【発明の詳細な説明】産業上の利用分野本発明は、内燃機関のシリンダー内燃焼圧力等の検出に
適した圧電型圧力センサに関するものである。DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a piezoelectric pressure sensor suitable for detecting combustion pressure in a cylinder of an internal combustion engine.
従来の技術力を加えて電気を発生する逆圧電効果を利用した圧電型
圧力センサは、従来よりよく用いられている。しかし、
直接シリンダ室内へ受圧面が来るように取り付けられる
内燃機関用圧力センサは、燃焼圧力を計測するため、高
温、高圧に耐えなければならない。従来、特願昭６２−
２７６．１１５号公報にみられるように円筒状の圧電素
子をその長手方向に分極し、円筒の上下面から円筒に対
し圧縮あるいはせん断力として印加する形の圧力センサ
が考えられている。第３図は、従来より用いられている
せん断効果型圧カセンサの基本原理を表す縦断面図構造
を示した。圧力検出機構部は、筐体１１の内部に図のよ
うに構成されていて、圧力伝達部材１２、円筒形圧電素
子１３、素子固定部材１４、セラミックプリント基板１
５に構成した電気回路１６および金属板１７を備える。Piezoelectric pressure sensors that utilize the inverse piezoelectric effect to generate electricity by applying conventional technology have been widely used. but,
Pressure sensors for internal combustion engines, which are installed so that the pressure-receiving surface is directly in the cylinder chamber, must withstand high temperatures and pressures in order to measure combustion pressure. Previously, patent application 1986-
As seen in Japanese Patent Application No. 276.115, a pressure sensor has been proposed in which a cylindrical piezoelectric element is polarized in its longitudinal direction and compressive or shear force is applied to the cylinder from the upper and lower surfaces of the cylinder. FIG. 3 shows a vertical cross-sectional view showing the basic principle of a conventionally used shear effect type pressure sensor. The pressure detection mechanism section is configured inside the housing 11 as shown in the figure, and includes a pressure transmission member 12, a cylindrical piezoelectric element 13, an element fixing member 14, and a ceramic printed circuit board 1.
The electric circuit 16 and the metal plate 17 configured as shown in FIG.
円筒の長手（円柱座標で２軸方向）方向に分極軸を有し
内外周囲に電極を持つ円筒形圧電素子１３は、その底面
内周部分に、圧力伝達部材１２が固定され、該圧力伝達
部材１２は内燃機関のシリンダに取り付けられる筐体１
１内部の受圧面１１ａの中心部分に固定されている。圧
電素子１３の上面外周部分には、素子固定部材１４が接
し、センサ出力に必要な電気回路１６を構成したセラミ
ックプリント基板１５と金属板１７を挟んで、固定部材
１８で筐体１１に固定されている。この構成のセンサで
は円筒形圧電素子１３の一端面の外周部分が固定され、
他端面の内周部分に圧力伝達部材１２により圧力が印加
されるので、これによって発生したせん断力に応じた電
荷をそれぞれ内周囲電極、バネ部材１９および外周囲電
極、素子固定部材１４によって取出し、圧力に比例した
出力信号をケーブル２０によって取り出すことができる
。The cylindrical piezoelectric element 13 has a polarization axis in the longitudinal direction of the cylinder (biaxial direction in cylindrical coordinates) and has electrodes on the inner and outer peripheries.A pressure transmitting member 12 is fixed to the inner peripheral portion of the bottom surface of the cylindrical piezoelectric element 13. 12 is a housing 1 that is attached to the cylinder of an internal combustion engine.
1 is fixed to the center of the pressure receiving surface 11a inside the pressure receiving surface 11a. An element fixing member 14 is in contact with the outer periphery of the upper surface of the piezoelectric element 13, and is fixed to the housing 11 with a fixing member 18, sandwiching a ceramic printed circuit board 15 and a metal plate 17 that constitute an electric circuit 16 necessary for sensor output. ing. In the sensor with this configuration, the outer peripheral portion of one end surface of the cylindrical piezoelectric element 13 is fixed,
Since pressure is applied to the inner peripheral portion of the other end surface by the pressure transmission member 12, charges corresponding to the shearing force generated thereby are extracted by the inner peripheral electrode, the spring member 19, the outer peripheral electrode, and the element fixing member 14, respectively. An output signal proportional to pressure can be tapped off by cable 20.
