JPH0453244B2 - - Google Patents
Info
- Publication number
- JPH0453244B2 JPH0453244B2 JP59203996A JP20399684A JPH0453244B2 JP H0453244 B2 JPH0453244 B2 JP H0453244B2 JP 59203996 A JP59203996 A JP 59203996A JP 20399684 A JP20399684 A JP 20399684A JP H0453244 B2 JPH0453244 B2 JP H0453244B2
- Authority
- JP
- Japan
- Prior art keywords
- liquid level
- liquid
- detection device
- circuit
- oscillation
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 239000007788 liquid Substances 0.000 claims description 88
- 230000010355 oscillation Effects 0.000 claims description 48
- 238000001514 detection method Methods 0.000 claims description 32
- 239000003990 capacitor Substances 0.000 claims description 15
- 238000003780 insertion Methods 0.000 claims description 3
- 230000037431 insertion Effects 0.000 claims description 3
- 238000009499 grossing Methods 0.000 description 10
- 230000000694 effects Effects 0.000 description 7
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 6
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 4
- 239000005708 Sodium hypochlorite Substances 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 238000009434 installation Methods 0.000 description 3
- SUKJFIGYRHOWBL-UHFFFAOYSA-N sodium hypochlorite Chemical compound [Na+].Cl[O-] SUKJFIGYRHOWBL-UHFFFAOYSA-N 0.000 description 3
- 238000010586 diagram Methods 0.000 description 2
- 239000012895 dilution Substances 0.000 description 2
- 238000010790 dilution Methods 0.000 description 2
- 239000008151 electrolyte solution Substances 0.000 description 2
- 229940021013 electrolyte solution Drugs 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 238000012544 monitoring process Methods 0.000 description 2
- 230000002093 peripheral effect Effects 0.000 description 2
- 229920000915 polyvinyl chloride Polymers 0.000 description 2
- 239000004800 polyvinyl chloride Substances 0.000 description 2
- 229920006395 saturated elastomer Polymers 0.000 description 2
- 235000011121 sodium hydroxide Nutrition 0.000 description 2
- 230000004308 accommodation Effects 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 239000007844 bleaching agent Substances 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 239000000284 extract Substances 0.000 description 1
- 230000007257 malfunction Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000000615 nonconductor Substances 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
- G01F23/22—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water
- G01F23/26—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of capacity or inductance of capacitors or inductors arising from the presence of liquid or fluent solid material in the electric or electromagnetic fields
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
- G01F23/80—Arrangements for signal processing
Description
【発明の詳細な説明】
(1) 発明の目的
［産業上の利用分野］
本発明は、液体レベル検出装置に関し、特に水
処理プラント等で薬品溶液の液面レベルを検出し
て制御するための液体レベル検出装置に関するも
のである。
［従来の技術］
従来、この種の液体レベル検出装置としては、
所定の高さ位置に配設された電極棒等に対し対象
液体を直接に接触せしめてその液面レベルが所定
の高さ位置まで到達したか否かを測定してなるも
のが、主として提案されていた。
［解決すべき問題点］
しかしながら、従来の液体レベル検出装置で
は、電極棒等を対象液体に対して直接に接触せし
める必要があつたので、（）対象液体の性質に
応じて電極棒等の材質を選定し対象液体による電
極棒等の腐食を防止しなければならない欠点があ
り、また（）材質によつては電極棒等が過度に
高価なものとなつてしまう欠点があり、更に
（）対象液体の液面レベルを調整する液面レベ
ル制御器等が必要となつて電気回路が複雑となつ
