axis zz ′ of the line yy ′ crossing the central section of the tube body 1, and each surface electrode 2a, With reference to a line xx ′ connecting the centers of 2b, the cosine of the angle θ formed with the inner peripheral surface of the pipe, that is, is proportional to cos θ.

断面半径ｒの円管路に流量Ｑの導電性流体を流す。流量Ｑの方向をｚ軸、ｚ軸と直交する円形断面において磁界Ｈｏの印加方向をｙ軸、ｙ軸と直交する方向をｘ軸とする。 A conductive fluid having a flow rate Q is caused to flow through a circular pipe having a cross-sectional radius r. In the circular cross section perpendicular to the z axis, the direction of the flow rate Q is the y axis, and the direction perpendicular to the y axis is the x axis in the circular cross section perpendicular to the z axis.

このような構成において、ｘ軸からの角度θにおける点Ｐ（θ）における発生起電力から、マックスウエルの方程式を解いて流量Ｑを求めると、三次元モデルにおける基本式（１）が得られる。
μＨｏＱＬ=−∫φ（ｓ）ｉｘ・ｉｎｄｓ（１） In such a configuration, when the flow rate Q is obtained by solving Maxwell's equation from the generated electromotive force at the point P (θ) at the angle θ from the x-axis, the basic equation (1) in the three-dimensional model is obtained.
μHoQL = −∫φ (s) ix · inds (1)

ここで、μは流体の導磁率、Ｈｏは磁界、Ｌはｘ軸方向の長さ、ｉｘはｘ軸における単位ベクトル、ｉｎはＰ点における法線の単位ベクトル、φはＰ点における電位である。
円形二次元断面においては、ｉｘ・ｉｎ＝ｃｏｓθなので、
μＨｏＱ＝−∫φ（ｃ）ｉｘ・ｉｎｄｃ（２）
Ｂｏ＝μＨｏなので、
Ｑ＝−（ａ／Ｂｏ）∫φ（θ）ｃｏｓθｄθ （３） Where μ is the magnetic conductivity of the fluid, Ho is the magnetic field, L is the length in the x-axis direction, ix is the unit vector on the x-axis, in is the normal unit vector at the P point, and φ is the potential at the P point. .
In a circular two-dimensional cross section, since ix · in = cos θ,
μHoQ = −∫φ (c) ix · indc (2)
Since Bo = μHo,
Q = − (a / Bo) ∫φ (θ) cos θdθ (3)

（３）式から、流速方向に直交する向きに磁界Ｈｏを加え、一対の面電極２ａ、２ｂの円管路断面のｘ軸から角度θの位置の電極幅をｃｏｓθとして、誘起された電位にｃｏｓθの重み付けを行う。そして、これらを積分加算すれば、流速分布に依存しない電流の起電力信号が得られる。 From equation (3), the magnetic field Ho is applied in a direction orthogonal to the flow velocity direction, and the induced potential is set to cos θ, where the electrode width at the angle θ from the x-axis of the circular cross section of the pair of surface electrodes 2a, 2b is cos θ. Cos θ is weighted. If these are integrated and added, an electromotive force signal of a current independent of the flow velocity distribution can be obtained.

また、上位液面ＡＤが磁界Ｈｏと直交していれば、（３）式が成り立つので、非満水の場合にも測定が可能となる。 Further, if the upper liquid level AD is orthogonal to the magnetic field Ho, the equation (3) is established, so that measurement is possible even when the water level is not full.

特許第３０３１０９６号公報Japanese Patent No. 3031096

この特許文献１による容量式電磁流量計は、上述したように検出信号の精度維持のために、絶縁体である管壁材の温度特性等に強く、誘電容量の安定性を維持したアルミナ等のセラミック材料により管体を使用する必要がある。 As described above, the capacitive electromagnetic flow meter according to Patent Document 1 is resistant to the temperature characteristics of the tube wall material that is an insulator and maintains the stability of the dielectric capacitance in order to maintain the accuracy of the detection signal. It is necessary to use a tube with a ceramic material.