また、この構成の圧力センサでは周囲の温度変化による
出力変化を生じなくするため、圧力伝達方向の該圧力検
出機構部と該固定部の合わせたみかけ上の線熱膨張係数
と該筐体の線熱膨張係数を一致させる手段が一般に実施
されている。In addition, in order to prevent output changes due to ambient temperature changes in the pressure sensor with this configuration, the combined apparent linear thermal expansion coefficient of the pressure detection mechanism section and the fixed section in the pressure transmission direction and the linear thermal expansion coefficient of the casing are determined. Measures to match the coefficients of thermal expansion are commonly implemented.
発明が解決しようとする課題しかしながら、上述したせん断効果型圧力センサは、そ
の圧力検出機構部の圧電素子にセンサ構成時に固定部材
による圧縮応力や圧力計測時の圧力の直流成分が印加さ
れ、圧電素子内部に静的な一方向バイアス応力が常に印
加された状態を生じる。このような状態下では静的な一
方向バイアス応力の変化により、圧電および誘電定数の
変化をもたらし、第２図の破線に示すように示すように
２０ ＨＺ、 ±１０ｋｇｆ／ｃｍ２の一定圧力変化
状態においても、バイアス圧力の変化により、出力が変
化する（バイアス圧力による出力特性変化）。Problems to be Solved by the Invention However, in the above-mentioned shear effect type pressure sensor, compressive stress due to a fixing member and a direct current component of pressure during pressure measurement are applied to the piezoelectric element of the pressure detection mechanism when the sensor is configured, and the piezoelectric element A static unidirectional bias stress is constantly applied internally. Under such conditions, changes in static unidirectional bias stress result in changes in piezoelectric and dielectric constants, resulting in a constant pressure change state of 20 Hz, ±10 kgf/cm2, as shown by the broken line in Figure 2. Also, the output changes due to changes in bias pressure (change in output characteristics due to bias pressure).
圧電形圧力センサは交流成分の圧力検出が可能であるが
直流成分、いわゆるバイアス圧力の計測はできない。シ
リンダー内圧センサの場合、圧力波形は逐次変化し、そ
のバイアス圧力も常に変化する。すなわち上述の従来例
のセンサでは出力がそのバイアス圧力によって変化し、
正確な圧力計測はできないという欠点を有する。Piezoelectric pressure sensors are capable of detecting alternating current component pressure, but cannot measure direct current component, so-called bias pressure. In the case of a cylinder internal pressure sensor, the pressure waveform changes sequentially, and its bias pressure also changes constantly. In other words, in the conventional sensor described above, the output changes depending on the bias pressure,
It has the disadvantage that accurate pressure measurement is not possible.
本発明は、このような従来の圧力センサの課題を解決す
ることを目的とする。The present invention aims to solve the problems of such conventional pressure sensors.
課題を解決するための手段本発明は、センサの受圧面に、圧力による変位がより容
易な偏度のより薄い一部分を設け、該部分以外は受圧時
の変位がほとんど生じない構造とし、該一部分の圧力の
みを圧力検出機構部に伝達する受圧面構造とすることに
より、圧力検出機構ｇＢへの伝達応力を従来のセンサに
比べ低減させるものである。Means for Solving the Problems The present invention provides a thinner part on the pressure-receiving surface of a sensor that is easier to displace due to pressure, and has a structure in which almost no displacement occurs when pressure is received other than this part. By having a pressure receiving surface structure that transmits only the pressure of 1 to the pressure detection mechanism section, the stress transmitted to the pressure detection mechanism gB is reduced compared to conventional sensors.
作用従来例のせん断効果型圧カセンサでは、基本的に受圧面
が筐体の底面部全体であり、この面積に作用する全圧力
がより面積の小さい圧力伝達部材１２に作用し、この部
材を介して圧力検出機構部に伝達される。このため、圧
力検出機構部に伝達される応力（単位面積が受ける力）
は受圧面が受ける応力（単位面積が受ける力）より大き
くなる。Function In the conventional shear effect type pressure sensor, the pressure receiving surface is basically the entire bottom surface of the casing, and the total pressure acting on this area acts on the pressure transmission member 12, which has a smaller area, and is transmitted through this member. and is transmitted to the pressure detection mechanism. Therefore, the stress transmitted to the pressure detection mechanism (force applied to unit area)
is larger than the stress applied to the pressure-receiving surface (force applied to unit area).