てしまう欠点があつた。
そこで、本発明は、これらの欠点を除去する目
的で、次亜塩素酸ナトリウム、カセイソーダ、硫
酸等の腐蝕性液体が一般に導電率の高い電解質溶
液であることに着目して高周波電磁方式による対
象液体の液面レベルの検出を可能とし、かつ対象
液体に対し直接に接触することを回避して簡単な
電気回路で液面レベルの検出を高精度で実現する
液体レベル検出装置を提供しようとするものであ
る。
(2) 発明の構成
［問題点の解決手段］
本発明により提供される問題点の解決手段は、
「(a) 対象液体中の所望の高さ位置に挿入された
不導筒体と、
(b) エミツタが第１の抵抗を介して定電圧源に接
続され、かつベースが第２の抵抗および第１の
コンデンサの並列回路を介して接地されかつ第
３の抵抗を介して定電圧源に接続され、かつコ
レクタが第２のコンデンサを介してエミツタに
接続されかつ不導筒体中に収容されシールド板
の装着されたコイルおよび第３のコンデンサの
並列回路を介して接地され、かつリニア領域で
発振するトランジスタを包有しており、不導筒
体の挿入位置まで対象液体の液面レベルが到達
したか否かに応じ発振強度が変化する発振回路
と
を備えてなることを特徴とする液体レベル検出
装置」
である。
［作用］
本発明にかかる液体レベル検出装置は、上述の
［問題点の解決手段］の欄に明示したごとく構成
されているので、
() 不導筒体の挿入位置に対象液体の液面レベ
ルが到達したか否かを、コイルの発生する磁界
に伴なう渦電流の変化として検知し、発振回路
の発振出力の強度変化に変えて取り出す作用
をなし、また
() 対象液体の容量変化に伴なう発振回路の発
振出力の強度変化を、コイルに装着したシール
ド板で除去する作用
をなし、加えて
() 発振回路の動作領域をリニア領域とする作
用
をなし、ひいては
() 対象液体の液面レベルの検知精度を向上せ
しめる作用
をなす
［実施例］
次に、本発明にかかる液体レベル検出装置につ
いて、その好ましい実施例を挙げ、添付図面を参
照しつつ、具体的に説明する。
しかしながら、以下に説明する実施例は、本発
明の理解を容易化ないし促進化するために記載さ
れるものであつて、本発明を限定するために記載
されるものではない。
換言すれば、以下に説明する実施例において開
示される各要素は、本発明の精神ならびに技術的
範囲に属する全ての設計変更ならびに均等物置換
を含むものである。
（添付図面の説明）
第１図は、本発明にかかる液体レベル検出装置
の一実施例を示すための断面図である。
第２図は、第１図に示した実施例の一部を拡大
して示すための斜視図である。
第３図は、第１図に示した実施例の電気回路を
示すための回路図である。
第４図は、第１図に示した実施例の動作を示す
ためのグラフであつて、特に発振回路１２Ａの入
力信号（すなわちトランジスタTRのベース電
流）S1と出力信号（すなわちトランジスタTRの
コレクタ電流）S0との関係を示している。
第５図は、第１図に示した実施例の作用を示す
ためのグラフであつて、特に対象液体２１の濃度
（ここでは希釈倍率）Ｄに応じて出力端Ｅに出現
する出力電圧V0を示している。
（実施例の構成）
まず、第１図ないし第３図を参照しつつ、本発
明にかかる液体レベル検出装置の一実施例につい
て、その構成を詳細に説明する。
１０は、本発明にかかる液体レベル検出装置で
あつて、対象液体（たとえば次亜塩素酸ナトリウ
ム、カセイソーダ、硫酸等の腐蝕性液体のうち高
い導電率をもつ電解質溶液）２１の収容された容
器２２の側壁に対して形成された取付孔２２ａに
対し配設された不導筒体１１と、不導筒体１１の
収容孔１１ａ中に少なくとも一部が配設された検
出回路１２とを、備えている。対象液体２１は、
導電率が10000μS／cm以上のものが好ましく、こ
の導電率未満であると後述の発振回路１２Ａの発
振強度の変化が小さく、その液面レベルを検知す
るのが困難となる。
不導筒体１１は、対象液体２１に接触されても
変質ないし損傷を受けないポリビニルクロライド
などの適宜の不導体によつて形成されている。不
導筒体１１は、容器２２の取付孔２２ａに挿入さ
れかつ一端部が閉鎖されており外周面が対象液体
２１に接触される筒体１１Ａと、筒体１１Ａの他
端部に形成されており筒部１１Ａが取付孔２２ａ
に挿入された状態で取付孔２２ａの周縁部（すな
わち容器２２の側壁）にビスなどで取り付けられ
るフランジ部１１Ｂとを、包有している。
検出回路１２は、対象液体２１の液面レベルに
応じて発振強度の変化する発振回路１２Ａと、発
振回路１２Ａの出力端に配設されており発振回路
１２Ａの発振出力を整流し平滑化するための整流
平滑回路１２Ｂとを、包有している。
検出回路１２に包有された発振回路１２Ａは、
エミツタが抵抗R1を介して定電圧源Vccに接続さ
れかつベースが抵抗R2を介して定電圧源Vccに接
続されたトランジスタTRと、トランジスタTR
のベースに一端部が接続されかつ他端部が接地さ
れた抵抗R3と、抵抗R3に対し並列に接続された
コンデンサC1と、トランジスタTRのエミツタコ
レクタ間に挿入されたコンデンサC2と、トラン
ジスタTRのコレクタに一端部が接続されかつ他
端部が接地されており不導筒体１１中に挿入され
たコイルＬと、コイルＬに対し並列に接続された
コンデンサC3とを、包有している。コイルＬは、
不導筒体１１の配設位置に対象液体２１が存在す
るとき、その発生した磁界が対象液体２１中を横
切るに際し発生される渦電流に応じてコンデンサ
C3の放電電流を大きくしている。コイルＬには、
容器２２の内面に付着した対象液体２１の容量変
化に伴なう誤動作を防止する目的で、シールド板
SHが配設されている。発振回路１２Ａの発振周波
数は、大きいほど対象液体２１の液面レベルの検
知感度を改善できて好ましいが、検知動作を確保
できかつコイルＬの大きさおよび巻数を製作容易
な範囲とできるので、10〜40MHzとされているこ
とが特に好ましい。
検出回路１２に包有された整流平滑回路１２Ｂ
は、トランジスタTRのコレクタとコンデンサC3
およびコイルＬの並列回路との接続点にアノード
が接続されたダイオードＤと、ダイオードＤのカ
ソードを接地するためのコンデンサC4と、ダイ
オードＤのカソードと出力端Ｅとの間に挿入され
た抵抗R4と、出力端Ｅを接地するためのコンデ
ンサC5とを、包有している。
検出回路１２に包まれた発振回路１２Ａ中のト
ランジスタTRにおける入力信号（すなわちベー
ス電流）S1と出力信号（すなわちコレクタ電流）
S0との関係は、第４図に示したごとく、（）入
力信号S1が小さい領域では、入力信号S1が大きく
なるに比例して出力信号S0が大きくなり、これに
対し（）入力信号S1が大きい領域では、出力信
号S0が飽和してしまい、入力信号S1が大きくなつ
ても出力信号S0が実質的に大きくならない。した
がつて、ここでは、入力信号S1が大きくなるに比
例して出力信号S0が大きくなる領域をリニア領域
といい、入力信号S1が大きくなつても出力信号S0
が実質的に大きくならない領域を飽和領域とい
う。
発振回路１２Ａは、トランジスタTRの飽和領
域で動作させると、その動作が安定であるため、
対象液体２１の液面レベルを検知しようとしても
出力信号S0が１〜２％程度変化するに過ぎないの
で、実質的に対象液体２１の液面レベルを検知で
きない。それ故、本発明では、発振回路１２Ａ
（具体的にはトランジスタTR）をリニア領域で
動作せしめて対象液体２１の液面レベルを検知し
