WO2019167660A1 - Liquid level position detection device - Google Patents

Abstract

Provided is a liquid level position detection device having good precision of liquid level position detection. A liquid level position detection device is provided with a propagation body 10 in which the ratio of a portion thereof that is immersed in a liquid varies according to the liquid level position, a first transmitting/receiving part 21, a second transmitting/receiving part 22, and a detection part for detecting the liquid level position on the basis of the propagation time of a first surface wave W1 and/or a second surface wave W2. The propagation body 10 has a bottom surface part 16 which connects a main surface part 11 and a main surface part 12 and forms a curved surface shape in side view. The first transmitting/receiving part 21 generates a first surface wave W1 propagated through the main surface part 11, and the second transmitting/receiving part 22 receives the first surface wave W1 propagated through the bottom surface part 16 and the main surface part 12 via the main surface part 11. The second transmitting/receiving part 22 generates a second surface wave W2 propagated through the main surface part 12, and the first transmitting/receiving part 21 receives the second surface wave W2 propagated through the bottom surface part 16 and the main surface part 11 via the main surface part 12.

Description

液面位置検出装置Liquid level detection device

　本発明は、液面位置検出装置に関する。 The present invention relates to a liquid level position detection device.

　液面位置検出装置として、例えば、特許文献１には、伝搬体のうち液体中の部分を伝搬する表面波の音速が、液体から露出している部分を伝搬する表面波の音速よりも遅くなることを利用して液体の液面位置を検出するものが開示されている。 As a liquid surface position detection device, for example, in Patent Document 1, the speed of sound of a surface wave propagating through a portion of a propagating body in a liquid is slower than the speed of sound of a surface wave propagating through a portion exposed from the liquid. The thing which detects the liquid level position of a liquid using this is disclosed.

特開平４－８６５２５号公報Japanese Patent Laid-Open No. 4-86525

　特許文献１に開示された液面位置検出装置では、液面位置によっては伝搬体を伝搬する表面波が減衰してＳ／Ｎ比（Signal-Noise ratio）が悪化してしまい、液面位置の検出精度が悪くなる場合がある。 In the liquid level position detection device disclosed in Patent Document 1, depending on the liquid level position, the surface wave propagating through the propagating body is attenuated and the S / N ratio (Signal-Noise ratio) is deteriorated. The detection accuracy may deteriorate.

　本発明は、上記実情に鑑みてなされたものであり、液面位置の検出精度が良い液面位置検出装置を提供することを目的とする。 The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a liquid surface position detection device with high liquid surface position detection accuracy.

　上記目的を達成するため、本発明に係る液面位置検出装置は、
　液体の液面位置に応じて、前記液体に浸る部分の割合が変化する伝搬体と、
　前記伝搬体に第１表面波を発生させるとともに第２表面波を受ける第１送受波部と、
　前記伝搬体に前記第２表面波を発生させるとともに前記第１表面波を受ける第２送受波部と、
　前記第２送受波部が受けた前記第１表面波の伝搬時間と、前記第１送受波部が受けた前記第２表面波の伝搬時間との少なくともいずれかに基づいて前記液面位置を検出する検出部と、を備え、
　前記伝搬体は、
　互いに裏表の関係にある第１主面部及び第２主面部と、
　前記第１主面部と前記第２主面部とを繋ぐとともに、側面視において曲面状をなす底面部と、を有し、
　前記第１送受波部は、前記第１主面部を伝搬する前記第１表面波を発生させ、
　前記第２送受波部は、前記第１主面部を経て前記底面部と前記第２主面部とを伝搬した前記第１表面波を受け、
　前記第２送受波部は、前記第２主面部を伝搬する前記第２表面波を発生させ、
　前記第１送受波部は、前記第２主面部を経て前記底面部と前記第１主面部とを伝搬した前記第２表面波を受ける。 In order to achieve the above object, a liquid surface position detection device according to the present invention is
A propagating body in which a ratio of a portion immersed in the liquid changes according to a liquid surface position;
A first transmission / reception unit for generating a first surface wave in the propagation body and receiving a second surface wave;
A second transmission / reception unit for generating the second surface wave in the propagating body and receiving the first surface wave;
The liquid level position is detected based on at least one of the propagation time of the first surface wave received by the second wave transmitting / receiving unit and the propagation time of the second surface wave received by the first wave transmitting / receiving unit. And a detecting unit
The propagator is
A first main surface portion and a second main surface portion, which are in reverse relation to each other;
And connecting the first main surface portion and the second main surface portion, and a bottom surface portion having a curved shape in a side view,
The first transmitting / receiving unit generates the first surface wave propagating through the first main surface unit,
The second transmission / reception unit receives the first surface wave that has propagated through the first main surface portion and the bottom surface portion and the second main surface portion,
The second wave transmitting / receiving unit generates the second surface wave propagating through the second main surface part,
The first wave transmitting / receiving unit receives the second surface wave that has propagated through the second main surface portion and the bottom surface portion and the first main surface portion.

　本発明によれば、液面位置の検出精度が良い液面位置検出装置を提供することができる。 According to the present invention, it is possible to provide a liquid surface position detection device with good liquid surface position detection accuracy.

本発明の第１実施形態に係る液面位置検出装置の概略構成図である。It is a schematic block diagram of the liquid level position detection apparatus which concerns on 1st Embodiment of this invention. （ａ）は、第１実施形態に係る伝搬体及び振動子の正面図であり、（ｂ）は、第１実施形態に係る伝搬体及び振動子の側面図である。(A) is a front view of the propagating body and vibrator according to the first embodiment, and (b) is a side view of the propagating body and vibrator according to the first embodiment. 第１表面波と第２表面波を説明するための模式図である。It is a schematic diagram for demonstrating a 1st surface wave and a 2nd surface wave. 液面位置検出処理の一例を示すフローチャートである。It is a flowchart which shows an example of a liquid level position detection process. （ａ）は、第２実施形態に係る伝搬体及び振動子の正面図であり、（ｂ）は、第２実施形態に係る伝搬体及び振動子の側面図であり、（ｃ）は、第２実施形態に係る伝搬体の振動子側の平面図である。(A) is a front view of the propagating body and vibrator according to the second embodiment, (b) is a side view of the propagating body and vibrator according to the second embodiment, and (c) It is a top view at the vibrator side of the propagating body according to the second embodiment. 第３表面波と第４表面波を説明するための模式図である。It is a schematic diagram for demonstrating a 3rd surface wave and a 4th surface wave. （ａ）は、主に内部伝搬波を説明するための波形の模式図であり、（ｂ）は、第２実施形態に係る伝搬体による波形の模式図である。(A) is a schematic diagram of the waveform for mainly explaining an internal propagation wave, (b) is a schematic diagram of the waveform by the propagation body which concerns on 2nd Embodiment. 液面位置検出処理の一例を示すフローチャートである。It is a flowchart which shows an example of a liquid level position detection process.

　本発明の一実施形態に係る液面位置検出装置について図面を参照して説明する。 DETAILED DESCRIPTION A liquid level position detection apparatus according to an embodiment of the present invention will be described with reference to the drawings.

（第１実施形態）
　第１実施形態に係る液面位置検出装置１００は、図１に示すように、容器８０内に入れられた液体９０の液面９１の位置を検出する装置である。液体９０の量の増減に伴い、液面９１も上下する。 (First embodiment)
As shown in FIG. 1, the liquid surface position detection device 100 according to the first embodiment is a device that detects the position of the liquid surface 91 of the liquid 90 put in the container 80. As the amount of the liquid 90 increases or decreases, the liquid level 91 also moves up and down.

　液面位置検出装置１００は、伝搬体１０と、振動子２０と、送受信回路３０と、制御部４０と、を備える。 The liquid level position detection apparatus 100 includes a propagation body 10, a vibrator 20, a transmission / reception circuit 30, and a control unit 40.

　伝搬体１０は、表面波が伝搬するものであり、例えば、ＰＰＳ（ポリフェニレンサルファイド）などの合成樹脂から形成されている。伝搬体１０は、上下方向に長尺な帯板形状である。伝搬体１０の外面は、振動子２０に向く上面と、上面とは反対側の底面と、上面と底面を繋ぐとともに互いに裏表の関係となる２つの主面と、上面と底面を繋ぐとともに互いに裏表の関係となる２つの側面と、の６面から主に構成される。 The propagating body 10 propagates a surface wave and is made of a synthetic resin such as PPS (polyphenylene sulfide). The propagating body 10 has a strip shape that is long in the vertical direction. The outer surface of the propagating body 10 includes an upper surface facing the vibrator 20, a bottom surface opposite to the upper surface, two main surfaces that connect the upper surface and the bottom surface, and have a reverse relationship with each other, and an upper surface and a bottom surface that are connected to each other. It is mainly composed of six sides, which are the two side surfaces that are in the relationship.

　伝搬体１０は、図２（ａ）、（ｂ）に示すように、２つの主面のうち一方を含む主面部１１（第１主面部の一例）、他方を含む主面部１２（第２主面部の一例）と、２つの側面のうち一方を含む側面部１３、他方を含む側面部１４と、上面を含み振動子２０と当接する当接部１５と、底面を含む底面部１６と、を有する。後述のように、表面波は、伝搬体１０を伝搬するが、伝搬の際には伝搬体１０の表面から表面波の波長とほぼ同じ深さまで達する。主面部１１や主面部１２は、伝搬体１０の主面だけでなく当該深さをも含む部分である。当接部１５や底面部１６なども同様である。 2A and 2B, the propagating body 10 includes a main surface portion 11 (an example of a first main surface portion) including one of two main surfaces, and a main surface portion 12 (second main surface) including the other. An example of the surface portion), a side surface portion 13 including one of the two side surfaces, a side surface portion 14 including the other, a contact portion 15 including the upper surface and contacting the vibrator 20, and a bottom surface portion 16 including the bottom surface. Have. As will be described later, the surface wave propagates through the propagating body 10, but reaches the same depth as the wavelength of the surface wave from the surface of the propagating body 10 during propagation. The main surface portion 11 and the main surface portion 12 are portions including not only the main surface of the propagation body 10 but also the depth. The same applies to the contact portion 15 and the bottom surface portion 16.

　図２（ｂ）に示すように、側面視では、主面部１１は、当接部１５の一端から垂下する。また、主面部１２は、当接部１５の他端から垂下する。また、底面部１６は、当接部１５とは反対側において主面部１１と主面部１２とを繋ぐとともに、下方に凸となるＵ字状の滑らかな曲面状をなしている。このように形成された底面部１６は、後述の第１表面波Ｗ１及び第２表面波Ｗ２が底面部１６に伝搬する際の漏洩による損失を低減する。 2B, the main surface portion 11 hangs from one end of the contact portion 15 in a side view. The main surface portion 12 hangs from the other end of the contact portion 15. Further, the bottom surface portion 16 connects the main surface portion 11 and the main surface portion 12 on the side opposite to the contact portion 15 and has a U-shaped smooth curved surface that protrudes downward. The bottom surface portion 16 formed in this way reduces loss due to leakage when a first surface wave W1 and a second surface wave W2 described later propagate to the bottom surface portion 16.

　伝搬体１０は、図１に示すように、側面部１３及び側面部１４で容器８０に設けられた固定部材８１、８２に挟まれることによって固定されている。なお、伝搬体１０は、表面波の伝搬を阻害しないように、表面波が伝搬する主面部１１及び主面部１２以外の部分で固定されれば、その固定方法は任意である。 As shown in FIG. 1, the propagating body 10 is fixed by being sandwiched between fixing members 81 and 82 provided on the container 80 by the side surface portion 13 and the side surface portion 14. In addition, if the propagation body 10 is fixed in parts other than the main surface part 11 and the main surface part 12 which a surface wave propagates so that propagation of a surface wave may not be inhibited, the fixing method is arbitrary.

