JP2008128805A - Pressure sensor for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reliable pressure sensor for an internal combustion engine capable of eliminating the breakdown of a pressure sensitive body when the pressure sensors for the internal combustion engine having a pressure sensitive bodies made of ceramics are assembled to the internal combustion engine or used. <P>SOLUTION: The pressure sensor for the internal combustion engine is incorporated into a tool assembled to the internal combustion engine and detects the pressure in a cylinder of the internal combustion engine. Between a housing bearing surface of the tool and an attaching surface of the internal combustion engine to which the tool is attached, the pressure sensor has the pressure sensitive body mainly made of substantially annular ceramics incorporated in a state where a housing screw section of the tool penetrates, and a washer that is tightly disposed on the upper surface and the bottom of the pressure sensitive body via an insulator and has Young's modulus of 70-220 GPa. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

本発明は、内燃機関用圧力センサに関するものである。   The present invention relates to a pressure sensor for an internal combustion engine.

近年、燃費や排ガスの規制を受けて自動車用センサの多様化が進んできており、高温や高圧に耐えうるセンサが求められている。この中の一つにエンジンのシリンダ内圧を計測する内燃機関用圧力センサである筒内圧センサがあり、例えば特許文献１にはエンジンの点火プラグとシリンダヘッドの間に取り付けて間接的に筒内圧を計測する座金式の筒内圧センサが記載されている（特許文献１）。この筒内圧センサでは、センサが直接火炎に接することはないが、それでも３００℃程度の高温に耐えられることが要求される。そして、現在主流である半導体圧力センサはシリコン単結晶を圧力検出媒体、いわゆる感圧体として使用し、加圧時にシリコンの電気抵抗が変化する現象を使用して圧力を検出しているが、その温度特性のために１５０℃以上の環境で使用することは困難であった。   In recent years, automobile sensors have been diversified in response to regulations on fuel consumption and exhaust gas, and sensors that can withstand high temperatures and high pressures are required. One of these is an in-cylinder pressure sensor that is a pressure sensor for an internal combustion engine that measures the cylinder internal pressure of the engine. For example, Patent Literature 1 is attached between an engine spark plug and a cylinder head to indirectly increase the in-cylinder pressure. A washer type in-cylinder pressure sensor to be measured is described (Patent Document 1). In this in-cylinder pressure sensor, the sensor does not directly contact the flame, but it is still required to withstand a high temperature of about 300 ° C. The mainstream semiconductor pressure sensor uses a silicon single crystal as a pressure detection medium, a so-called pressure sensitive body, and detects the pressure using a phenomenon in which the electrical resistance of silicon changes during pressurization. Due to temperature characteristics, it was difficult to use in an environment of 150 ° C. or higher.

この問題を解決するために、３００℃以上の高温下においても使用可能である圧力センサとしてＳｉＣに窒素をドープした材料や、Ｓｉ_３Ｎ_４に導電性物質をドープした材料等、セラミックスで構成された感圧体を有する圧力センサが研究されている（非特許文献１、特許文献２）。これらの材料は３００℃以上の高温でも化学的で安定であり、機械強度も高く、高温・高圧下においても圧力を検出することができる。 In order to solve this problem, as a pressure sensor that can be used even at a high temperature of 300 ° C. or higher, it is composed of ceramics such as a material in which SiC is doped with nitrogen, or a material in which Si ₃ N ₄ is doped with a conductive material. A pressure sensor having a pressure sensitive body has been studied (Non-patent Document 1, Patent Document 2). These materials are chemically stable at high temperatures of 300 ° C. or higher, have high mechanical strength, and can detect pressure even at high temperatures and high pressures.

しかしながら、セラミックスは金属のような延性を持った材料とは違い、材料強度以上の応力が加わると脆性破壊しやすいという性質を有している。そして、シリンダヘッドに取り付けるため規定の締め付けトルクで点火プラグを締め付けると、点火プラグのハウジング座面とシリンダヘッドの取付面との間に挟みこまれた圧力センサには８０ＭＰａ以上の高圧が加わる。   However, unlike materials having ductility such as metals, ceramics have the property of being susceptible to brittle fracture when stress exceeding the material strength is applied. When the spark plug is tightened with a specified tightening torque for mounting on the cylinder head, a high pressure of 80 MPa or more is applied to the pressure sensor sandwiched between the housing seat surface of the spark plug and the mounting surface of the cylinder head.