それに対し本発明の手段を用いることにより、圧力検出
機構部に印加されるバイアス圧力による伝達応力を大き
く低減することができ、バイアス圧力変化による出力変
化を低減することができる。In contrast, by using the means of the present invention, it is possible to greatly reduce the transmitted stress due to the bias pressure applied to the pressure detection mechanism section, and it is possible to reduce the output change due to the bias pressure change.
これによってバイアス圧力変化を伴う各種の測定圧力波
形にも影響を受けない安定した精度の良い出力信号を得
ることができる。This makes it possible to obtain a stable and highly accurate output signal that is not affected by various measured pressure waveforms accompanied by bias pressure changes.
実施例以下、本発明の実施例について、図面を用いて詳細に説
明する。Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
第１図は、本発明にかかる圧電型圧力センサの一実施例
の断面図であり、同図（ａ）は縦断面図、同図（ｂ）は
その分解斜視図である。FIG. 1 is a cross-sectional view of an embodiment of a piezoelectric pressure sensor according to the present invention, with FIG. 1(a) being a longitudinal sectional view and FIG. 1(b) being an exploded perspective view thereof.
圧力検出機構部は、筐体１の内部に構成され、圧力伝達
部材２、円筒形圧電素子３、素子固定部材４、セラミッ
クプリント基板５に構成した電気回路６および金属板７
からなり、円筒の長手方向（円柱座標で２方向）に分極
軸を有し内外周面に電極を持つ円筒形圧電素子３は、そ
の底面内周部分に、耐熱性樹脂あるいは金属等に耐熱性
樹脂をコーティーングした断熱効果を有する圧力伝達部
材２が固定され、内燃機関のシリンダーに取り付けられ
る筺体１内部の受圧面１ａの中心部分に、接着等により
固着されている。筐体１の受圧面１ａはその中心部（直
径３ ｍ ｍ ）の厚さが周辺部（直径１０ｍｒｎまで
）に比べ１１５以下と薄く、この部分が受圧により変位
が周辺より容易な部分ｉｂであり、基本的にこの部分に
作用する圧力のみが圧力伝達部材２を通して圧電素子に
伝えられる構造となっている。圧電素子３の上面外周部
分には、金属等からなる素子固定部材４が接し、さらに
インピーダンス変換回路、増幅器等の電気回路６を構成
したセラミックプリント基板５と金属板７を挟んで、固
定部材８で締め付け固定することにより、筐体ｌに取り
付けられている。ここでセラミックプリント基板５は、
筐体ｌからの直接の熱を避けるとともに、円筒形圧電素
子４の内外周面電極との絶縁および筐体との絶縁を計る
ものである。金属板７は、固定部材８によって締め付け
られる部分への小さく且つ均一な荷重を生み出すための
一種の＠術部材であり、バネ性を有する中空金属である
。 円筒形圧電素子３の外周部分が素子固定部材４で
固定され、他端面の内周部分に圧力伝達部材２により圧
力が印加されるので、円筒形圧電素子３にはせん断応力
に応じた電荷が発生し、これを該圧電素子３の内周に接
触したバネ部材９と外周に接触した素子固定部材４のそ
れぞれを介して取り出し、前記電気回路６を通じてケー
ブルｌＯによって圧力に比例した出力信号として取り出
すことができる。The pressure detection mechanism section is configured inside the housing 1 and includes a pressure transmission member 2, a cylindrical piezoelectric element 3, an element fixing member 4, an electric circuit 6 configured on a ceramic printed circuit board 5, and a metal plate 7.