　伝搬体１０は、底面部１６の下端が容器８０の底面と長さｄだけ離間して配置される。伝搬体１０における、当接部１５の上端から液面９１までの上下方向に沿った長さ（伝搬体１０が液体９０に浸っていない部分である第１部分１０ａの長さ）Ｌ１と、底面部１６の下端から液面９１までの上下方向に沿った長さ（伝搬体１０が液体９０に浸っている部分である第２部分１０ｂの長さ）Ｌ２とは、液体９０の増減によって変化する。 The propagating body 10 is arranged such that the lower end of the bottom surface portion 16 is separated from the bottom surface of the container 80 by a length d. The length along the vertical direction from the upper end of the contact portion 15 to the liquid surface 91 in the propagation body 10 (the length of the first portion 10a where the propagation body 10 is not immersed in the liquid 90) L1 and the bottom surface The length along the vertical direction from the lower end of the portion 16 to the liquid level 91 (the length of the second portion 10b where the propagation body 10 is immersed in the liquid 90) L2 varies depending on the increase or decrease of the liquid 90. .

　振動子２０は、例えば、横波トランスデューサであり、回路基板に実装された圧電素子などを含んで構成される。振動子２０は、伝搬体１０の当接部１５に押しつけられ、伝搬体１０の主面部１１及び主面部１２に表面波を発生させる。 The vibrator 20 is, for example, a transverse wave transducer and includes a piezoelectric element mounted on a circuit board. The vibrator 20 is pressed against the contact portion 15 of the propagating body 10 to generate surface waves on the main surface portion 11 and the main surface portion 12 of the propagating body 10.

　以下では、振動子２０が主面部１１に発生させる表面波を第１表面波Ｗ１と呼び、主面部１２に発生させる表面波を第２表面波Ｗ２と呼ぶ。また、第１表面波Ｗ１と第２表面波Ｗ２とを区別なく、単に表面波と呼ぶこともある。 Hereinafter, the surface wave generated by the vibrator 20 on the main surface portion 11 is referred to as a first surface wave W1, and the surface wave generated on the main surface portion 12 is referred to as a second surface wave W2. Further, the first surface wave W1 and the second surface wave W2 may be simply referred to as surface waves without being distinguished.

　振動子２０は、伝搬体１０に第１表面波Ｗ１を発生させるとともに、第２表面波Ｗ２を受ける第１送受波部２１と、伝搬体１０に第２表面波Ｗ２を発生させるとともに、第１表面波Ｗ１を受ける第２送受波部２２と、を有する。 The vibrator 20 generates the first surface wave W1 in the propagating body 10 and generates the first surface wave receiving and receiving unit 21 that receives the second surface wave W2, and the propagating body 10 generates the second surface wave W2 and And a second transmission / reception unit 22 that receives the surface wave W1.

　第１送受波部２１は、送受信回路３０から供給される電気信号によって振動する。第１送受波部２１の振動は伝搬体１０に伝達され、主面部１１の上端に第１表面波Ｗ１が発生する。発生した第１表面波Ｗ１は、図３に示すように、主面部１１の下端へ向かって伝搬し、前記のように滑らかな曲面を有する底面部１６に沿って伝搬した後、主面部１２の上端へ向かって伝搬する。主面部１２の上端へ到達した第１表面波Ｗ１は、第２送受波部２２を振動させる。第２送受波部２２は、この振動を電気信号に変換して送受信回路３０に供給する。 The first transmission / reception unit 21 vibrates by an electrical signal supplied from the transmission / reception circuit 30. The vibration of the first transmitting / receiving unit 21 is transmitted to the propagation body 10, and the first surface wave W <b> 1 is generated at the upper end of the main surface part 11. As shown in FIG. 3, the generated first surface wave W <b> 1 propagates toward the lower end of the main surface portion 11, propagates along the bottom surface portion 16 having a smooth curved surface as described above, and then Propagate towards the top. The first surface wave W1 that has reached the upper end of the main surface portion 12 causes the second wave transmitting / receiving portion 22 to vibrate. The second transmission / reception unit 22 converts this vibration into an electric signal and supplies it to the transmission / reception circuit 30.

　第２送受波部２２は、送受信回路３０から供給される電気信号によって振動する。第２送受波部２２の振動は伝搬体１０に伝達され、主面部１２の上端に第２表面波Ｗ２が発生する。発生した第２表面波Ｗ２は、図３に示すように、主面部１２の下端へ向かって伝搬し、前記のように滑らかな曲面を有する底面部１６に沿って伝搬した後、主面部１１の上端へ向かって伝搬する。主面部１１の上端へ到達した第２表面波Ｗ２は、第１送受波部２１を振動させる。第１送受波部２１は、この振動を電気信号に変換して送受信回路３０に供給する。 The second transmission / reception unit 22 vibrates by the electric signal supplied from the transmission / reception circuit 30. The vibration of the second transmission / reception unit 22 is transmitted to the propagation body 10, and the second surface wave W <b> 2 is generated at the upper end of the main surface portion 12. As shown in FIG. 3, the generated second surface wave W2 propagates toward the lower end of the main surface portion 12, propagates along the bottom surface portion 16 having a smooth curved surface as described above, and then Propagate towards the top. The second surface wave W2 that has reached the upper end of the main surface part 11 vibrates the first wave transmitting / receiving part 21. The first transmission / reception unit 21 converts this vibration into an electric signal and supplies it to the transmission / reception circuit 30.

　なお、以上のように第１送受波部２１が伝搬体１０に第１表面波Ｗ１を発生させることを、第１表面波Ｗ１を送る、とも表現する。同様に、第２送受波部２２が伝搬体１０に第２表面波Ｗ２を発生させることを、第２表面波Ｗ２を送る、とも表現する。 Note that, as described above, the generation of the first surface wave W1 in the propagation body 10 by the first transmitting / receiving unit 21 is also expressed as transmitting the first surface wave W1. Similarly, the generation of the second surface wave W2 in the propagation body 10 by the second transmitting / receiving unit 22 is also expressed as transmitting the second surface wave W2.

　この実施形態では、第１表面波Ｗ１及び第２表面波Ｗ２は、超音波（例えば、２０ＫＨｚ以上の音波であればよい。）のパルス（超音波パルス）となっている。また、第１表面波Ｗ１及び第２表面波Ｗ２は、レイリー波である。なお、振動子２０は、圧電素子と伝搬体１０との間に介在され、振動の伝わりを効率良くするための超音波用接触媒質を含んでいてもよい。 In this embodiment, the first surface wave W1 and the second surface wave W2 are pulses (ultrasonic pulses) of ultrasonic waves (for example, a sound wave of 20 KHz or higher). The first surface wave W1 and the second surface wave W2 are Rayleigh waves. Note that the vibrator 20 may include an ultrasonic contact medium that is interposed between the piezoelectric element and the propagating body 10 and that efficiently transmits vibration.

　送受信回路３０は、振動子２０に接続される。送受信回路３０は、超音波発生回路として、表面波として超音波パルスを発生させる電気信号を振動子２０に供給し、振動子２０を振動させる。送受信回路３０は、超音波受信回路として、振動子２０から供給される電気信号を受け取り、受け取った電気信号を増幅、変換する。 The transmission / reception circuit 30 is connected to the vibrator 20. As the ultrasonic wave generation circuit, the transmission / reception circuit 30 supplies an electric signal for generating an ultrasonic pulse as a surface wave to the vibrator 20 to vibrate the vibrator 20. The transmission / reception circuit 30 receives an electrical signal supplied from the transducer 20 as an ultrasonic reception circuit, and amplifies and converts the received electrical signal.

　具体的には、送受信回路３０は、第１表面波Ｗ１の送波用の電気信号を第１送受波部２１に供給し、第１送受波部２１を振動させる。また、第１表面波Ｗ１を受けた第２送受波部２２から供給される電気信号を受け取り、受け取った電気信号を増幅、変換する。また、送受信回路３０は、第２表面波Ｗ２の送波用の電気信号を第２送受波部２２に供給し、第２送受波部２２を振動させる。また、第２表面波Ｗ２を受けた第１送受波部２１から供給される電気信号を受け取り、受け取った電気信号を増幅、変換する。 Specifically, the transmission / reception circuit 30 supplies an electric signal for transmission of the first surface wave W1 to the first transmission / reception unit 21 to vibrate the first transmission / reception unit 21. Further, it receives an electrical signal supplied from the second transmitting / receiving unit 22 that has received the first surface wave W1, and amplifies and converts the received electrical signal. In addition, the transmission / reception circuit 30 supplies an electric signal for transmission of the second surface wave W <b> 2 to the second transmission / reception unit 22 to vibrate the second transmission / reception unit 22. Further, it receives an electrical signal supplied from the first transmitting / receiving unit 21 that has received the second surface wave W2, and amplifies and converts the received electrical signal.

　制御部４０は、ＣＰＵ（Central Processing Unit）、ＲＯＭ（Read Only Memory）、ＲＡＭ（Random Access Memory）、タイマなどから構成されるマイクロコンピュータ、Ｄ／Ａ（デジタル／アナログ）変換器、Ａ／Ｄ（アナログ／デジタル）変換器などを含んで構成される。制御部４０は、送受信回路３０に接続される。制御部４０は、送受信回路３０を制御し、送受信回路３０から電気信号を振動子２０の第１送受波部２１と第２送受波部２２の各々に供給させる。これにより、第１表面波Ｗ１を主面部１１に発生させ、第２表面波Ｗ２を主面部１２に発生させる。また、制御部４０は、送受信回路３０で増幅、変換された、振動子２０の第１送受波部２１と第２送受波部２２の各々からの電気信号を受け取り、受け取った電気信号に基づいて後述のように液面位置を検出する。また、制御部４０は、液面位置検出装置１００の外部の外部装置６０とデータのやり取りが可能になっている。液面位置検出装置１００の構成の説明は以上である。 The control unit 40 includes a microcomputer including a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), a timer, a D / A (digital / analog) converter, an A / D ( An analog / digital converter is included. The control unit 40 is connected to the transmission / reception circuit 30. The control unit 40 controls the transmission / reception circuit 30 to supply an electrical signal from the transmission / reception circuit 30 to each of the first transmission / reception unit 21 and the second transmission / reception unit 22 of the vibrator 20. Thus, the first surface wave W1 is generated on the main surface portion 11 and the second surface wave W2 is generated on the main surface portion 12. Further, the control unit 40 receives electrical signals from each of the first transmission / reception unit 21 and the second transmission / reception unit 22 of the vibrator 20 that are amplified and converted by the transmission / reception circuit 30, and based on the received electrical signals. The liquid level position is detected as will be described later. In addition, the control unit 40 can exchange data with an external device 60 outside the liquid level position detection device 100. The configuration of the liquid surface position detection device 100 has been described above.

　次に、液面位置検出装置１００の動作を、制御部４０が実行する液面位置検出処理（図４参照）を中心に説明する。例えば、制御部４０のＣＰＵが、ＲＡＭをメインメモリとして、ＲＯＭに格納されているプログラムに従って、及びＲＯＭに格納されている各種データを用いて、液面位置検出処理を実行する。制御部４０は、例えば、外部装置６０からの指令に基づいて、液面位置検出処理を開始する。 Next, the operation of the liquid level position detection apparatus 100 will be described focusing on the liquid level position detection process (see FIG. 4) executed by the control unit 40. For example, the CPU of the control unit 40 executes the liquid surface position detection process using the RAM as a main memory, according to a program stored in the ROM, and using various data stored in the ROM. For example, the control unit 40 starts the liquid surface position detection process based on a command from the external device 60.