ここで、上記のセラミックスで構成された感圧体は機械的強度が高く、組み付け時に加わる圧縮応力には充分に耐えることは出来る。しかしながら、感圧体が接触するシリンダヘッドの取付面や点火プラグのハウジング座面は、通常微小な凹凸があり平面度が悪い。そのため、実際に、非特許文献１や特許文献２の圧力センサをシリンダヘッドに組み付けると、当該凹凸により感圧体には応力が集中し、破壊してしまうといった問題があった。さらに、組付時のみならず、エンジンの駆動により当該感圧体に繰返応力が作用するとこの問題は顕著となる。   Here, the pressure-sensitive body made of the above ceramics has high mechanical strength and can sufficiently withstand the compressive stress applied during assembly. However, the mounting surface of the cylinder head and the housing seat surface of the spark plug, which are in contact with the pressure sensitive body, usually have minute irregularities and poor flatness. Therefore, when the pressure sensor of Non-Patent Document 1 or Patent Document 2 is actually assembled to the cylinder head, there is a problem that stress is concentrated on the pressure-sensitive body due to the unevenness and the pressure sensor is destroyed. Furthermore, this problem becomes significant when repeated stress acts on the pressure sensitive body not only during assembly but also by driving the engine.

実開平５-０４５５４２号公報Japanese Utility Model Publication No. 5-045542 特開平１１-２０１８３６号公報JP 11-201836 A 「粉体および粉末冶金」第５１巻第５号"Powder and powder metallurgy" Vol. 51, No. 5

本発明は、上記従来の問題を鑑みてなされたものであり、セラミックスで構成された感圧体を有する内燃機関用圧力センサにおいて、それらを内燃機関に組み付けるとき又はそれらを使用するときに、感圧体の破壊を解消できる信頼性の高い内燃機関用圧力センサを提供することを目的としている。   The present invention has been made in view of the above-described conventional problems. In a pressure sensor for an internal combustion engine having a pressure-sensitive body made of ceramics, the sensor is used when the sensor is assembled to or used in an internal combustion engine. An object of the present invention is to provide a highly reliable pressure sensor for an internal combustion engine that can eliminate the destruction of the pressure body.

上記課題を解決する第一の発明は、内燃機関に取り付けられた器具に組み込まれ当該内燃機関のシリンダ内の圧力を検出する内燃機関用圧力センサであって、前記器具のハウジング座面と当該器具が取り付けられた前記内燃機関の取付面との間に、前記器具のハウジング螺子部が貫通する状態で組み込まれた略円環状のセラミックスを主体としてなる感圧体と、絶縁体を介して前記感圧体の上面と底面に密接して設けられヤング率が７０〜２２０ＧＰaである座金とを有する内燃機関用圧力センサである。器具のハウジング座面及び内燃機関の取付面が接触する感圧体の上面と底面にヤング率が７０〜２２０ＧＰaである座金を設けることによって、器具のハウジング座面及び内燃機関の取付面の微小な凹凸を座金が変形することによって吸収する。その結果、感圧体の上面及び底面には面方向に一様に圧力が加わり、応力集中を防ぐことができ、応力集中による組付け時又は使用時における感圧体の破壊を防止することができる。ここで、座金のヤング率が７０ＧＰa以下の場合には、座金が変形しやすく内燃機関に組付けることができなかったり、内燃機関を介して伝播される圧力波を座金で吸収してしまい圧力の測定精度が劣化するので好ましくない。一方、座金のヤング率が２２０ＧＰaよりも大きい場合には、座金が変形し難いため、器具のハウジング座面及び内燃機関の取付面の微小な凹凸を吸収できず、感圧体に応力が集中して破壊し易いので好ましくない。なお、座金の厚みは厚いほど応力集中を防ぐ効果が高いが、取り付けスペースの観点から２．０ｍｍ以下であることが望ましい。   A first invention for solving the above-described problems is a pressure sensor for an internal combustion engine that is incorporated in a tool attached to the internal combustion engine and detects a pressure in a cylinder of the internal combustion engine, and includes a housing seat surface of the tool and the tool. Between the mounting surface of the internal combustion engine to which the housing is mounted, a pressure-sensitive body mainly composed of a substantially annular ceramic incorporated in a state in which the housing screw portion of the instrument penetrates, and the sensitivity through the insulator. This is a pressure sensor for an internal combustion engine having a washer having a Young's modulus of 70 to 220 GPa provided in close contact with the top and bottom surfaces of the pressure body. By providing washers having a Young's modulus of 70 to 220 GPa on the top and bottom surfaces of the pressure-sensitive body with which the housing seat surface of the instrument and the mounting surface of the internal combustion engine are in contact, a minute amount of the housing seat surface of the instrument and the mounting surface of the internal combustion engine is obtained. The unevenness is absorbed by the deformation of the washer. As a result, pressure is uniformly applied to the top and bottom surfaces of the pressure sensitive body to prevent stress concentration, and the pressure sensitive body can be prevented from being destroyed during assembly or use due to stress concentration. it can. Here, when the Young's modulus of the washer is 70 GPa or less, the washer is easily deformed and cannot be assembled to the internal combustion engine, or the pressure wave propagated through the internal combustion engine is absorbed by the washer. Since measurement accuracy deteriorates, it is not preferable. On the other hand, when the Young's modulus of the washer is larger than 220 GPa, the washer is difficult to deform, so that minute unevenness on the housing seat surface of the instrument and the mounting surface of the internal combustion engine cannot be absorbed, and stress is concentrated on the pressure sensitive body. It is not preferable because it is easy to break. In addition, although the effect which prevents stress concentration is so high that the thickness of a washer is thick, it is desirable that it is 2.0 mm or less from a viewpoint of attachment space.