ている。発振回路１２Ａ（具体的にはトランジス
タTR）をリニア領域の中間点で動作せしめれ
ば、対象液体２１の液面レベルの検知能率を改善
できるので、特に好ましい。
本発明によれば、対象液体２１の液面レベルが
上昇して不導筒体１１の配設位置に到達すると、
発振回路１２Ａ（具体的にはトランジスタTR）
の出力信号S0（ひいては整流平滑回路１２Ａの出
力電圧V0）が大きく変化するので、対象液体２
１の液面レベルを良好に検知できる。
（実施例の作用）
また、第１図ないし第５図を参照しつつ、本発
明にかかる液体レベル検出装置の一実施例につい
て、その作用を詳細に説明する。
本発明にかかる液面レベル検出装置１０では、
容器２２中に収容された対象液体２１の液面レベ
ルが不導筒体１１の配設位置に到達せずかつその
配設位置から十分に離間している場合、発振回路
１２Ａ中のコイルＬが容器２２中の対象液体２１
によつて影響を殆ど受けないので、発振回路１２
Ａの発振強度ひいては整流平滑回路１２Ｂの出力
電圧V0が小さい。
容器２２中に収容された対象液体２１の液面レ
ベルが上昇し不導筒体１１の配設位置に徐々に接
近する場合、発振回路１２ＡのコイルＬが容器２
２中の対象液体２１によつて影響を受け始めるの
で、発振回路１２Ａの発振強度ひいては整流平滑
回路１２Ｂの出力電圧V0が徐々に大きくなる。
更に、容器２２中に収容された対象液体２１の
液面レベルが上昇し不導筒体１１の配設位置に到
達した場合、発振回路１２Ａ中のコイルＬが容器
２２中の対象液体２１によつて影響を十分に受け
るので、発振回路１２Ａの発振強度ひいては整流
平滑回路１２Ｂの出力電圧V0が一層大きくなる。
これに対し、容器２２中に収容された対象液体
２１の液面レベルが低下し不導筒体１１の配設位
置から徐々に離間する場合、発振回路１２Ａ中の
コイルＬが容器２２中の対象液体２１によつて影
響を徐々に受けなくなるので、発振回路１２Ａの
発振強度ひいては整流平滑回路１２Ｂの出力電圧
V0が徐々に小さくなる。
それ故、本発明にかかる液体レベル検出装置１
０では、発振回路１２Ａの発振出力ひいては整流
平滑回路１２Ｂの出力電圧V0を監視することに
よつて、対象液体２１の液面レベルが上昇して不
導筒体１１の配設位置まで到達したか否かを容易
かつ確実に検出できる。
（具体例）
更に、本発明にかかる液体レベル検出装置につ
いて、その理解を促進する目的で、一層具体的な
数値などを挙げて説明する。
直径が25mmでかつ厚さが３mmのポリビニルクロ
ライドでできた不導筒体に対し、直径が約16mmで
かつ長さが10mmであり、8.5回巻回されたコイル
を有する発振回路を挿入し、7.2ボルトの定電圧
電源に接続した。
容器には、液温25℃の市販の漂白剤（ここでは
次亜塩素酸ナトリウム）が不導筒体の配設位置を
超えて収容されていた。
このとき、整流平滑回路の出力電圧V0は、第
５図に示すごとく、その濃度（ここでは希釈倍
率）Ｄに応じて変化していた。
（変形例）
なお、上述では、単一の発振回路１２Ａが容器
２２の所定高さ位置に配置されており対象液体２
１の液面レベルが到達したか否かを監視する場合
について説明したが、本発明は、これに限定され
るものではなく、容器２２の異なる高さ位置にそ
れぞれ同一構成の異なる発振回路１２Ａを配設し
て各高さ位置に対象液体２１の液面レベルが到達
したか否かを検出する場合も包摂している。
(3) 発明の効果
上述より明らかなように、本発明にかかる液体
レベル検出装置は、［問題点の解決手段］の欄に
明示したごとく構成されているので、
() 不導筒体の挿入位置に対象液体の液面レベ
ルが到達したか否かを、コイルの発生する磁界
に伴なう渦電流の変化として検知し、発振回路
の発振出力の強度変化に変えて取り出すことが
できる効果
を有し、また
() 対象液体の容量変化に伴なう発振回路の発
振出力の強度変化を、コイルに装着したシール
ド板で除去できる効果
を有し、加えて
() 発振回路の発振領域をリニア領域とできる
効果
を有し、ひいては
() 対象液体の液面レベルの検知精度を向上せ
しめることができる効果
を有す。 [Detailed Description of the Invention] (1) Purpose of the Invention [Field of Industrial Application] The present invention relates to a liquid level detection device, particularly for detecting and controlling the liquid level of a chemical solution in a water treatment plant or the like. This invention relates to a liquid level detection device. [Prior art] Conventionally, this type of liquid level detection device has
The main method proposed is to directly contact the target liquid with an electrode rod placed at a predetermined height and measure whether the liquid level has reached a predetermined height. was. [Problems to be solved] However, in conventional liquid level detection devices, it was necessary to bring the electrode rod etc. into direct contact with the target liquid. There is a disadvantage that it is necessary to prevent corrosion of the electrode rod etc. due to the target liquid by selecting the target liquid, and () the electrode rod etc. may become excessively expensive depending on the material. This has the disadvantage that a liquid level controller or the like is required to adjust the level of the liquid, making the electrical circuit complicated. Therefore, in order to eliminate these drawbacks, the present invention focuses on the fact that corrosive liquids such as sodium hypochlorite, caustic soda, and sulfuric acid are generally electrolyte solutions with high conductivity, and uses a high-frequency