（液面位置検出処理）
　液面位置検出処理を開始すると、図４に示すように、制御部４０は、送受信回路３０を介して第１送受波部２１を振動させ、主面部１１の上端に第１表面波Ｗ１を発生させる（ステップＳ１）。 (Liquid surface position detection process)
When the liquid level position detection process is started, as shown in FIG. 4, the control unit 40 vibrates the first transmission / reception unit 21 via the transmission / reception circuit 30 and generates the first surface wave W <b> 1 at the upper end of the main surface unit 11. (Step S1).

　発生した第１表面波Ｗ１は、図３に示すように、主面部１１の下端へ向かって伝搬し、滑らかな曲面を有する底面部１６に沿って伝搬した後、主面部１２の上端へ向かって伝搬する。主面部１２の上端へ到達した第１表面波Ｗ１は、第２送受波部２２を振動させる。第２送受波部２２は、この振動を電気信号に変換して送受信回路３０に供給する。送受信回路３０は、供給された電気信号を増幅、変換して制御部４０に供給する。以下では、この増幅、変換された電気信号（つまり、底面部１６への伝搬を経て第２送受波部２２に到達する第１表面波Ｗ１が、第２送受波部２２に発生させる振動を示す電気信号）を、第１伝搬波信号と言う。このように、第１送受波部２１から送られた第１表面波Ｗ１は、第２送受波部２２に到達する間に、気体に接触する第１部分１０ａと液体９０に接触する第２部分１０ｂとの境界を二回跨いで伝搬する。 As shown in FIG. 3, the generated first surface wave W <b> 1 propagates toward the lower end of the main surface portion 11, propagates along the bottom surface portion 16 having a smooth curved surface, and then toward the upper end of the main surface portion 12. Propagate. The first surface wave W1 that has reached the upper end of the main surface portion 12 causes the second wave transmitting / receiving portion 22 to vibrate. The second transmission / reception unit 22 converts this vibration into an electric signal and supplies it to the transmission / reception circuit 30. The transmission / reception circuit 30 amplifies and converts the supplied electric signal and supplies it to the control unit 40. In the following, this amplified and converted electrical signal (that is, the first surface wave W1 that reaches the second transmitting / receiving unit 22 through propagation to the bottom surface part 16 shows vibrations generated by the second transmitting / receiving unit 22). The electric signal) is referred to as a first propagation wave signal. As described above, the first surface wave W1 transmitted from the first wave transmitting / receiving unit 21 reaches the second wave transmitting / receiving unit 22 while the first portion 10a in contact with the gas and the second portion in contact with the liquid 90. It propagates across the boundary with 10b twice.

　続いて、制御部４０は、ステップＳ１の処理を行ってから第１伝搬波信号を受信するまでの期間を計測するために、タイマを初期値の０に設定する（ステップＳ２）。当該期間は、第１送受波部２１が第１表面波Ｗ１を発生させたタイミングから、第２送受波部２２が第１表面波Ｗ１を受けるタイミングまでの期間であり、要するに、第１送受波部２１から第２送受波部２２までの第１表面波Ｗ１の伝搬時間（以下、第１伝搬時間と言う。）である。 Subsequently, the control unit 40 sets a timer to an initial value of 0 in order to measure a period from when the process of step S1 is performed until the first propagation wave signal is received (step S2). The period is a period from the timing at which the first transmitting / receiving unit 21 generates the first surface wave W1 to the timing at which the second transmitting / receiving unit 22 receives the first surface wave W1, and in short, the first transmitting / receiving wave. It is the propagation time of the first surface wave W1 from the unit 21 to the second transmission / reception unit 22 (hereinafter referred to as the first propagation time).

　続いて、制御部４０は、送受信回路３０から第１伝搬波信号を受信したか否かを判別する（ステップＳ３）。この判別は、適宜の方法で行うことができるが、例えば、制御部４０は、第２送受波部２２から供給されて送受信回路３０で増幅、変換された電気信号を取得し、取得した電気信号の電圧に基づく値（例えば、電圧値、電圧値の２乗の所定期間における平均値、前記電圧値又は前記平均値の変化度、電気信号の振幅など）が予めＲＯＭ内に格納された閾値以上となったか否かを判別する。例えば、予め実験によって第１伝搬波信号を測定しておき、測定結果に基づいて閾値を定めておけばよい。そして、制御部４０は、電気信号の電圧に基づく値が閾値以上となった場合に、第１伝搬波信号を受信した（ステップＳ３；Ｙｅｓ）と判別する。一方、制御部４０は、電気信号の電圧に基づく値が閾値未満である場合は、第１伝搬波信号を受信していない（ステップＳ３；Ｎｏ）と判別する。 Subsequently, the control unit 40 determines whether or not the first propagation wave signal is received from the transmission / reception circuit 30 (step S3). This determination can be performed by an appropriate method. For example, the control unit 40 acquires the electric signal supplied from the second transmission / reception unit 22 and amplified and converted by the transmission / reception circuit 30. A value based on the voltage (for example, the voltage value, the average value of the square of the voltage value in a predetermined period, the change of the voltage value or the average value, the amplitude of the electrical signal, etc.) is equal to or greater than a threshold value stored in the ROM in advance. It is determined whether or not. For example, the first propagation wave signal may be measured in advance by an experiment, and the threshold value may be determined based on the measurement result. And the control part 40 discriminate | determines that the 1st propagation wave signal was received when the value based on the voltage of an electrical signal becomes more than a threshold value (step S3; Yes). On the other hand, the control part 40 discriminate | determines that the 1st propagation wave signal is not received when the value based on the voltage of an electrical signal is less than a threshold value (step S3; No).

　第１伝搬波信号を未だ受信していない場合（ステップＳ３；Ｎｏ）、制御部４０は、タイマのタイマ値を＋１などして更新し（ステップＳ４）、再度ステップＳ３の処理を実行する。これにより、制御部４０は、第１伝搬波信号を受信するまで計時を行う。 When the first propagation wave signal has not been received yet (step S3; No), the control unit 40 updates the timer value of the timer by +1 (step S4), and executes the process of step S3 again. As a result, the control unit 40 keeps timing until the first propagation wave signal is received.

　第１伝搬波信号を受信した場合（ステップＳ３；Ｙｅｓ）、制御部４０は、現在のタイマ値を第１伝搬時間として、例えばＲＡＭに記憶する（ステップＳ５）。 When the first propagation wave signal is received (step S3; Yes), the control unit 40 stores the current timer value as the first propagation time, for example, in the RAM (step S5).

　続いて、制御部４０は、送受信回路３０を介して第２送受波部２２を振動させ、主面部１２の上端に第２表面波Ｗ２を発生させる（ステップＳ６）。 Subsequently, the control unit 40 vibrates the second transmission / reception unit 22 via the transmission / reception circuit 30 to generate the second surface wave W2 at the upper end of the main surface unit 12 (step S6).

　発生した第２表面波Ｗ２は、図３に示すように、主面部１２の下端へ向かって伝搬し、滑らかな曲面を有する底面部１６に沿って伝搬した後、主面部１１の上端へ向かって伝搬する。主面部１１の上端へ到達した第２表面波Ｗ２は、第１送受波部２１を振動させる。第１送受波部２１は、この振動を電気信号に変換して送受信回路３０に供給する。送受信回路３０は、供給された電気信号を増幅、変換して制御部４０に供給する。以下では、この増幅、変換された電気信号（つまり、底面部１６への伝搬を経て第１送受波部２１に到達する第２表面波Ｗ２が、第１送受波部２１に発生させる振動を示す電気信号）を、第２伝搬波信号と言う。このように、第２送受波部２２から送られた第２表面波Ｗ２は、第１送受波部２１に到達する間に、気体に接触する第１部分１０ａと液体９０に接触する第２部分１０ｂとの境界を二回跨いで伝搬する。 As shown in FIG. 3, the generated second surface wave W <b> 2 propagates toward the lower end of the main surface portion 12, propagates along the bottom surface portion 16 having a smooth curved surface, and then toward the upper end of the main surface portion 11. Propagate. The second surface wave W2 that has reached the upper end of the main surface part 11 vibrates the first wave transmitting / receiving part 21. The first transmission / reception unit 21 converts this vibration into an electric signal and supplies it to the transmission / reception circuit 30. The transmission / reception circuit 30 amplifies and converts the supplied electric signal and supplies it to the control unit 40. In the following, this amplified and converted electrical signal (that is, the second surface wave W2 that reaches the first transmission / reception unit 21 through propagation to the bottom surface part 16 shows vibration generated in the first transmission / reception unit 21). Electrical signal) is referred to as a second propagation wave signal. As described above, the second surface wave W2 transmitted from the second transmitting / receiving unit 22 reaches the first transmitting / receiving unit 21 while the first portion 10a contacting the gas and the second portion contacting the liquid 90. It propagates across the boundary with 10b twice.

　続いて、制御部４０は、ステップＳ６の処理を行ってから第２伝搬波信号を受信するまでの期間を計測するために、タイマを初期値の０に設定する（ステップＳ７）。当該期間は、第２送受波部２２が第２表面波Ｗ２を発生させたタイミングから、第１送受波部２１が第２表面波Ｗ２を受けるタイミングまでの期間であり、要するに、第２送受波部２２から第１送受波部２１までの第２表面波Ｗ２の伝搬時間（以下、第２伝搬時間と言う。）である。なお、以下では、第１伝搬時間と第２伝搬時間とを区別なく、単に伝搬時間と呼ぶこともある。 Subsequently, the control unit 40 sets a timer to an initial value of 0 in order to measure a period from when the process of step S6 is performed until the second propagation wave signal is received (step S7). The period is a period from the timing at which the second transmitting / receiving unit 22 generates the second surface wave W2 to the timing at which the first transmitting / receiving unit 21 receives the second surface wave W2, in short, the second transmitting / receiving wave. This is the propagation time of the second surface wave W2 from the unit 22 to the first transmission / reception unit 21 (hereinafter referred to as the second propagation time). Hereinafter, the first propagation time and the second propagation time may be simply referred to as propagation time without being distinguished.

　続いて、制御部４０は、送受信回路３０から第２伝搬波信号を受信したか否かを判別する（ステップＳ８）。この判別は、ステップＳ３と同様な手法で行われ、第２伝搬波信号を未だ受信していない場合（ステップＳ８；Ｎｏ）、制御部４０は、タイマのタイマ値を＋１などして更新し（ステップＳ９）、再度ステップＳ８の処理を実行する。これにより、制御部４０は、第２伝搬波信号を受信するまで計時を行う。 Subsequently, the control unit 40 determines whether or not the second propagation wave signal is received from the transmission / reception circuit 30 (step S8). This determination is performed in the same manner as in step S3, and when the second propagation wave signal has not been received yet (step S8; No), the control unit 40 updates the timer value of the timer to +1 or the like ( Step S9), the process of step S8 is executed again. Thereby, the control unit 40 performs time measurement until the second propagation wave signal is received.

　第２伝搬波信号を受信した場合（ステップＳ８；Ｙｅｓ）、制御部４０は、現在のタイマ値を第２伝搬時間として、例えばＲＡＭに記憶する（ステップＳ１０）。 When the second propagation wave signal is received (step S8; Yes), the control unit 40 stores the current timer value as the second propagation time, for example, in the RAM (step S10).