しかし、例えば発展途上国等の上下水道においては、口径が１５０ｍｍを越える中口径や１０００ｍｍを越える大口径の管体が要求されるが、１ＭＰａ以上の耐圧を有するセラミックパイプの口径の上限は高々２００ｍｍ程度であり、上述の中口径、大口径のセラミック材料による管路の製造はなかなか困難である。 However, in the water and sewage systems of developing countries, for example, a pipe having a medium diameter exceeding 150 mm or a large diameter exceeding 1000 mm is required. Therefore, it is difficult to manufacture a pipeline using the above-mentioned medium-diameter and large-diameter ceramic materials.

また、電極を測定流体に接液して測定する接液式電磁流量計は知られているが、この場合の電極は点状電極であり、一対の点状電極を管路内に露出させて測定する方式である。しかし、この点状電極は中心対称流に対しては測定可能であるが、偏流があると測定誤差が大きくなるという問題もある。 In addition, there are known wetted electromagnetic flowmeters that measure by contacting an electrode with a measurement fluid. In this case, the electrode is a point electrode, and a pair of point electrodes are exposed in a pipe line. This is a measurement method. However, this point-like electrode can be measured for a centrally symmetric flow, but there is also a problem that a measurement error increases if there is a drift.

本発明の目的は、上述の課題を解決し、特許文献１の発明の原理を利用し、流量分布の影響を受けることなく、口径が中口径、大口径の管路に対しても適用可能で、良好な測定精度が得られる接液式電磁流量計を提供することにある。 The object of the present invention solves the above-mentioned problems, uses the principle of the invention of Patent Document 1, and can be applied to pipes having a medium diameter and a large diameter without being affected by the flow rate distribution. Another object of the present invention is to provide a wetted electromagnetic flow meter capable of obtaining good measurement accuracy.

上記目的を達成するための本発明に係る接液式電磁流量計は、内面を絶縁材により断面円形に形成した管路と、該管路の管軸に直交して測定流体に磁界を形成する励磁手段と、前記管軸及び前記磁界と直交する方向であって前記絶縁材の内周面に対向して係止し相互に絶縁した一対の接液電極板とを備え、前記接液電極板に生ずる起電力を基に測定流体の流量を測定する接液式電磁流量計であって、前記接液電極板は表面板と裏面板との同形の２枚の金属板を貼り合わせて形成し、前記表面板を平面状の接液面とし、前記裏面板の裏面に設けた係止部により前記絶縁材に密着して係止し、前記接液電極板の管軸方向の電極長を、前記管路の内壁に立つ法線方向と前記管軸及び前記磁界に直交する軸とでなす角度θの余弦に比例するようにしたことを特徴とする。 In order to achieve the above object, a wetted electromagnetic flowmeter according to the present invention includes a pipe having an inner surface formed in a circular cross section by an insulating material, and forms a magnetic field in a measurement fluid perpendicular to the pipe axis of the pipe. An excitation means; a pair of liquid contact electrode plates that are in a direction perpendicular to the tube axis and the magnetic field and are opposed to the inner peripheral surface of the insulating material and insulated from each other; A wetted electromagnetic flowmeter that measures the flow rate of the measurement fluid based on the electromotive force generated in the substrate, wherein the wetted electrode plate is formed by bonding two identical metal plates, a front plate and a back plate. The surface plate is a flat liquid contact surface, and is locked in close contact with the insulating material by a locking portion provided on the back surface of the back plate, and the electrode length in the tube axis direction of the liquid contact electrode plate is It is proportional to the cosine of the angle θ formed by the normal direction standing on the inner wall of the pipe and the axis perpendicular to the pipe axis and the magnetic field. And wherein the door.

本発明に係る接液式電磁流量計によれば、流速分布による誤差を少なくするために、所定形状を持つ接液電極板を管路の絶縁材の内面に取り付け、これらの接液電極板から得られる管路内の起電力を荷重平均して取り出すことで、流速分布の影響を少なくできる。また、中口径、大口径の管路についても良好な精度を安価に実現できる。更に、本発明では非満水回路においても、同様に測定可能である。 According to the wetted electromagnetic flow meter according to the present invention, in order to reduce errors due to the flow velocity distribution, wetted electrode plates having a predetermined shape are attached to the inner surface of the insulating material of the pipe line, The influence of the flow velocity distribution can be reduced by taking out the electromotive force in the obtained pipe line with a load average. Also, good accuracy can be realized at low cost for medium-diameter and large-diameter pipes. Furthermore, in the present invention, it is possible to measure in a non-full circuit as well.

