JPS60138435A - Pressure and differential pressure transmitter - Google Patents

Abstract

PURPOSE:To obtain at a low cost a titled device high in accuracy and reliability by calculating the sum of a signal proportional to a dielectric constant, and a signal related to the product of the dielectric constant and measured pressure and differential pressure, and obtaining the zero point variation and span variation compensating signals. CONSTITUTION:A signal related to electrostatic capacities C1, C2 varied in response to a differential pressure is inputted to a detecting circuit 11. The signal related to the electrostatic capacities C1, C2 from the detecting circuit 11 and a signal related to a pressure and a differential pressure are led to a compensating signal operating circuit 19, and the sum with a zero point variation compensating signal and a span variation compensating signal being proportional to a dielectric constant epsilon is calculated, added to an output signal of the operating circuit 19 at an adding point 20, and a zero point variation and a span variation due to variations of a temperature and a static pressure are compensated at the same time.

Description

【発明の詳細な説明】 〈産業上の利用分野〉 本発明はプロセス制御装置に用いられるベローズ又はダ
イヤフラム等の受圧要素を用いた差圧又は圧力伝送器に
おいて問題とされる、温度、静圧変動に起因するゼロ点
変動及びスパン変動を相互干渉なしに調整し補償する手
段に関する。Detailed Description of the Invention <Industrial Application Field> The present invention addresses temperature and static pressure fluctuations that are a problem in differential pressure or pressure transmitters using pressure receiving elements such as bellows or diaphragms used in process control devices. The present invention relates to a means for adjusting and compensating for zero point fluctuations and span fluctuations caused by zero point fluctuations and span fluctuations without mutual interference.

〈従来技術〉 第１図は差圧伝送器の従来の温度、静圧変動によるゼロ
点変動、スパン変動補償の概念を説明するだめの構成図
である。１は一室構造の差圧伝送器の本体断面を示し、
両端面に測定すべき圧力ｐ。<Prior Art> FIG. 1 is a block diagram for explaining the concept of compensating for zero point fluctuations and span fluctuations due to temperature and static pressure fluctuations in a conventional differential pressure transmitter. 1 shows a cross section of the main body of a differential pressure transmitter with a one-chamber structure,
The pressure p to be measured on both end faces.

■ ＰＬを受けるダイヤフラム２，５がその周縁をこの本体
に溶接されて配置されており、本体に形成された貫通孔
４とこれらダイヤフラムで囲まれた中空室内にはシリコ
ン油等の封液５が満たされている。■ Diaphragms 2 and 5 that receive the PL are arranged with their peripheral edges welded to the main body, and a sealing liquid 5 such as silicone oil is inside the through hole 4 formed in the main body and the hollow chamber surrounded by these diaphragms. be satisfied.

中空室中央部には拡大された電極室が形成され、この電
極室内には本体に嵌合した絶縁材６に片側が支持された
移動電極７及びこれに対向して静電容量Ｃ１，Ｃ２を形
成するための固定電極８，９が配置されている。１ｏは
中空室を介して両ダイヤスラム２．３の中央部を連結す
るロッドで、その中央部は電極室内において移動電極７
に固定されておプ、差圧に応動したダイヤフラムの変位
を移動電極に算が施され、直流出力信号ｅ。Ｋ変換され
る。この信号ｅ。は出力回路１２に導かれて、遠隔点の
負荷ＲＬ。An enlarged electrode chamber is formed in the center of the hollow chamber, and within this electrode chamber there is a movable electrode 7 supported on one side by an insulating material 6 fitted to the main body, and a movable electrode 7 having capacitances C1 and C2 opposite thereto. Fixed electrodes 8 and 9 are arranged for formation. 1o is a rod connecting the central parts of both diamond slams 2.3 through a hollow chamber, and the central part is connected to the movable electrode 7 in the electrode chamber.
The displacement of the diaphragm in response to the differential pressure is calculated on the moving electrode, and a DC output signal e is generated. K-transformed. This signal e. is directed to the output circuit 12 and the remote load RL.

電源ＥＢの直列回路に対し、４〜２０　ｍＡ　スパンの
出力電流工。Ｋ変換される。１３は本体１の温度Ｔを測
定する温度センサ、１４け封液５の圧力即ち静圧Ｐｓを
測定する圧力センサであり、これらセンサの出力は、補
償電圧発生回路１５．１６に導かれ、ゼロ点補償用温度
信号ｅＴ＋ゼロ点補償用靜圧信号ｅｐに変換され、加算
点１７．１８で演算回路１１の出力信号ｅ。4 to 20 mA span output current for the series circuit of power supply EB. K-transformed. 13 is a temperature sensor that measures the temperature T of the main body 1; 14 is a pressure sensor that measures the pressure of the sealing liquid 5, that is, the static pressure Ps; the outputs of these sensors are led to a compensation voltage generation circuit 15, 16, and The point compensation temperature signal eT+zero point compensation static pressure signal ep is converted into the output signal e of the arithmetic circuit 11 at addition points 17 and 18.