　続いて、制御部４０は、ステップＳ５で記憶した第１伝搬時間と、ステップＳ１０で記憶した第２伝搬時間とに基づいて、液面９１の位置（液面位置）を特定する（ステップＳ１１）。 Subsequently, the control unit 40 specifies the position of the liquid surface 91 (liquid surface position) based on the first propagation time stored in step S5 and the second propagation time stored in step S10 (step S11). .

　例えば、第１伝搬時間と第２伝搬時間と液面９１の位置との関係を予め実験などで特定し、特定した関係をテーブル又は演算式としてＲＯＭに格納しておく。制御部４０は、ＲＯＭに格納されたテーブル又は演算式と、第１伝搬時間及び第２伝搬時間に基づいて液面位置を特定する。 For example, the relationship between the first propagation time, the second propagation time, and the position of the liquid level 91 is specified in advance by experiments or the like, and the specified relationship is stored in the ROM as a table or an arithmetic expression. The control unit 40 specifies the liquid level position based on the table or arithmetic expression stored in the ROM, and the first propagation time and the second propagation time.

　なお、制御部４０は、第１伝搬時間に基づいて液面位置を特定するためのテーブル又は演算式を用いて、第１伝搬時間に基づく液面位置（以下、第１液面位置と言う。）を特定し、第２伝搬時間に基づいて液面位置を特定するためのテーブル又は演算式を用いて、第２伝搬時間に基づく液面位置（以下、第２液面位置と言う。）を特定してもよい。つまり、制御部４０は、第１液面位置と第２液面位置の各々を特定してもよい。そして、第１液面位置と第２液面位置の平均（単純平均でも加重平均でもよい）を、今回検出すべき液面位置としてもよい。なお、加重平均を求める場合は、予め実験などにより、第１液面位置と第２液面位置との各々の重み付け定数を求めておけばよい。また、第１液面位置と第２液面位置のいずれかが、エラー値を示している場合は、エラー値を示していない方を、今回検出すべき液面位置としてもよい。 In addition, the control part 40 uses the table for calculating a liquid level position based on 1st propagation time, or a computing equation, and says the liquid level position (henceforth a 1st liquid level position) based on 1st propagation time. ) And a liquid surface position based on the second propagation time (hereinafter referred to as the second liquid surface position) using a table or an arithmetic expression for identifying the liquid surface position based on the second propagation time. You may specify. That is, the control unit 40 may specify each of the first liquid level position and the second liquid level position. The average of the first liquid level position and the second liquid level position (simple average or weighted average) may be used as the liquid level position to be detected this time. In addition, when calculating | requiring a weighted average, what is necessary is just to obtain | require each weighting constant of a 1st liquid level position and a 2nd liquid level position by experiment etc. previously. Further, when either the first liquid level position or the second liquid level position indicates an error value, the liquid level position to be detected this time may be determined as the one not indicating the error value.

　続いて、制御部４０は、ステップＳ１１で特定した液面９１の位置を外部装置６０に出力する（ステップＳ１２）。外部装置６０は、例えば、ＬＣＤ（Liquid Crystal Display）、ＯＬＥＤ(Organic Light Emitting Diode）などの画像表示ディスプレイを含み、当該画像表示ディスプレイに、液面９１の位置を表示する。液面位置検出処理の説明は以上である。 Subsequently, the control unit 40 outputs the position of the liquid level 91 specified in step S11 to the external device 60 (step S12). The external device 60 includes, for example, an image display such as an LCD (Liquid Crystal Display) or an OLED (Organic Light Emitting Diode), and displays the position of the liquid level 91 on the image display. This is the end of the description of the liquid surface position detection process.

　なお、伝搬体１０を合成樹脂で形成した場合は、液体９０に接触する第２部分１０ｂを伝搬する表面波の伝搬速度（以下、第２音速という。）が、空気に接触する第１部分１０ａを伝搬する表面波の伝搬速度（以下、第１音速という。）よりも遅くなることが知られている。このため、タイマで計測される伝搬時間（第１伝搬時間、第２伝搬時間）は、第２部分１０ｂの長さＬ２が長いほど、長くなる。つまり、容器８０に多く液体９０が入っており容器８０の底面からの液面９１の位置が高いほど、伝搬時間も長くなる。伝搬体１０を形成する合成樹脂としては、表面波の伝搬時間を検出することができれば、その組成は限定されるものではないが、ＰＰＳ（ポリフェニレンサルファイド）の他に、ポリエチレン、ポリスチレンなどを採用することができる。なお、当該合成樹脂としては、表面波の伝搬波を観測しやすいＰＰＳが好適であると考えられる。 When the propagating body 10 is formed of synthetic resin, the propagation speed of the surface wave propagating through the second portion 10b that contacts the liquid 90 (hereinafter referred to as the second sound velocity) is the first portion 10a that contacts the air. It is known that the velocity is slower than the propagation speed of the surface wave propagating through (hereinafter referred to as the first sound velocity). For this reason, the propagation time (first propagation time, second propagation time) measured by the timer becomes longer as the length L2 of the second portion 10b is longer. That is, the longer the liquid 90 is in the container 80 and the higher the position of the liquid level 91 from the bottom surface of the container 80, the longer the propagation time. The composition of the synthetic resin forming the propagating body 10 is not limited as long as the propagation time of the surface wave can be detected, but polyethylene, polystyrene, etc. are adopted in addition to PPS (polyphenylene sulfide). be able to. In addition, it is thought that PPS which can observe the propagation wave of a surface wave is suitable as the said synthetic resin.

　制御部４０は、液体９０の液面９１の位置に応じて液体接触部分（第２部分１０ｂ）が長くなるほど期間が長くなる伝搬時間を検出し、検出した伝搬時間に基づいて液面９１の位置を検出する。液面９１の位置は、例えば、伝搬体１０が液体９０に浸る第２部分１０ｂの長さＬ２や、容器８０の底面から液面９１の高さや、長さＬ２や液面９１の高さに応じた値などで表されればよい。容器８０の底面から液面９１の高さは、液体９０の深さであり、長さＬ２＋長さｄ（図１参照）で求められる。 The control unit 40 detects a propagation time in which the period becomes longer as the liquid contact portion (second portion 10b) becomes longer according to the position of the liquid surface 91 of the liquid 90, and the position of the liquid surface 91 is based on the detected propagation time. Is detected. The position of the liquid level 91 is, for example, the length L2 of the second portion 10b where the propagating body 10 is immersed in the liquid 90, the height of the liquid level 91 from the bottom surface of the container 80, the length L2 or the height of the liquid level 91. What is necessary is just to represent with the value etc. according to. The height of the liquid surface 91 from the bottom surface of the container 80 is the depth of the liquid 90, and is obtained by length L2 + length d (see FIG. 1).

　ここで、底面部１６が滑らかな曲面でなく、四角柱などで構成される伝搬体１０では、第１表面波Ｗ１及び第２表面波Ｗ２が底面部１６で反射する。このため漏洩が生じ、損失となる。一方、底面部１６を滑らかな曲線にすることで、第１表面波Ｗ１、第２表面波Ｗ２は底面部１６で反射せず、漏洩が生じないため、底面部１６での損失がなく、振動子２０が受ける表面波Ｗｒの減衰が少ないため、Ｓ／Ｎ比を改善することができる。但し、不要な伝搬波Ｕが表面波の近くに発生することがある。 Here, in the propagation body 10 in which the bottom surface portion 16 is not a smooth curved surface but is formed of a quadrangular column or the like, the first surface wave W1 and the second surface wave W2 are reflected by the bottom surface portion 16. This causes leakage and loss. On the other hand, by making the bottom surface portion 16 into a smooth curve, the first surface wave W1 and the second surface wave W2 are not reflected by the bottom surface portion 16 and leakage does not occur. Since the attenuation of the surface wave Wr received by the child 20 is small, the S / N ratio can be improved. However, an unnecessary propagation wave U may be generated near the surface wave.

　図７（ａ）は、不要な伝搬波Ｕを模式的に示したものである。Ｗｄは、振動子２０から伝搬体１０に送られる表面波を示し、Ｗｒは、振動子２０が受ける表面波を示している。 FIG. 7 (a) schematically shows an unnecessary propagation wave U. FIG. Wd represents a surface wave sent from the vibrator 20 to the propagating body 10, and Wr represents a surface wave received by the vibrator 20.

　また、制御部４０は、第１表面波Ｗ１と第２表面波Ｗ２を同時に発生させる液面位置検出処理を実行してもよい。このとき、第１、第２伝搬波信号は重畳されて伝搬波信号として観測（受信）される。当該液面位置検出処理について図８を参照して説明する。 Further, the control unit 40 may execute a liquid surface position detection process for simultaneously generating the first surface wave W1 and the second surface wave W2. At this time, the first and second propagation wave signals are superimposed and observed (received) as propagation wave signals. The liquid surface position detection process will be described with reference to FIG.

　図８に示すように、制御部４０は、送受信回路３０を介して第１送受波部２１を振動させ、主面部１１の上端に第１表面波Ｗ１を発生させる。また、同時に第２送受波部２２を振動させ、主面部１２の上端に第２表面波Ｗ２を発生させる（ステップＳ１０１）。 As shown in FIG. 8, the control unit 40 vibrates the first transmission / reception unit 21 via the transmission / reception circuit 30 to generate the first surface wave W <b> 1 at the upper end of the main surface part 11. At the same time, the second transmission / reception unit 22 is vibrated to generate the second surface wave W2 at the upper end of the main surface part 12 (step S101).

　続いて、制御部４０は、ステップＳ１０１の処理を行ってから伝搬波信号を受信するまでの期間を計測するために、タイマを初期値の０に設定する（ステップＳ１０２）。当該期間は、第１送受波部２１が第１表面波Ｗ１を発生させ、同時に第２送受波部２２が第２表面波Ｗ２を発生させたタイミングから、第１，第２送受波部２１，２２が伝搬波信号を受けるタイミングまでの期間、つまり伝搬時間である。 Subsequently, the control unit 40 sets a timer to an initial value of 0 in order to measure a period from when the process of step S101 is performed until the propagation wave signal is received (step S102). During the period, from the timing when the first transmitting / receiving unit 21 generates the first surface wave W1 and the second transmitting / receiving unit 22 generates the second surface wave W2, the first and second transmitting / receiving units 21, 22 is a period until the timing of receiving a propagation wave signal, that is, a propagation time.

　続いて、制御部４０は、送受信回路３０から伝搬波信号を受信したか否かを判別する（ステップＳ１０３）。この判別は、前述のステップＳ３と同様な手法で行われ、伝搬波信号を未だ受信していない場合（ステップＳ１０３；Ｎｏ）、制御部４０は、タイマのタイマ値を＋１などして更新し（ステップＳ１０４）、再度ステップＳ１０３の処理を実行する。これにより、制御部４０は、伝搬波信号を受信するまで計時を行う。 Subsequently, the control unit 40 determines whether or not a propagation wave signal has been received from the transmission / reception circuit 30 (step S103). This determination is performed by the same method as in step S3 described above, and when the propagation wave signal has not been received yet (step S103; No), the control unit 40 updates the timer value of the timer by +1 or the like ( Step S104), the process of step S103 is executed again. Thereby, the control part 40 performs time measurement until a propagation wave signal is received.

　制御部４０は、伝搬波信号を受信した場合（ステップＳ１０３；Ｙｅｓ）、現在のタイマ値を伝搬時間として、例えばＲＡＭに記憶する（ステップＳ１０５）。 When receiving the propagation wave signal (step S103; Yes), the control unit 40 stores the current timer value as the propagation time, for example, in the RAM (step S105).