実施例の接液式電磁流量計の基本的構成図である。It is a basic block diagram of the liquid-contact type electromagnetic flow meter of an Example. 管路の切断斜視図である。It is a cut perspective view of a pipe line. 接液電極板の平面図である。It is a top view of a liquid-contact electrode plate. 接液電極板の配置の変形例の説明図である。It is explanatory drawing of the modification of arrangement | positioning of a liquid-contact electrode plate. 表面板と裏面板の断面図である。It is sectional drawing of a surface board and a back surface board. 他の実施例の裏面板の断面図である。It is sectional drawing of the back surface board of another Example. 接液電極板の係止部を絶縁材中に埋設した状態の断面図である。It is sectional drawing of the state which embed | buried the latching | locking part of the liquid-contact electrode plate in the insulating material. 測定回路の構成図である。It is a block diagram of a measurement circuit. 特許文献１の容量式電磁流量計の断面構成図である。2 is a cross-sectional configuration diagram of a capacitive electromagnetic flow meter of Patent Document 1. FIG. 特許文献１の容量式電磁流量計の測定原理の説明図である。It is explanatory drawing of the measurement principle of the capacitive electromagnetic flow meter of patent document 1. FIG.

本発明を図１〜図８に図示の実施例により詳細に説明する。
図１は接液式電磁流量計の基本的構成図、図２は断面円形の管路の切断斜視図であり、例えばＳＵＳ製の金属管１１の内側に絶縁材１２がライニングされている。絶縁材１２の内周面には、管路の管軸を挟んで図３に示すように一対の接液電極板１３ａ、１３ｂが対向して配置され、絶縁材１２に密着して係止されている。また、励磁手段により管軸に沿って平行に、管軸と直交した方向に均一磁場Ｂの印加による磁界Ｈｏが形成されている。そして、接液電極板１３ａ、１３ｂから管路外に信号線１４ａ、１４ｂが引き出されている。 The present invention will be described in detail with reference to the embodiments shown in FIGS.
FIG. 1 is a basic configuration diagram of a wetted electromagnetic flow meter, and FIG. 2 is a cut perspective view of a pipe having a circular cross section. For example, an insulating material 12 is lined inside a metal pipe 11 made of SUS. As shown in FIG. 3, a pair of liquid contact electrode plates 13 a and 13 b are arranged on the inner peripheral surface of the insulating material 12 so as to sandwich the tube axis of the conduit, and are closely attached and locked to the insulating material 12. ing. In addition, a magnetic field Ho is formed by applying a uniform magnetic field B in a direction perpendicular to the tube axis in parallel with the tube axis by the excitation means. The signal lines 14a and 14b are drawn out from the liquid contact electrode plates 13a and 13b to the outside of the pipeline.

図３は一対の接液電極板１３ａ、１３ｂの平面図である。この金属板から成る接液電極板１３ａ、１３ｂの形状は、特許文献１の面電極２ａ、２ｂと同様であり、接液電極板１３ａ、１３ｂの管軸方向の電極長ａが、管路の内壁に立つ法線方向と管軸及び磁界に直交する軸とでなす角度θの余弦、つまりｃｏｓθに比例するように形成された一対のリーフ形状とされている。そして、各接液電極板１３ａ、１３ｂの管軸方向と直交する長さｂの２倍が、絶縁材１２の内周と等しくされている。 FIG. 3 is a plan view of the pair of liquid contact electrode plates 13a and 13b. The shape of the wetted electrode plates 13a and 13b made of this metal plate is the same as that of the surface electrodes 2a and 2b of Patent Document 1, and the electrode length a in the tube axis direction of the wetted electrode plates 13a and 13b A pair of leaf shapes formed so as to be proportional to the cosine of an angle θ formed by the normal direction standing on the inner wall and the axis perpendicular to the tube axis and the magnetic field, that is, cos θ. Then, twice the length b perpendicular to the tube axis direction of each liquid contact electrode plate 13a, 13b is made equal to the inner circumference of the insulating material 12.