に加算又は減算されて温度変動又は静圧変動に対するゼ
ロ点の変動が補償される。温度又は静圧変動に対してダ
イヤフラム２，３のバネ定数変化等によシ生ずるスパン
変動は、補償電圧発生回路１５゜１６よシ点線で示すス
パン変動補償用温度信号、静圧信号ｅＴ’　ｒ　ｅｐ’
を発生させ、出力回路１２の電圧−電流変換利得を変化
させてスパンの変動を補償する。is added to or subtracted from to compensate for zero point fluctuations due to temperature fluctuations or static pressure fluctuations. Span fluctuations caused by changes in the spring constants of the diaphragms 2 and 3 due to temperature or static pressure fluctuations are handled by the temperature signal for span fluctuation compensation and the static pressure signal eT' r shown by dotted lines from the compensation voltage generation circuit 15 and 16. ep'
is generated, and the voltage-to-current conversion gain of the output circuit 12 is changed to compensate for the span variation.

このような補償方式をとる場合は、温度センサ１３及び
圧力センサ１４を本体１内に設ける必要がある。本体内
Ｋ１１度センサを設けた従来技術は例えは実開昭５５−
１３３１７号Ｋ、又本体内に圧力センナを設けた従来技
術は例えば特開昭５４−６７４８０号に示されている。If such a compensation method is used, it is necessary to provide the temperature sensor 13 and the pressure sensor 14 inside the main body 1. The conventional technology that installed a K11 degree sensor inside the main body is, for example,
No. 13317K, and a conventional technique in which a pressure sensor is provided within the main body is shown in, for example, Japanese Patent Laid-Open No. 54-67480.

このように、温度センサ、圧力センサを特別に設ける構
成は、特に圧力センナを本体内圧設ける場合、伝送器の
構造が複雑高価となる欠点を有する。As described above, the configuration in which a temperature sensor and a pressure sensor are specially provided has the disadvantage that the structure of the transmitter becomes complicated and expensive, especially when a pressure sensor is provided for the internal pressure of the main body.

〈本発明の構成〉 本発明は上記従来技術の欠点を解消する温度。<Configuration of the present invention> The present invention overcomes the drawbacks of the prior art described above.

静圧変動によるゼロ点変動スパン変動補償手段を提供す
るものであって、その特徴点は、封液の誘電率の変化が
温度又は静圧によって変化することに着目し、誘電率変
化を検出しとの誘を率に比例した信号及びこの誘電率と
測定圧力、差圧との積に関連した信号の和を演算し、ゼ
ロ点質動、スパン変動補償信号を得るようにした点にあ
る。The present invention provides a means for compensating for zero point fluctuations and span fluctuations due to static pressure fluctuations, and its feature is that it detects changes in the dielectric constant by focusing on the fact that changes in the dielectric constant of the sealing liquid change depending on temperature or static pressure. The point is that a signal proportional to the dielectric constant and a signal related to the product of this dielectric constant, measured pressure, and differential pressure are calculated to obtain a zero point displacement and span fluctuation compensation signal.

実施例の説明に先立ち、ゼロ点変動圧着目し、その発生
要因並びに本発明における補償手段の原理につき、第２
図〜第４図を用いて説明する。第２図は、第１図の一室
構造の差圧伝送器を模型的に示したものであって、ダイ
ヤフラム２，３、封液５、ロッド１０よシなる。ＡＨｌ
ＡＬはダイヤフラム２゜３の有効面積、ＦＨ”Ｌはダイ
ヤフラム２，３よシロラド１０に与えられる力、■は封
液５の容積、ｐ□は封液５の内圧、Ｐ８は静圧を夫々示
す。−室構造の差圧伝送器のゼロ点変動の要因のほとん
どは、ダイヤフラム２，５の有効面積ＡＨ２ＡＬに製造
過程でわずかの差が生じることに起因する。Prior to the explanation of the embodiments, we will focus on the zero point fluctuation pressure and explain the causes of its occurrence and the principle of the compensation means in the present invention in the second section.
This will be explained using FIGS. FIG. 2 schematically shows the one-chamber structure differential pressure transmitter shown in FIG. AHL
AL is the effective area of the diaphragm 2゜3, FH''L is the force exerted on the Shirorad 10 by the diaphragms 2 and 3, ■ is the volume of the sealing liquid 5, p□ is the internal pressure of the sealing liquid 5, and P8 is the static pressure. - Most of the causes of zero point fluctuations in the differential pressure transmitter having a chamber structure are due to slight differences in the effective areas AH2AL of the diaphragms 2 and 5 during the manufacturing process.

今、有効面積Ａ１（〉ＡＬの場合に温度変化ΔＴによシ
封液の体積■がΔＶ増加し、その結果封液の内圧ｐがΔ
Ｆ　上昇する（ｐよ〉Ｐの状態となる）と、１　１１ Ｆ、Ｆ　の変化ΔＦ　、ΔＦ　は、夫々ＨＬ　ＨＩ　Ｌ
ｌ ΔＦＨ１＝ＡＨｘΔｐｉｌ　（左方向に発生）ΔＦＬよ
＝ＡＬ×Δｐ　（右方向に発生）１ となる。ここでＡＨ＞ＡＬであるから、ΔＦ　〉ΔＦ　
となシ、左方向のゼロ点質１１１　ＬＬ 動が発生する。Now, when the effective area A1 (〉AL), the volume ■ of the sealing liquid increases by ΔV due to the temperature change ΔT, and as a result, the internal pressure p of the sealing liquid increases Δ
When F rises (becomes a state of p>P), the changes ΔF and ΔF in 1 11 F and F are respectively HL HI L
l ΔFH1=AHxΔpil (occurs to the left) ΔFL yo=AL×Δp (occurs to the right) 1. Here, since AH>AL, ΔF > ΔF
Tonanashi, a zero-point mass 111 LL movement to the left occurs.

