JP4342190B2

JP4342190B2 - Ultrasonic sensor and manufacturing method thereof

Info

Publication number: JP4342190B2
Application number: JP2003032718A
Authority: JP
Inventors: 英司吉田; 桂二高木
Original assignee: NGK Spark Plug Co Ltd
Current assignee: NGK Spark Plug Co Ltd
Priority date: 2003-02-10
Filing date: 2003-02-10
Publication date: 2009-10-14
Anticipated expiration: 2023-02-10
Also published as: JP2004245603A

Description

【０００１】
【発明の属する技術分野】
本発明は、圧電振動子を利用した超音波センサに関し、特にガス配管中に設置され、ガス流量の測定に用いる超音波センサに関する。
【０００２】
【従来の技術】
超音波センサは、圧電素子を震度させ超音波を外方に向けて送信し、測定対象となる受信体で反射して戻ってくる反射波を圧電素子で受信し、送信から受信までの経過時間から送信位置から受信体まで距離を測定したり、ガス流量計において、ガス配管中に所定間隔で一対の超音波センサを対向して取り付け、一方の超音波センサから他方の超音波センサに超音波を送信するとともに他方の超音波センサで超音波を受信し、送受信に要する時間の差から、ガス流量を測定したりするために用いられている。
【０００３】
特に、ガス流量計のように高い精度が要求される用途に用いる場合は、長期間にわたって安定した送受信特性を有する超音波センサが要求される。
圧電素子を用いた超音波センサには、両面に電極を形成した板状の圧電振動子を有底筒状ケースの底面に固着するとともに有底筒状ケースの開口部に一対の端子を固定したベース部材を固定し、一対の端子をそれぞれ圧電素子の両面の電極と電気的に接続し、この一対端子を介して電気回路に接続されるものがある。そして、超音波を送信する際には、電気回路からパルス信号を圧電振動子に印加され、圧電振動子を振動させる。一方、超音波を受信する際には、圧電振動子が超音波を受けて振動し、圧電振動子の振動を電気回路で所定の電気信号に変換している。
【０００４】
また、このような構成を有する超音波センサは、圧電振動子の振動がケースの外周側面に伝わりケースの外周側面が振動すると、不要な残響波が生じ、送受信時の超音波信号や電気信号にノイズが生じて送受信特性を損なうので、ケース外周側面の振動を抑制するために、ケースの外周側面にゴム系の収縮チューブを装着したものがある。（例えば、特許文献１参照）
【０００５】
【特許文献１】
特開平２００２−２０４４９８号公報（第３−５頁、第１図）
【０００６】
【発明が解決しようとする課題】
しかしながら、特許文献１に開示された超音波センサによれば、一般にゴム系の収縮チューブのガラス転移点が数十度と低い為、ガラス転移点を越える高温下では収縮チューブが軟化し、ケース外周側面の振動の抑制力が弱まり、送受信信号にノイズが生じ送受信特性を損なうことがあった。また、ガス流量計にこの超音波センサ用いると、収縮チューブがガス雰囲気中に長期間曝されることによって、収縮チューブのゴム成分が変質し、ケース外周側面の振動の抑制力が弱まるという問題もあった。
【０００７】
本発明は、前記問題点を解決するもので、超音波センサを高温雰囲気中やガス雰囲気中において用いても、ケース外周側面の振動を抑制して残響波の発生を抑制し、送受信特性が優れ、且つ、温度特性や耐環境特性に優れた超音波センサを提供することを目的とする。
【０００８】
【課題を解決するための手段及び発明の効果】
かかる目的を達成するためになされた本発明の超音波センサは、軸方向の一端に開口部を有するとともに軸方向の他端に底面を有する有底筒状ケースと、該有底筒状ケースの内方の底面に接合された圧電振動子と、該有底筒状ケースの開口部を遮蔽するように該有底筒状ケースに固定されたベース部材と、該ベース部材に固定されるとともに該圧電振動子と電気的に接続された一対の入出力端子とを備え、前記有底筒状ケースの外周側面に、前記有底筒状ケースの外径よりも僅かに小さい内径を有するリング状部材又は筒状部材を圧入嵌合し、前記リング状部材又は筒状部材は、ガラス移転点が超音波センサの使用温度における上限値を越える樹脂材料からなることを特徴とする。（請求項１）
本発明の超音波センサは、有底筒状ケースの外周側面にリング状部材又は筒状部材を嵌合することにより、圧電振動子の振動に起因する有底筒状ケースの外周側面の振動を抑制しているため、残響波が発生し難い利点がある。また、高温中で使用しても送受信特性が優れ、且つ、温度特性や耐環境特性を向上できる。
【０００９】
また、前記リング状部材又は筒状部材は、ガラス移転点が超音波センサの使用温度における上限値を越える樹脂材料からなるので、超音波センサの使用温度範囲において、リング状部材又は筒状部材の機械的物性や化学的物性が損なわれることなく、有底筒状ケースの外周側面にリング状部材又は筒状部材を確実に嵌合することができる。その結果、ガラス転移点未満のガス雰囲気中（例えば、プロパンガス、水素ガス等）で長期間使用しても、リング状部材又は筒状部材が変質しにくいため、残響波の発生を抑制して、送受信特性を向上できる利点がある。
【００１０】
本発明の超音波センサの別の一態様は、前記リング状部材又は筒状部材は、前記有底筒状ケースの外周側面において、少なくとも前記底面から前記開口部までの距離の１／２の範囲内を覆うように嵌合されていることを特徴とする。（請求項２）
少なくとも、底面から開口部までの距離の１／２の範囲内を覆うようにリング状部材又は筒状部材を嵌合していれば、有底筒状ケースの外周側面に伝播する振動を抑制でき、残響波の発生を抑制できる。この理由の詳細は不明であるが、圧電振動子の振動が有底筒状ケースの外周側面に伝播する際に、底面から開口部までの距離の１／２の範囲内で、有底筒状ケースの外周側面に伝播する振動の振幅の影響が大きいためと推定される。
本発明の超音波センサの別の一態様は、前記リング状部材又は筒状部材は、前記有底筒状ケースの外周側面における、振幅又は振動量の最も大きい位置を抑える位置に圧入されていることを特徴とする。（請求項３）
【００１１】
本発明の超音波センサの製造方法の一態様は、軸方向の一端に開口部を有するとともに軸方向の他端に底面を有する有底筒状ケースと、該有底筒状ケースの内方の底面に接合された圧電振動子と、該有底筒状ケースの開口部を遮蔽するように該有底筒状ケースに固定されたベース部材と、該ベース部材に固定されるとともに該圧電振動子と電気的に接続された一対の入出力端子とを備え、前記有底筒状ケースの外周側面に樹脂材料からなるリング状部材又は筒状部材を圧入により嵌合する圧入工程を備えた超音波センサの製造方法であって、前記圧入工程において、前記樹脂材料からなるリング状部材又は筒状部材を該樹脂材料のガラス転移点を越える温度で加熱しながら圧入して嵌合することを特徴とする。（請求項４）
本発明の超音波センサの製造方法によれば、有底筒状ケースの外周側面に樹脂材料からなるリング状部材又は筒状部材を、該樹脂材料のガラス転移点を越える温度で加熱しながら圧入により嵌合する圧入工程を備えることによって、有底筒状ケースの外周側面に密着するように嵌合できるので、有底筒状ケースの外周側面に伝播する振動を抑制して、残響波の発生を抑制できる利点がある。
【００１２】
