JP2004245781A

JP2004245781A - Pressure detection device

Info

Publication number: JP2004245781A
Application number: JP2003038230A
Authority: JP
Inventors: Teruo Oda; 輝夫小田
Original assignee: Denso Corp
Current assignee: Denso Corp
Priority date: 2003-02-17
Filing date: 2003-02-17
Publication date: 2004-09-02
Anticipated expiration: 2023-02-17
Also published as: JP3991881B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pressure detection device suitable for reducing the diameter of a housing while reducing thermal output. <P>SOLUTION: This pressure detection device comprises the housing 10 mountable on a detected body for which pressure is detected, a pressure sensing element 20 stored in the housing 10 and outputting signals according to the pressure, and a pressure transmission member 30 stored in the housing 10 and transmitting the pressure to the pressure sensing element 20. The pressure transmission member 30 is formed by connecting a plurality of spherical members 31 formed in a spherical shape in one row along the longitudinal direction of the housing 10. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、圧力が検出される被検出体に取付可能なハウジング内に、圧力に応じた信号を出力する感圧素子および該感圧素子に圧力を伝達する圧力伝達部材を収納してなる圧力検出装置に関する。
【０００２】
【従来の技術】
従来この種の圧力検出装置は、一般に、圧力が検出される被検出体に取付可能なハウジングと、ハウジングに収納され圧力に応じた信号を出力する感圧素子と、ハウジングに収納され感圧素子に圧力を伝達する金属製棒状の圧力伝達部材とを備えている（例えば、特許文献１参照）。
【０００３】
一方、この種の圧力検出装置として、圧力伝達部材を棒状ではなく、空間部に充填された多数の球状部材によって構成したものが提案されている（特許文献２参照）。
【０００４】
【特許文献１】
特開平７−２５３３７４号公報
【０００５】
【特許文献２】
特許第２７６４９９３号公報
【０００６】
【発明が解決しようとする課題】
しかしながら、金属製棒状の圧力伝達部材では、熱伝達性がよいがゆえに結果として線膨張係数に基づいて伸張収縮が発生し、その差が熱応力として出力され、ノイズとなってしまうという問題がある。
【０００７】
また、このような圧力検出装置を、例えばエンジンの燃焼圧センサに適用する場合、ハウジングにおける圧力伝達部材の収納部をエンジンブロックの穴に挿入し、燃焼室内の圧力を圧力伝達部材で受圧して検出することになる。
【０００８】
ここで、エンジンに対しては、小型化や軽量化の要望があり、圧力検出装置の搭載スペースも小さくする必要がある。そのため、圧力検出装置においては特に受圧部である圧力伝達部材の部分の細径化が望まれている。しかし、そのような事情から、棒状の圧力伝達部材を細径化した場合には、圧力伝達部材の強度が低下して座屈が発生するという問題がある。
【０００９】
一方、上述したような充填された多数の球状部材によって圧力伝達部材を構成した圧力検出装置の場合では、座屈の問題は抑制されるものの、細径化という点では不利である。
【００１０】
そこで本発明は上記問題に鑑み、熱出力を低減しつつハウジングの細径化に適した圧力検出装置を提供することを目的とする。
【００１１】
【課題を解決するための手段】
上記目的を達成するため、請求項１に記載の発明では、圧力が検出される被検出体に取付可能なハウジング（１０）と、ハウジングに収納され圧力に応じた信号を出力する感圧素子（２０）と、ハウジングに収納され感圧素子に圧力を伝達する圧力伝達部材（３０）とを備える圧力検出装置において、圧力伝達部材は、球状をなす球状部材（３１）をハウジングの長手方向に沿って一列に複数個連結させてなるものであることを特徴とする。
【００１２】
それによれば、圧力伝達部材は、球状部材をハウジングの長手方向に沿って一列に複数個連結した構成となるため、従来の多数の球状部材を充填した構成に比べて大幅な細径化が図れる。