The cylindrical piezoelectric element 3 has a polarization axis in the longitudinal direction of the cylinder (two directions in cylindrical coordinates) and has electrodes on the inner and outer peripheral surfaces. A pressure transmitting member 2 coated with resin and having a heat insulating effect is fixed, and is fixed by adhesive or the like to the center portion of a pressure receiving surface 1a inside a casing 1 that is attached to a cylinder of an internal combustion engine. The pressure-receiving surface 1a of the casing 1 has a thickness of 115 or less at the center (diameter 3 mm) compared to the peripheral portion (up to 10 mrn), and this portion is a portion ib that is easier to displace due to pressure than the surrounding area. Basically, only the pressure acting on this portion is transmitted to the piezoelectric element through the pressure transmission member 2. An element fixing member 4 made of metal or the like is in contact with the outer periphery of the upper surface of the piezoelectric element 3, and a fixing member 8 is sandwiched between a ceramic printed circuit board 5 and a metal plate 7 that constitute an electric circuit 6 such as an impedance conversion circuit or an amplifier. It is attached to the housing l by tightening and fixing it. Here, the ceramic printed circuit board 5 is
This is to avoid direct heat from the casing 1, and to insulate the cylindrical piezoelectric element 4 from the inner and outer circumferential electrodes and from the casing. The metal plate 7 is a type of mechanical member for producing a small and uniform load on the portion tightened by the fixing member 8, and is a hollow metal having spring properties. The outer periphery of the cylindrical piezoelectric element 3 is fixed by the element fixing member 4, and pressure is applied to the inner periphery of the other end surface by the pressure transmitting member 2, so that the cylindrical piezoelectric element 3 is charged with an electric charge corresponding to the shear stress. This is extracted through the spring member 9 in contact with the inner periphery of the piezoelectric element 3 and the element fixing member 4 in contact with the outer periphery of the piezoelectric element 3, and is extracted as an output signal proportional to the pressure by the cable IO through the electric circuit 6. be able to.
上記実施例の構成により、１０ｍｍ直径の受圧面全体に
作用する圧力全体が圧電素子に伝達される従来例の構造
のセンサに比べ、伝達される応力が１／ｌＯ以下とする
ことができる。この結果、センサとしてのバイアス圧力
による出力特性変化は第２図の実線に示すようになり、
バイアス圧力が変化しても特に低いバイアス圧力領域で
出力特性変化が極めて小さい圧力センサを供給すること
ができる。With the configuration of the above embodiment, the transmitted stress can be reduced to 1/1O or less compared to a sensor having a conventional structure in which the entire pressure acting on the entire 10 mm diameter pressure receiving surface is transmitted to the piezoelectric element. As a result, the output characteristic change due to bias pressure as a sensor is shown by the solid line in Figure 2,
It is possible to provide a pressure sensor whose output characteristics change extremely little even when the bias pressure changes, especially in a low bias pressure region.
また、本発明においても該圧力検出機構部と該固定部材
との合わせたみかけ上の線熱膨張係数と該筐体の線熱膨
張係数とを等しくすることが出来る。さらに素子固定部
材４は、筐体１と電気的絶縁が計られるように筐体ｌと
接触しない構造、あるいは素子固定部材４の外周部分に
耐熱性樹脂なコーティングした構造にすることにより、
円筒形圧電素子３の内外周面電極と筐体ｌと絶縁がはか
られる。従って圧力による電気信号は、筐体すなわち車
体によりシールドされるのでノイズに強い構造となる。Also in the present invention, the combined apparent linear thermal expansion coefficient of the pressure detection mechanism section and the fixing member can be made equal to the linear thermal expansion coefficient of the housing. Furthermore, the element fixing member 4 may have a structure in which it does not come into contact with the casing 1 so as to provide electrical insulation from the casing 1, or a structure in which the outer periphery of the element fixing member 4 is coated with heat-resistant resin.
The inner and outer circumferential electrodes of the cylindrical piezoelectric element 3 are insulated from the housing l. Therefore, electrical signals caused by pressure are shielded by the casing, that is, the vehicle body, resulting in a structure that is resistant to noise.
発明の効果本発明は、センサ出力がそのバイアス（静圧、圧力の直
流成分）圧力によって変化しない圧電形シリンダ内圧セ
ンサを提供するものであり、正確なシリンダ内圧力計測
が可能となる。またこのセンサは構造が簡単であり、感
度も高いことがらセンサ間のバラツキを少なくでき、量
産性に向いた汎用形センサである。Effects of the Invention The present invention provides a piezoelectric cylinder internal pressure sensor whose sensor output does not change depending on its bias (static pressure, DC component of pressure) pressure, and enables accurate cylinder internal pressure measurement. Furthermore, this sensor has a simple structure and high sensitivity, which reduces variations between sensors, making it a general-purpose sensor suitable for mass production.