　続いて、制御部４０は、ステップＳ１０５で記憶した伝搬時間に基づいて、液面９１の位置（液面位置）を特定する（ステップＳ１０６）。 Subsequently, the control unit 40 specifies the position of the liquid level 91 (liquid level position) based on the propagation time stored in step S105 (step S106).

　例えば、伝搬時間と液面９１の位置との関係を予め実験などで特定し、特定した関係をテーブル又は演算式としてＲＯＭに格納しておく。制御部４０は、ＲＯＭに格納されたテーブル又は演算式と、伝搬時間に基づいて液面位置を特定する。 For example, the relationship between the propagation time and the position of the liquid surface 91 is specified in advance by experiments or the like, and the specified relationship is stored in the ROM as a table or an arithmetic expression. The control unit 40 specifies the liquid level position based on the table or arithmetic expression stored in the ROM and the propagation time.

　続いて、制御部４０は、ステップＳ１０６で特定した液面９１の位置を外部装置６０に出力する（ステップＳ１０７）。外部装置６０は、画像表示ディスプレイに液面９１の位置を表示する。 Subsequently, the control unit 40 outputs the position of the liquid level 91 specified in step S106 to the external device 60 (step S107). The external device 60 displays the position of the liquid level 91 on the image display.

　このように、第１表面波Ｗ１と、第２表面波Ｗ２を同時に発生させることによって、振動子２０が受ける表面波Ｗｒの振幅が大きくなる。従って、Ｓ／Ｎ比を更に改善することができる。 Thus, by simultaneously generating the first surface wave W1 and the second surface wave W2, the amplitude of the surface wave Wr received by the vibrator 20 is increased. Therefore, the S / N ratio can be further improved.

（第２実施形態）
　ここからは、第２実施形態に係る液面位置検出装置について、主に図５～図７を参照して説明する。なお、第１実施形態と同様な構成及び機能を有する各部については、第１実施形態と同一又は対応する符号を付すとともに、適宜説明を省略する。また、第２実施形態では、第１実施形態と異なる点を中心に説明する。 (Second Embodiment)
From here, the liquid level position detection apparatus according to the second embodiment will be described mainly with reference to FIGS. In addition, about each part which has the structure and function similar to 1st Embodiment, while attaching | subjecting the code | symbol same or corresponding to 1st Embodiment, description is abbreviate | omitted suitably. Further, in the second embodiment, a description will be given focusing on differences from the first embodiment.

　第２実施形態に係る伝搬体２１０は、第１実施形態と同様に、主面部１１及び主面部１２と、側面部１３及び側面部１４と、当接部１５と、底面部１６と、を有する。また、第２実施形態に係る振動子２２０は、図５（ｂ）、図６に示すように、第１実施形態と同様の第１送受波部２１及び第２送受波部２２の他に、第３送受波部２３と、第４送受波部２４と、を備える。 Similar to the first embodiment, the propagating body 210 according to the second embodiment includes the main surface portion 11 and the main surface portion 12, the side surface portion 13 and the side surface portion 14, the contact portion 15, and the bottom surface portion 16. . Further, as shown in FIG. 5B and FIG. 6, the vibrator 220 according to the second embodiment includes the same as the first transmission / reception unit 21 and the second transmission / reception unit 22 as in the first embodiment. A third transmission / reception unit 23 and a fourth transmission / reception unit 24 are provided.

　伝搬体２１０は、図５（ａ）～（ｃ）に示すように、当接部１５から底面部１６に向かって凹む凹部１７を有する。凹部１７は、図５（ｂ）に示すように、側面視では主面部１１と第２主面部１２との間に位置する。 As shown in FIGS. 5A to 5C, the propagating body 210 has a concave portion 17 that is recessed from the contact portion 15 toward the bottom surface portion 16. As shown in FIG. 5B, the recess 17 is located between the main surface portion 11 and the second main surface portion 12 in a side view.

　凹部１７は、当接部１５から底面部１６に向かって、例えば直方体状にくり抜かれた部分であり、第１～第４内側面部１７ａ～１７ｄと、内底面部１７ｅとを有する。 The concave portion 17 is a portion that is hollowed out in, for example, a rectangular parallelepiped shape from the contact portion 15 toward the bottom surface portion 16, and includes first to fourth inner side surface portions 17a to 17d and an inner bottom surface portion 17e.

　第１内側面部１７ａは、主面部１１の裏側に位置する。第２内側面部１７ｂは、主面部１２の裏側に位置する。第１内側面部１７ａと第２内側面部１７ｂとは互いに対向している。第３内側面部１７ｃは、側面部１３の裏側に位置する。第４内側面部１７ｄは、側面部１４の裏側に位置する。第３内側面部１７ｃと第４内側面部１７ｄとは互いに対向している。内底面部１７ｅは、凹部１７の底に位置し、図５（ｃ）に示すように、平面視で矩形状をなす。 The first inner side surface portion 17 a is located on the back side of the main surface portion 11. The second inner side surface portion 17 b is located on the back side of the main surface portion 12. The first inner side surface portion 17a and the second inner side surface portion 17b face each other. The third inner side surface portion 17 c is located on the back side of the side surface portion 13. The fourth inner side surface portion 17 d is located on the back side of the side surface portion 14. The third inner side surface portion 17c and the fourth inner side surface portion 17d face each other. The inner bottom surface portion 17e is located at the bottom of the concave portion 17, and has a rectangular shape in plan view as shown in FIG.

　図７（ｂ）は、伝搬体２１０に凹部１７を設けることにより、検出波Ｄが生じる様子を模式的に示したものである。検出波Ｄは、後述の第１検出波Ｄ１又は第２検出波Ｄ２を示す。 FIG. 7B schematically shows a state in which the detection wave D is generated by providing the propagation body 210 with the concave portion 17. The detection wave D indicates a first detection wave D1 or a second detection wave D2 described later.

　第３送受波部２３は、伝搬体２１０に表面波又は板波からなる第１検出波Ｄ１を発生させるとともに、凹部１７の内底面部１７ｅで反射した第１検出波Ｄ１を受ける。第４送受波部２４は、伝搬体２１０に表面波又は板波からなる第２検出波Ｄ２を発生させるとともに、凹部１７の内底面部１７ｅで反射した第２検出波Ｄ２を受ける。 The third wave transmitting / receiving unit 23 generates a first detection wave D1 made of a surface wave or a plate wave in the propagation body 210 and receives the first detection wave D1 reflected by the inner bottom surface part 17e of the recess 17. The fourth transmission / reception unit 24 generates a second detection wave D <b> 2 composed of a surface wave or a plate wave in the propagation body 210 and receives the second detection wave D <b> 2 reflected by the inner bottom surface part 17 e of the recess 17.

　第３送受波部２３は、送受信回路３０から供給される電気信号によって振動する。第３送受波部２３の振動は伝搬体２１０に伝達され、第１内側面部１７ａの上端に第１検出波Ｄ１が発生する。発生した第１検出波Ｄ１は、図６に示すように、第１内側面部１７ａの下端へ向かって伝搬し、内底面部１７ｅで反射した後、第１内側面部１７ａの上端へ向かって伝搬する。第１内側面部１７ａの上端へ到達した第１検出波Ｄ１は、第３送受波部２３を振動させる。第３送受波部２３は、この振動を電気信号に変換して送受信回路３０に供給する。 The third transmission / reception unit 23 vibrates by the electric signal supplied from the transmission / reception circuit 30. The vibration of the third transmission / reception unit 23 is transmitted to the propagation body 210, and the first detection wave D1 is generated at the upper end of the first inner side surface portion 17a. As shown in FIG. 6, the generated first detection wave D1 propagates toward the lower end of the first inner side surface portion 17a, reflects off the inner bottom surface portion 17e, and then propagates toward the upper end of the first inner side surface portion 17a. . The first detection wave D1 that has reached the upper end of the first inner side surface portion 17a vibrates the third transmission / reception unit 23. The third transmission / reception unit 23 converts this vibration into an electric signal and supplies it to the transmission / reception circuit 30.

　第４送受波部２４は、送受信回路３０から供給される電気信号によって振動する。第４送受波部２４の振動は伝搬体２１０に伝達され、第２内側面部１７ｂの上端に第２検出波Ｄ２が発生する。発生した第２検出波Ｄ２は、図６に示すように、第２内側面部１７ｂの下端へ向かって伝搬し、内底面部１７ｅで反射した後、第２内側面部１７ｂの上端へ向かって伝搬する。第２内側面部１７ｂの上端へ到達した第２検出波Ｄ２は、第４送受波部２４を振動させる。第４送受波部２４は、この振動を電気信号に変換して送受信回路３０に供給する。 The fourth transmission / reception unit 24 vibrates by the electric signal supplied from the transmission / reception circuit 30. The vibration of the fourth transmission / reception unit 24 is transmitted to the propagation body 210, and the second detection wave D2 is generated at the upper end of the second inner side surface portion 17b. As shown in FIG. 6, the generated second detection wave D2 propagates toward the lower end of the second inner side surface portion 17b, reflects off the inner bottom surface portion 17e, and then propagates toward the upper end of the second inner side surface portion 17b. . The second detection wave D2 that has reached the upper end of the second inner side surface portion 17b vibrates the fourth transmission / reception unit 24. The fourth transmission / reception unit 24 converts this vibration into an electric signal and supplies it to the transmission / reception circuit 30.

　第３送受波部２３が受ける第１検出波Ｄ１と、第４送受波部２４が受ける第２検出波Ｄ２とは、液面９１の位置に関係なく、伝搬体２１０の温度に依存して音速が変化する。第２実施形態では、第１検出波Ｄ１と第２検出波Ｄ２との少なくともいずれかを用いて、伝搬体２１０の温度を検出し、検出した温度を、表面波（第１表面波Ｗ１及び第２表面波Ｗ２）を検出する際の温度補正に利用する。このため、従来の液面位置検出装置に設けていたサーミスタチップなどからなる温度センサを設けずに済む。 The first detection wave D1 received by the third transmission / reception unit 23 and the second detection wave D2 received by the fourth transmission / reception unit 24 depend on the temperature of the propagating body 210 regardless of the position of the liquid surface 91. Changes. In the second embodiment, the temperature of the propagating body 210 is detected using at least one of the first detection wave D1 and the second detection wave D2, and the detected temperature is converted into a surface wave (the first surface wave W1 and the first detection wave D1). This is used for temperature correction when detecting the two surface waves W2). For this reason, it is not necessary to provide the temperature sensor which consists of the thermistor chip etc. which were provided in the conventional liquid level position detection apparatus.

　送受信回路３０は、第１検出波Ｄ１の送波用の電気信号を第３送受波部２３に供給し、第３送受波部２３を振動させる。また、第１検出波Ｄ１を受けた第３送受波部２３から供給される電気信号を受け取り、受け取った電気信号を増幅、変換する。また、送受信回路３０は、第２検出波Ｄ２の送波用の電気信号を第４送受波部２４に供給し、第４送受波部２４を振動させる。また、第２検出波Ｄ２を受けた第４送受波部２４から供給される電気信号を受け取り、受け取った電気信号を増幅、変換する。 The transmission / reception circuit 30 supplies the third transmission / reception unit 23 with the electrical signal for transmission of the first detection wave D1 to vibrate the third transmission / reception unit 23. Further, it receives an electrical signal supplied from the third transmitting / receiving unit 23 that has received the first detection wave D1, and amplifies and converts the received electrical signal. In addition, the transmission / reception circuit 30 supplies an electric signal for transmission of the second detection wave D2 to the fourth transmission / reception unit 24, and vibrates the fourth transmission / reception unit 24. Also, the electric signal supplied from the fourth transmitting / receiving unit 24 that has received the second detection wave D2 is received, and the received electric signal is amplified and converted.