しかし、このまま接液電極板１３ａ、１３ｂの角度θを０〜９０゜として、絶縁材１２に取り付けると、接液電極板１３ａ、１３ｂ同士は短絡することになるので、接液電極板１３ａ、１３ｂの先端の細状部ｃをそれぞれ切欠して、相互に絶縁状態のすることが必要である。 However, if the liquid contact electrode plates 13a and 13b are attached to the insulating material 12 with the angle θ of the liquid contact electrode plates 13a and 13b being 0 to 90 °, the liquid contact electrode plates 13a and 13b are short-circuited. It is necessary to cut out the narrow portions c at the tips of each other so as to be insulated from each other.

なお、接液電極板１３ａ、１３ｂの細状部ｃを切欠することなく、更に絶縁状態を維持すためには、図４に示すように接液電極板１３ａ、１３ｂ同士を管軸方向に僅かにずらせて貼り付ける。或いは、相互に円周方向から稍々傾けて、一対の接液電極板１３ａ、１３ｂの細状部ｃ同士を完全に離隔すればよい。この場合においても、若干の誤差は発生するものの、その誤差は細状部ｃを切欠する場合の誤差よりも小さくて済む。 In order to maintain the insulation state without cutting out the narrow portions c of the liquid contact electrode plates 13a and 13b, the liquid contact electrode plates 13a and 13b are slightly moved in the tube axis direction as shown in FIG. Paste it. Alternatively, the narrow portions c of the pair of liquid contact electrode plates 13a and 13b may be completely separated from each other by inclining from the circumferential direction. Even in this case, although a slight error occurs, the error may be smaller than the error in the case where the thin portion c is notched.

図５に示すように、接液電極板１３ａ、１３ｂはそれぞれ同形の２枚の例えば厚さ１ｍｍのＳＵＳ板から成る表面板１５と裏面板１６とから成り、表面板１５の接液面は平面状であるが、裏面板１６には例えばＬ字片状、鉤片状の突起を後方に突出する多数の係止部１７が設けられている。これらの表面板１５と裏面板１６は、溶接等の手段により貼り合わせにより結合されている。なお、表面板１５と裏面板１６とは、それぞれを絶縁材１２の内周に密着するように湾曲させてから結合してもよいし、結合後に湾曲してもよい。 As shown in FIG. 5, each of the liquid contact electrode plates 13a and 13b is composed of two front plates 15 and a back plate 16 each having the same shape, for example, a 1 mm thick SUS plate, and the liquid contact surface of the front plate 15 is a flat surface. However, the back plate 16 is provided with a large number of locking portions 17 that project rearwardly, for example, L-shaped and hook-shaped protrusions. These front plate 15 and back plate 16 are bonded together by means such as welding. The front plate 15 and the back plate 16 may be joined after being curved so as to be in close contact with the inner periphery of the insulating material 12, or may be curved after joining.

図６（ａ）、（ｂ）はそれぞれ他の裏面板１６の断面図であり、（ａ）のように裏面板１６に多数の孔部から成る係止部１７を設けたり、（ｂ）に示すようにプレス機械による膨出部から成る係止部１７を設けることもできる。更に他の実施例として、裏面板１６は使用せずに、厚めの表面板１５の裏面側に多数の凹部を穿設して係止部１７とすることもできる。 6 (a) and 6 (b) are cross-sectional views of the other back plate 16, respectively. As shown in FIG. 6 (a), the back plate 16 is provided with a locking portion 17 composed of a large number of holes, and FIG. As shown, a locking portion 17 formed of a bulging portion by a press machine can also be provided. As still another embodiment, the locking plate 17 can be formed by drilling a large number of recesses on the back side of the thick front plate 15 without using the back plate 16.

図７に示すように、図５で示した裏面板１６の係止部１７は絶縁材１２中に固定され、接液電極板１３ａ、１３ｂの絶縁材１２からの脱落防止機能を有している。絶縁材１２は突起から成る係止部１７の周囲を囲み、更には裏面板１６の孔内に入り込む。なお、絶縁材１２の厚みは、たとえ突出した係止部１７を挿入しても、係止部１７が外側の金属管１１に達しない程度の十分な厚みとする必要がある。 As shown in FIG. 7, the locking portion 17 of the back plate 16 shown in FIG. 5 is fixed in the insulating material 12 and has a function of preventing the liquid contact electrode plates 13 a and 13 b from falling off from the insulating material 12. . The insulating material 12 surrounds the periphery of the locking portion 17 made of a protrusion, and further enters the hole of the back plate 16. The insulating material 12 needs to have a sufficient thickness such that the locking portion 17 does not reach the outer metal tube 11 even if the protruding locking portion 17 is inserted.