次に静圧ＰがΔｐ上昇することＫよシ封液の容Ｓ　Ｓ 積がΔＶ減少しく非圧縮性の封液でも実際にはわずかな
圧縮特性を有する）、内圧がΔＰ１□　減少する（ｐ＜
ｐの状態となる）と、ＦＨｌＦＬの変化ΔＦ　、ΔＦＬ
□は、夫々 ２ ΔＦＨ２＝　’ＡＨ×Δｐ□２　（右方向に発生）ΔＦ
Ｌ２；ＡＬ×ΔＰ□２　（左方向に発生）となる。ここ
でＡＨ＞ＡＬであるから、ΔＦ　〉ΔＦ　となり、右方
向のゼロ点質１２　Ｌ２ 動が発生する。Next, as the static pressure P increases by Δp, the volume of the sealing liquid decreases by ΔV (even incompressible liquid actually has slight compressive properties), and the internal pressure decreases by ΔP1□ (p <
p state) and changes in FHlFL ΔF, ΔFL
□ is 2 respectively ΔFH2= 'AH×Δp□2 (occurs to the right) ΔF
L2; AL×ΔP□2 (occurs to the left). Here, since AH>AL, ΔF>ΔF, and zero point mass 12 L2 movement in the right direction occurs.

有効面積の関係が逆の場合、即ちＡＨ＜ＡＬの場合は温
度及び静圧変動による変動の発生方向は上記とは逆方向
となる。When the effective area relationship is reversed, that is, when AH<AL, the direction of variation due to temperature and static pressure variation is opposite to that described above.

即ち、・有効面積差に起因するゼロ点変動の発生方向は
、温度上昇によるものと静圧上昇によるものとは反対方
向となることがわかる。第３図（４）。That is, it can be seen that the direction in which the zero point fluctuation occurs due to the effective area difference is opposite to that due to the temperature increase and the static pressure increase. Figure 3 (4).

ψ）はこれらの関係を図示したものであって、温度誤差
が（４）のごとく負方向であれば、静圧誤差は（＋３）
のごとく正方向となる。（４）、ω）において点線で示
したものが有効面積差に起因する誤差であり、これを補
償することＫより、ゼロ点変動を大幅に減少させること
ができる。ψ) is an illustration of these relationships; if the temperature error is in the negative direction as in (4), the static pressure error is (+3)
The direction is positive. In (4), ω), what is shown by the dotted line is an error caused by the effective area difference, and by compensating for this, the zero point fluctuation can be significantly reduced.

上記ゼロ点変動は、封液の体積変化（密度変化）に基づ
く内圧変化に起因して発生している。ζこで封液の温度
変化及び静圧変化に対する変化率と、封液の誘電率εの
温度変化及び静圧変化に対する変化率との関係をみると
、例えば一般的なシリコンオイルでは、 と表わされ、誘電率εの温度又は静圧による変化率と封
液の温度又は静圧による体積変化率とはほぼ等しいこと
がわかる。このことは、ｇ電率櫨の変化を検出して封液
の温度又は静圧による体積変化を検出することが可能で
あることを示している。The above-mentioned zero point fluctuation occurs due to an internal pressure change based on a volume change (density change) of the sealing liquid. ζNow, looking at the relationship between the rate of change of the sealing liquid with respect to temperature changes and static pressure changes, and the rate of change of the dielectric constant ε of the sealing liquid with respect to temperature changes and static pressure changes, for example, for general silicone oil, it is expressed as follows. It can be seen that the rate of change in dielectric constant ε due to temperature or static pressure is almost equal to the rate of change in volume of the sealing liquid due to temperature or static pressure. This shows that it is possible to detect changes in volume due to temperature or static pressure of the sealing liquid by detecting changes in the g-electricity.

ゼロ変動は封液の体積変化に起因して有効面積差がある
場合に生ずるのであるから、！Ｅ１ｍ率の変化により封
液の体積変化が検出できれば、この検出信号に基づいて
ゼロ点変動の補償が可能である。Zero fluctuation occurs when there is a difference in effective area due to a change in the volume of the sealing liquid! If a change in the volume of the sealing liquid can be detected by a change in the E1m rate, it is possible to compensate for the zero point fluctuation based on this detection signal.

ここで、誘電率εは一般に基準状態（Ｔ＝２０’Ｃ。Here, the dielectric constant ε is generally in a reference state (T=20'C).

Ｐ　＝　Ｏｋｇ／ａｍ　）の誘電率ε８に対してＴ、Ｐ
の変化ΔＴ。T, P for the dielectric constant ε8 of P = Okg/am)
Change in ΔT.

ΔＰに対し、α、βを定数として ６＝ε５（１−αΔＴ＋βΔＰ　）　（５）で表わされ
、温度に対する変化方向と静圧に対する変化方向とが逆
の特性を有している。ΔP is expressed as 6=ε5(1−αΔT+βΔP) (5) where α and β are constants, and the direction of change with respect to temperature and the direction of change with respect to static pressure are opposite to each other.