特に、樹脂材料としては、超音波センサの使用温度範囲における上限値を越えるガラス転移点を有するものを用いるのが好ましい。（請求項５）
超音波センサの使用条件が例えば４０℃（上限値）の高温中で使用するものであったとしても、ガラス転移点が４０℃を越える樹脂材料からなるリング状部材又は筒状部材を用いれば、送受信特性が優れ、且つ、温度特性や耐環境特性を向上した超音波センサを製造できる利点がある。
また、前記リング状部材又は筒状部材は、前記有底筒状ケースの外径よりも僅かに小さい内径を有するのが好ましい。（請求項６）
また、前記リング状部材又は筒状部材は、前記有底筒状ケースの外周側面における、振幅又は振動量の最も大きい位置を抑える位置に圧入されるのが好ましい。（請求項７）
【００１３】
【発明の実施の形態】
以下、本発明の実施の形態を図面と共に説明する。
図１は本発明が適用された超音波センサの構成を表す断面図である。
図１において、１は超音波センサであり、この超音波センサ１は、有底筒状ケース１１と、有底筒状ケース１１の内方の底面２１に接合された圧電振動子２と、有底筒状ケース１１の開口部１３を遮蔽するように有底筒状ケース１１に固定されたベース部材３と、ベース部材３に固定されるとともに圧電振動子２と電気的に接続された一対の入出力端子４、５と、有底筒状ケース１１の底面２１の外側に接着した整合層８と、有底筒状ケース１１の外周側面１４に沿って圧入した筒状のリング１０（所謂、リング状部材又は筒状部材である）とを備えて構成されている。
【００１４】
圧電振動子２は、圧電特性を有するセラミック材料から形成され、この両面に銀ペーストが印刷され電極１６、１７が形成されている。また、圧電振動子２は、外径が約８ｍｍ、厚みが約２ｍｍの円板状に形成されている。
また、圧電振動子２は、金属製の有底筒状ケース１１の底面２１に接合され、一方の電極１６が有底筒状ケース１１と電気的に接続し、他方の電極１７が導電線９と例えば半田付け、溶接、導電性接着等によって電気的に接続されている。
【００１５】
次に、有底筒状ケース１１は、導電性を有するとともにガス雰囲気中における耐食性や耐熱性等に優れたステンレス材料（厚みが約０．２ｍｍ）から形成され、軸方向（図中のＹ方向）の一方の端部に底面１２が付設され、他方の端部が開口して開口部１３が形成されている。また、有底筒状ケース１１は、外径が約１０ｍｍ、軸方向の長さが約８ｍｍに形成されている。
【００１６】
また、有底筒状ケース１１は、底面２１に圧電振動子２が接着して接合され、開口部１３を遮蔽するようにベース部材３の凸部１５が嵌合し、開口部１３がベース部材３と溶接によって固定されている。
また、有底筒状ケース１１は、外周側面１４に沿って筒状のリング１０が圧入されている。
【００１７】
次に、ベース部材３は、導電性を有するＮｉメッキ処理をしたＳＰＣ（冷間圧延鋼）から形成され、有底筒状ケース１１の開口部１３の内方に嵌合する凸１５部と、有底筒状ケース１１の開口部１３に当接する座１８が形成され、凸部１５の上面には絶縁シート７が貼り付けられている。
【００１８】
また、有底筒状ケース１１は、入力端子５を挿入するための貫通孔１９と入力端子４を接続するための係合穴２０が形成されている。
次に、一対の入出力端子４、５は、圧電振動子２の電極１６、１７及び有底筒状ケース１１の外方の電気回路（図示せず）と電気的に接続するために、鉄合金等の導電性を有する金属から形成されている。
【００１９】
また、一方の入出力端子５は、ベース部材３の貫通孔１９に挿通され、貫通孔１９との間の隙間にガラスペーストなどの絶縁材６が注入されハーメチックシール構造で固定され、ベース部材３に対して電気的に絶縁している。そして、入出力端子５の一端は、有底筒状ケース１１の内方に突き出し、圧電振動子２の電極１７と導電線１０によって電気的に接続され、入出力端子５の他端は、有底筒状ケース１１の外方の電気回路（図示せず）に接続するために、有底筒状ケース１１の外方に突き出している。
【００２０】
また、他方の入出力端子４は、ベース部材３の、外面に形成された係合穴２０に一端が係合し溶接によって固定され、ベース部材３に対して電気的に導通するように接続され、入出力端子４の他端は、有底筒状ケース１１の外方の電気回路（図示せず）に接続するために、有底筒状ケース１１の外方に突き出している。そして、入出力端子４は、導電性のベース部材３と導電性の有底筒状ケース１１を介して、圧電振動子２の電極１６と電気的に接続されている。
【００２１】
次に、整合層８は、有底筒状ケース１１と空気とのインピーダンス整合を図るために、Ｑ値の低い発泡性の材料（例えば、発泡カーボン、発泡プラスチック等）によって形成され、有底筒状ケース１１の底面２１の外面に接着されている。次に、リング１０は、ガス雰囲気中や高温中で使用しても耐久性が強く、超音波センサ１の使用温度範囲７０°を越えたガラス転移点をもつのポリプロピレン樹脂（ガラス転移点が１２０℃である）を筒状に成形して形成されている（所謂、成形リングである）。
【００２２】
また、リング１０は、内径が有底筒状ケース１１の外径よりも僅かに小さい内径を有するように形成され、有底筒状ケース１１の底面２１側から外周側面１４に沿って圧入されている。また、リング１０は、有底筒状ケース１１に圧入する際に、リング１０のガラス転移点１２０℃を僅かに越えた温度（約１３０℃）でリング１０を加熱しながら圧入されている。
【００２３】
前記のように構成された超音波センサについて、以下にその製造方法を説明する。
まず、両面に電極１６、１７が焼き付けられた圧電振動子２と入出力端子４、５が接続されたベース部材３とを準備する。圧電振動子２は、公知の製造方法により、圧電特性を有するセラミック材料を焼成して板状に形成され、この板状の両面に銀ペーストを印刷して焼き付け、電極１６、１７が形成される。
【００２４】
また、ベース部材３には、公知の製造方法により、絶縁材６を介して入出力端子５がハーメチックシール構造で固定され、入出力端子４が溶接によって固定される。
次いで、有底筒状ケース１１の底面１２に、接着剤（図示せず）を塗布し、圧電振動子２を有底筒状ケース１１の底面２１に接着する。このとき、圧電振動子２と有底筒状ケース１１の底面１２との間に間隙が生じないように、必要に応じて、圧電振動子２を有底筒状ケース１１の底面１２に加圧しながら加熱し接着を行う。
【００２５】
次いで、圧電振動子２の電極１７の表面に、導電線９の一端を半田付けによって電気的に接続し、入出力端子４、５が接続されたベース部材３を有底筒状ケース１１の開口部１３に近づけ、導電線９の他端を入出力端子５の端部に半田付けや溶接、導電性接着等によって電気的に接続する（本発明の接続工程に相当する）。
【００２６】
次いで、ベース部材３の凸部１５を有底筒状ケース１１の開口部１３に嵌合させ、開口部１３の先端の周囲とをベース部材３とを溶接によって接合する。また、この接合によって、接続端子４が導電性を有するベース部材４と有底筒状ケース１１を介して、圧電振動子２の電極１６と電気的に接続される。
【００２７】
次いで、リング１０を有底筒状ケース１１の底面１２側から外周側面１４に沿って圧入して嵌合する（本発明の圧入工程に相当する）。リング１１を圧入する際には、リング１０をリング１０のガラス転移点１２０℃を僅かに越えた温度１３０℃（ガラス転移点を約１０℃越えた温度）で加熱しながら有底筒状ケース１１の外周側面１４に圧入する。また、リング１０を加熱する方法は、リング１０をヒータに保持したり、リング１０を高温槽中に放置したり、或いはリング１０に熱風を吹き付けたりする多種の方法があるので、それらの中から生産性に応じて選択している。
【００２８】