electromagnetic method to analyze target liquids. An object of the present invention is to provide a liquid level detection device that can detect the liquid level of a target liquid and that can detect the liquid level with high precision using a simple electric circuit by avoiding direct contact with the target liquid. It is. (2) Structure of the invention [Means for solving the problem] The means for solving the problem provided by the present invention is as follows: ``(a) A nonconducting cylinder inserted at a desired height position in a target liquid; b) The emitter is connected to a constant voltage source through a first resistor, and the base is grounded through a parallel circuit of a second resistor and a first capacitor, and connected to a constant voltage source through a third resistor. connected, and the collector is connected to the emitter via the second capacitor, and is grounded via a parallel circuit of a coil housed in a nonconducting cylinder and equipped with a shield plate, and a third capacitor, and in a linear region. and an oscillation circuit whose oscillation intensity changes depending on whether the level of the target liquid has reached the insertion position of the nonconducting cylinder. liquid level detection device. [Function] Since the liquid level detection device according to the present invention is configured as specified in the column of [Means for solving problems] above, () the liquid level of the target liquid is detected at the insertion position of the non-conducting cylinder; It detects whether the eddy current has reached or not as a change in the eddy current accompanying the magnetic field generated by the coil, and extracts it by converting it into a change in the intensity of the oscillation output of the oscillation circuit. The accompanying change in the intensity of the oscillation output of the oscillation circuit is removed by the shield plate attached to the coil, and () the operating region of the oscillation circuit is made into a linear region, which in turn () [Embodiment] Effects of Improving Liquid Level Detection Accuracy Next, a preferred embodiment of the liquid level detection device according to the present invention will be described in detail with reference to the accompanying drawings. However, the examples described below are described to facilitate or accelerate understanding of the present invention, and are not described to limit the present invention. In other words, each element disclosed in the embodiments described below includes all design changes and equivalent substitutions that fall within the spirit and technical scope of the present invention. (Description of the attached drawings) FIG. 1 is a sectional view showing an embodiment of a liquid level detection device according to the present invention. FIG. 2 is an enlarged perspective view of a part of the embodiment shown in FIG. FIG. 3 is a circuit diagram showing the electric circuit of the embodiment shown in FIG. 1. FIG . 