金属管１１、絶縁材１２には両側から絶縁円筒管１８ａ、１８ｂが挿入され、接液電極板１３ａ、１３ｂからの信号線１４ａ、１４ｂが引き出されている。絶縁円筒管１８ａ、１８ｂ内の信号線１４ａ、１４ｂは絶縁シール材１９と抑えブッシング２０により絶縁保護され、絶縁シール材１９と抑えブッシング２０との間にはコイルスプリング２１が介在されている。 Insulating cylindrical tubes 18a and 18b are inserted into the metal tube 11 and the insulating material 12 from both sides, and signal lines 14a and 14b from the liquid contact electrode plates 13a and 13b are drawn out. The signal lines 14 a and 14 b in the insulating cylindrical tubes 18 a and 18 b are insulated and protected by the insulating sealing material 19 and the restraining bushing 20, and a coil spring 21 is interposed between the insulating sealing material 19 and the restraining bushing 20.

絶縁材１２はゴム材、ポリウレタン、テフロン（登録商標）等の合成樹脂材から成る電気絶縁材料を、例えば金属管１１を軸中心に回転させながら、遠心注型法等により金属管１１の内面に数ｃｍの厚さにライニングする。接液電極板１３ａ、１３ｂの絶縁材１２への取付け手順には幾つかの方法が考えられる。例えば、接液電極板１３ａ、１３ｂを金属管１１内に仮固定しておき、接液電極板１３ａ、１３ｂの部分については、金属管１１との間に絶縁材１２を入り込ませるようにライニングして、接液電極板１３ａ、１３ｂを絶縁材１２に取り付ける。 The insulating material 12 is made of an electrically insulating material made of a synthetic resin material such as rubber, polyurethane, Teflon (registered trademark) or the like on the inner surface of the metal tube 11 by, for example, centrifugal casting while rotating the metal tube 11 about the axis. Lining to a thickness of several centimeters. There are several methods for attaching the wetted electrode plates 13a and 13b to the insulating material 12. For example, the liquid contact electrode plates 13 a and 13 b are temporarily fixed in the metal tube 11, and the liquid contact electrode plates 13 a and 13 b are lined so that the insulating material 12 enters between the metal tube 11. Then, the wetted electrode plates 13 a and 13 b are attached to the insulating material 12.

このとき、接液電極板１３ａ、１３ｂの背面側の突起等から成る係止部１７が絶縁材１２中に挿し込まれ、接液電極板１３ａ、１３ｂの保持が確実となる。絶縁材１２への貼り付けに際しては、なるべくは表面板１５の接液面は管路の内面である絶縁材１２の内面と面一近くにすることが、流量抵抗が少なくなり好ましい。 At this time, the locking portion 17 formed of a protrusion on the back side of the liquid contact electrode plates 13a and 13b is inserted into the insulating material 12, and the liquid contact electrode plates 13a and 13b are securely held. When attaching to the insulating material 12, it is preferable that the liquid contact surface of the surface plate 15 is as close as possible to the inner surface of the insulating material 12, which is the inner surface of the pipe, because flow resistance is reduced.

図８は測定回路の構成図であり、接液電極板１３ａ、１３ｂの各中央部に接続された信号線１４ａ、１４ｂは、図７に示すように、金属管１１に対して絶縁された状態で金属管１１の外側に引き出され、信号処理回路２２に接続されている。 FIG. 8 is a configuration diagram of the measurement circuit, and the signal lines 14a and 14b connected to the central portions of the liquid contact electrode plates 13a and 13b are insulated from the metal tube 11 as shown in FIG. Is pulled out of the metal tube 11 and connected to the signal processing circuit 22.