　制御部４０は、送受信回路３０を介して、第３送受波部２３及び第４送受波部２４の各々を駆動制御する。また、制御部４０は、送受信回路３０で増幅、変換された、第３送受波部２３と第４送受波部２４の各々からの電気信号を受け取り、受け取った電気信号に基づいて伝搬体２１０の温度を検出する。 The control unit 40 drives and controls each of the third transmission / reception unit 23 and the fourth transmission / reception unit 24 via the transmission / reception circuit 30. In addition, the control unit 40 receives electrical signals from each of the third transmission / reception unit 23 and the fourth transmission / reception unit 24 that are amplified and converted by the transmission / reception circuit 30, and based on the received electrical signals, Detect temperature.

　制御部４０は、前述の液面位置検出処理で説明した手法と同様な手法で、第１検出波Ｄ１と第２検出波Ｄ２の各々の伝搬時間を検出する。以下では、第１検出波Ｄ１の伝搬時間を第１検出時間、第２検出波Ｄ２の伝搬時間を第２検出時間と言う。 The control unit 40 detects the propagation time of each of the first detection wave D1 and the second detection wave D2 by a method similar to the method described in the liquid level position detection process described above. Hereinafter, the propagation time of the first detection wave D1 is referred to as a first detection time, and the propagation time of the second detection wave D2 is referred to as a second detection time.

　具体的には、制御部４０は、第３送受波部２３で第１検出波Ｄ１を発生させてから、内底面部１７ｅで反射後に、第３送受波部２３が第１検出波Ｄ１を受けるまでの時間をタイマ値に基づいて特定する。そして、特定した時間を第１検出時間としてＲＡＭに記憶する。また、第４送受波部２４で第２検出波Ｄ２を発生させてから、内底面部１７ｅで反射後に、第４送受波部２４が第２検出波Ｄ２を受けるまでの時間をタイマ値に基づいて特定する。そして、特定した時間を第２検出時間としてＲＡＭに記憶する。制御部４０は、このようにして得た、第１検出時間と第２検出時間の少なくともいずれかに基づいて、伝搬体２１０の温度を特定（検出）する。 Specifically, the control unit 40 generates the first detection wave D1 by the third transmission / reception unit 23, and then the third transmission / reception unit 23 receives the first detection wave D1 after being reflected by the inner bottom surface part 17e. Is determined based on the timer value. Then, the specified time is stored in the RAM as the first detection time. Further, based on the timer value, the time from when the fourth transmission / reception unit 24 generates the second detection wave D2 to when the fourth transmission / reception unit 24 receives the second detection wave D2 after being reflected by the inner bottom surface portion 17e. To identify. Then, the specified time is stored in the RAM as the second detection time. The control unit 40 specifies (detects) the temperature of the propagating body 210 based on at least one of the first detection time and the second detection time obtained as described above.

　前記のように、第１検出波Ｄ１と第２検出波Ｄ２は、液面９１の位置に関係なく、伝搬体２１０の温度に依存して音速が変化する。このため、第１検出時間と第２検出時間も、液面９１の位置に関係なく、伝搬体２１０の温度に依存して変化する。この特性を利用して、例えば、第１検出時間と第２検出時間と伝搬体２１０の温度との関係を予め実験などで特定し、特定した関係をテーブル又は演算式としてＲＯＭに格納しておく。制御部４０は、ＲＯＭに格納されたテーブル又は演算式と、第１検出時間及び第２検出時間とに基づいて伝搬体２１０の温度を特定する。 As described above, the sound velocity of the first detection wave D1 and the second detection wave D2 changes depending on the temperature of the propagating body 210 regardless of the position of the liquid surface 91. For this reason, the first detection time and the second detection time also change depending on the temperature of the propagating body 210 regardless of the position of the liquid surface 91. Using this characteristic, for example, the relationship between the first detection time, the second detection time, and the temperature of the propagation body 210 is specified in advance by experiments, and the specified relationship is stored in the ROM as a table or an arithmetic expression. . The control unit 40 specifies the temperature of the propagating body 210 based on the table or arithmetic expression stored in the ROM and the first detection time and the second detection time.

　なお、制御部４０は、第１検出時間に基づいて伝搬体２１０の温度を特定するためのテーブル又は演算式を用いて、第１検出時間に基づく伝搬体２１０の温度（以下、第１温度と言う。）を特定し、第２検出時間に基づいて伝搬体２１０の温度を特定するためのテーブル又は演算式を用いて、第２検出時間に基づく伝搬体２１０の温度（以下、第２温度と言う。）を特定してもよい。つまり、制御部４０は、第１温度と第２温度の各々を特定してもよい。そして、第１温度と第２温度の平均（単純平均でも加重平均でもよい）を、今回検出すべき温度としてもよい。なお、加重平均を求める場合は、予め実験などにより、第１温度と第２温度との各々の重み付け定数を求めておけばよい。また、第１温度と第２温度のいずれかが、エラー値を示している場合は、エラー値を示していない方を、今回検出すべき温度としてもよい。 The control unit 40 uses a table or an arithmetic expression for specifying the temperature of the propagating body 210 based on the first detection time, and uses the temperature of the propagating body 210 based on the first detection time (hereinafter referred to as the first temperature). The temperature of the propagating body 210 based on the second detection time (hereinafter referred to as the second temperature) using a table or an arithmetic expression for identifying the temperature of the propagating body 210 based on the second detection time. Say). That is, the control unit 40 may specify each of the first temperature and the second temperature. The average of the first temperature and the second temperature (simple average or weighted average) may be used as the temperature to be detected this time. In addition, when calculating | requiring a weighted average, what is necessary is just to obtain | require each weighting constant of 1st temperature and 2nd temperature by experiment etc. previously. In addition, when one of the first temperature and the second temperature indicates an error value, the temperature that does not indicate the error value may be set as the temperature to be detected this time.

　そして、制御部４０は、以上のように特定（検出）した伝搬体２１０の温度に基づいて、第１伝搬時間と第２伝搬時間の温度補正を行う。音速は、温度依存性があり、伝搬体２１０の温度に応じて変化する。つまり、第１伝搬時間と第２伝搬時間も伝搬体２１０の温度に応じて変化する。このため、液面位置の検出精度を保つには、当該温度補正が必要となる。例えば、伝搬体２１０の温度と、伝搬時間の補正量や補正係数とを対応付けて構成されるテーブルを予めＲＯＭ内に格納しておき、制御部４０は、テーブルを参照して、特定した伝搬体２１０の温度に応じた補正量や補正係数を取得すればよい。そして、制御部４０は、第１伝搬時間と第２伝搬時間との各々に、取得した補正量を加減する演算や、補正係数を乗算する演算を行うことで、第１伝搬時間と第２伝搬時間の温度補正を行えばよい。 And the control part 40 performs temperature correction of 1st propagation time and 2nd propagation time based on the temperature of the propagation body 210 specified (detected) as mentioned above. The speed of sound is temperature dependent and changes according to the temperature of the propagating body 210. That is, the first propagation time and the second propagation time also change according to the temperature of the propagation body 210. For this reason, in order to maintain the detection accuracy of the liquid surface position, the temperature correction is necessary. For example, a table configured by associating the temperature of the propagating body 210 with the correction amount and correction coefficient of the propagation time is stored in the ROM in advance, and the control unit 40 refers to the table and determines the specified propagation. A correction amount or correction coefficient corresponding to the temperature of the body 210 may be acquired. And the control part 40 performs the calculation which adds / subtracts the acquired correction amount to each of 1st propagation time and 2nd propagation time, and the calculation which multiplies a correction coefficient, and is 1st propagation time and 2nd propagation time. Time temperature correction may be performed.

　なお、伝搬体２１０の温度と、液面位置の補正量や補正係数とを対応付けて構成されるテーブルを予めＲＯＭ内に格納しておき、第１伝搬時間や第２伝搬時間に基づいて特定した液面位置を補正してもよい。また、制御部４０は、テーブルに限らず、音速の温度依存性を表す式（近似式であってもよい）をＲＯＭ内に格納しておき、当該式を用いて、伝搬時間または液面位置の補正量や補正係数を求めてもよい。伝搬時間や液面位置の温度補正手法は、公知のテーブル構成法や演算法を適宜用いることができ、任意である。 A table configured by associating the temperature of the propagating body 210 with the correction amount and correction coefficient of the liquid surface position is stored in advance in the ROM and specified based on the first propagation time and the second propagation time. The liquid surface position may be corrected. The control unit 40 is not limited to the table, and stores an expression (may be an approximate expression) representing the temperature dependence of the sound speed in the ROM, and the propagation time or the liquid surface position is stored using the expression. The correction amount and the correction coefficient may be obtained. The temperature correction method for the propagation time and the liquid surface position can be arbitrarily selected from known table construction methods and calculation methods.

　また、以上の温度補正処理は、第１検出波Ｄ１や第２検出波Ｄ２が、第１表面波Ｗ１や第２表面波Ｗ２と干渉しない限りにおいては、前述の液面位置検出処理の中に組み込み、第１検出波Ｄ１及び第２検出波Ｄ２の発生タイミングを、第１表面波Ｗ１及び第２表面波Ｗ２の発生タイミングと同時にしてもよい。また、温度補正処理は、液面位置検出処理とは独立した処理として実行されてもよい。 In addition, the above temperature correction process includes the above-described liquid surface position detection process as long as the first detection wave D1 and the second detection wave D2 do not interfere with the first surface wave W1 and the second surface wave W2. The generation timing of the first detection wave D1 and the second detection wave D2 may be made simultaneously with the generation timing of the first surface wave W1 and the second surface wave W2. Further, the temperature correction process may be executed as a process independent of the liquid surface position detection process.

　本発明は以上の実施形態及び図面によって限定されるものではない。本発明の要旨を変更しない範囲で、適宜、変更（構成要素の削除も含む）を加えることが可能である。 The present invention is not limited to the above embodiments and drawings. Changes (including deletion of components) can be made as appropriate without departing from the scope of the present invention.

（変形例）
　以上では、第１送受波部２１と第２送受波部２２とが当接部１５に当接する構成例を説明したが、第１送受波部２１を、第１主面部１１と当接して設け、第２送受波部２２を、第２主面部１２と当接して設ける構成を採用してもよい。 (Modification)
The configuration example in which the first transmission / reception unit 21 and the second transmission / reception unit 22 are in contact with the contact unit 15 has been described above. However, the first transmission / reception unit 21 is provided in contact with the first main surface unit 11. In addition, a configuration in which the second transmission / reception unit 22 is provided in contact with the second main surface portion 12 may be employed.