4 is a graph showing the operation of the embodiment shown in FIG. Current) shows the relationship with S 0 . FIG. 5 is a graph showing the effect of the embodiment shown in FIG. 1, in particular, the output voltage V 0 appearing at the output terminal E according to the concentration (here, the dilution factor) D of the target liquid 21. It shows. (Configuration of Embodiment) First, the configuration of an embodiment of the liquid level detection device according to the present invention will be described in detail with reference to FIGS. 1 to 3. Reference numeral 10 denotes a liquid level detection device according to the present invention, which includes a container 22 containing a target liquid (for example, an electrolyte solution with high conductivity among corrosive liquids such as sodium hypochlorite, caustic soda, and sulfuric acid). A non-conducting cylinder 11 disposed in a mounting hole 22a formed in a side wall of the non-conducting cylinder 11, and a detection circuit 12 at least partially disposed in a housing hole 11a of the non-conducting cylinder 11. ing. The target liquid 21 is
It is preferable that the conductivity is 10,000 μS/cm or more. If the conductivity is less than this, the change in the oscillation intensity of the oscillation circuit 12A described later will be small, making it difficult to detect the liquid level. The nonconducting cylinder 11 is made of a suitable nonconductor such as polyvinyl chloride, which does not undergo deterioration or damage even if it comes into contact with the target liquid 21. The non-conducting cylindrical body 11 is formed at a cylindrical body 11A that is inserted into the mounting hole 22a of the container 22 and has one end closed and whose outer peripheral surface is in contact with the target liquid 21, and at the other end of the cylindrical body 11A. The cage tube portion 11A is the mounting hole 22a.
The flange portion 11B is attached to the peripheral edge of the attachment hole 22a (ie, the side wall of the container 22) with screws or the like while being inserted into the flange portion 11B. The detection circuit 12 is provided with an oscillation circuit 12A whose oscillation intensity changes depending on the liquid level of the target liquid 21, and an output end of the oscillation circuit 12A to rectify and smooth the oscillation output of the oscillation circuit 12A. It includes a rectifying and smoothing circuit 12B. The oscillation circuit 12A included in the detection circuit 12 is
A transistor TR whose emitter is connected to a constant voltage source Vcc via a resistor R1 and whose base is connected to a constant voltage source Vcc via a resistor R2 ;
A resistor R3 whose one end is connected to the base of the transistor TR and whose other end is grounded, a capacitor C1 connected in parallel to the resistor R3, and a capacitor C2 inserted between the emitter collector of the transistor TR . A coil L whose one end is connected to the collector of the transistor TR and whose other end is grounded and inserted into the non-conducting cylinder 11, and a capacitor C3 connected in parallel to the coil L, contains. Coil L is
When the target liquid 21 is present at the location where the non-conducting cylindrical body 11 is disposed, the capacitor is
The discharge current of C3 is increased. In coil L,
In order to prevent malfunctions due to changes in the volume of the target liquid 21 attached to the inner surface of the container 22, a shield plate is installed.