次いで、有底筒状ケース１１の底面１２の外面に接着剤を塗布し整合層８を接着し、超音波センサ１の組み立てを完了する。
以下に、超音波センサ１における、有底筒状ケース１１の外周側面１４の振動を抑制する効果を確認するために行った試験結果について、図を用いて説明する。尚、本発明の実施形態の効果を確認するために、比較例とともに比較試験を行った。尚、比較例は、本実施の形態の超音波センサ１において、リング１０に代え有底筒状ケース１１の外径より大きい内径を有する収縮チューブを有底筒状ケース１１の外周側面１４に挿入し、７５℃〜１１５℃で加熱して収縮し、有底筒状ケース１１の外周側面１４に密着させたものである。
【００２９】
実施の形態および比較例の試験結果を図４〜図７に表した。図４は実施形態のインピーダンス特性図、図５は比較例のインピーダンス特性図、図６は実施の形態の受信波形を表す特性図、図７は比較例の受信波形を表す特性図である。
図４、図５は、実施の形態の超音波センサ１及び比較例の超音波センサを恒温槽中に入れ、恒温層（タバイエスペック製；ＭＩＮＩＳＵＢＺＥＲＯＭＣ−７１０）内の温度を−３５度から＋８５℃まで変化させ、インピーダンスアナライザ（ＹＨＰ４１９４Ａ）を用い、所定の温度変化毎に実施の形態の超音波センサ１及び比較例の超音波センサのインピーダンス特性を測定し、初期特性である２５℃におけるインピーダンス特性特と、インピーダンス特性の変化が顕著に表れる＋８５℃におけるインピーダンス特性とを表した。
【００３０】
図４、図５において横軸は２００ｋＨｚ〜３００ｋＨｚの範囲を表す周波数であって、縦軸は１００Ω〜５０ｋΩの範囲を表すインピーダンスであり、反共振点Ｐは送受信に使用される信号の周波数である。
本実施例は、図４に示すように、初期特性である２５℃のインピーダンス特性特と＋８５℃のインピーダンス特性特とを比較すると、両者の間に殆ど差がなく、高温中で使用しても有底筒状ケースの外周側面の振動を抑制して残響波の発生を抑制できることが判る。
【００３１】
一方、比較例は、図５に示すように、初期特性である２５℃のインピーダンス特性特と＋８５℃のインピーダンス特性特とを比較すると、８５℃においてインピーダンス波形の乱れ（図中のＮ１、Ｎ２）が生じ、高温中で使用すると、有底筒状ケース１１の外周側面１４の振動を抑制する効果を損なうことが判る。
【００３２】
また、図６、図７に表した受信波形は、一方の超音波センサから送信された超音波を他方の超音波センサで受信したときの受信波形をオシロスコープで記録したものであり、縦軸が電圧値（Ｖ）、横軸が時間（μｓ）である。尚、本実施例と比較例の送受信感度を比較するために、Ｖ３とＶｍａｘの電圧値を読み取った。
【００３３】
本実施例は、図６に示すように、Ｖ３の電圧値が−８２０ｍＶ、Ｖｍａｘの電圧値が−３３００ｍＶ、比較例は、図７に示すように、Ｖ３の電圧値が−７４０ｍＶ、Ｖｍａｘの電圧値が−３１００ｍＶを示し、本実施例は比較例に対し、超音波センサ間の送受信感度が良好であることが判る。
【００３４】
前記の実施形態の超音波センサ及びその製造方法の作用効果を、以下に記載する。
本発明の実施の形態における超音波センサ１によれば、有底筒状ケース１１の外周側面１４に筒状のリング１０を嵌合することによって、有底筒状ケース１１の外周側面１４の振動を抑制して残響波の発生を抑制でき送受信特性を向上できる。そして、筒状のリング１０を、筒状のリング１０のガラス移転点が超音波センサ１の使用温度における上限値以上を有する樹脂材料で形成したので、高温中及びガス雰囲気中で使用しても残響波の発生を抑制して送受信特性を向上でき、高温雰囲気やガス雰囲気などの耐環境特性に優れている。
【００３５】
また、本発明の実施の形態における超音波センサ１の製造方法によれば、有底筒状ケース１１の外周に筒状のリング１０を圧入により嵌合することによって、有底筒状ケース１１の外周側面の振動（所謂、残響波である）を抑制でき、且つ、成形リング１０を成形リング１０のガラス転移点を超える温度で加熱しながら有底筒状ケース１１の外周側面１４に圧入したので、成形リング１０を有底筒状ケース１１の外周側面１４に密着するように圧入することができ、残響波を確実に抑制でき送受信特性を向上できる。
【００３６】
（変形例）
次に、図２、図３を用いて、本発明の超音波センサ１におけるの変形例について説明する。図２、図３は超音波センサ１の変形例を表す外観図であり、基本的な構成は、前述した実施の形態と同一なので、同一符号を付与して説明を省き、特徴とする部分について以下に記載する。
【００３７】
図２において、超音波センサ１は、リング１２（所謂、リング状部材又は筒状部材である）として高さがＬ／３のものが有底筒状ケース１１の外周側面１４における底面２１から開口部１３までの距離（図中Ｌの距離）の１／２の範囲内（図中Ｌ／２の範囲内）を覆うように圧入により嵌合されている。
【００３８】
また、図３において、超音波センサ１は、リング１２として高さがＬ／２のものが有底筒状ケース１１の外周側面１４における底面２１から開口部１３までの距離（図中Ｌの距離）の１／２の範囲内（図中Ｌ／２の範囲内）を覆うように圧入により嵌合されている。
【００３９】
この変形例によれば、圧電振動子２の振動が有底筒状ケース１１の外周側面１４に伝播する際に、底面２１から開口部１３までの距離の１／２の範囲内に発生すると推察される、有底筒状ケース１１の外周側面に伝播する振動の振幅の影響を抑制する効果を顕著に得ることができ、残響波の発生を抑制できる。また、リング１２を圧入する範囲は有底筒状ケース１１の外周側面１４における底面２１から開口部１３までの距離Ｌの１／２の範囲内で良いので、リング１２の製作コストを安価にできる。
【００４０】
尚、本発明の実施の形態或いは変形例によれば、リング１０、リング１２が有底筒状ケース１１の外周側面１４の略全体或いは底面２１から２開口部までの距離Ｌの１／２の範囲内を覆うように、リング１１、リング１２を有底筒状ケース１１の外周側面１４に圧入したが、リング１０を圧入することなく圧電振動子２を振動させ、有底筒状ケース１１の外周側面１４における円周方向に沿って発生する振幅や振動量を解析し、この振幅や振動量の最も大きい位置をリングで抑えるように、リングの圧入範囲や圧入位置を定めても良い。
【００４１】
また、本発明は、ガスセンサ、物体感知センサ、距離センサ、位置センサ、アクチュエータ、防犯センサなど、超音波を送受信信号に用いた多種のセンサに用いることができる。
【図面の簡単な説明】
【図１】本発明が適用された実施の形態１の、超音波センサの構成を表す断面図である。
【図２】同実施形態の変形例の、超音波センサの構成を表す断面図である。
【図３】同実施形態の別の変形例の、超音波センサの構成を表す断面図である。
【図４】同実施形態のインピーダンス特性図である。
【図５】比較例のインピーダンス特性図である。
【図６】同実施形態の受信波形を表す特性図である。
【図７】比較例の受信波形を表す特性図である。
【符号の説明】
１…超音波センサ、２…圧電振動子、３…ベース部材、４、５…入出力端子、６…絶縁材、７…絶縁シート、８…整合層、９…導電線、１０、１２…リング（成形リング）、１１…有底筒状ケース、１３…開口部、１４…外周側面、１５…凸部，１６，１７…電極、１８…座、１９…貫通孔、２０…係合穴２１…底面。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ultrasonic sensor using a piezoelectric vibrator, and more particularly to an ultrasonic sensor that is installed in a gas pipe and used for measuring a gas flow rate.
