JP4842766B2

JP4842766B2 - Capacity type electromagnetic flow meter

Info

Publication number: JP4842766B2
Application number: JP2006295738A
Authority: JP
Inventors: 豊原田
Original assignee: Azbil Corp
Current assignee: Azbil Corp
Priority date: 2006-10-31
Filing date: 2006-10-31
Publication date: 2011-12-21
Anticipated expiration: 2026-10-31
Also published as: JP2008111759A

Description

この発明は、測定管内を流れる流体と静電容量結合する信号電極を備えた容量式電磁流量計に関するものである。 The present invention relates to a capacitive electromagnetic flow meter provided with a signal electrode that capacitively couples with a fluid flowing in a measurement tube.

従来より、この種の容量式電磁流量計は、測定管内を流れる流体の流れ方向に対して直交する方向に磁界を作る励磁コイルと、測定管に設けられこの測定管内を流れる流体と静電容量結合する信号電極とを有し、励磁コイルが作る磁界により測定管内を流れる流体に発生する起電力を信号電極より取り出すようにしている。なお、通常、信号電極に対してはその信号電極をシールドするガード電極が設けられ、信号電極およびガード電極は対として、励磁コイルが作る磁界と直交する方向に設けられる。 Conventionally, this type of capacitive electromagnetic flow meter has an excitation coil that creates a magnetic field in a direction perpendicular to the flow direction of the fluid flowing in the measurement tube, and the fluid and capacitance that are provided in the measurement tube and flow in the measurement tube. An electromotive force generated in the fluid flowing in the measurement tube by the magnetic field generated by the excitation coil is extracted from the signal electrode. Normally, a guard electrode that shields the signal electrode is provided for the signal electrode, and the signal electrode and the guard electrode are provided as a pair in a direction orthogonal to the magnetic field created by the exciting coil.

図４（ａ）に容量式電磁流量計の従来例の要部を示す（例えば、特許文献１参照）。同図において、１は測定管であり、非磁性パイプ（例えば、ステンレス製のパイプ）２の内側に絶縁性の樹脂ライニング３が施されている。４は信号電極、５は信号電極４をシールドするガード電極である。信号電極４およびガード電極５は、樹脂ライニング３中に設けられている。図４（ｂ）に図４（ａ）におけるＩ−Ｉ線断面図を示す。 The principal part of the conventional example of a capacity | capacitance type electromagnetic flowmeter is shown to Fig.4 (a) (for example, refer patent document 1). In the figure, reference numeral 1 denotes a measuring tube, and an insulating resin lining 3 is applied to the inside of a nonmagnetic pipe (for example, a stainless steel pipe) 2. 4 is a signal electrode, and 5 is a guard electrode for shielding the signal electrode 4. The signal electrode 4 and the guard electrode 5 are provided in the resin lining 3. FIG. 4B shows a cross-sectional view taken along the line II in FIG.

なお、図４には示されていないが、測定管１内を流れる流体の流れ方向に対して直交する方向に磁界を作る励磁コイルが設けられており、この励磁コイルが作る磁界と直交する方向に、対向して２つの信号電極４およびガード電極５が設けられている。 Although not shown in FIG. 4, an exciting coil for creating a magnetic field is provided in a direction orthogonal to the flow direction of the fluid flowing in the measuring tube 1, and the direction perpendicular to the magnetic field created by the exciting coil is provided. Two signal electrodes 4 and a guard electrode 5 are provided opposite to each other.

米国特許第４６３１９６９号U.S. Pat. No. 4,631,969 特開２００２−７１４０８号公報JP 2002-71408 A 特開２００４−２２６３９４号公報JP 2004-226394 A

図４に示した従来例の構造において、樹脂ライニング３としては、一般にフッ素樹脂が用いられる。フッ素樹脂は非粘着性を有しているため、信号電極４と樹脂ライニング３との密着力が弱く、外力などの負荷や振動などにより、信号電極４が樹脂ライニング３から剥がれ易い。これにより、信号電極４と樹脂ライニング３との接触面積の変化による静電気や擦れによる摩擦電気が生じ、測定の精度に影響を及ぼすことがある。 In the structure of the conventional example shown in FIG. 4, a fluororesin is generally used as the resin lining 3. Since the fluororesin is non-adhesive, the adhesion between the signal electrode 4 and the resin lining 3 is weak, and the signal electrode 4 is easily peeled off from the resin lining 3 due to a load or vibration such as an external force. As a result, static electricity due to a change in the contact area between the signal electrode 4 and the resin lining 3 or triboelectricity due to rubbing is generated, which may affect the measurement accuracy.