S H is installed. The higher the oscillation frequency of the oscillation circuit 12A, the better the detection sensitivity of the liquid level of the target liquid 21 can be improved, but it is preferable to set the oscillation frequency to 10 because it can ensure the detection operation and keep the size and number of turns of the coil L within a range that is easy to manufacture. It is particularly preferable that the frequency be ˜40 MHz. Rectifying and smoothing circuit 12B included in detection circuit 12
is the collector of transistor TR and capacitor C3
and a diode D whose anode is connected to the connection point with the parallel circuit of the coil L, a capacitor C4 for grounding the cathode of the diode D, and a resistor inserted between the cathode of the diode D and the output terminal E. R 4 and a capacitor C 5 for grounding the output terminal E. Input signal (i.e. base current) S 1 and output signal (i.e. collector current) in transistor TR in oscillation circuit 12A wrapped in detection circuit 12
As shown in Figure 4, the relationship with S 0 is as follows: () In the region where the input signal S 1 is small, the output signal S 0 increases in proportion to the increase in the input signal S 1; In a region where the input signal S 1 is large, the output signal S 0 is saturated, and even if the input signal S 1 becomes large, the output signal S 0 does not substantially increase. Therefore, here, the region in which the output signal S 0 increases in proportion to the increase in the input signal S 1 is called a linear region, and even if the input signal S 1 increases, the output signal S 0
The region where the value does not become substantially large is called the saturated region. The oscillation circuit 12A operates stably when operated in the saturation region of the transistor TR.
Even if an attempt is made to detect the level of the target liquid 21, the output signal S0 only changes by about 1 to 2%, so the level of the target liquid 21 cannot be substantially detected. Therefore, in the present invention, the oscillation circuit 12A
(Specifically, the transistor TR) is operated in a linear region to detect the level of the target liquid 21. It is particularly preferable to operate the oscillation circuit 12A (specifically, the transistor TR) at the midpoint of the linear region, since the detection rate of the level of the target liquid 21 can be improved. According to the present invention, when the liquid level of the target liquid 21 rises and reaches the position where the non-conducting cylinder 11 is disposed,
Oscillation circuit 12A (specifically transistor TR)
Since the output signal S 0 (and thus the output voltage V 0 of the rectifying and smoothing circuit 12A) changes greatly,
1 liquid level can be detected well. (Operations of the Embodiment) Further, the operation of an embodiment of the liquid level detection device according to the present invention will be described in detail with reference to FIGS. 1 to 5. In the liquid level detection device 10 according to the present invention,
When the liquid level of the target liquid 21 contained in the container 22 does not reach the disposed position of the non-conducting cylinder 11 and is sufficiently separated from the disposed position, the coil L in the oscillation circuit 12A Target liquid 21 in container 22
The oscillation circuit 12
The oscillation intensity of A and therefore the output voltage V 0 of the rectifier and smoothing circuit 12B is small. When the liquid level of the target liquid 21 contained in the container 22 rises and gradually approaches the installation position of the nonconducting cylinder 11, the coil L of the oscillation circuit 12A
2, the oscillation intensity of the oscillation circuit 12A and the output voltage V 0 of the rectifying and smoothing circuit 12B gradually increase. Further, when the liquid level of the target liquid 21 contained in the container 22 rises and reaches the installation position of the non-conducting cylinder 11, the coil L in the oscillation circuit 12A is caused by the target liquid 21 in the container 22. As a result, the oscillation intensity of the oscillation circuit 12A and the output voltage V 0 of the rectifying and smoothing circuit 12B further increase. On the other hand, when the liquid level of the target liquid 21 contained in the container 22 decreases and gradually moves away from the installation position of the nonconducting cylinder 11, the coil L in the oscillation circuit 12A Since it gradually ceases to be affected by the liquid 21, the oscillation intensity of the oscillation circuit 12A and the output voltage of the rectifying and smoothing circuit 12B decrease.