[0002]
[Prior art]
The ultrasonic sensor transmits the ultrasonic wave outward with the piezoelectric element seismic, receives the reflected wave reflected by the receiver to be measured and returns, and the elapsed time from transmission to reception Measure the distance from the transmission position to the receiver, or in a gas flow meter, attach a pair of ultrasonic sensors facing each other at a predetermined interval in the gas pipe, and ultrasonic waves from one ultrasonic sensor to the other ultrasonic sensor Is used to measure the gas flow rate from the difference in time required for transmission and reception.
[0003]
In particular, when used for an application that requires high accuracy such as a gas flow meter, an ultrasonic sensor having stable transmission and reception characteristics over a long period of time is required.
In an ultrasonic sensor using a piezoelectric element, a plate-like piezoelectric vibrator having electrodes formed on both sides is fixed to the bottom surface of the bottomed cylindrical case, and a pair of terminals are fixed to the opening of the bottomed cylindrical case. There is a type in which a base member is fixed, a pair of terminals are electrically connected to electrodes on both surfaces of a piezoelectric element, and are connected to an electric circuit through the pair of terminals. When transmitting an ultrasonic wave, a pulse signal is applied to the piezoelectric vibrator from the electric circuit to vibrate the piezoelectric vibrator. On the other hand, when receiving an ultrasonic wave, the piezoelectric vibrator receives the ultrasonic wave and vibrates, and the vibration of the piezoelectric vibrator is converted into a predetermined electric signal by an electric circuit.
[0004]
Also, the ultrasonic sensor having such a configuration generates an unnecessary reverberation wave when the vibration of the piezoelectric vibrator is transmitted to the outer peripheral side surface of the case and the outer peripheral side surface of the case vibrates. Since noise is generated and transmission / reception characteristics are impaired, in order to suppress vibration on the outer peripheral side surface of the case, there is one in which a rubber-based shrink tube is attached to the outer peripheral side surface of the case. (For example, see Patent Document 1)
[0005]
[Patent Document 1]
Japanese Patent Laid-Open No. 2002-204498 (page 3-5, FIG. 1)
[0006]
[Problems to be solved by the invention]
However, according to the ultrasonic sensor disclosed in Patent Document 1, since the glass transition point of a rubber-based shrink tube is generally as low as several tens of degrees, the shrink tube softens at a high temperature exceeding the glass transition point, and the outer periphery of the case In some cases, the suppression of side vibration is weakened, and noise is generated in the transmission / reception signal, thereby impairing transmission / reception characteristics. In addition, when this ultrasonic sensor is used for a gas flow meter, the rubber component of the shrinkable tube is altered by exposing the shrinkable tube to the gas atmosphere for a long period of time, and the vibration suppressing force on the outer peripheral side surface of the case is weakened. there were.