−力筒５図のようにゼロ点誤差は温度、静圧では逆極性
に発生するから、誘電率に比例する信号に適当な係数（
極性を含む）を乗じて、第１図における出力信号ｅ。Ｋ
加算するようにすれば、温度変動によるゼロ点変動と静
圧変動によるゼロ点変動を同時に補正することが可能で
ある。- As shown in Figure 5, the zero point error occurs with opposite polarity at temperature and static pressure, so an appropriate coefficient (
(including polarity) to produce the output signal e in FIG. K
By adding them, it is possible to simultaneously correct zero point fluctuations due to temperature fluctuations and zero point fluctuations due to static pressure fluctuations.

即ち、誘電率の変化を検出して補償する方法をとれば、
変動の発生要因がダイヤフラムの有効面積差に起因する
場合は、従来技術のように、温度センサ、圧力センサを
本体内に設けることなく、ゼロ点変動を有効に補償する
ことがてきる。In other words, if a method is used to detect and compensate for changes in permittivity,
If the cause of the fluctuation is due to a difference in the effective area of the diaphragm, the zero point fluctuation can be effectively compensated for without providing a temperature sensor or a pressure sensor inside the main body as in the prior art.

誘電＄ａの検出の具体的手段は、封液５内に基準静電容
量を設け、この容量変化を検出する方法でもよいが、差
圧に応動して変化する静電容量Ｃ１゜Ｃ２に基づいても
演算で容易にめることができ、特別なセンサを必要とし
ない構成が可能である。A specific means for detecting the dielectric $a may be a method of providing a reference capacitance in the sealing liquid 5 and detecting a change in this capacitance. It can be easily determined by calculation, and a configuration that does not require a special sensor is possible.

スパン変動についても同様に、誘電率と測定圧力。Dielectric constant and measured pressure similarly for span variation.

差圧の積を演算することによシ特別なセンナを必要とせ
ずに実現できる。This can be achieved without the need for a special sensor by calculating the product of differential pressures.

第４図は本発明の補償方法を適用した差圧・圧力伝送器
の原理的ブロック線図であり、第１図と対応する要素は
同−何分で示す。検出回路１１を介して得られるＣ工、
Ｃ２に関連した信号及び圧力、差圧に関連した信号は、
補償信号演算回路１９１Ｃ導かれて誘電率εに比例した
ゼロ点変動補償信号（第１信号）ｅＴｐ　と、スパン変
動補償信号（第２信号）ｅＴｐＩの和が算出され、加算
点２０で演算回路１１の出力信号ｅ。と加算されて温度
、静圧の変動によるゼロ点変動スパン変動が同時に補償
される。２１は封液５内に設けた基準静電容量手段であ
シ、この静電容１ＩＣ８に基づいて誘電率６を演算する
ようにしてもよい。FIG. 4 is a principle block diagram of a differential pressure/pressure transmitter to which the compensation method of the present invention is applied, and elements corresponding to those in FIG. 1 are indicated by the same number of minutes. C obtained through the detection circuit 11,
Signals related to C2 and pressure, signals related to differential pressure are:
The sum of the zero point fluctuation compensation signal (first signal) eTp proportional to the dielectric constant ε and the span fluctuation compensation signal (second signal) eTpI is calculated by the compensation signal calculation circuit 191C, and the sum is calculated by the calculation circuit 11 at the addition point 20. output signal e. The zero point fluctuation and span fluctuation due to temperature and static pressure fluctuations are simultaneously compensated for. 21 is a reference capacitance means provided in the sealing liquid 5, and the dielectric constant 6 may be calculated based on this capacitance 1IC8.

第５図は第４図の回路の具体例を示すものであって、差
圧に関連して変化する静電容量Ｃ□、Ｃ２け検出回路１
１に導かれて、デー−ティがＣ□、Ｃ２１ｃ関連したパ
ルス信号に変換された後、平滑されて直流出力信号ｅ。FIG. 5 shows a specific example of the circuit shown in FIG.
1, the data is converted into a pulse signal related to C□, C21c, and then smoothed to produce a DC output signal e.

に変換される。１１内の構成要素はコンパレータを形成
する増幅器Ｇ工、Ｇ２、切換スイッチを形成するゲート
０３〜Ｇ５、カウンタＣＴ工、インバータＧ６．Ｃ７及
び双方向性定電流回路ＣＣ１を組合せた自己発振回路で
、Ｃ工に関連する周期の発振パルスがカウンタＣＴｉ　
でｎ個計数されると０２に関連する発振に切換わシ、こ
のパルスが同様にｎ個計数されると元に戻る動作を繰返
し、カウンタＣＴ１の出力又はインバータＧ７の出力に
、オン時間がＣ工にオフ時間が０２（又はその逆）に関
連し、振幅が基準電圧Ｖのデー−ティサイクル信号を得
る（この演算回路の詳細については特開昭５７−１．４
７１．４号に説明されている）。is converted to The components in 11 are an amplifier G and G2 forming a comparator, gates 03 to G5 forming a changeover switch, a counter CT, and an inverter G6. This is a self-oscillating circuit that combines C7 and bidirectional constant current circuit CC1, and the oscillation pulse with the period related to C is the counter CTi.
When n pulses are counted, it switches to oscillation related to 02, and when n pulses are counted in the same way, the operation returns to the original state, and the on-time C In this process, a data cycle signal whose off time is related to 02 (or vice versa) and whose amplitude is the reference voltage V is obtained.
71.4).