V 0 gradually decreases. Therefore, the liquid level detection device 1 according to the present invention
0, by monitoring the oscillation output of the oscillation circuit 12A and the output voltage V0 of the rectifying and smoothing circuit 12B, it is determined that the level of the target liquid 21 rises and reaches the position where the nonconducting cylinder 11 is disposed. It is possible to easily and reliably detect whether the (Specific Example) Further, the liquid level detection device according to the present invention will be described with more specific numerical values and the like for the purpose of promoting understanding thereof. An oscillation circuit having a diameter of approximately 16 mm, a length of 10 mm, and a coil wound 8.5 times is inserted into a nonconducting cylinder made of polyvinyl chloride with a diameter of 25 mm and a thickness of 3 mm. Connected to a 7.2 volt constant voltage power supply. A commercially available bleach (in this case, sodium hypochlorite) with a liquid temperature of 25°C was contained in the container beyond the location of the nonconducting cylinder. At this time, the output voltage V 0 of the rectifying and smoothing circuit varied in accordance with the concentration (here, the dilution factor) D, as shown in FIG. (Modified example) In the above description, the single oscillation circuit 12A is arranged at a predetermined height position of the container 22, and the target liquid 2
Although the case of monitoring whether or not the liquid level of 1 has been reached has been described, the present invention is not limited to this, and different oscillation circuits 12A having the same configuration may be installed at different height positions of the container 22. This also includes a case where the liquid level of the target liquid 21 is detected at each height position. (3) Effects of the invention As is clear from the above, the liquid level detection device according to the present invention is constructed as specified in the column of [Means for solving problems]. The effect can be detected by detecting whether the liquid level of the target liquid has reached the position as a change in the eddy current caused by the magnetic field generated by the coil, and converting it into a change in the intensity of the oscillation output of the oscillation circuit. It also has the effect of () being able to eliminate changes in the intensity of the oscillation output of the oscillation circuit due to changes in the volume of the target liquid with the shield plate attached to the coil; This has the effect of improving the area and, in turn, improving the accuracy of detecting the liquid level of the target liquid.
第１図は本発明にかかる液体レベル検出装置の
一実施例を示すための断面図、第２図は第１図に
示した実施例の一部を拡大して示すための斜視
図、第３図は第１図に示した実施例の電気回路を
示すための回路図、第４図は第１図に示した実施
例の動作を示すためのグラフ、第５図は第１図に
示した実施例の作用を示すためのグラフである。
１０……液体レベル検出装置、１１……不導筒
体、１１Ａ……筒部、１１Ｂ……フランジ部、１
１ａ……収容孔、１２……検出回路、１２Ａ……
発振回路、C1〜C3……コンデンサ、Ｌ……コイ
ル、R1〜R3……抵抗、SH……シールド板、TR…
…トランジスタ、Vcc……定電圧源、１２Ｂ……
整流平滑回路、C4，C5……コンデンサ、Ｄ……
ダイオード、Ｅ……出力端、２１……対象液体、
２２……容器、２２ａ……取付孔。
FIG. 1 is a cross-sectional view showing one embodiment of the liquid level detection device according to the present invention, FIG. 2 is a perspective view showing an enlarged part of the embodiment shown in FIG. 1, and FIG. The figure is a circuit diagram showing the electric circuit of the embodiment shown in Fig. 1, Fig. 4 is a graph showing the operation of the embodiment shown in Fig. 1, and Fig. 5 is the same as that shown in Fig. 1. It is a graph for showing the effect of the example. 10 ...Liquid level detection device, 11...Nonconducting cylindrical body, 11A...Cylinder part, 11B...Flange part, 1
1a...accommodation hole, 12...detection circuit, 12A...
Oscillation circuit, C1 to C3 ...Capacitor, L...Coil, R1 to R3 ...Resistor, S H ...Shield plate, TR...
...Transistor, Vcc... Constant voltage source, 12B...
Rectifier and smoothing circuit, C 4 , C 5 ... Capacitor, D ...
Diode, E...Output end, 21...Target liquid,
22...Container, 22a...Mounting hole.
Claims (1)
た不導筒体と、 (b) エミツタが第１の抵抗を介して定電圧源に接
続され、かつベースが第２の抵抗および第１の
コンデンサの並列回路を介して接地されかつ第
３の抵抗を介して定電圧源に接続され、かつコ
レクタが第２のコンデンサを介してエミツタに
接続されかつ不導筒体中に収容されシールド板
の装着されたコイルおよび第３のコンデンサの
並列回路を介して接地され、かつリニア領域で
発振するトランジスタを包有しており、不導筒
体の挿入位置まで対象液体の液面レベルが到達
したか否かに応じ発振強度が変化する発振回路
と を備えてなる液体レベル検出装置。 ２ 不導筒体が、対象液体を収容した容器の側壁
に対して取付けるためのフランジ部を備えてなる
ことを特徴とする特許請求の範囲第１項記載の液
体レベル検出装置。 ３ 発振回路が、10〜40MHzの周波数で発振して
なることを特徴とする特許請求の範囲第１項もし
くは第２項記載の液体レベル検出装置。 ４ 対象液体が、10000μS／cm以上の導電率を有
してなることを特徴とする特許請求の範囲第１項
ないし第３項のいずれか一項記載の液体レベル検