第１図は本発明の一実施例の圧電型圧力センサを示し、
同図（ａ）はその縦断面図、同図（ｂ）はその分解斜視
図、第２図は従来例および本発明のバイアス圧力変化に
よる出力特性変化を示すグラフであり、第３図は従来例
のせん断効果型の圧力センサの縦断面図である。１．１１ ・・・筐体、１ ａ、 １１ ａ・−受圧
面、ｌｌｂ・・・受圧面の圧力による変位がより容易な
部分、２．１２・・・圧力伝達部材、３．１３・・・円
筒形圧電素子、４．１４・・・素子固定部材、５．１５
・・・セラミックプリント基板、６．１６・・・電気回
路、７．１７・・・金属板、８．１８・・・固定部材、
９．１９・・・バネ部材、 １０、２０・・・ケーブル
。代理人の氏名 弁理士 粟野重孝 はか１名第］図（ａ）］ａ受圧面第図バイアス圧力（Ｋｇｆ／ｃｍり第］図（ｂ）鼾２／Ｉカイ云満ＩＢ材第図FIG. 1 shows a piezoelectric pressure sensor according to an embodiment of the present invention,
FIG. 2(a) is a longitudinal sectional view thereof, FIG. 2(b) is an exploded perspective view thereof, FIG. 2 is a graph showing changes in output characteristics due to bias pressure changes in the conventional example and the present invention, and FIG. 3 is a graph showing the conventional example. FIG. 2 is a longitudinal cross-sectional view of an example shear effect type pressure sensor. 1.11... Housing, 1 a, 11 a - Pressure receiving surface, llb... Portion that is easier to displace due to pressure on the pressure receiving surface, 2.12... Pressure transmission member, 3.13...・Cylindrical piezoelectric element, 4.14...element fixing member, 5.15
...Ceramic printed circuit board, 6.16...Electric circuit, 7.17...Metal plate, 8.18...Fixing member,
9.19... Spring member, 10, 20... Cable. Name of agent: Patent attorney Shigetaka Awano No. 1] Figure (a) ] a Pressure-receiving surface diagram Bias pressure (Kgf/cm) Figure (b) Snore 2/I Kai Yunman IB material diagram
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63248171AJPH0295232A (en) | 1988-09-30 | 1988-09-30 | piezoelectric pressure sensor |
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63248171AJPH0295232A (en) | 1988-09-30 | 1988-09-30 | piezoelectric pressure sensor |
| Publication Number | Publication Date |
|---|---|
| JPH0295232Atrue JPH0295232A (en) | 1990-04-06 |
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP63248171APendingJPH0295232A (en) | 1988-09-30 | 1988-09-30 | piezoelectric pressure sensor |
| Country | Link |
|---|---|
| JP (1) | JPH0295232A (en) |
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH04203944A (en)* | 1990-11-29 | 1992-07-24 | Matsushita Electric Ind Co Ltd | Piezoelectric pressure sensor |
| US5138885A (en)* | 1990-03-16 | 1992-08-18 | Matsushita Electric Industrial Co., Ltd. | Piezoelectric-type pressure sensor |
| JPH05157651A (en)* | 1991-12-04 | 1993-06-25 | Japan Electron Control Syst Co Ltd | Pressure sensor |
| JP2010509574A (en)* | 2006-11-10 | 2010-03-25 | キストラー ホールディング アクチエンゲゼルシャフト | Pressure sensor for measurement in high temperature and dynamic processes |
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS63122926A (en)* | 1986-11-13 | 1988-05-26 | Nippon Denso Co Ltd | Piezoelectric pressure detector |
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS63122926A (en)* | 1986-11-13 | 1988-05-26 | Nippon Denso Co Ltd | Piezoelectric pressure detector |
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5138885A (en)* | 1990-03-16 | 1992-08-18 | Matsushita Electric Industrial Co., Ltd. | Piezoelectric-type pressure sensor |
| JPH04203944A (en)* | 1990-11-29 | 1992-07-24 | Matsushita Electric Ind Co Ltd | Piezoelectric pressure sensor |
| JPH05157651A (en)* | 1991-12-04 | 1993-06-25 | Japan Electron Control Syst Co Ltd | Pressure sensor |
| JP2010509574A (en)* | 2006-11-10 | 2010-03-25 | キストラー ホールディング アクチエンゲゼルシャフト | Pressure sensor for measurement in high temperature and dynamic processes |
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