第６図のはカウンタＣＴ１の出力波形で、オン時間Ｔ工
が０１に、オフ時間Ｔ２が０２に関連する。■はインバ
ータＧ７の出力で、■と逆位相の信号である。FIG. 6 shows the output waveform of the counter CT1, in which the on time T is associated with 01 and the off time T2 is associated with 02. 2 is the output of the inverter G7, and is a signal with the opposite phase to 2.

この信号が抵抗Ｒ１、コンデンサＣ３のフィルタで平滑
されて直流出力信号ｅ。に変換され、出力回路１２の増
幅器Ａ□の非反転入力端子Ｙ点に加算抵抗Ｒ２を介して
供給される。ｖＲｌはゼロ点調整手段で、その出力は加
算抵抗Ｒ３を介して加算点２ｏを形成するＹ点に接続さ
れている。ＶＲ２は増幅器へ〇の帰還回路に設けたスパ
ン調整手段で、増幅器Ａ２により、増幅器へ〇の出力は
増幅器Ａ３に導かれて、出力電流工。が与えられる帰還
抵抗ＲＬＫ発生する帰還電圧ｅＦと比較増幅され、出力
トランジスタＴＲを駆動して出力電流工を制御する。This signal is smoothed by a filter including a resistor R1 and a capacitor C3 to form a DC output signal e. and is supplied to the non-inverting input terminal Y point of the amplifier A□ of the output circuit 12 via the adding resistor R2. vRl is a zero point adjustment means, the output of which is connected to the Y point forming the addition point 2o via the addition resistor R3. VR2 is a span adjustment means provided in the feedback circuit of 〇 to the amplifier, and the output of 〇 to the amplifier is guided to amplifier A3 by amplifier A2, and the output current is adjusted. is compared and amplified with the feedback voltage eF generated by the feedback resistor RLK, which is applied, and drives the output transistor TR to control the output current.

次にこのような構成に付加される、本発明を適用した補
償信号演算回路１９について説明する。ＭＭは単安定回
路で、第６図■のデー−ティサイクル信号を受け、その
立上シでトリガされてＴ　十Ｔ　よ　２ シは短い■のごとき一定時間Ｔ。の出力パルスを発生さ
せる。Ｒ４，Ｃ４はＴ。を決定する時定数回路である。Next, the compensation signal calculation circuit 19 to which the present invention is applied, which is added to such a configuration, will be explained. MM is a monostable circuit that receives the data cycle signal shown in Figure 6, and is triggered by the rising edge of the signal. generates an output pulse of R4 and C4 are T. This is a time constant circuit that determines .

ＳＷ□は信号のを信号■で開閉するスイッチ、Ｒ５，Ｃ
５はスイッチＳＷ□の出力信号を平滑するフィルタであ
る。従って、このフィルタの出力信号０の電圧Ｖ。は、
Ｃ１＝　１１γ歇。（Ｋ’定数−ΔＰ：差圧　Ｃ８：定
数）とすると、 となる。この電圧は更に■の信号で開閉するスイッチＳ
Ｗ２を介してフィルタＲ６，Ｃ６を充電する。SW□ is a switch that opens and closes the signal by signal ■, R5, C
5 is a filter that smoothes the output signal of the switch SW□. Therefore, the voltage V of the output signal 0 of this filter. teeth,
C1 = 11γ intervals. When (K' constant - ΔP: differential pressure C8: constant), it becomes. This voltage is further increased by the switch S, which opens and closes with the signal ■.
Filters R6 and C6 are charged via W2.

ｓｗ３は同じく■の信号でｓｗ２ど逆位相で開閉し、こ
のフィルタの充電々荷を放電するスイッチである。この
構成によりフィルタＲ６，Ｃ６の出力［Ｆ］の電圧ＶＥ
は、 となシ、■は誘電率εに比例する。Similarly, sw3 is a switch that opens and closes in the opposite phase to sw2 with the signal ◯, and discharges the charge of this filter. With this configuration, the voltage VE of the output [F] of filters R6 and C6
is, and ■ is proportional to the dielectric constant ε.

この電圧Ｖおは信号■で可逆的に開閉するスイッチｓｗ
　、　ｓｗ　で■との積が演算され、Ｒ６，Ｃ６より５ なるフィルタを介して［Ｆ］点に、 なる電圧を得る。同様Ｋｖは信号ので可逆的に開閉する
スイッチ、ｓｗ　、　ｓｗ７でのとの積が演算され、Ｒ
７，Ｃ７よシなるフィルタを介して０点に、なる電圧を
得る。A switch sw that reversibly opens and closes with this voltage V and signal ■
, sw calculates the product with ■, and from R6 and C6, a voltage of 5 is obtained at point [F] through a filter of 5. Similarly, since Kv is a signal, the product of the switches sw and sw7, which open and close reversibly, is calculated, and R
7. A voltage of 0 point is obtained through a filter such as C7.