[0007]
The present invention solves the above problems, and even when an ultrasonic sensor is used in a high-temperature atmosphere or a gas atmosphere, it suppresses the vibration on the outer peripheral side surface of the case, suppresses the generation of reverberant waves, and has excellent transmission and reception characteristics An object of the present invention is to provide an ultrasonic sensor excellent in temperature characteristics and environmental resistance characteristics.
[0008]
[Means for Solving the Problems and Effects of the Invention]
An ultrasonic sensor of the present invention made to achieve the above object includes a bottomed cylindrical case having an opening at one end in the axial direction and a bottom surface at the other end in the axial direction, and the bottomed cylindrical case. A piezoelectric vibrator bonded to the inner bottom surface, a base member fixed to the bottomed cylindrical case so as to shield the opening of the bottomed cylindrical case, and fixed to the base member and the base member A ring-shaped member having a pair of input / output terminals electrically connected to the piezoelectric vibrator and having an inner diameter slightly smaller than the outer diameter of the bottomed cylindrical case on the outer peripheral side surface of the bottomed cylindrical case or a tubular member with press fit, the ring-shaped member or a tubular member is characterized in that the glass transition point is made of a resin material exceeds the upper limit in the use temperature of the ultrasonic sensor. (Claim 1)
The ultrasonic sensor according to the present invention, by fitting a ring-shaped member or a cylindrical member to the outer peripheral side surface of the bottomed cylindrical case, can vibrate the outer peripheral side surface of the bottomed cylindrical case caused by the vibration of the piezoelectric vibrator. Since it is suppressed, there is an advantage that a reverberation wave hardly occurs. In addition, even when used at high temperatures, the transmission and reception characteristics are excellent, and the temperature characteristics and environmental resistance characteristics can be improved.
[0009]
In addition, since the ring-shaped member or the cylindrical member is made of a resin material having a glass transition point exceeding the upper limit value in the operating temperature of the ultrasonic sensor, the ring-shaped member or the cylindrical member is used in the operating temperature range of the ultrasonic sensor. A ring-shaped member or a cylindrical member can be reliably fitted to the outer peripheral side surface of the bottomed cylindrical case without impairing mechanical properties and chemical properties. As a result, even if it is used for a long time in a gas atmosphere below the glass transition point (for example, propane gas, hydrogen gas, etc.), the ring-shaped member or the cylindrical member is unlikely to be deteriorated. There is an advantage that transmission / reception characteristics can be improved.
[0010]
According to another aspect of the ultrasonic sensor of the present invention, the ring-shaped member or the cylindrical member has a range of at least a half of the distance from the bottom surface to the opening on the outer peripheral side surface of the bottomed cylindrical case. It is fitted so that the inside may be covered. ( Claim 2 )
If a ring-shaped member or a cylindrical member is fitted so as to cover at least half of the distance from the bottom surface to the opening, vibrations propagating to the outer peripheral side surface of the bottomed cylindrical case can be suppressed. The generation of reverberation waves can be suppressed. Although the details of this reason are unknown, when the vibration of the piezoelectric vibrator propagates to the outer peripheral side surface of the bottomed cylindrical case, the bottomed cylindrical shape is within the range of ½ of the distance from the bottom surface to the opening. It is estimated that the influence of the amplitude of vibration propagating to the outer peripheral side surface of the case is large.
In another aspect of the ultrasonic sensor of the present invention, the ring-shaped member or the cylindrical member is press-fitted into a position that suppresses the position where the amplitude or the vibration amount is maximum on the outer peripheral side surface of the bottomed cylindrical case. It is characterized by that. ( Claim 3 )
[0011]
One aspect of a method for manufacturing an ultrasonic sensor according to the present invention includes a bottomed cylindrical case having an opening at one end in the axial direction and a bottom surface at the other end in the axial direction, and an inner side of the bottomed cylindrical case. A piezoelectric vibrator bonded to the bottom surface, a base member fixed to the bottomed cylindrical case so as to shield the opening of the bottomed cylindrical case, and the piezoelectric vibrator fixed to the base member and the piezoelectric vibrator And a pair of input / output terminals electrically connected to each other, and an ultrasonic wave including a press-fitting step of fitting a ring-shaped member or a cylindrical member made of a resin material into the outer peripheral side surface of the bottomed cylindrical case by press-fitting A method of manufacturing a sensor, wherein in the press-fitting step, a ring-shaped member or a cylindrical member made of the resin material is press-fitted and fitted while being heated at a temperature exceeding the glass transition point of the resin material. To do. ( Claim 4 )
According to the method for manufacturing an ultrasonic sensor of the present invention, a ring-shaped member or a cylindrical member made of a resin material is press-fitted on the outer peripheral side surface of a bottomed cylindrical case while heating at a temperature exceeding the glass transition point of the resin material. Since it can be fitted so as to be in close contact with the outer peripheral side surface of the bottomed cylindrical case by providing a press-fitting process that fits in, the generation of reverberation waves is suppressed by suppressing the vibration propagating to the outer peripheral side surface of the bottomed cylindrical case. There is an advantage that can be suppressed.
[0012]
In particular, it is preferable to use a resin material having a glass transition point exceeding the upper limit in the operating temperature range of the ultrasonic sensor. ( Claim 5 )
Even if the use conditions of the ultrasonic sensor are, for example, those used in a high temperature of 40 ° C. (upper limit value), if a ring-shaped member or a cylindrical member made of a resin material having a glass transition point exceeding 40 ° C. is used, There is an advantage that an ultrasonic sensor having excellent transmission / reception characteristics and improved temperature characteristics and environmental resistance characteristics can be manufactured.
Moreover, it is preferable that the said ring-shaped member or a cylindrical member has an internal diameter slightly smaller than the outer diameter of the said bottomed cylindrical case. ( Claim 6 )
Moreover, it is preferable that the said ring-shaped member or a cylindrical member is press-fit in the position which suppresses the position with the largest amplitude or vibration amount in the outer peripheral side surface of the said bottomed cylindrical case. ( Claim 7 )
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a cross-sectional view showing the configuration of an ultrasonic sensor to which the present invention is applied.