【００１３】
また、圧力伝達部材における個々の球状部材と球状部材との間は点接触なので、熱伝達性は棒状の圧力伝達部材に比べて大幅に低減することができる。そのため、圧力伝達部材の熱による伸張収縮を極力抑制できる。
【００１４】
また、球は強度的に安定な形であるため、球状部材のサイズを小さくする、すなわち圧力伝達部材を細くしても球状部材は変形しにくく、座屈を抑制できる。よって、本発明によれば、熱出力を低減しつつハウジングの細径化に適した圧力検出装置を提供することができる。
【００１５】
請求項２に記載の発明では、複数個の球状部材（３１）は、金属からなる球状部材と少なくとも一つのセラミックからなる球状部材とから構成されていることを特徴とする。
【００１６】
従来の棒状の圧力伝達部材では、セラミックからなるものにすると強度の確保が困難であり割れやすいという問題がある。それに対して、本発明では、圧力伝達部材を球状とすることで強度的に安定な形となるのでセラミックを用いることができる。
【００１７】
そして、少なくとも一つの球状部材をセラミックからなるものにすることで、すべての球状部材が金属製である場合に比べて、圧力伝達部材の断熱性を大幅に向上させることができる。
【００１８】
また、金属に比べセラミックは高価であるので、すべての球状部材をセラミックからなるものにすると好ましくないが、本発明によれば、少なくとも一つの球状部材がセラミックであればよいので安価な構成にできる。
【００１９】
以上のように、本発明によれば、圧力伝達部材において、比較的安価な構成でより断熱性を高めることができるため、好ましい。
【００２０】
請求項３に記載の発明では、複数個の球状部材（３１）は、ハウジング（１０）の短手方向の径は同一でありハウジングの長手方向の径が異なるものから構成されていることを特徴とする。
【００２１】
それによれば、複数個の球状部材におけるハウジングの短手方向の径を同一にすることで、ハウジングの細径化を確保できる。また、複数個の球状部材におけるハウジングの長手方向の径を異ならせることで、個々の球状部材の共振点を異ならせることができる。そのため、出力信号の周波数にノイズが乗らないように圧力伝達部材全体の共振点を調整することが容易になり、好ましい。
【００２２】
請求項４に記載の発明では、複数個の球状部材（３１）は、防振部材（３３）にて被覆されていることを特徴とする。それによれば、圧力伝達部材の振動を抑えやすくできるため、好ましい。
【００２３】
なお、上記各手段の括弧内の符号は、後述する実施形態に記載の具体的手段との対応関係を示す一例である。
【００２４】
【発明の実施の形態】
以下、本発明を図に示す実施形態について説明する。図１は本発明の実施形態に係る圧力検出装置Ｓ１の概略断面構成を示す図であり、図２は図１中の感圧素子２０の近傍部拡大図である。限定するものではないが、この圧力検出装置Ｓ１は、被検出体であるエンジンの燃焼室内の圧力（燃焼圧）を検出する燃焼圧センサとして適用できる。
【００２５】
この圧力検出装置Ｓ１は、大きくは、圧力が検出される被検出体に取付可能なハウジング１０と、ハウジング１０に収納され圧力に応じた信号を出力する感圧素子２０と、ハウジング１０内にて感圧素子２０よりもハウジング１０の一端１１側に収納され感圧素子２０に圧力を伝達する圧力伝達部材３０と、ハウジング１０の他端１２側に設けられ感圧素子２０からの信号を取り出すためのコネクタ部４０とを備える。
【００２６】
ハウジング１０は、例えばステンレス等の金属からなる筒状のものであり、ハウジング１０のうち圧力伝達部材３０を収納する部位は、感圧素子２０を収納する部位よりも細くなっている。
【００２７】
このハウジング１０の一端１１側には、受圧部としての金属からなるダイアフラム１５が溶接等にて取り付けられている。このダイアフラム１５は、圧力を受けることにより歪むものである。
【００２８】
例えば、圧力検出装置Ｓ１を上記燃焼圧センサに適用する場合には、このハウジング１０の一端１１側が燃焼室に露出するように、ハウジング１０のうちの圧力伝達部材３０の収納部がエンジンブロックの穴に挿入される。そして、ハウジング１０は、エンジンブロックの穴に対し、ハウジング１０の外周面に設けられたネジ部１３を介してネジ結合されるようになっている。
【００２９】
ここで、ハウジング１０内に収納されている圧力伝達部材３０は、球状をなす球状部材３１をハウジング１０の長手方向に沿って一列に複数個連結させてなるものである。この球状部材３１は、炭素鋼等の硬い金属材料からなるものである。
【００３０】
この圧力伝達部材３０のうち最もハウジング１０の一端側に位置する球状部材３１は、ダイアフラム１５に接して配置されている。そして、各球状部材３１は互いに隙間無く接しており、また、ハウジング１０の内面に対しては摺動可能なように接している。なお、ハウジング１０と球状部材３１との間には、セラミック潤滑剤等の潤滑剤が設けられる。
【００３１】
ここで、図１中の白抜き矢印に示すように、ダイアフラム１５に接する球状部材３１に、ダイアフラム１５を介して測定圧力が印加されると、全ての球状部材３１がハウジング１０の長手方向に一体に摺動し、最もハウジング１０の他端１２側に位置する球状部材３１から感圧素子２０へ圧力が伝達されるようになっている。
【００３２】