　第２実施形態では、凹部１７が直方体状にくり抜かれ、内底面部１７ｅが平坦な例を説明したが、これに限られない。凹部１７の内底面部１７ｅを、第１実施形態に係る底面部１６のように、下方に凸となるＵ字状の滑らかな曲面状に形成してもよい。また、このように内底面部１７ｅを曲面状に形成した場合、第３送受波部２３が伝搬体２１０に送った第１検出波Ｄ１を第４送受波部２４で受け、第４送受波部２４が伝搬体２１０に送った第２検出波Ｄ２を第３送受波部２３で受けるように構成してもよい。また、第３送受波部２３と第４送受波部２４のいずれか一方を省いてもよい。 In the second embodiment, the example in which the concave portion 17 is cut out in a rectangular parallelepiped shape and the inner bottom surface portion 17e is flat has been described, but the present invention is not limited to this. The inner bottom surface portion 17e of the concave portion 17 may be formed in a U-shaped smooth curved surface that protrudes downward like the bottom surface portion 16 according to the first embodiment. Further, when the inner bottom surface portion 17e is formed in a curved surface as described above, the fourth transmission / reception unit 24 receives the first detection wave D1 transmitted from the third transmission / reception unit 23 to the propagating body 210, and the fourth transmission / reception unit. You may comprise so that the 2nd detection wave D2 which 24 sent to the propagation body 210 may be received in the 3rd transmission / reception part 23. FIG. Further, either one of the third transmission / reception unit 23 and the fourth transmission / reception unit 24 may be omitted.

　液面位置検出は、液面９１の詳細な位置を検出すること（上記のように、容器８０の底面からの液面９１の高さを検出すること）の他、液面９１の位置を何段階かに分けて現在の液面９１の位置がどの段階に属するかを検出することなども含む。また、制御部４０が液面位置検出後に外部装置６０に表示させる画像は、液面位置そのものを示していなくともよく、液面位置に応じた液体９０の量を示していてもよい。 In the liquid level position detection, in addition to detecting the detailed position of the liquid level 91 (detecting the height of the liquid level 91 from the bottom surface of the container 80 as described above), what is the position of the liquid level 91. It also includes detecting to which stage the current position of the liquid level 91 belongs, divided into stages. Further, the image displayed on the external device 60 after the liquid level position is detected by the control unit 40 may not indicate the liquid level position itself, but may indicate the amount of the liquid 90 corresponding to the liquid level position.

　また、伝搬体１０、２１０は合成樹脂製であり、液体９０の液面位置に応じて第２部分１０ｂ（液体接触部分）が長くなるほど伝搬時間が長くなることが好ましく、第２部分１０ｂを伝搬する表面波の速さと、第１部分１０ａ（液体９０から露出する部分）を伝搬する表面波の速さとの差がより顕著となる方が好ましい。しかしながら、以上に説明した手法で液面位置を検出することができれば、伝搬体１０、２１０を、アルミ、ステンレス、鋼などの金属で構成してもよい。 Further, the propagation bodies 10 and 210 are made of synthetic resin, and it is preferable that the propagation time becomes longer as the second portion 10b (liquid contact portion) becomes longer according to the liquid surface position of the liquid 90, and propagates through the second portion 10b. It is preferable that the difference between the speed of the surface wave that travels and the speed of the surface wave that propagates through the first portion 10a (the portion exposed from the liquid 90) becomes more significant. However, the propagating bodies 10 and 210 may be made of a metal such as aluminum, stainless steel, or steel as long as the liquid level position can be detected by the method described above.

　また、伝搬体１０、２１０は、その長尺方向を液面９１の法線方向と平行として配置するほか、その長尺方向を液面９１の法線方向に対して傾けるように配置してもよい。また、伝搬体１０、２１０のうち表面波が伝搬する面に、表面波の進行方向の沿って延びる凹部又は凸部を複数形成し、この面に凹凸を形成してもよい。 Further, the propagating bodies 10 and 210 may be arranged such that the longitudinal direction thereof is parallel to the normal direction of the liquid surface 91 and the longitudinal direction is inclined with respect to the normal direction of the liquid surface 91. Good. Further, a plurality of concave portions or convex portions extending along the traveling direction of the surface wave may be formed on the surface of the propagating bodies 10 and 210 where the surface wave propagates, and the concave and convex portions may be formed on this surface.

　液面位置検出対象の液体９０の種類は限られず、水、ガソリン、洗浄液など任意である。また、液面９１の上は空気以外の他の気体であってもよく、真空であってもよい。 The type of the liquid 90 whose liquid level position is to be detected is not limited, and water, gasoline, cleaning liquid and the like are arbitrary. Further, the liquid surface 91 may be a gas other than air or a vacuum.

　例えば、容器８０は、車両に搭載される燃料タンクであってもよい。この場合、液体９０は、ガソリンなどの燃料になる。このような場合、伝搬体１０、２１０は、例えば、燃料タンクに取り付けられる、燃料タンクから燃料を取り出す燃料ポンプを備える燃料圧送ユニットなどに取り付けられてもよい。なお、このような燃料タンクの場合、耐薬品性などの観点から伝搬体１０、２１０として使用される樹脂は、ＰＰＳ（ポリフェニレンサルファイド）、ＰＯＭ（ポリアセタール）、ＰＢＴ（ポリブチレンテレフタレート）が用いられることが多いが、これらの中では、検出信号のＳ／Ｎ比が良いＰＰＳを用いることが好ましい。 For example, the container 80 may be a fuel tank mounted on a vehicle. In this case, the liquid 90 becomes a fuel such as gasoline. In such a case, the propagating bodies 10 and 210 may be attached to, for example, a fuel pumping unit that is attached to the fuel tank and includes a fuel pump that extracts fuel from the fuel tank. In the case of such a fuel tank, PPS (polyphenylene sulfide), POM (polyacetal), and PBT (polybutylene terephthalate) are used as the resins used as the propagation bodies 10 and 210 from the viewpoint of chemical resistance. However, among these, it is preferable to use PPS with a good S / N ratio of the detection signal.

　ＰＰＳとしては、直鎖型、架橋型、反架橋型などがあり、さらに、ガラス繊維や無機フィラーなどのフィラー（添加材料）を添加したものなどがあるが、伝搬体１０に用いるＰＰＳとしては各種のＰＰＳを用いることができる。直鎖型、架橋型、反架橋型などの違い、フィラーの添加の有無やフィラーの種類の違いなどによる、表面波や板波の伝搬の状態（例えば、Ｓ／Ｎ比が良好なこと、表面波又は板波の音速など）への影響は小さいものと考えられる。 Examples of PPS include linear type, cross-linked type, and anti-cross-linked type. Further, there are those added with fillers (additive materials) such as glass fibers and inorganic fillers. PPS can be used. Surface wave or plate wave propagation state (for example, good S / N ratio, surface due to differences in linear type, cross-linked type, anti-cross-linked type, presence / absence of filler addition, type of filler, etc. The effect on the sound speed of waves or plate waves is considered to be small.

　表面波は、レイリー波以外のものであってもよい。表面波は、超音波よりも低い周波数の音波であってもよい。また、表面波は、パルス波でなくてもよく、例えば、バースト波などであってもよい。また、板波もパルス波やバースト波などであればよい。 Surface waves may be other than Rayleigh waves. The surface wave may be a sound wave having a lower frequency than the ultrasonic wave. Further, the surface wave may not be a pulse wave, and may be a burst wave, for example. The plate wave may be a pulse wave or a burst wave.

（１）以上に説明した液面位置検出装置１００は、液体９０の液面位置（液面９１の位置）に応じて、液体９０に浸る部分の割合が変化する伝搬体１０、２１０と、伝搬体１０、２１０に第１表面波Ｗ１を発生させるとともに第２表面波Ｗ２を受ける第１送受波部２１と、伝搬体１０、２１０に第２表面波Ｗ２を発生させるとともに第１表面波Ｗ１を受ける第２送受波部２２と、第２送受波部２２が受けた第１表面波Ｗ１の伝搬時間と、第１送受波部２１が受けた第２表面波Ｗ２の伝搬時間との少なくともいずれかに基づいて液面位置を検出する検出部（例えば、制御部４０）と、を備える。伝搬体１０、２１０は、互いに裏表の関係にある主面部１１（第１主面部）及び主面部１２（第２主面部）と、主面部１１と主面部１２とを繋ぐとともに、側面視において曲面状をなす底面部１６と、を有する。
　第１送受波部２１は、主面部１１を伝搬する第１表面波Ｗ１を発生させ、第２送受波部２２は、主面部１１を経て底面部１６と主面部１２とを伝搬した第１表面波Ｗ１を受ける。第２送受波部２２は、主面部１２を伝搬する第２表面波Ｗ２を発生させ、第１送受波部２１は、主面部１２を経て底面部１６と主面部１１とを伝搬した第２表面波Ｗ２を受ける。 (1) The liquid surface position detection device 100 described above includes the propagation bodies 10 and 210 in which the ratio of the portion immersed in the liquid 90 changes according to the liquid surface position of the liquid 90 (the position of the liquid surface 91). The first transmitting / receiving unit 21 that generates the first surface wave W1 in the bodies 10 and 210 and receives the second surface wave W2, and the second surface wave W2 in the propagation bodies 10 and 210 and the first surface wave W1 The second transmission / reception unit 22 to receive, the propagation time of the first surface wave W1 received by the second transmission / reception unit 22, and the propagation time of the second surface wave W2 received by the first transmission / reception unit 21 And a detection part (for example, control part 40) which detects a liquid level position based on. The propagating bodies 10 and 210 connect the main surface portion 11 (first main surface portion) and the main surface portion 12 (second main surface portion), and the main surface portion 11 and the main surface portion 12, which are in reverse relation to each other, and are curved in a side view. And a bottom surface portion 16 having a shape.
The first transmission / reception unit 21 generates a first surface wave W1 propagating through the main surface part 11, and the second transmission / reception unit 22 is transmitted through the main surface part 11 through the bottom surface part 16 and the main surface part 12. Receive wave W1. The second transmission / reception unit 22 generates a second surface wave W2 that propagates through the main surface portion 12, and the first transmission / reception unit 21 propagates through the main surface portion 12 through the bottom surface portion 16 and the main surface portion 11. Receive wave W2.

　このように、側面視において曲面状をなす底面部１６を設けたため、第１表面波Ｗ１及び第２表面波Ｗ２が底面部１６へ伝搬する際の漏洩による損失を低減することができ、Ｓ／Ｎ比の悪化を低減することができる。結果として、液面位置の検出精度を良好とすることができる。また、第１表面波Ｗ１の伝搬時間と、第１送受波部２１が受けた第２表面波Ｗ２の伝搬時間との少なくともいずれかに基づいて液面位置を検出するため、ノイズの重畳などにより一方の伝搬時間の検出精度が劣る場合であっても、液面位置の検出精度を良好とすることができる。 As described above, since the bottom surface portion 16 having a curved shape in the side view is provided, loss due to leakage when the first surface wave W1 and the second surface wave W2 propagate to the bottom surface portion 16 can be reduced. The deterioration of the N ratio can be reduced. As a result, the detection accuracy of the liquid surface position can be improved. Further, since the liquid surface position is detected based on at least one of the propagation time of the first surface wave W1 and the propagation time of the second surface wave W2 received by the first transmission / reception unit 21, it is possible to superimpose noise. Even when the detection accuracy of one propagation time is inferior, the detection accuracy of the liquid level can be improved.

（２）具体的には、伝搬体１０、２１０は、第１送受波部２１及び第２送受波部２２と当接する当接部１５を有し、主面部１１は、側面視において当接部１５の一端から垂下し、主面部１２は、側面視において当接部１５の他端から垂下する。そして、第１送受波部２１は、当接部１５を介して主面部１１を伝搬する第１表面波Ｗ１を発生させ、第２送受波部２２は、当接部１５を介して主面部１２を伝搬する第２表面波Ｗ２を発生させる。なお、前記の変形例で述べたように、第１送受波部２１を、第１主面部１１と当接して設け、第２送受波部２２を、第２主面部１２と当接して設ける構成を採用してもよい。 (2) Specifically, the propagation bodies 10 and 210 have the contact part 15 which contacts the 1st transmission / reception part 21 and the 2nd transmission / reception part 22, and the main surface part 11 is a contact part in side view. The main surface portion 12 hangs down from the other end of the contact portion 15 in a side view. The first wave transmitting / receiving unit 21 generates the first surface wave W1 propagating through the main surface part 11 via the contact part 15, and the second wave transmitting / receiving part 22 is transmitted through the contact part 15 to the main surface part 12. 2nd surface wave W2 which propagates is generated. As described in the modification, the first transmission / reception unit 21 is provided in contact with the first main surface portion 11, and the second transmission / reception unit 22 is provided in contact with the second main surface portion 12. May be adopted.