各接液電極板１３ａ、１３ｂで検出される起電力信号は、信号処理回路２２において、電流信号としてそれぞれ各演算増幅器２３ａ、２３ｂに送信され、演算増幅器２３ａ、２３ｂはこれらを電圧信号に変換する。そして、電圧信号は演算増幅器２４で差動演算がなされて出力端２５に出力される。 The electromotive force signals detected by the respective liquid contact electrode plates 13a and 13b are transmitted as current signals to the respective operational amplifiers 23a and 23b in the signal processing circuit 22, and the operational amplifiers 23a and 23b convert these into voltage signals. . The voltage signal is subjected to differential calculation by the operational amplifier 24 and output to the output terminal 25.

このように、管路の内部で発生する起電力に対して、接液電極板１３ａ、１３ｂの出力を余弦であるｃｏｓθの重み付けをして、全体から得られる電流信号を加算して出力端２５から出力することにより、測定流体の流速分布の影響を受けずに流量Ｑを測定することができる。 In this way, the electromotive force generated inside the pipe is weighted by cos θ, which is the cosine, of the outputs of the liquid contact electrode plates 13a and 13b, and the current signal obtained from the whole is added to the output terminal 25. The flow rate Q can be measured without being influenced by the flow velocity distribution of the measurement fluid.

本発明の測定原理は、管軸方向の電極長ａの大きさが角度θの余弦に比例することにおいて、特許文献１と同一である。しかし、特許文献１では誘起される起電力信号を静電容量を基に電極を接液することなく検出するのに対し、本発明では電極を測定流体に接液して検出するので、変換器は通常の電極に接続して使用する汎用型で済む利点がある。 The measurement principle of the present invention is the same as that of Patent Document 1 in that the size of the electrode length a in the tube axis direction is proportional to the cosine of the angle θ. However, in Patent Document 1, an induced electromotive force signal is detected based on the capacitance without contacting the electrode, but in the present invention, the electrode is detected by contacting the measurement fluid. Is advantageous in that it can be a general-purpose type connected to a normal electrode.

また本願発明では、管路の内面に接液電極板１３ａ、１３ｂを設けるため、特許文献１のような温度特性等に強く、かつ誘電容量の安定性を維持したセラミック材料のような管壁材を用いる必要がない。そして、前述の中口径、大口径の既製の金属管に対するライニングによる絶縁材１２の形成は比較的容易であるので、中口径、大口径の管路においても、本発明に係る接液式電磁流量計を使用することで、精度良く流量を測定できる。 Further, in the present invention, since the wetted electrode plates 13a and 13b are provided on the inner surface of the pipe line, the tube wall material such as a ceramic material which is strong in temperature characteristics and the like as in Patent Document 1 and maintains the stability of the dielectric capacity. Need not be used. Since the formation of the insulating material 12 by lining the above-mentioned ready-made metal pipe with a medium diameter and a large diameter is relatively easy, the wetted electromagnetic flow rate according to the present invention is also applied to the medium diameter and large diameter pipes. By using a meter, the flow rate can be measured with high accuracy.

なお、特許文献１の面電極２ａ、２ｂは絶縁体の外側に配置し、測定流体と接することがないために、面電極２ａ、２ｂ自体の耐摩耗性等は不要であり、箔や導電塗料によって形成できる。しかし、本発明の接液電極板１３ａ、１３ｂは測定流体に対する耐摩耗性等を必要とするので、接液電極板１３ａ、１３ｂとしてはＳＵＳ板を使用することが好ましい。 In addition, since the surface electrodes 2a and 2b of Patent Document 1 are arranged outside the insulator and do not come into contact with the measurement fluid, the surface electrodes 2a and 2b themselves do not require wear resistance and the like. Can be formed. However, since the wetted electrode plates 13a and 13b of the present invention require wear resistance to the measurement fluid, it is preferable to use SUS plates as the wetted electrode plates 13a and 13b.

また、本発明に係る接液式電磁流量計は、管路の内部の一部に空間が存在する非満水管路においても、測定流体を同様に測定することが可能である。 In addition, the liquid contact type electromagnetic flow meter according to the present invention can measure the measurement fluid in the same manner even in a non-full pipe having a space inside a part of the pipe.