また、感圧素子２０は、印加された圧力に応じた信号を出力するものであれば特に限定されないが、例えば、半導体基板にゲージ抵抗を形成したものを用いることができる。具体的には、シリコン基板にゲージ抵抗として拡散抵抗を形成し、この拡散抵抗によってブリッジ回路を形成したものを採用することができる。
【００３３】
そして、図２に示すように、この感圧素子２０には、ガラスからなる介在部材２１が陽極接合等にて接合され、その介在部材２１の上には炭素鋼等の鋼材からなる半球２２が接着等にて接合され、感圧素子２０、介在部材２１および半球２２は一体化されている。
【００３４】
そして、半球２２の曲面と最もハウジング１０の他端１２側に位置する球状部材３１とが接して配置されており、圧力伝達部材３０からの圧力は、半球２２、介在部材２１を介して感圧素子２０へ伝達されるようになっている。
【００３５】
また、コネクタ部４０は、ＰＰＳ（ポリフェニレンサルファイド）等からなるコネクタプラグ４１にターミナル４２およびプレート４３をインサート成形にて一体化させたものである。このコネクタ部４０を外部の配線部材に結合することにより、圧力検出装置Ｓ１の信号を外部へ取り出すことが可能となる。
【００３６】
ターミナル４２は銅等からなり、プレート４３はステンレス等の金属からなる。プレート４３は、感圧素子２０を支持しており、感圧素子２０に圧力伝達部材３０から圧力が印加されたときに感圧素子２０を受け止める役割を果たすものである。
【００３７】
そして、ターミナル４２の一端側は、プレート４３に形成された穴から感圧素子２０側へ露出し、ターミナル４２の他端側はコネクタプラグ４１の開口部４１ａ内に露出している。このターミナル４２の他端側は外部配線部材等と接続される部分である。
【００３８】
ここで、図２に示すように、感圧素子２０は、プレート４３の上に電気絶縁性の台座２３を介して搭載されている。この台座２３は、例えば樹脂接着剤またはコネクタプラグ４１と同一の樹脂からなるものにできる。後者の場合、台座２３は、コネクタ部４０をインサート成形する際に同時成形することができ、安価である。
【００３９】
また、感圧素子２０とターミナル４２の一端側とは、金やアルミ等のボンディングワイヤ２４によって結線され、電気的に接続されている。そして、コネクタ部４０とハウジング１０とは、コネクタ部４０のプレート４３とハウジング１０とを溶接したりかしめたりする等により接合されている。
【００４０】
このような圧力検出装置Ｓ１は、例えば、次のようにして作ることができる。コネクタ部４０に対して、介在部材２１および半球２２が一体化された感圧素子２０を搭載し、ワイヤボンディングを行って感圧素子２０とターミナル４２とを結線する。
【００４１】
続いて、このものを複数個の球状部材３１を一列に挿入したハウジング１０と一体化させ、溶接やかしめ等により固定する。こうして、圧力検出装置Ｓ１を製造することができる。
【００４２】
この圧力検出装置Ｓ１は、燃焼圧センサに適用される場合、上述したように、ダイアフラム１５側が燃焼室に露出するように、エンジンブロックの穴に挿入されてネジ結合され取り付けられる。
【００４３】
その状態にて、ダイアフラム１５に燃焼圧が印加されると、ダイアフラム１５が歪んで圧力伝達部材３０がハウジング１０の長手方向に変位する。それによって、燃焼圧は圧力伝達部材３０、半球２２、介在部材２１を介して感圧素子２０に印加される。
【００４４】
そして、感圧素子２０では、印加された圧力に応じた信号が出力され、その信号は、ボンディングワイヤ２４から、ターミナル４２を介して外部へ取り出される。こうして、燃焼圧の検出が行われる。
【００４５】
ところで、本実施形態によれば、圧力伝達部材３０は、球状部材３１をハウジングの長手方向に沿って一列に複数個連結した構成となるため、従来の多数の球状部材を充填した構成に比べて大幅な細径化が図れる。
【００４６】
また、圧力伝達部材３０における個々の球状部材３１と球状部材３１との間は点接触なので、熱伝達性は棒状の圧力伝達部材に比べて大幅に低減することができる。そのため、圧力伝達部材３０の熱による伸張収縮を極力抑制できる。
【００４７】
また、球は強度的に安定な形であるため、球状部材３１のサイズを小さくする、すなわち圧力伝達部材３０を細くしても球状部材３１は変形しにくく、座屈を抑制できる。
【００４８】
さらに、圧力伝達部材３０を球状部材３１の連続体にて構成した場合、従来の円柱状の伝達部材に比べて、圧力伝達部材３０の重量を軽減でき、装置の軽量化に効果的である。例えば、半径ｒ、高さ２ｒの円柱の体積は２πｒ^３であるが、それと同じ半径ｒの球体の体積は４πｒ^３／３である。そのため、円柱から球に変えることにより、重量は２／３に軽減できる。
【００４９】
また、圧力伝達部材３０を球状部材３１の連続体にて構成し、重量を軽くした場合、圧力伝達部材３０の固有振動数を従来に比べて高くすることができる。従来の円柱状のものでは、圧力伝達部材の重量が大きいため、その固有振動数が低くなり、測定範囲内に共振点を持つ場合があった。その場合、圧力伝達部材の振動が出力信号の周波数にノイズとして乗るため、測定誤差を生じる。
【００５０】
その点、本実施形態では、圧力伝達部材３０の固有振動数を従来に比べて高くすることができるため、そのような問題を回避することができる。ちなみに、圧力伝達部材の固有振動数をｆ、重量をｍとしたとき、ｆ＝（１／２）・π・（ｋ／ｍ）^１／２であるから、圧力伝達部材を円柱から球に変えることにより、重量を２／３に軽減した場合には、固有振動数は１．２２倍に高くできる。