（３）第１送受波部２１及び第２送受波部２２は、第１表面波Ｗ１と、第２表面波Ｗ２を同時に発生させてもよい（第１送受波部２１による第１表面波Ｗ１の発生と、第２送受波部２２による第２表面波Ｗ２の発生とは同時であってもよい）。 (3) The first transmission / reception unit 21 and the second transmission / reception unit 22 may simultaneously generate the first surface wave W1 and the second surface wave W2 (the first surface wave W1 by the first transmission / reception unit 21). And the generation of the second surface wave W2 by the second transmission / reception unit 22 may be simultaneous).

（４）第２実施形態に係る伝搬体２１０は、当接部１５から底面部１６に向かって凹むとともに、側面視において主面部１１と主面部１２との間に位置する凹部１７を有する。
　この凹部１７により、振動子２２０から伝搬体２１０に発生する内部伝搬波Ｕを低減又は消滅させることができる。これにより、液面位置検出の検出誤差を低減させることができる。 (4) The propagating body 210 according to the second embodiment is recessed from the contact portion 15 toward the bottom surface portion 16, and has a recess 17 located between the main surface portion 11 and the main surface portion 12 in a side view.
With this recess 17, the internal propagation wave U generated from the vibrator 220 to the propagation body 210 can be reduced or eliminated. Thereby, the detection error of liquid level position detection can be reduced.

（５）また、第２実施形態に係る液面位置検出装置は、伝搬体２１０に表面波又は板波である検出波（第１検出波Ｄ１と第２検出波Ｄ２との少なくともいずれか）を発生させる特定送受波部（第３送受波部２３と第４送受波部２４との少なくともいずれか）をさらに備える。特定送受波部は、当接部１５を介して凹部１７の内側面部を伝搬する検出波を発生させるとともに、内側面部を経て凹部１７の内底面部１７ｅで反射した検出波を受ける。検出部は、特定送受波部が受けた検出波の伝搬時間に基づいて、伝搬体２１０の温度を検出する。
　このようにしたから、従来の液面位置検出装置に設けていたサーミスタチップなどからなる温度センサを設けずに済み、部品点数の削減が可能である。 (5) Moreover, the liquid level position detection apparatus according to the second embodiment applies a detection wave (at least one of the first detection wave D1 and the second detection wave D2) that is a surface wave or a plate wave to the propagating body 210. A specific transmitting / receiving unit (at least one of the third transmitting / receiving unit 23 and the fourth transmitting / receiving unit 24) to be generated is further provided. The specific transmission / reception unit generates a detection wave propagating through the inner side surface portion of the concave portion 17 via the contact portion 15 and receives the detection wave reflected by the inner bottom surface portion 17e of the concave portion 17 through the inner side surface portion. The detection unit detects the temperature of the propagation body 210 based on the propagation time of the detection wave received by the specific transmission / reception unit.
Since it did in this way, it is not necessary to provide the temperature sensor which consists of thermistor chips etc. which were provided in the conventional liquid level position detection apparatus, and reduction of a number of parts is possible.

（６）また、第１送受波部２１と第２送受波部２２と特定送受波部は、第１表面波Ｗ１と、第２表面波Ｗ２と、検出波を同時に発生させてもよい（第１送受波部２１による第１表面波Ｗ１の発生と、第２送受波部２２による第２表面波Ｗ２の発生と、特定送受波部による検出波の発生とは同時であってもよい）。 (6) Moreover, the 1st transmission / reception part 21, the 2nd transmission / reception part 22, and the specific transmission / reception part may generate | occur | produce the 1st surface wave W1, the 2nd surface wave W2, and a detection wave simultaneously (1st The generation of the first surface wave W1 by the first transmission / reception unit 21, the generation of the second surface wave W2 by the second transmission / reception unit 22, and the generation of the detection wave by the specific transmission / reception unit may be simultaneous).

　以上の説明では、本発明の理解を容易にするために、公知の技術的事項の説明を適宜省略した。 In the above description, in order to facilitate understanding of the present invention, descriptions of known technical matters are omitted as appropriate.

　１００…液面位置検出装置
　　１０、２１０…伝搬体
　　１０ａ…第１部分、１０ｂ…第２部分
　　１１…主面部（第１主面部の一例）
　　１２…主面部（第２主面部の一例）
　　１３、１４…側面部
　　１５…当接部
　　１６…底面部
　　２０、２２０…振動子
　　２１…第１送受波部、２２…第２送受波部
　　Ｗ１…第１表面波、Ｗ２…第２表面波
　　２３…第３送受波部、２４…第４送受波部
　　Ｄ１…第１検出波、Ｄ２…第２検出波
　　３０…送受信回路
　　４０…制御部 DESCRIPTION OF SYMBOLS 100 ... Liquid level position detection apparatus 10, 210 ... Propagation body 10a ... 1st part, 10b ... 2nd part 11 ... Main surface part (an example of 1st main surface part)
12 ... Main surface portion (an example of a second main surface portion)
DESCRIPTION OF SYMBOLS 13, 14 ... Side surface part 15 ... Contact part 16 ... Bottom part 20, 220 ... Vibrator 21 ... 1st transmission / reception part, 22 ... 2nd transmission / reception part W1 ... 1st surface wave, W2 ... 2nd surface wave 23 ... 3rd transmission / reception part, 24 ... 4th transmission / reception part D1 ... 1st detection wave, D2 ... 2nd detection wave 30 ... Transmission / reception circuit 40 ... Control part

Claims (6)

1. 　液体の液面位置に応じて、前記液体に浸る部分の割合が変化する伝搬体と、
   　前記伝搬体に第１表面波を発生させるとともに第２表面波を受ける第１送受波部と、
   　前記伝搬体に前記第２表面波を発生させるとともに前記第１表面波を受ける第２送受波部と、
   　前記第２送受波部が受けた前記第１表面波の伝搬時間と、前記第１送受波部が受けた前記第２表面波の伝搬時間との少なくともいずれかに基づいて前記液面位置を検出する検出部と、を備え、
   　前記伝搬体は、
   　互いに裏表の関係にある第１主面部及び第２主面部と、
   　前記第１主面部と前記第２主面部とを繋ぐとともに、側面視において曲面状をなす底面部と、を有し、
   　前記第１送受波部は、前記第１主面部を伝搬する前記第１表面波を発生させ、
   　前記第２送受波部は、前記第１主面部を経て前記底面部と前記第２主面部とを伝搬した前記第１表面波を受け、
   　前記第２送受波部は、前記第２主面部を伝搬する前記第２表面波を発生させ、
   　前記第１送受波部は、前記第２主面部を経て前記底面部と前記第１主面部とを伝搬した前記第２表面波を受ける、
   　液面位置検出装置。 A propagating body in which a ratio of a portion immersed in the liquid changes according to a liquid surface position;
   A first transmission / reception unit for generating a first surface wave in the propagation body and receiving a second surface wave;
   A second transmission / reception unit for generating the second surface wave in the propagating body and receiving the first surface wave;
   The liquid level position is detected based on at least one of the propagation time of the first surface wave received by the second wave transmitting / receiving unit and the propagation time of the second surface wave received by the first wave transmitting / receiving unit. And a detecting unit
   The propagator is
   A first main surface portion and a second main surface portion, which are in reverse relation to each other;
   And connecting the first main surface portion and the second main surface portion, and a bottom surface portion having a curved shape in a side view,
   The first transmitting / receiving unit generates the first surface wave propagating through the first main surface unit,
   The second transmission / reception unit receives the first surface wave that has propagated through the first main surface portion and the bottom surface portion and the second main surface portion,
   The second wave transmitting / receiving unit generates the second surface wave propagating through the second main surface part,
   The first transmission / reception unit receives the second surface wave that has propagated through the second main surface portion and the bottom surface portion and the first main surface portion,
   Liquid level position detection device.
2. 　前記伝搬体は、前記第１送受波部及び前記第２送受波部と当接する当接部を有し、
   　前記第１主面部は、前記側面視において前記当接部の一端から垂下し、
   　前記第２主面部は、前記側面視において前記当接部の他端から垂下し、
   　前記第１送受波部は、前記当接部を介して前記第１主面部を伝搬する前記第１表面波を発生させ、
   　前記第２送受波部は、前記当接部を介して前記第２主面部を伝搬する前記第２表面波を発生させる、
   　請求項１に記載の液面位置検出装置。 The propagation body has a contact portion that contacts the first transmission / reception unit and the second transmission / reception unit,
   The first main surface portion hangs down from one end of the contact portion in the side view,
   The second main surface portion hangs down from the other end of the contact portion in the side view,
   The first wave transmitting / receiving unit generates the first surface wave propagating through the first main surface part via the contact part,
   The second wave transmitting / receiving unit generates the second surface wave propagating through the second main surface part via the contact part.
   The liquid level position detection apparatus according to claim 1.
3. 　前記第１送受波部及び前記第２送受波部は、前記第１表面波と、前記第２表面波を同時に発生させる、
   　請求項１又は２に記載の液面位置検出装置。 The first transmission / reception unit and the second transmission / reception unit generate the first surface wave and the second surface wave simultaneously,
   The liquid level position detection apparatus according to claim 1 or 2.
4. 　前記伝搬体は、前記当接部から前記底面部に向かって凹むとともに、前記側面視において前記第１主面部と前記第２主面部との間に位置する凹部を有する、
   　請求項２に記載の液面位置検出装置。 The propagating body is recessed from the contact portion toward the bottom surface portion, and has a recess positioned between the first main surface portion and the second main surface portion in the side view.
   The liquid level position detection apparatus according to claim 2.
5. 　前記伝搬体に表面波又は板波である検出波を発生させる特定送受波部をさらに備え、
   　前記特定送受波部は、前記当接部を介して前記凹部の内側面部を伝搬する前記検出波を発生させるとともに、前記内側面部を経て前記凹部の内底面部で反射した前記検出波を受け、
   　前記検出部は、前記特定送受波部が受けた前記検出波の伝搬時間に基づいて、前記伝搬体の温度を検出する、
   　請求項４に記載の液面位置検出装置。 A specific transmitting / receiving unit that generates a detection wave that is a surface wave or a plate wave in the propagating body;
   The specific transmission / reception unit generates the detection wave propagating through the abutment portion through the inner side surface portion of the recess, receives the detection wave reflected by the inner bottom surface portion of the recess through the inner side surface portion,
   The detection unit detects the temperature of the propagation body based on the propagation time of the detection wave received by the specific transmission / reception unit,
   The liquid level position detection apparatus according to claim 4.
6. 　前記第１送受波部と前記第２送受波部と前記特定送受波部は、前記第１表面波と、前記第２表面波と、前記検出波を同時に発生させる、
   　請求項５に記載の液面検出装置。 The first transmission / reception unit, the second transmission / reception unit, and the specific transmission / reception unit simultaneously generate the first surface wave, the second surface wave, and the detection wave.
   The liquid level detection device according to claim 5.

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