なお、特許文献２や特許文献３では、信号電極をゲル状樹脂や軟質ゴムなどの絶縁性物質で覆うことによって密着力を維持することが示されているが、信号電極とそれを覆う絶縁性物質とでは線膨張係数が異なるため、温度変化に対して剥がれようとする力を生じる。そのため、密着を長く維持させることは難しい。また、製造で界面に気泡溜まりを生じれば、そこが静電気や摩擦電気の発生源になるため、非常に注意を払わなければならず、生産コストが高くなってしまう。 In Patent Document 2 and Patent Document 3, it is shown that the adhesion is maintained by covering the signal electrode with an insulating material such as gel resin or soft rubber. Since the linear expansion coefficient is different from that of a substance, a force that tends to peel off with respect to a temperature change is generated. Therefore, it is difficult to maintain the adhesion for a long time. Further, if bubble accumulation occurs at the interface during production, it becomes a generation source of static electricity and triboelectricity, so great care must be taken, resulting in high production costs.

本発明は、このような課題を解決するためになされたもので、その目的とするところは、信号電極が剥がれても、静電気や摩擦電気が発生することがない容量式電磁流量計を提供することにある。 The present invention has been made to solve such problems, and an object of the present invention is to provide a capacitive electromagnetic flow meter that does not generate static electricity or triboelectricity even if the signal electrode is peeled off. There is.

このような目的を達成するために本発明は、非磁性パイプの内側に絶縁性の樹脂ライニングが施された測定管と、この測定管内を流れる流体の流れ方向に対して直交する方向に磁界を作る励磁コイルと、樹脂ライニング中に設けられ測定管内を流れる流体と静電容量結合する信号電極とを備え、励磁コイルが作る磁界により測定管内を流れる流体に発生する起電力を信号電極より取り出す容量式電磁流量計において、信号電極の表面に、その電極表面との密着力よりも樹脂ライニングとの密着力の方が強い導電性の膜を形成したものである。 In order to achieve such an object, the present invention provides a measuring tube in which an insulating resin lining is applied to the inside of a nonmagnetic pipe, and a magnetic field in a direction perpendicular to the flow direction of the fluid flowing in the measuring tube. The excitation coil to be made and a signal electrode capacitively coupled to the fluid flowing in the measurement tube provided in the resin lining, and the capacity to extract from the signal electrode the electromotive force generated in the fluid flowing in the measurement tube by the magnetic field created by the excitation coil In this type of electromagnetic flow meter, a conductive film is formed on the surface of the signal electrode, which has a stronger adhesion with the resin lining than the adhesion with the electrode surface.

本発明において、信号電極が樹脂ライニングから剥がれると、樹脂ライニングとの密着力の方が強いので、樹脂ライニングの表面に導電性の膜が残る。したがって、信号電極が樹脂ライニングから剥がれてその間に空間ができても、その空間を介して信号電極の表面と樹脂ライニングの表面に残された導電性の膜とが対向するものとなり、信号電極と樹脂ライニングとの間に静電気や摩擦電気が生じ難くなる。 In the present invention, when the signal electrode is peeled off from the resin lining, the adhesion with the resin lining is stronger, so that a conductive film remains on the surface of the resin lining. Therefore, even if the signal electrode is peeled off from the resin lining and a space is formed between them, the surface of the signal electrode and the conductive film left on the surface of the resin lining are opposed to each other through the space. Static electricity and triboelectricity are less likely to occur between the resin lining.

本発明によれば、信号電極の表面に樹脂ライニングとの密着力の方が強い導電性の膜を形成するようにしたので、信号電極が樹脂ライニングから剥がれた場合、樹脂ライニングの表面に導電性の膜が残り、信号電極と樹脂ライニングとの間に静電気や摩擦電気が生じ難くいものとなる。
また、本発明によれば、信号電極と導電性の膜とが常に同電位となるので、信号電極と樹脂ライニングとが再接触しても電位差が生じず、ノイズが生じ難いものとなる。 According to the present invention, a conductive film having a stronger adhesion with the resin lining is formed on the surface of the signal electrode. Therefore, when the signal electrode is peeled off from the resin lining, the conductive surface is exposed to the surface of the resin lining. Thus, static electricity and triboelectricity are hardly generated between the signal electrode and the resin lining.
Further, according to the present invention, since the signal electrode and the conductive film are always at the same potential, even if the signal electrode and the resin lining are brought into contact again, no potential difference is generated, and noise is hardly generated.

以下、本発明を図面に基づいて詳細に説明する。
〔実施の形態１〕
図１（ａ）はこの発明に係る容量式電磁流量計の一実施の形態（実施の形態１）の要部を示す図である。図１（ｂ）は図１（ａ）におけるIII −III 線断面図である。図１において、図４と同一符号は図４を参照して説明した構成要素と同一或いは同等構成要素を示し、その説明は省略する。 Hereinafter, the present invention will be described in detail with reference to the drawings.
[Embodiment 1]
Fig.1 (a) is a figure which shows the principal part of one Embodiment (Embodiment 1) of the capacity | capacitance type electromagnetic flowmeter based on this invention. FIG.1 (b) is the III-III sectional view taken on the line in Fig.1 (a). In FIG. 1, the same reference numerals as those in FIG. 4 denote the same or equivalent components as those described with reference to FIG.