一方、ポテンショメータＶＲ３で設定される一定電圧Ｖ
Ｂは信号ので可逆的に開閉されるスイッチｓｗ８＋、　
ｓｗ９を介してのとの積が演算され、Ｒ８，Ｃ８よυな
るフィルタを介して０点に、 ｖＨ＝　ｖＢ（１−ＫＪＰ　）　Ａ　（８）なる電圧を
得る。同様に一定電圧ｖＢｔ−を信号Ｑで可逆的に開閉
されるスイッチｓｗ　、ｓｗ　を介して０１０　１１ との積が演算され、０点に、 Ｖ＝Ｖ（１＋にΔｐ　）　Ａ　（９） Ｂ なる電圧Ｖ工を得る。On the other hand, a constant voltage V set by potentiometer VR3
B is a switch sw8+ that is reversibly opened and closed due to the signal;
The product of and is calculated through sw9, and a voltage of vH=vB(1-KJP)A (8) is obtained at the 0 point via a filter υ such as R8 and C8. Similarly, the constant voltage vBt- is multiplied by 010 11 through the switches sw and sw which are reversibly opened and closed by the signal Q, and at the 0 point, V=V(Δp to 1+) A (9) B becomes. Obtain voltage V.

上記電圧ｖＦ、ｙ□は加算抵抗Ｒ１ｏ　、Ｒ，ｔ、□を
介してポテンショメータＶＲ４の一端Ｗへ、電圧ｖＧ、
■□は同様に加算抵抗Ｒ１゜、Ｒ１３を介してポテンシ
ョメータＶＲの他端２へ導かれる。抵抗Ｒ□。〜Ｒ□２
が岬しく　ＶＲ４のインピーダンスより充分大きい場合
に、ＶＲの摺動子０点の電圧Ｖは、ＶＲ４の２点か４　
Ｋ らの分圧比をαとするとき、 Ｖ　＝（ａ（１＋にΔｐ）Ａ＋（ｊ−にΔＰ）ＶＢ）。The voltage vF, y□ is applied to one end W of the potentiometer VR4 via the addition resistors R1o, R, t, □, and the voltage vG,
□ is similarly led to the other end 2 of the potentiometer VR via addition resistors R1° and R13. Resistance R□. ~R□2
When the impedance is sufficiently larger than the impedance of VR4, the voltage V at the 0 point of the VR slider is between 2 and 4 points of VR4.
When the partial pressure ratio of K et al. is α, V = (a(Δp to 1+)A+(ΔP to j−)VB).

＋（ｓ（１−にΔＰ）Ａ＋（１−にΔｐ）ｖ）−ｏｎ２ となる。+(s(ΔP to 1-)A+(Δp to 1-)v)-on2 becomes.

ここで一定電圧Ｖの値をＶＢ＝　Ａ　／　ｔ　に選定す
ると、６１式の電圧ｖＫは、 と表わせる。Here, if the value of the constant voltage V is selected as VB=A/t, the voltage vK of equation 61 can be expressed as follows.

この電圧ＶＫは基準状態謔＝６８のときはＶＫ＝Ａａ。This voltage VK is VK=Aa when the reference state is 68.

となシ、差圧ΔＰ　＋ＶＲ４の分圧比αには無関係とな
る。又差圧Δｐ＝ｏの時はＶＲの分圧比αには無関係に
誘電率１に比例する。In other words, the differential pressure ΔP + VR4 has no relation to the partial pressure ratio α. Further, when the differential pressure Δp=o, it is proportional to the dielectric constant 1 regardless of the VR partial pressure ratio α.

Ａは電圧Ｖを非反転入力端子に受けるバッファ４に 増幅器で、その出力電圧ｖＫはポテンショメータｖＲ５
の一端Ｔ点に与えられると共に抵抗Ｒ□４を介して増幅
器Ａ５の非反転入力端子に与えられる。ポテンショメー
タｖＲ６は一定電圧Ｖ。＝８．Ａを増幅器Ａ５の非反転
入力端子に設定する。増幅器Δ５の出力はポテンショメ
ータｖＲ５の他端０点に与えられると共に抵抗Ｒ１５を
介して非反転入力端子に負帰還される。A is an amplifier in the buffer 4 which receives the voltage V at its non-inverting input terminal, and its output voltage vK is connected to the potentiometer vR5.
is applied to one end of point T, and also applied to the non-inverting input terminal of amplifier A5 via resistor R□4. Potentiometer vR6 has a constant voltage V. =8. A is set as the non-inverting input terminal of amplifier A5. The output of the amplifier Δ5 is applied to the 0 point of the other end of the potentiometer vR5, and is also negatively fed back to the non-inverting input terminal via the resistor R15.

こξで抵抗Ｒ□４＝Ｒ□５に選定した場合にＵ点のとな
る。When the resistance R□4=R□5 is selected in this ξ, the value of point U is obtained.

ポテンショメータｖＲ５の摺動子０点の電圧Ｖ、が、温
度、静圧変動に対するゼロ点変動補償信号ｅＴｐ及びス
パン変動補償信号”ＴＰ’の和表して抵抗Ｒ□６を介し
て出力回路１２め加算点Ｙに導かれる。The voltage V at the zero point of the slider of the potentiometer vR5 is the sum of the zero point fluctuation compensation signal eTp and the span fluctuation compensation signal "TP" for temperature and static pressure fluctuations, and is added to the output circuit 12 via the resistor R□6. guided to point Y.

次にゼロ点変動及びスパン変動の補償の調整手順につき
説明する。Next, the adjustment procedure for compensating for zero point fluctuation and span fluctuation will be explained.