In FIG. 1, reference numeral 1 denotes an ultrasonic sensor. The ultrasonic sensor 1 includes a bottomed cylindrical case 11, a piezoelectric vibrator 2 bonded to an inner bottom surface 21 of the bottomed cylindrical case 11, A base member 3 fixed to the bottomed cylindrical case 11 so as to shield the opening 13 of the bottom cylindrical case 11, and a pair of electrodes fixed to the base member 3 and electrically connected to the piezoelectric vibrator 2 Input / output terminals 4 and 5, a matching layer 8 bonded to the outside of the bottom surface 21 of the bottomed cylindrical case 11, and a cylindrical ring 10 (so-called “so-called”) that is press-fitted along the outer peripheral side surface 14 of the bottomed cylindrical case 11. A ring-shaped member or a cylindrical member).
[0014]
The piezoelectric vibrator 2 is made of a ceramic material having piezoelectric characteristics, and silver paste is printed on both sides thereof to form electrodes 16 and 17. The piezoelectric vibrator 2 is formed in a disk shape having an outer diameter of about 8 mm and a thickness of about 2 mm.
The piezoelectric vibrator 2 is bonded to the bottom surface 21 of the bottomed cylindrical case 11 made of metal, one electrode 16 is electrically connected to the bottomed cylindrical case 11, and the other electrode 17 is the conductive wire 9. For example, they are electrically connected by soldering, welding, conductive bonding or the like.
[0015]
Next, the bottomed cylindrical case 11 is made of a stainless material (thickness is about 0.2 mm) that has conductivity and is excellent in corrosion resistance and heat resistance in a gas atmosphere, and is axially (Y direction in the figure). ) Is provided with a bottom surface 12, and the other end is opened to form an opening 13. The bottomed cylindrical case 11 has an outer diameter of about 10 mm and an axial length of about 8 mm.
[0016]
Further, the bottomed cylindrical case 11 is bonded to the bottom surface 21 by bonding the piezoelectric vibrator 2, the convex portion 15 of the base member 3 is fitted so as to shield the opening portion 13, and the opening portion 13 is the base member. 3 and fixed by welding.
The bottomed cylindrical case 11 is press-fitted with a cylindrical ring 10 along the outer peripheral side surface 14.
[0017]
Next, the base member 3 is formed of a conductive Ni-plated SPC (cold rolled steel), and a convex 15 portion that fits inside the opening 13 of the bottomed cylindrical case 11; A seat 18 that contacts the opening 13 of the bottomed cylindrical case 11 is formed, and an insulating sheet 7 is attached to the upper surface of the convex portion 15.
[0018]
Further, the bottomed cylindrical case 11 has a through hole 19 for inserting the input terminal 5 and an engagement hole 20 for connecting the input terminal 4.
Next, the pair of input / output terminals 4 and 5 are made of iron to be electrically connected to the electrodes 16 and 17 of the piezoelectric vibrator 2 and an electric circuit (not shown) outside the bottomed cylindrical case 11. It is made of a conductive metal such as an alloy.
[0019]
One input / output terminal 5 is inserted into the through hole 19 of the base member 3, and an insulating material 6 such as glass paste is injected into the gap between the through hole 19 and fixed with a hermetic seal structure. Is electrically insulated. One end of the input / output terminal 5 protrudes inward of the bottomed cylindrical case 11 and is electrically connected to the electrode 17 of the piezoelectric vibrator 2 by the conductive wire 10. The other end of the input / output terminal 5 is In order to connect to an electric circuit (not shown) outside the bottom cylindrical case 11, the bottom cylindrical case 11 protrudes outward.
[0020]
The other input / output terminal 4 is connected so that one end engages with an engagement hole 20 formed on the outer surface of the base member 3 and is fixed by welding, and is electrically connected to the base member 3. The other end of the input / output terminal 4 protrudes outward from the bottomed cylindrical case 11 so as to be connected to an electric circuit (not shown) outside the bottomed cylindrical case 11. The input / output terminal 4 is electrically connected to the electrode 16 of the piezoelectric vibrator 2 through the conductive base member 3 and the conductive bottomed cylindrical case 11.
[0021]
Next, the matching layer 8 is formed of a foamable material (for example, foamed carbon, foamed plastic, etc.) having a low Q value in order to achieve impedance matching between the bottomed cylindrical case 11 and air, and the bottomed cylinder The case 11 is bonded to the outer surface of the bottom surface 21. Next, the ring 10 has a strong durability even when used in a gas atmosphere or at a high temperature, and has a glass transition point exceeding the operating temperature range of 70 ° of the ultrasonic sensor 1 (glass transition point is 120). (That is, a so-called molded ring).
[0022]
The ring 10 is formed so that the inner diameter is slightly smaller than the outer diameter of the bottomed cylindrical case 11 and is press-fitted along the outer peripheral side surface 14 from the bottom surface 21 side of the bottomed cylindrical case 11. Yes. Further, when the ring 10 is press-fitted into the bottomed cylindrical case 11, the ring 10 is press-fitted while heating the ring 10 at a temperature slightly exceeding the glass transition point 120 ° C. of the ring 10 (about 130 ° C.).
[0023]
About the ultrasonic sensor comprised as mentioned above, the manufacturing method is demonstrated below.
First, a piezoelectric vibrator 2 having electrodes 16 and 17 baked on both sides and a base member 3 to which input / output terminals 4 and 5 are connected are prepared. The piezoelectric vibrator 2 is formed into a plate shape by firing a ceramic material having piezoelectric characteristics by a known manufacturing method, and the electrodes 16 and 17 are formed by printing and baking a silver paste on both sides of the plate shape. .
[0024]
In addition, the input / output terminal 5 is fixed to the base member 3 with a hermetic seal structure and the input / output terminal 4 is fixed by welding with an insulating material 6 by a known manufacturing method.
Next, an adhesive (not shown) is applied to the bottom surface 12 of the bottomed cylindrical case 11, and the piezoelectric vibrator 2 is bonded to the bottom surface 21 of the bottomed cylindrical case 11. At this time, the piezoelectric vibrator 2 is pressed against the bottom surface 12 of the bottomed cylindrical case 11 as necessary so that no gap is generated between the piezoelectric vibrator 2 and the bottom surface 12 of the bottomed cylindrical case 11. Heat while adhering.