この実施の形態１では、信号電極４の表面に、カーボンなどの導電性物質が含まれたフッ素樹脂（以下、導電性フッ素樹脂と呼ぶ）をコーティングして導電性の膜４ａを形成し、この状態でライニング成形を行ったり、ライニング材と熱溶着したりして、樹脂ライニング３中に信号電極４を設けている。図２にこの場合の信号電極４、導電性の膜４ａ、樹脂ライニング３の積層構造の概略を示す。なお、この実施の形態１において、導電性の膜４ａと信号電極４とはそれほど強固に密着させる必要はない。 In the first embodiment, the surface of the signal electrode 4 is coated with a fluororesin containing a conductive material such as carbon (hereinafter referred to as a conductive fluororesin) to form a conductive film 4a. The signal electrode 4 is provided in the resin lining 3 by performing lining molding in the state or by heat welding with the lining material. FIG. 2 shows an outline of the laminated structure of the signal electrode 4, the conductive film 4a, and the resin lining 3 in this case. In the first embodiment, the conductive film 4a and the signal electrode 4 do not need to be adhered so firmly.

図２に示した積層構造において、導電性の膜４ａは、樹脂ライニング３と同等の材質が使われているため、樹脂ライニング３と溶融し合い、樹脂ライニング３と強固に密着する。これにより、導電性の膜４ａの密着力は、信号電極４の表面との密着力よりも樹脂ラインニング３との密着力の方が強くなる。 In the laminated structure shown in FIG. 2, the conductive film 4 a is made of the same material as the resin lining 3, and therefore melts with the resin lining 3 and adheres firmly to the resin lining 3. As a result, the adhesive force of the conductive film 4 a is stronger in the adhesive force with the resin lined 3 than the adhesive force with the surface of the signal electrode 4.

この実施の形態１において、信号電極４が樹脂ライニング３から剥がれると、樹脂ライニング３との密着力の方が強いので、樹脂ライニング３の表面に導電性の膜４ａが残る（図３参照）。したがって、信号電極４が樹脂ライニング３から剥がれてその間に空間ができても、その空間を介して信号電極４の表面と樹脂ライニング３の表面に残された導電性の膜４ａとが対向するものとなり、信号電極４と導電性の膜４ａとが常に同電位となる。これは信号電極４と導電性の膜４ａは完全に離れることは無く，かつお互いが導電体のため同電位となる。よって、信号電極４と樹脂ライニング３とが再接触しても電位差が生じず、ノイズが生じ難くなる。 In the first embodiment, when the signal electrode 4 is peeled off from the resin lining 3, the adhesive force with the resin lining 3 is stronger, so that the conductive film 4a remains on the surface of the resin lining 3 (see FIG. 3). Therefore, even if the signal electrode 4 is peeled off from the resin lining 3 and a space is formed between them, the surface of the signal electrode 4 and the conductive film 4a left on the surface of the resin lining 3 face each other through the space. Thus, the signal electrode 4 and the conductive film 4a are always at the same potential. This is because the signal electrode 4 and the conductive film 4a are not completely separated from each other, and have the same potential because they are conductors. Therefore, even if the signal electrode 4 and the resin lining 3 are brought into contact with each other again, no potential difference is generated and noise is hardly generated.

〔実施の形態２〕
上述した実施の形態１では、信号電極４の表面に、カーボンなどが含まれた導電性フッ素樹脂をコーティングして導電性の膜４ａを形成するようにした。これに対して、実施の形態２では、信号電極４の表面に、導電塗料を塗布することによって導電性の膜４ａ（図１参照）を形成する。なお、導電塗料とは、金属、金属化合物、カーボンブラックなどの導電性物質の微粒子（フィラー）を接着剤や熱硬化性物質に混ぜたもののことを言う。 [Embodiment 2]
In the first embodiment described above, the conductive film 4a is formed by coating the surface of the signal electrode 4 with a conductive fluororesin containing carbon or the like. On the other hand, in the second embodiment, the conductive film 4a (see FIG. 1) is formed on the surface of the signal electrode 4 by applying a conductive paint. The conductive paint refers to a mixture of fine particles (filler) of a conductive material such as metal, metal compound, or carbon black mixed with an adhesive or a thermosetting material.