１１金属管
１２絶縁材
１３ａ、１３ｂ接液電極板
１４ａ、１４ｂ信号線
１５表面板
１６裏面板
１７係止部
２２信号処理装置
２３ａ、２３ｂ、２４演算増幅器
２５出力端 DESCRIPTION OF SYMBOLS 11 Metal pipe 12 Insulation material 13a, 13b Liquid contact electrode plate 14a, 14b Signal line 15 Front plate 16 Back plate 17 Locking part 22 Signal processing device 23a, 23b, 24 Operational amplifier 25 Output terminal

Claims

内面を絶縁材により断面円形に形成した管路と、該管路の管軸に直交して測定流体に磁界を形成する励磁手段と、前記管軸及び前記磁界と直交する方向であって前記絶縁材の内周面に対向して係止し相互に絶縁した一対の接液電極板とを備え、前記接液電極板に生ずる起電力を基に測定流体の流量を測定する接液式電磁流量計であって、
前記接液電極板は表面板と裏面板との同形の２枚の金属板を貼り合わせて形成し、前記表面板を平面状の接液面とし、前記裏面板の裏面に設けた係止部により前記絶縁材に密着して係止し、
前記接液電極板の管軸方向の電極長を、前記管路の内壁に立つ法線方向と前記管軸及び前記磁界に直交する軸とでなす角度θの余弦に比例するようにしたことを特徴とする接液式電磁流量計。 A pipe having an inner surface formed into a circular shape by an insulating material, excitation means for forming a magnetic field in a measurement fluid perpendicular to the pipe axis of the pipe, and the insulation in a direction perpendicular to the pipe axis and the magnetic field A liquid contact type electromagnetic flow rate which measures a flow rate of a measurement fluid based on an electromotive force generated in the liquid contact electrode plate. A total of
The liquid contact electrode plate is formed by bonding two metal plates having the same shape of a front surface plate and a back surface plate, the front surface plate is a flat liquid contact surface, and a locking portion provided on the back surface of the back surface plate To closely contact and lock the insulating material,
The electrode length in the tube axis direction of the liquid contact electrode plate is proportional to the cosine of the angle θ formed by the normal direction standing on the inner wall of the conduit and the tube axis and the axis orthogonal to the magnetic field. Features a wetted electromagnetic flow meter.

前記裏面板の係止部は後方に突出した多数の突起とし、前記接液電極板を前記突起により前記絶縁材に係止したことを特徴とする請求項１に記載の接液式電磁流量計。 The liquid contact type electromagnetic flowmeter according to claim 1 , wherein the engaging portion of the back plate is a large number of protrusions protruding rearward, and the liquid contact electrode plate is locked to the insulating material by the protrusions. .

前記裏面板の係止部は前記裏面板に設けた多数の孔部とし、前記接液電極板を前記孔部により前記絶縁材に係止したことを特徴とする請求項１に記載の接液式電磁流量計。 The liquid contact according to claim 1 , wherein the locking portion of the back plate is a number of holes provided in the back plate, and the liquid contact electrode plate is locked to the insulating material by the hole. Type electromagnetic flow meter.

前記絶縁材はゴム材、合成樹脂材から成り、金属管の内面にライニングにより形成したことを特徴とする請求項１〜３の何れか１項に記載の接液式電磁流量計。 The insulating material is a rubber material, made of a synthetic resin material, wetted-type electromagnetic flow meter according to any one of claim 1 to 3, characterized in that formed by lining the inner surface of the metal tube.

前記一対の接液電極板は先端の細状部をそれぞれ切欠することにより、相互に絶縁したことを特徴とする請求項１〜４の何れか１項に記載の接液式電磁流量計。 The pair of liquid contact electrodes plates by notch fine-shaped portion of the tip respectively, wetted type electromagnetic flowmeter according to any one of claims 1-4, characterized in that the mutually insulated.

前記一対の接液電極板の細状部同士は前記管路の管軸方向にずらして、前記細状部同士を絶縁したことを特徴とする請求項１〜４の何れか１項に記載の接液式電磁流量計。 Thin shaped portions of the pair of liquid contact electrodes plates are shifted in the axial direction of the tube of the conduit, according to any one of claim 1 to 4, characterized in that the insulated the Hosojo portions Liquid contact type electromagnetic flow meter.