【００５１】
このように、本実施形態によれば、熱出力を低減しつつハウジング１０の細径化に適した圧力検出装置Ｓ１を提供することができる。
【００５２】
次に、本実施形態における球状部材３１から構成した圧力伝達部材３０について、種々の変形例を図３に示しておく。
【００５３】
まず、図３（ａ）に示す第１の変形例では、複数個の球状部材３１を、金属からなる球状部材３１と少なくとも一つのセラミックからなる球状部材３１’とから構成したものである。図示例では、左端部のハッチングが施してある球状部材３１がアルミナ等のセラミックからなるものである。
【００５４】
従来の棒状の圧力伝達部材では、セラミックからなるものにすると強度の確保が困難であり割れやすいという問題がある。それに対して、本例では、圧力伝達部材３０を球状とすることで強度的に安定な形となるのでセラミックを用いることができる。
【００５５】
そして、少なくとも一つの球状部材３１をセラミックからなるものにすることで、すべての球状部材３１が金属製である場合に比べて、圧力伝達部材３０の断熱性を大幅に向上させることができる。
【００５６】
また、金属に比べセラミックは高価であるので、すべての球状部材３１をセラミックからなるものにすると好ましくないが、本例によれば、少なくとも一つの球状部材３１がセラミックであればよいので安価な構成にできる。よって、本例によれば、比較的安価な構成でより断熱性を高めた圧力伝達部材３０を提供することができる。
【００５７】
図３（ｂ）に示す第２の変形例では、複数個の球状部材３１を、ハウジング１０の短手方向の径は同一のものとし、ハウジング１０の長手方向の径が異なるものから構成している。なお、ハウジング長手方向の径が長径である球状部材３１と、短径である球状部材３１の配列順序は図示例以外のものであっても良く、任意である。
【００５８】
それによれば、複数個の球状部材３１におけるハウジング１０の短手方向の径を同一にすることで、ハウジング１０の細径化を確保できる。また、複数個の球状部材３１におけるハウジング１０の長手方向の径を異ならせることで、個々の球状部材３１の共振点を異ならせることができる。
【００５９】
そのため、出力信号の周波数にノイズが乗らないように圧力伝達部材３０全体の共振点を調整することが容易になり、好ましい。
【００６０】
また、図３（ｃ）に示す第３の変形例は、圧力伝達部材３０の一部を棒状部材３２に置き換えたものである。圧力伝達部材３０の熱伝達性を低く確保できる範囲で棒状部材３２を用いても良い。この場合も、出力信号の周波数にノイズが乗らないように圧力伝達部材３０全体の共振点を調整することが容易になる。
【００６１】
また、図３（ｄ）、（ｅ）に示す第４、第５の変形例では、複数個の球状部材３１を防振部材３３にて被覆したものである。この防振部材３３としてはフッ素ゴム等を採用できる。
【００６２】
図３（ｄ）の例では、複数個の球状部材３１を、防振部材３３によって一体に被覆しており、図３（ｅ）の例では、個々の球状部材３１を防振部材３３で被覆し、これを連結した構成としている。
【００６３】
前者は、金型内に複数個の球状部材３１を連結して配置させた後、防振部材３３の材料を流し込んで成形する等により作ることができ、後者は、個々の球状部材３１を防振部材３３の材料に浸漬させることにより作ることができる。
【００６４】
これら第４、第５の変形例に示すように、複数個の球状部材３１を防振部材３３にて被覆すれば、圧力伝達部材３１の振動を抑えやすくできるため、好ましい。なお、この防振部材３３で被覆する手法は、上記第３の変形例に対しても適用可能である。
【００６５】
以上述べてきたように、本発明は、圧力伝達部材３０を、球状をなす球状部材３１をハウジング１０の長手方向に沿って一列に複数個連結させてなるものとしたことを要部とするものであり、圧力検出装置においてその他の部分は、適宜設計変更しても良い。
【図面の簡単な説明】
【図１】本発明の実施形態に係る圧力検出装置の概略断面図である。
【図２】図１中の感圧素子の近傍部拡大図である。
【図３】上記実施形態における圧力伝達部材の種々の変形例を示す図である。
【符号の説明】
１０…ハウジング、２０…感圧素子、３０…圧力伝達部材、
３１…球状部材、３３…防振部材。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention provides a pressure-sensitive element in which a pressure-sensitive element that outputs a signal corresponding to pressure and a pressure-transmitting member that transmits pressure to the pressure-sensitive element are housed in a housing that can be attached to a detection target from which pressure is detected. It relates to a detection device.