[0025]
Next, one end of the conductive wire 9 is electrically connected to the surface of the electrode 17 of the piezoelectric vibrator 2 by soldering, and the base member 3 to which the input / output terminals 4 and 5 are connected is opened in the bottomed cylindrical case 11. The other end of the conductive wire 9 is electrically connected to the end of the input / output terminal 5 by soldering, welding, conductive bonding, or the like (corresponding to the connection step of the present invention).
[0026]
Next, the convex portion 15 of the base member 3 is fitted into the opening 13 of the bottomed cylindrical case 11, and the periphery of the tip of the opening 13 is joined to the base member 3 by welding. Further, by this bonding, the connection terminal 4 is electrically connected to the electrode 16 of the piezoelectric vibrator 2 through the conductive base member 4 and the bottomed cylindrical case 11.
[0027]
Next, the ring 10 is press-fitted along the outer peripheral side surface 14 from the bottom surface 12 side of the bottomed cylindrical case 11 (corresponding to the press-fitting step of the present invention). When the ring 11 is press-fitted, the bottomed cylindrical case 11 is heated while the ring 10 is heated at a temperature 130 ° C. slightly exceeding the glass transition point 120 ° C. of the ring 10 (temperature exceeding the glass transition point 10 ° C.). Is press-fitted into the outer peripheral side surface 14. There are various methods for heating the ring 10, such as holding the ring 10 in a heater, leaving the ring 10 in a high-temperature tank, or blowing hot air onto the ring 10. It is selected according to productivity.
[0028]
Next, an adhesive is applied to the outer surface of the bottom surface 12 of the bottomed cylindrical case 11 to bond the matching layer 8, and the assembly of the ultrasonic sensor 1 is completed.
Below, the test result performed in order to confirm the effect which suppresses the vibration of the outer peripheral side surface 14 of the bottomed cylindrical case 11 in the ultrasonic sensor 1 is demonstrated using figures. In addition, in order to confirm the effect of embodiment of this invention, the comparative test was done with the comparative example. In the comparative example, in the ultrasonic sensor 1 of the present embodiment, instead of the ring 10, a contraction tube having an inner diameter larger than the outer diameter of the bottomed cylindrical case 11 is inserted into the outer peripheral side surface 14 of the bottomed cylindrical case 11. Then, it is shrunk by heating at 75 ° C. to 115 ° C. and brought into close contact with the outer peripheral side surface 14 of the bottomed cylindrical case 11.
[0029]
The test results of the embodiment and the comparative example are shown in FIGS. FIG. 4 is an impedance characteristic diagram of the embodiment, FIG. 5 is an impedance characteristic diagram of the comparative example, FIG. 6 is a characteristic diagram showing a reception waveform of the embodiment, and FIG. 7 is a characteristic chart showing a reception waveform of the comparative example.
4 and 5, the ultrasonic sensor 1 of the embodiment and the ultrasonic sensor of the comparative example are placed in a thermostatic bath, and the temperature in the thermostatic layer (manufactured by Tabai Espec; MINISUBZERO MC-710) is changed from −35 degrees to +85 degrees. The impedance characteristic of the ultrasonic sensor 1 of the embodiment and the ultrasonic sensor of the comparative example is measured at every predetermined temperature change using an impedance analyzer (YHP4194A), and the impedance characteristic at 25 ° C. which is an initial characteristic is measured. The characteristic and the impedance characteristic at + 85 ° C. in which the change of the impedance characteristic appears remarkably.
[0030]
4 and 5, the horizontal axis represents the frequency representing the range of 200 kHz to 300 kHz, the vertical axis represents the impedance representing the range of 100Ω to 50 kΩ, and the antiresonance point P is the frequency of the signal used for transmission and reception. .
In this example, as shown in FIG. 4, when the impedance characteristic of 25 ° C. which is the initial characteristic is compared with the characteristic of impedance characteristic of + 85 ° C., there is almost no difference between them, and even when used at a high temperature. It can be seen that the generation of reverberation waves can be suppressed by suppressing the vibration of the outer peripheral side surface of the bottomed cylindrical case.
[0031]
On the other hand, in the comparative example, as shown in FIG. 5, when the impedance characteristic characteristic of 25 ° C. which is the initial characteristic is compared with the impedance characteristic characteristic of + 85 ° C., the impedance waveform is disturbed at 85 ° C. (N1, N2 in the figure). It can be seen that the effect of suppressing the vibration of the outer peripheral side surface 14 of the bottomed cylindrical case 11 is impaired when used at a high temperature.
[0032]
The received waveforms shown in FIGS. 6 and 7 are recorded with an oscilloscope when the ultrasonic wave transmitted from one ultrasonic sensor is received by the other ultrasonic sensor. The voltage value (V) and the horizontal axis are time (μs). In order to compare the transmission and reception sensitivities of the present example and the comparative example, the voltage values of V3 and Vmax were read.
[0033]
In this embodiment, as shown in FIG. 6, the voltage value of V3 is −820 mV, the voltage value of Vmax is −3300 mV, and in the comparative example, the voltage value of V3 is −740 mV and Vmax as shown in FIG. The value is -3100 mV, and it can be seen that the present embodiment has better transmission / reception sensitivity between ultrasonic sensors than the comparative example.
[0034]
The operational effects of the ultrasonic sensor and the manufacturing method thereof according to the above embodiment will be described below.
According to the ultrasonic sensor 1 in the embodiment of the present invention, the cylindrical ring 10 is fitted to the outer peripheral side surface 14 of the bottomed cylindrical case 11 to thereby vibrate the outer peripheral side surface 14 of the bottomed cylindrical case 11. Can suppress the generation of reverberant waves and improve transmission / reception characteristics. And since the cylindrical ring 10 was formed with the resin material in which the glass transition point of the cylindrical ring 10 has more than the upper limit in the use temperature of the ultrasonic sensor 1, even if it uses it in high temperature and gas atmosphere The transmission and reception characteristics can be improved by suppressing the generation of reverberation waves, and the environment resistance characteristics such as high temperature atmosphere and gas atmosphere are excellent.
[0035]
Moreover, according to the manufacturing method of the ultrasonic sensor 1 in the embodiment of the present invention, the cylindrical ring 10 is fitted into the outer periphery of the bottomed cylindrical case 11 by press-fitting, so that the bottomed cylindrical case 11 is Since vibration of the outer peripheral side surface (so-called reverberation wave) can be suppressed and the molding ring 10 is pressed into the outer peripheral side surface 14 of the bottomed cylindrical case 11 while heating at a temperature exceeding the glass transition point of the molding ring 10. The molded ring 10 can be press-fitted so as to be in close contact with the outer peripheral side surface 14 of the bottomed cylindrical case 11, and reverberation waves can be reliably suppressed and transmission / reception characteristics can be improved.