（１）　ゼロ点変動補償 差圧Δｐ＝ｏの状態とすると、　ｖ、　ｈ　（１式よシ
、８Ａ（１±ａ／ｓ）／ｚの範囲で変化する。この状態
で温度又社静圧を基準状態より変化させたときに出力電
流工。ｋ発生する正方向又は負方向のゼロ点の変化をポ
テンショメータｖＲ６の分圧比βを調整してゼロにすれ
ば、温度、静圧変動によるゼロ点変動が補償される。(1) Zero point fluctuation compensation When the differential pressure Δp=o, v, h (as in equation 1, changes in the range of 8A (1±a/s)/z. In this state, the temperature or static pressure When the output current changes from the reference state, the change in the zero point in the positive or negative direction that occurs can be made zero by adjusting the partial pressure ratio β of the potentiometer vR6. Fluctuations are compensated.

（２）　スパン変動補償 次に差圧ΔＰを印加した状態において温度又は静圧を基
準状態よシ変化させたときに出力電流工。(2) Span fluctuation compensation Next, when the temperature or static pressure is changed from the reference state with the differential pressure ΔP applied, the output current will change.

の値の変化（スパン変動）をポテンショメータＶＲの分
圧比αによってゼロにすれば温度、静圧変動によるスパ
ン変動が補償される。α傘式よシ明らかなように、αの
変化０〜１に対して（１力式第２項は、ＫΔＰ（１−ｇ
／ｇ）−−１（Δｐ（１−ａ／＆）の範囲て変化するの
で、温度、静圧変動の方向に対してスパン変動の方向が
正方向になりても負方向になってもゼロ点変動補償の場
合と同様に対応することができる。If the change in value (span fluctuation) is made zero by the partial pressure ratio α of the potentiometer VR, the span fluctuation due to temperature and static pressure fluctuations can be compensated. As is clear from the α umbrella equation, for a change of α from 0 to 1, the second term of the equation is KΔP(1−g
/g)--1(Δp(1-a/&), so it is zero whether the direction of span fluctuation is positive or negative with respect to the direction of temperature and static pressure fluctuation. This can be handled in the same way as in the case of point fluctuation compensation.

第７図は、本発明の主要部１９の他の実施例を示すもの
で、誘電率−の逆数１／εに関連した補償信号を得るも
のである。第５図との相違点は、単安定回路ＭＭの出力
■が直接サンプリングスイッチＳＷ１□に導かれて信号
ＯでサンプルされてフィルタＲ６，Ｃ６に導かれ、同様
に５Ｗ１３によって信号■でサンプルさｉｔてフィルタ
Ｒ７，Ｃ７に導かれる。尚一定電圧Ｖが信号■で可逆的
に開閉するスイッチＳＷ８ ＳＷ９に上りのとの積が演算されてフィルタＲ８”８に
、同様ＫｖＢが信号◎で可逆的に開閉するスイ。FIG. 7 shows another embodiment of the main part 19 of the present invention, which obtains a compensation signal related to the reciprocal of the dielectric constant - 1/ε. The difference from Fig. 5 is that the output ■ of the monostable circuit MM is directly guided to the sampling switch SW1□, sampled with the signal O, and guided to filters R6 and C6, and similarly sampled with the signal ■ by 5W13. and is guided to filters R7 and C7. Furthermore, the constant voltage V is a switch SW8 which is reversibly opened and closed by the signal ■, and the product of the upstream and the SW9 is calculated and applied to the filter R8''8, and similarly KvB is a switch which is reversibly opened and closed by the signal ◎.

チ５Ｗ１ｏ、ＳＷ□１により■との積が演算されてフィ
ルタＲ９，Ｃ８に導かれる構成は第５図と同様である。The configuration in which the product with ■ is calculated by CH5W1o and SW□1 and guided to filters R9 and C8 is the same as that shown in FIG.

この結果０点に得られる電圧ｖＫは、 となり、０や式と対比して明らかなように、１／６に関
連した電圧となる。As a result, the voltage vK obtained at the 0 point is as follows, and as is clear from the comparison with 0 and the formula, it is a voltage related to 1/6.

一般に君の変化幅が小さい場合には１／εも温度。Generally, if the range of change is small, 1/ε is also the temperature.

静圧に関連して直線的に変化するので、（１１１式の場
合と同様な補償が可能である。第７図のごとき１７ａの
演算の場合の方が８を演算する回路構成よシもスイッチ
の構成がやや簡素化される利点がある。Since it changes linearly in relation to the static pressure, it is possible to perform the same compensation as in the case of formula 111. This has the advantage that the configuration is somewhat simplified.

上記した実施例は、いずれも差圧又は圧力を測定する本
体の基本構造が、２枚の測定ダイヤフラムをロッドで連
結した、いわゆる−室構造のゼロ点変動、スパン変動の
補償に本発明を適用した例であるが、受圧ダイヤスラム
を介して一枚の測定ダイヤフラムの両側に測定すべき圧
力を受け、この測定ダイヤフラムの変位よシ差圧又は圧
力を測定する、いわゆるニア≧構造の伝送器の場合にも
、封液の防電率変化を演算又は誘電率変化検出のための
センサを用いて、温度、静圧変動に基づくゼロ点質動、
スパン変動を補償することができる。In all of the above-mentioned embodiments, the present invention is applied to compensate for zero point fluctuations and span fluctuations in a so-called -chamber structure in which the basic structure of the main body for measuring differential pressure or pressure is two measurement diaphragms connected by a rod. This is an example of a transmitter with a so-called near≧ structure, which receives the pressure to be measured on both sides of a single measuring diaphragm via a pressure receiving diaphragm and measures the differential pressure or pressure depending on the displacement of the measuring diaphragm. In some cases, zero point movement based on temperature and static pressure fluctuations can be calculated by calculating the change in electrical resistivity of the sealing liquid or using a sensor to detect changes in dielectric constant.
Span variations can be compensated for.