[0002]
[Prior art]
Conventionally, a pressure detecting device of this type generally includes a housing that can be attached to a detection target from which pressure is detected, a pressure-sensitive element that is housed in the housing, and outputs a signal corresponding to the pressure, and a pressure-sensitive element that is housed in the housing. And a metal rod-shaped pressure transmission member that transmits pressure to the pressure sensor (for example, see Patent Document 1).
[0003]
On the other hand, as this type of pressure detecting device, there has been proposed a device in which a pressure transmitting member is not formed in a rod shape but is constituted by a large number of spherical members filled in a space portion (see Patent Document 2).
[0004]
[Patent Document 1]
JP-A-7-253374
[Patent Document 2]
Japanese Patent No. 2764993 [0006]
[Problems to be solved by the invention]
However, the metal rod-shaped pressure transmitting member has a problem that, because of its good heat transferability, expansion and contraction occur as a result based on the coefficient of linear expansion, and the difference is output as thermal stress, resulting in noise. .
[0007]
Further, when such a pressure detecting device is applied to, for example, a combustion pressure sensor of an engine, the housing of the pressure transmitting member in the housing is inserted into a hole of the engine block, and the pressure in the combustion chamber is received by the pressure transmitting member. Will be detected.
[0008]
Here, there is a demand for miniaturization and weight reduction of the engine, and it is necessary to reduce the mounting space of the pressure detecting device. For this reason, in the pressure detecting device, it is particularly desired to reduce the diameter of the pressure transmitting member which is the pressure receiving portion. However, under such circumstances, when the diameter of the rod-shaped pressure transmitting member is reduced, there is a problem that the strength of the pressure transmitting member is reduced and buckling occurs.
[0009]
On the other hand, in the case of the pressure detecting device in which the pressure transmitting member is constituted by a large number of filled spherical members as described above, the problem of buckling is suppressed, but it is disadvantageous in terms of reducing the diameter.
[0010]
In view of the above problems, an object of the present invention is to provide a pressure detection device suitable for reducing the diameter of a housing while reducing the heat output.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, according to the first aspect of the present invention, a housing (10) attachable to an object to be detected of pressure, and a pressure-sensitive element housed in the housing and outputting a signal corresponding to the pressure ( 20) and a pressure detecting member (30) housed in the housing and transmitting pressure to the pressure-sensitive element, wherein the pressure transmitting member includes a spherical member (31) having a spherical shape along the longitudinal direction of the housing. And a plurality of them connected in a row.
[0012]
According to this, since the pressure transmitting member has a configuration in which a plurality of spherical members are connected in a row along the longitudinal direction of the housing, the diameter can be significantly reduced as compared with a conventional configuration in which a large number of spherical members are filled. .
[0013]
Further, since the individual spherical members in the pressure transmitting member are in point contact with each other, the heat transferability can be greatly reduced as compared with the rod-shaped pressure transmitting member. Therefore, expansion and contraction of the pressure transmitting member due to heat can be suppressed as much as possible.
[0014]
Further, since the sphere has a stable shape in terms of strength, the size of the spherical member is reduced, that is, even if the pressure transmitting member is made thinner, the spherical member is hardly deformed and buckling can be suppressed. Therefore, according to the present invention, it is possible to provide a pressure detection device suitable for reducing the diameter of the housing while reducing the heat output.
[0015]
The invention according to claim 2 is characterized in that the plurality of spherical members (31) include a spherical member made of metal and a spherical member made of at least one ceramic.
[0016]
In the case of a conventional rod-shaped pressure transmitting member, when it is made of ceramic, there is a problem that it is difficult to secure strength and it is easy to crack. On the other hand, in the present invention, since the pressure transmitting member has a spherical shape, the shape becomes stable in terms of strength, so that ceramic can be used.
[0017]
By making at least one spherical member made of ceramic, the heat insulation of the pressure transmitting member can be greatly improved as compared with a case where all the spherical members are made of metal.
[0018]
In addition, since ceramics are more expensive than metals, it is not preferable to make all the spherical members made of ceramic. However, according to the present invention, at least one spherical member may be made of ceramic, so that the structure can be made inexpensive. .
[0019]
As described above, according to the present invention, the pressure transmitting member is preferable because the heat insulating property can be further improved with a relatively inexpensive configuration.