[0036]
(Modification)
Next, a modification of the ultrasonic sensor 1 according to the present invention will be described with reference to FIGS. 2 and 3 are external views showing a modification of the ultrasonic sensor 1, and the basic configuration is the same as that of the above-described embodiment. Described below.
[0037]
In FIG. 2, the ultrasonic sensor 1 has a ring 12 (so-called ring-shaped member or cylindrical member) having a height of L / 3 that opens from the bottom surface 21 on the outer peripheral side surface 14 of the bottomed cylindrical case 11. It is fitted by press-fitting so as to cover a range of 1/2 of the distance to the portion 13 (distance L in the drawing) (in the range of L / 2 in the drawing).
[0038]
In FIG. 3, the ultrasonic sensor 1 having a ring 12 having a height of L / 2 is the distance from the bottom surface 21 to the opening 13 on the outer peripheral side surface 14 of the bottomed cylindrical case 11 (distance L in the drawing). ) In a range of 1/2 (within L / 2 in the figure).
[0039]
According to this modification, when the vibration of the piezoelectric vibrator 2 propagates to the outer peripheral side surface 14 of the bottomed cylindrical case 11, it is assumed that it occurs within a range of ½ of the distance from the bottom surface 21 to the opening 13. The effect which suppresses the influence of the amplitude of the vibration which propagates to the outer peripheral side of the bottomed cylindrical case 11 can be acquired notably, and generation | occurrence | production of a reverberation wave can be suppressed. Further, the range in which the ring 12 is press-fitted may be within a range of ½ of the distance L from the bottom surface 21 to the opening 13 on the outer peripheral side surface 14 of the bottomed cylindrical case 11, so that the manufacturing cost of the ring 12 can be reduced. .
[0040]
According to the embodiment or the modification of the present invention, the ring 10 and the ring 12 are approximately the entire outer peripheral side surface 14 of the bottomed cylindrical case 11 or 1/2 of the distance L from the bottom surface 21 to the two openings. The ring 11 and the ring 12 are press-fitted into the outer peripheral side surface 14 of the bottomed cylindrical case 11 so as to cover the range, but the piezoelectric vibrator 2 is vibrated without press-fitting the ring 10, so that the bottomed cylindrical case 11 The amplitude and vibration amount generated along the circumferential direction on the outer peripheral side surface 14 are analyzed, and the press-fitting range and the press-fitting position of the ring may be determined so that the position having the largest amplitude and vibration amount is suppressed by the ring.
[0041]
Further, the present invention can be used for various sensors that use ultrasonic waves as transmission and reception signals, such as gas sensors, object detection sensors, distance sensors, position sensors, actuators, and security sensors.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating a configuration of an ultrasonic sensor according to a first embodiment to which the present invention is applied.
FIG. 2 is a cross-sectional view illustrating a configuration of an ultrasonic sensor according to a modification of the embodiment.
FIG. 3 is a cross-sectional view illustrating a configuration of an ultrasonic sensor according to another modification of the embodiment.
FIG. 4 is an impedance characteristic diagram of the same embodiment.
FIG. 5 is an impedance characteristic diagram of a comparative example.
FIG. 6 is a characteristic diagram showing a received waveform according to the embodiment.
FIG. 7 is a characteristic diagram showing a received waveform of a comparative example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Ultrasonic sensor, 2 ... Piezoelectric vibrator, 3 ... Base member, 4, 5 ... Input / output terminal, 6 ... Insulating material, 7 ... Insulating sheet, 8 ... Matching layer, 9 ... Conductive wire, 10, 12 ... Ring (Molding ring), 11 ... bottomed cylindrical case, 13 ... opening, 14 ... outer peripheral side, 15 ... convex part, 16, 17 ... electrode, 18 ... seat, 19 ... through hole, 20 ... engagement hole 21 ... Bottom.

Claims

A bottomed cylindrical case having an opening at one end in the axial direction and a bottom surface at the other end in the axial direction, a piezoelectric vibrator joined to an inner bottom surface of the bottomed cylindrical case, and the bottomed cylinder A base member fixed to the bottomed cylindrical case so as to shield the opening of the cylindrical case, and a pair of input / output terminals fixed to the base member and electrically connected to the piezoelectric vibrator wherein the the outer peripheral surface of the bottomed cylindrical case, said ring-shaped member or a tubular member having an inner diameter slightly smaller than the outer diameter of the bottomed cylindrical case with press fit, the ring-shaped member or tubular The member is made of a resin material having a glass transfer point exceeding an upper limit value at a use temperature of the ultrasonic sensor.

The ring-shaped member or the cylindrical member is fitted on the outer peripheral side surface of the bottomed cylindrical case so as to cover at least a half of the distance from the bottom surface to the opening. The ultrasonic sensor according to claim 1.

The ring-shaped member or the cylindrical member is press-fitted into a position that suppresses a position having the largest amplitude or vibration amount on the outer peripheral side surface of the bottomed cylindrical case. The described ultrasonic sensor.

A bottomed cylindrical case having an opening at one end in the axial direction and a bottom surface at the other end in the axial direction, a piezoelectric vibrator joined to an inner bottom surface of the bottomed cylindrical case, and the bottomed cylinder A base member fixed to the bottomed cylindrical case so as to shield the opening of the cylindrical case, and a pair of input / output terminals fixed to the base member and electrically connected to the piezoelectric vibrator An ultrasonic sensor manufacturing method comprising a press-fitting step of fitting a ring-shaped member or a cylindrical member made of a resin material into the outer peripheral side surface of the bottomed cylindrical case by press-fitting,
In the press-fitting step, the ultrasonic sensor is manufactured by press-fitting and fitting while heating at a temperature exceeding the glass transition point of the ring-shaped member or cylindrical member made of the resin material.

The method for manufacturing an ultrasonic sensor according to claim 4, wherein the resin material has a glass transition point exceeding an upper limit value at an operating temperature of the ultrasonic sensor.

The method for manufacturing an ultrasonic sensor according to claim 4, wherein the ring-shaped member or the cylindrical member has an inner diameter slightly smaller than an outer diameter of the bottomed cylindrical case .

The ring-shaped member or the cylindrical member is press-fitted into a position that suppresses a position having the largest amplitude or vibration amount on the outer peripheral side surface of the bottomed cylindrical case. The manufacturing method of the ultrasonic sensor of any one of Claims 1 .