〈効果〉 以上説明したように、本発明は封液を有する差圧・圧力
伝送器であればどのような形式のものでも、その封液の
誘電率の変化を検出する仁とにより温度変動又は静圧変
動の一方又は両方に起因するゼロ点変動又はスパン変動
を、圧力センサのごとき複雑な構造を本体内に内蔵させ
ることなく簡単に実現することができる。<Effects> As explained above, the present invention can be applied to any type of differential pressure/pressure transmitter that has a sealing liquid, by detecting temperature fluctuations or changes in the dielectric constant of the sealing liquid. Zero point fluctuations or span fluctuations caused by one or both of static pressure fluctuations can be easily realized without incorporating a complicated structure such as a pressure sensor into the main body.

特Ｋ、−室構造の差圧・圧力伝送器の場合は、変動の発
生要因が封液の体積変化（密度変化）に基づく２枚の測
定ダイヤスラムの有効面積差により発生する割合が大き
いので、本発明により、温度変動並びに静圧変動による
ゼロ点質動、スパン変動を、−個の加算点への補償信号
の供給という極めて簡単な回路構成で実現できる。しか
も静電容量変化を利用して変位を測定する形式であれば
、特別な防電率検出用のセンナを一切用いることなく補
償が可能であり、高精度、高信頼度の製品を低コストで
実現できる。Special K: In the case of a differential pressure/pressure transmitter with a -chamber structure, a large proportion of fluctuations are caused by the difference in the effective area of the two measuring diaphragms based on volume changes (density changes) of the sealing liquid. According to the present invention, zero point shifting and span variation due to temperature fluctuations and static pressure fluctuations can be realized with an extremely simple circuit configuration of supplying compensation signals to - addition points. Furthermore, if the displacement is measured using changes in capacitance, compensation can be performed without using any special sensors for detecting electrical resistance, and high-precision, high-reliability products can be manufactured at low cost. realizable.

【図面の簡単な説明】[Brief explanation of drawings]

第１図は従来の差圧伝送器のゼロ点変動補償。 スパン変動補償を説明する構成図、第２図、第３図は温
度、静圧の変動による誤差発生のメカニズムを説明する
模型図及び特性図、第４図は本発明の基本構成を示すブ
ロック線図、第５図は第４図を具体化した場合の回路構
成図、第６図はその動作説明図、第７図は主要部の他の
実施例を示す回路構成図を示す。 Ｃ１，Ｃ２・・・静電容量゛、１・・・本体、２．５・
・・ダイヤフラム、５・・・封液、１１・・・検出回路
、１２・・・出力回路、１９・・・補償信号演算回路、
Ｃ・・・防電率、”Ｔｐ点変動補償信号、ｅＴｐ′・・
・スパン変動補償信号。Figure 1 shows zero point fluctuation compensation for a conventional differential pressure transmitter. A configuration diagram explaining span variation compensation, Figures 2 and 3 are model diagrams and characteristic diagrams explaining the mechanism of error occurrence due to fluctuations in temperature and static pressure, and Figure 4 is a block diagram showing the basic configuration of the present invention. FIG. 5 is a circuit configuration diagram embodying FIG. 4, FIG. 6 is an explanatory diagram of its operation, and FIG. 7 is a circuit diagram showing another embodiment of the main part. C1, C2...Capacitance゛, 1...Body, 2.5.
...Diaphragm, 5...Sealing liquid, 11...Detection circuit, 12...Output circuit, 19...Compensation signal calculation circuit,
C: Electrical protection factor, "Tp point fluctuation compensation signal, eTp'...
・Span variation compensation signal.

Claims (1)

【特許請求の範囲】[Claims] 測定すべき圧力又は差圧を受叶て変位する受圧要素及び
封液を有する圧力・差圧伝送器において、上記封液の誘
電率を検出する手段と、この検出手段の出力及び上記圧
力又は差圧の検出手段の出力に基づき、上記誘電率に関
連した第１信号及び上記誘電率と上記圧力又は差圧に比
例した信号の積に関連した第２信号との和を演算する補
償信号演算手段と、この手段の出力信号を上記検出手段
の出力信号に加算する手段とを有する圧力・差圧伝送器
。In a pressure/differential pressure transmitter having a pressure receiving element and a sealing liquid that are displaced in response to the pressure or differential pressure to be measured, there is provided a means for detecting the dielectric constant of the sealing liquid, an output of the detecting means, and the pressure or difference. Compensation signal calculation means for calculating the sum of a first signal related to the dielectric constant and a second signal related to the product of the dielectric constant and the signal proportional to the pressure or differential pressure, based on the output of the pressure detection means. and means for adding the output signal of the means to the output signal of the detection means.