[0020]
According to the third aspect of the present invention, the plurality of spherical members (31) are configured such that the diameter of the housing (10) in the short direction is the same and the diameter of the housing in the long direction is different. And
[0021]
According to this, by making the diameter of the housing in the short direction of the plurality of spherical members the same, it is possible to secure a small diameter of the housing. In addition, by changing the diameter of the plurality of spherical members in the longitudinal direction of the housing, the resonance points of the individual spherical members can be different. Therefore, it is easy to adjust the resonance point of the entire pressure transmitting member so that noise does not occur on the frequency of the output signal, which is preferable.
[0022]
According to a fourth aspect of the present invention, the plurality of spherical members (31) are covered with a vibration isolating member (33). According to this, vibration of the pressure transmitting member can be easily suppressed, which is preferable.
[0023]
It should be noted that reference numerals in parentheses of the above-described units are examples showing the correspondence with specific units described in the embodiments described later.
[0024]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention shown in the drawings will be described. FIG. 1 is a diagram showing a schematic cross-sectional configuration of a pressure detecting device S1 according to an embodiment of the present invention, and FIG. 2 is an enlarged view of the vicinity of a pressure-sensitive element 20 in FIG. Although not limited, the pressure detecting device S1 can be applied as a combustion pressure sensor that detects a pressure (combustion pressure) in a combustion chamber of an engine that is an object to be detected.
[0025]
The pressure detecting device S1 is mainly composed of a housing 10 that can be attached to a detection target whose pressure is to be detected, a pressure-sensitive element 20 that is housed in the housing 10 and outputs a signal corresponding to the pressure, and A pressure transmitting member 30 that is housed at one end 11 side of the housing 10 with respect to the pressure sensitive element 20 and transmits pressure to the pressure sensitive element 20, and is provided at the other end 12 side of the housing 10 to extract a signal from the pressure sensitive element 20. And the connector section 40 of the above.
[0026]
The housing 10 is, for example, a cylindrical member made of metal such as stainless steel, and a portion of the housing 10 that stores the pressure transmitting member 30 is thinner than a portion that stores the pressure-sensitive element 20.
[0027]
A diaphragm 15 made of a metal as a pressure receiving portion is attached to one end 11 of the housing 10 by welding or the like. The diaphragm 15 is distorted by receiving pressure.
[0028]
For example, when the pressure detecting device S1 is applied to the combustion pressure sensor, the housing portion of the pressure transmitting member 30 of the housing 10 is provided with a hole in the engine block so that one end 11 of the housing 10 is exposed to the combustion chamber. Is inserted into The housing 10 is screwed to a hole in the engine block via a screw portion 13 provided on the outer peripheral surface of the housing 10.
[0029]
Here, the pressure transmitting member 30 housed in the housing 10 is formed by connecting a plurality of spherical members 31 having a spherical shape in a line along the longitudinal direction of the housing 10. The spherical member 31 is made of a hard metal material such as carbon steel.
[0030]
The spherical member 31 located at the one end side of the housing 10 among the pressure transmitting members 30 is disposed in contact with the diaphragm 15. The spherical members 31 are in contact with each other without any gap, and are in slidable contact with the inner surface of the housing 10. Note that a lubricant such as a ceramic lubricant is provided between the housing 10 and the spherical member 31.
[0031]
When a measurement pressure is applied to the spherical member 31 in contact with the diaphragm 15 through the diaphragm 15 as shown by a white arrow in FIG. 1, all the spherical members 31 are integrated in the longitudinal direction of the housing 10. The pressure is transmitted from the spherical member 31 located closest to the other end 12 of the housing 10 to the pressure-sensitive element 20.
[0032]
The pressure-sensitive element 20 is not particularly limited as long as it outputs a signal corresponding to the applied pressure. For example, an element in which a gauge resistance is formed on a semiconductor substrate can be used. Specifically, it is possible to adopt a device in which a diffused resistor is formed as a gauge resistor on a silicon substrate, and a bridge circuit is formed by the diffused resistor.
[0033]
As shown in FIG. 2, an intervening member 21 made of glass is joined to the pressure-sensitive element 20 by anodic bonding or the like, and a hemisphere 22 made of a steel material such as carbon steel is formed on the intervening member 21. The pressure-sensitive element 20, the intervening member 21, and the hemisphere 22 are integrated by bonding or the like.
[0034]
The curved surface of the hemisphere 22 and the spherical member 31 located closest to the other end 12 of the housing 10 are arranged in contact with each other, and the pressure from the pressure transmitting member 30 is pressure-sensitive through the hemisphere 22 and the intervening member 21. The signal is transmitted to the element 20.
[0035]
The connector section 40 is formed by integrating a terminal 42 and a plate 43 with a connector plug 41 made of PPS (polyphenylene sulfide) or the like by insert molding. By connecting the connector section 40 to an external wiring member, it is possible to take out the signal of the pressure detecting device S1 to the outside.
[0036]
The terminal 42 is made of copper or the like, and the plate 43 is made of metal such as stainless steel. The plate 43 supports the pressure-sensitive element 20 and serves to receive the pressure-sensitive element 20 when pressure is applied to the pressure-sensitive element 20 from the pressure transmitting member 30.