この実施の形態２では、信号電極４の表面に、導電塗料を塗布して導電性の膜４ａを形成し、この状態でライニング成形を行ったり、ライニング材と熱溶着したりして、樹脂ライニング３中に信号電極４を設ける。この場合、導電性の膜４ａの密着力は、信号電極４の表面との密着力よりも樹脂ラインニング３との密着力の方が強くなる様に信号電極４と導電性の膜４ａの接着力を弱めておく。 In the second embodiment, a conductive coating 4 is formed on the surface of the signal electrode 4 to form a conductive film 4a. In this state, lining molding is performed, or thermal welding is performed with a lining material, so that a resin lining is formed. 3 is provided with a signal electrode 4. In this case, the adhesion of the conductive film 4a is such that the adhesion with the resin linen 3 is stronger than the adhesion with the surface of the signal electrode 4. Keep your strength weak.

この実施の形態２においても、実施の形態１と同様、信号電極４が樹脂ライニング３から剥がれると、樹脂ライニング３との密着力の方が強いので、樹脂ライニング３の表面に導電性の膜４ａが残る（図３参照）。したがって、信号電極４が樹脂ライニング３から剥がれてその間に空間ができても、その空間を介して信号電極４の表面と樹脂ライニング３の表面に残された導電性の膜４ａとが対向するものとなり、信号電極４と樹脂ライニング３との間に静電気や摩擦電気が生じ難くなる。また、信号電極４と導電性の膜４ａとが常に同電位となるので、信号電極４と樹脂ライニング３とが再接触しても電位差が生じず、ノイズが生じ難くなる。 Also in the second embodiment, as in the first embodiment, when the signal electrode 4 is peeled off from the resin lining 3, the adhesive force with the resin lining 3 is stronger. Therefore, the conductive film 4 a is formed on the surface of the resin lining 3. Remains (see FIG. 3). Therefore, even if the signal electrode 4 is peeled off from the resin lining 3 and a space is formed between them, the surface of the signal electrode 4 and the conductive film 4a left on the surface of the resin lining 3 face each other through the space. Thus, static electricity and triboelectricity are hardly generated between the signal electrode 4 and the resin lining 3. In addition, since the signal electrode 4 and the conductive film 4a are always at the same potential, even if the signal electrode 4 and the resin lining 3 are brought into contact with each other again, a potential difference does not occur, and noise hardly occurs.

なお、上述した実施の形態１では導電性の膜４ａをカーボンなどが含まれた導電性フッ素樹脂、実施の形態２では導電性の膜４ａを導電塗料としたが、導電性の膜４ａはこれらに限られるものでないことは言うまでもない。 In the first embodiment described above, the conductive film 4a is made of a conductive fluororesin containing carbon or the like, and in the second embodiment, the conductive film 4a is made of a conductive paint. However, the conductive film 4a is made of these materials. It goes without saying that it is not limited to this.

本発明に係る容量式電磁流量計の実施の形態１，２の要部を示す図である。It is a figure which shows the principal part of Embodiment 1, 2 of the capacity | capacitance type electromagnetic flowmeter which concerns on this invention. 実施の形態１，２の容量式電磁流量計における信号電極、導線性の膜、樹脂ライニングの積層構造の概略を示す図である。It is a figure which shows the outline of the laminated structure of the signal electrode, conductive film, and resin lining in the capacitive electromagnetic flowmeter of Embodiment 1,2. 図２に示した積層構造において信号電極が剥がれた状態を例示する図である。It is a figure which illustrates the state from which the signal electrode peeled in the laminated structure shown in FIG. 容量式電磁流量計の従来例の要部を示す図である。It is a figure which shows the principal part of the prior art example of a capacity | capacitance type electromagnetic flowmeter.

Explanation of symbols

１…測定管、２…非磁性パイプ、３…樹脂ライニング、４…信号電極、４ａ…導電性の膜、５…ガード電極。 DESCRIPTION OF SYMBOLS 1 ... Measuring tube, 2 ... Nonmagnetic pipe, 3 ... Resin lining, 4 ... Signal electrode, 4a ... Conductive film | membrane, 5 ... Guard electrode.

Claims

A measuring tube having an insulating resin lining on the inside of a non-magnetic pipe, an exciting coil that creates a magnetic field in a direction orthogonal to the flow direction of the fluid flowing in the measuring tube, and the resin lining provided in the above-mentioned In a capacitive electromagnetic flowmeter comprising a fluid flowing in the measurement tube and a signal electrode capacitively coupled, and taking out an electromotive force generated in the fluid flowing in the measurement tube by the magnetic field generated by the excitation coil from the signal electrode,
A capacitive electromagnetic flowmeter, wherein a conductive film having a stronger adhesion with the resin lining than an adhesion with the electrode surface is formed on the surface of the signal electrode.

The capacitive electromagnetic flow meter according to claim 1,
The conductive electromagnetic flowmeter is characterized in that the conductive film is a fluororesin containing a conductive substance.

The capacitive electromagnetic flow meter according to claim 1,
The capacitive electromagnetic flow meter, wherein the conductive film is a conductive paint.