出装置。[Claims] 1 (a) a nonconducting cylinder inserted at a desired height in a target liquid; (b) an emitter connected to a constant voltage source via a first resistor; is grounded through a parallel circuit of a second resistor and a first capacitor, and connected to a constant voltage source through a third resistor, and whose collector is connected to an emitter through a second capacitor and is non-conducting. It is housed in a cylinder and is grounded through a parallel circuit of a coil equipped with a shield plate and a third capacitor, and includes a transistor that oscillates in a linear region, and is targeted up to the insertion position of the non-conducting cylinder. A liquid level detection device comprising an oscillation circuit whose oscillation intensity changes depending on whether the liquid surface level has been reached. 2. The liquid level detection device according to claim 1, wherein the non-conducting cylindrical body is provided with a flange portion for attachment to a side wall of a container containing a target liquid. 3. The liquid level detection device according to claim 1 or 2, wherein the oscillation circuit oscillates at a frequency of 10 to 40 MHz. 4. The liquid level detection device according to any one of claims 1 to 3, wherein the target liquid has a conductivity of 10000 μS/cm or more.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP59203996A JPS6183916A (en) | 1984-10-01 | 1984-10-01 | Liquid level detection method and apparatus |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP59203996A JPS6183916A (en) | 1984-10-01 | 1984-10-01 | Liquid level detection method and apparatus |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6183916A JPS6183916A (en) | 1986-04-28 |
| JPH0453244B2 true JPH0453244B2 (en) | 1992-08-26 |
Family
ID=16483045
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP59203996A Granted JPS6183916A (en) | 1984-10-01 | 1984-10-01 | Liquid level detection method and apparatus |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6183916A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4911738A (en) * | 1989-03-21 | 1990-03-27 | The United States Of America As Represented By The United States National Aeronautics And Space Administration | Zero-g phase detector and separator |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5092798A (en) * | 1973-12-15 | 1975-07-24 | ||
| JPS5162064A (en) * | 1974-11-27 | 1976-05-29 | Omron Tateisi Electronics Co | REBERUKENS HUTSUKI |
| JPS5164958A (en) * | 1974-10-14 | 1976-06-04 | Heisuberutosu Yoozefu Mateusu | |
| JPS537359A (en) * | 1976-05-20 | 1978-01-23 | Atomenergi Ab | Electromagnetic device for measuring quantity on conductive liquid |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5025557U (en) * | 1973-06-29 | 1975-03-24 |
-
1984
- 1984-10-01 JP JP59203996A patent/JPS6183916A/en active Granted
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5092798A (en) * | 1973-12-15 | 1975-07-24 | ||
| JPS5164958A (en) * | 1974-10-14 | 1976-06-04 | Heisuberutosu Yoozefu Mateusu | |
| JPS5162064A (en) * | 1974-11-27 | 1976-05-29 | Omron Tateisi Electronics Co | REBERUKENS HUTSUKI |
| JPS537359A (en) * | 1976-05-20 | 1978-01-23 | Atomenergi Ab | Electromagnetic device for measuring quantity on conductive liquid |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6183916A (en) | 1986-04-28 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| KR100535680B1 (en) | Sensor for detecting water level | |
| JPH0238988A (en) | Liquid sensor | |
| EA001606B1 (en) | Electrochemical machinning a workpiece | |
| KR20170141211A (en) | A device for sensing the electrical conductivity of liquids, in particular the electrical conductivity of washing machines | |
| JPH0453244B2 (en) | ||
| JPH11271323A (en) | Autoanalyzer | |
| US3989463A (en) | Sensing element and detection system employing such element for detection of environmental borne material | |
| JP2007127615A (en) | Capacitance level sensor | |
| JP5397055B2 (en) | Washing fluid sensor | |
| JP2006208234A (en) | Liquid concentration detector | |
| KR102361714B1 (en) | Capacitive level sensing apparatus and method | |
| JP2002340653A (en) | Capacitance type liquid-level sensor | |
| JPH06148123A (en) | Deteriorated degree detection device for treatment liquid for semi-conductor device | |
| JPS60194319A (en) | Liquid residue detector | |
| SU1619182A1 (en) | Sending unit for measuring electric parameters of foil | |
| JPH056655Y2 (en) | ||
| JPH07209228A (en) | Concentration meter | |
| JPS6038189Y2 (en) | Liquid level detection device | |
| JPS5847022B2 (en) | liquid detector | |
| JPS6023019Y2 (en) | Vibrator protection circuit | |
| WO1994014056A1 (en) | Densitometer | |
| JPH0233140Y2 (en) | ||
| JP3648681B2 (en) | Tube heater device | |
| RU1827617C (en) | Device for coulometric titration of liquids by electrically generated iodine | |
| JPS62233198A (en) | Method for measuring amount of washing article in washing machine |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| EXPY | Cancellation because of completion of term |