[0037]
One end of the terminal 42 is exposed toward the pressure-sensitive element 20 through a hole formed in the plate 43, and the other end of the terminal 42 is exposed inside the opening 41 a of the connector plug 41. The other end of the terminal 42 is a portion connected to an external wiring member or the like.
[0038]
Here, as shown in FIG. 2, the pressure-sensitive element 20 is mounted on the plate 43 via the electrically insulating pedestal 23. The pedestal 23 can be made of, for example, a resin adhesive or the same resin as the connector plug 41. In the latter case, the pedestal 23 can be formed simultaneously with the insert molding of the connector portion 40, and is inexpensive.
[0039]
Further, the pressure-sensitive element 20 and one end of the terminal 42 are connected by a bonding wire 24 of gold, aluminum or the like, and are electrically connected. The connector part 40 and the housing 10 are joined by welding or caulking the plate 43 of the connector part 40 and the housing 10.
[0040]
Such a pressure detecting device S1 can be manufactured, for example, as follows. The pressure-sensitive element 20 in which the interposition member 21 and the hemisphere 22 are integrated is mounted on the connector section 40, and the pressure-sensitive element 20 and the terminal 42 are connected by wire bonding.
[0041]
Subsequently, this is integrated with the housing 10 in which a plurality of spherical members 31 are inserted in a line, and fixed by welding, caulking, or the like. Thus, the pressure detecting device S1 can be manufactured.
[0042]
When applied to a combustion pressure sensor, the pressure detecting device S1 is inserted into a hole of an engine block, screwed and attached so that the diaphragm 15 side is exposed to the combustion chamber, as described above.
[0043]
In this state, when a combustion pressure is applied to the diaphragm 15, the diaphragm 15 is distorted and the pressure transmitting member 30 is displaced in the longitudinal direction of the housing 10. Thereby, the combustion pressure is applied to the pressure-sensitive element 20 via the pressure transmitting member 30, the hemisphere 22, and the interposed member 21.
[0044]
Then, the pressure-sensitive element 20 outputs a signal corresponding to the applied pressure, and the signal is extracted from the bonding wire 24 to the outside via the terminal 42. Thus, the detection of the combustion pressure is performed.
[0045]
By the way, according to the present embodiment, the pressure transmitting member 30 has a configuration in which a plurality of the spherical members 31 are connected in a line along the longitudinal direction of the housing, so that the pressure transmitting member 30 is compared with a conventional configuration in which many spherical members are filled. The diameter can be significantly reduced.
[0046]
In addition, since the individual spherical members 31 in the pressure transmitting member 30 are in point contact with each other, the heat transferability can be significantly reduced as compared with the rod-shaped pressure transmitting member. Therefore, expansion and contraction of the pressure transmitting member 30 due to heat can be suppressed as much as possible.
[0047]
In addition, since the sphere has a shape that is stable in strength, the size of the spherical member 31 is reduced, that is, the spherical member 31 is not easily deformed even if the pressure transmitting member 30 is thinned, and buckling can be suppressed.
[0048]
Further, when the pressure transmitting member 30 is formed of a continuum of the spherical members 31, the weight of the pressure transmitting member 30 can be reduced as compared with a conventional columnar transmitting member, which is effective in reducing the weight of the apparatus. For example, the radius r, but the volume of a cylinder of height 2r is 2.pi.r ^3, the same volume of a sphere of the same radius r is 4πr ^3/3. Therefore, by changing from a cylinder to a sphere, the weight can be reduced to 2/3.
[0049]
Further, when the pressure transmitting member 30 is formed of a continuum of the spherical members 31 and the weight is reduced, the natural frequency of the pressure transmitting member 30 can be increased as compared with the related art. In the case of the conventional columnar member, the weight of the pressure transmitting member is large, so that the natural frequency of the member is low, and there is a case where a resonance point exists within the measurement range. In this case, a measurement error occurs because the vibration of the pressure transmitting member rides on the frequency of the output signal as noise.
[0050]
In this regard, in the present embodiment, the natural frequency of the pressure transmitting member 30 can be increased as compared with the related art, so that such a problem can be avoided. Incidentally, when the natural frequency of the pressure transmitting member is f and the weight is m, since f = (1/2) .pi. (K / m) ^1/2 , the pressure transmitting member is changed from a cylinder to a sphere. Thus, when the weight is reduced to 2/3, the natural frequency can be increased to 1.22 times.
[0051]
As described above, according to the present embodiment, it is possible to provide the pressure detection device S1 suitable for reducing the diameter of the housing 10 while reducing the heat output.
[0052]
Next, various modifications of the pressure transmitting member 30 constituted by the spherical member 31 in the present embodiment are shown in FIG.
[0053]
First, in a first modified example shown in FIG. 3A, a plurality of spherical members 31 are configured by a spherical member 31 made of metal and a spherical member 31 ′ made of at least one ceramic. In the illustrated example, the hatched spherical member 31 at the left end is made of ceramic such as alumina.
[0054]
In the case of a conventional rod-shaped pressure transmitting member, when it is made of ceramic, there is a problem that it is difficult to secure strength and it is easy to crack. On the other hand, in this example, since the pressure transmitting member 30 has a spherically stable shape by making it spherical, ceramic can be used.
[0055]
By making at least one spherical member 31 made of ceramic, the heat insulating property of the pressure transmitting member 30 can be greatly improved as compared with the case where all the spherical members 31 are made of metal.
[0056]
In addition, since ceramic is more expensive than metal, it is not preferable to make all the spherical members 31 made of ceramic. However, according to this example, at least one spherical member 31 only needs to be made of ceramic, so that it is inexpensive. Can be. Therefore, according to the present example, it is possible to provide the pressure transmitting member 30 with a relatively inexpensive configuration and further improved heat insulation.
[0057]
In the second modified example shown in FIG. 3B, the plurality of spherical members 31 are configured such that the diameter of the housing 10 in the short direction is the same and the diameter of the housing 10 in the long direction is different. I have. The arrangement order of the spherical member 31 having a long diameter in the longitudinal direction of the housing and the spherical member 31 having a short diameter may be other than the illustrated example, and is arbitrary.
[0058]
According to this, by making the diameter of the housing 10 in the short direction of the plurality of spherical members 31 the same, the diameter of the housing 10 can be reduced. In addition, by making the diameters of the plurality of spherical members 31 in the longitudinal direction of the housing 10 different, the resonance points of the individual spherical members 31 can be made different.
[0059]
Therefore, it is easy to adjust the resonance point of the entire pressure transmitting member 30 so that noise does not occur on the frequency of the output signal, which is preferable.
[0060]
In a third modification shown in FIG. 3C, a part of the pressure transmitting member 30 is replaced with a rod-shaped member 32. The rod-shaped member 32 may be used as long as the heat transfer property of the pressure transfer member 30 can be kept low. Also in this case, it is easy to adjust the resonance point of the entire pressure transmitting member 30 so that the frequency of the output signal does not include noise.
[0061]
In the fourth and fifth modified examples shown in FIGS. 3D and 3E, a plurality of spherical members 31 are covered with a vibration isolating member 33. As the vibration damping member 33, fluorine rubber or the like can be adopted.
[0062]
In the example of FIG. 3D, the plurality of spherical members 31 are integrally covered with the vibration isolating member 33. In the example of FIG. 3E, the individual spherical members 31 are covered with the vibration isolating member 33. In addition, they are connected.
[0063]
The former can be made by connecting and arranging a plurality of spherical members 31 in a mold and then pouring and shaping the material of the vibration isolating member 33, and the latter can prevent the individual spherical members 31 from being formed. It can be made by immersing in the material of the vibration member 33.
[0064]
As shown in the fourth and fifth modified examples, it is preferable to cover the plurality of spherical members 31 with the vibration isolating member 33 because the vibration of the pressure transmitting member 31 can be easily suppressed. The method of covering with the vibration isolating member 33 can be applied to the third modification.
[0065]
As described above, the main part of the present invention is that the pressure transmitting member 30 is formed by connecting a plurality of spherical members 31 forming a spherical shape in a line along the longitudinal direction of the housing 10. The other parts of the pressure detecting device may be appropriately designed and changed.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view of a pressure detecting device according to an embodiment of the present invention.
FIG. 2 is an enlarged view of the vicinity of a pressure-sensitive element in FIG.
FIG. 3 is a view showing various modified examples of the pressure transmitting member in the embodiment.
[Explanation of symbols]
10 housing, 20 pressure-sensitive element, 30 pressure transmitting member
31: spherical member, 33: anti-vibration member.

Claims

A housing (10) that can be attached to a detection target from which pressure is detected;
A pressure-sensitive element (20) housed in the housing and outputting a signal corresponding to pressure;
A pressure transmitting member (30) housed in the housing and transmitting pressure to the pressure-sensitive element,
The pressure detecting device according to claim 1, wherein the pressure transmitting member is formed by connecting a plurality of spherical members (31) having a spherical shape in a line along a longitudinal direction of the housing.

The pressure detecting device according to claim 1, wherein the plurality of spherical members (31) are formed of a spherical member made of metal and a spherical member made of at least one ceramic.

2. The plurality of spherical members (31), wherein the diameter of the housing (10) in the short direction is the same, and the diameter of the housing in the long direction is different. 3. 3. The pressure detecting device according to 2.

The pressure detecting device according to any one of claims 1 to 3, wherein the plurality of spherical members (31) are covered with a vibration isolating member (33).