なお、前記絶縁体を介し感圧体と座金とが一体化されていることが望ましい。圧力検出素子と座金とが一体化されていることにより、組み付け時の座金及び感圧体の位置調整が不要となるばかりか、座金の落下を防止することができる。   It is desirable that the pressure sensitive body and the washer are integrated through the insulator. Since the pressure detection element and the washer are integrated, it is not necessary to adjust the position of the washer and the pressure sensitive body during assembly, and the washer can be prevented from falling.

さらに、前記感圧体の上面と底面には電極部が形成されていることが望ましい。座金を設けると内燃機関を介して伝播される圧力波を座金が吸収するため、座金を用いない場合と比べ感度が低下することがある。一方、感圧体の上面と底面に電極部を形成すると感圧体と電極部の接触面積が増加するため、電気的ノイズが低減され、高い感度を得ることができ、座金を用いたことによる感度の低下を補うことができる。なお、当該電極部は感圧体の上面と下面のほぼ全面に形成されていることが好ましい。   Furthermore, it is desirable that electrode portions are formed on the top and bottom surfaces of the pressure sensitive body. When the washer is provided, the pressure wave propagated through the internal combustion engine is absorbed by the washer, so the sensitivity may be lower than when the washer is not used. On the other hand, when the electrode parts are formed on the top and bottom surfaces of the pressure sensitive body, the contact area between the pressure sensitive body and the electrode part increases, so that electrical noise can be reduced and high sensitivity can be obtained. The decrease in sensitivity can be compensated. In addition, it is preferable that the said electrode part is formed in the substantially whole surface of the upper surface and lower surface of a pressure sensitive body.

さらに、上記内燃機関用圧力センサにおいて、セラミックスからなる第１の粒子を主体とした母材中に前記第１の粒子とは導電性が異なるセラミックスからなる第２の粒子が分散し、前記第１の粒子と第２の粒子との加圧による接触状態の変化により電気抵抗が変化する特性を有する感圧体を備えていることが望ましい。かかる感圧体によれば、感圧体に圧力が作用していない又は圧力が低い状態に対し、作用する圧力が増加した状態では、第１の粒子と前記第１の粒子とは導電性が異なる第２の粒子との接触面積が増加するなど両者の接触状態が変化する。この作用する圧力に応じた接触状態の変化により第１の粒子と第２の粒子の界面の接触抵抗が変化し、その結果、作用する圧力に応じて感圧体の電気抵抗が変化する。このように、上記感圧体が組み込まれた内燃機関用圧力センサでは導電性粒子等のピエゾ抵抗効果を利用するのではなく、第１の粒子と前記第１の粒子とは導電性の異なる第２の導電性粒子との接触界面における接触状態の変化、具体的に言えば接触抵抗の変化を利用して圧力を検出するので、従来のピエゾ抵抗効果を利用するものに比べて第１の粒子又は第２の粒子を広い範囲から選択することができ、仕様に対応した特性を有する内燃機関用圧力センサを製造することができ、低コストな内燃機関用圧力センサを得ることができる。その一方で、上記構成のセンサは第１の粒子と第２の粒子との間に空孔が形成されており、圧力が作用するとその空孔を起点としてクラックが伸展し、破壊しやすい。そこで、上記座金を用いることにより応力集中による過大な圧力が加わることを防ぐことができ、感圧体の破壊を防止できる。   Further, in the pressure sensor for an internal combustion engine, second particles made of ceramics having a conductivity different from that of the first particles are dispersed in a base material mainly composed of the first particles made of ceramics. It is desirable to provide a pressure-sensitive body having a characteristic that the electrical resistance changes due to a change in the contact state caused by pressurization of the particles and the second particles. According to such a pressure-sensitive body, the first particle and the first particle have electrical conductivity in a state in which the pressure acting on the pressure-sensitive body is not applied or low, while the pressure applied is increased. The contact state between the two changes, for example, the contact area with different second particles increases. The contact resistance at the interface between the first particle and the second particle changes due to the change in the contact state according to the acting pressure, and as a result, the electrical resistance of the pressure sensitive body changes according to the acting pressure. Thus, the pressure sensor for an internal combustion engine in which the pressure sensitive body is incorporated does not use the piezoresistance effect of conductive particles or the like, but the first particles and the first particles have different conductivity. Since the pressure is detected by using the change in the contact state at the contact interface with the two conductive particles, specifically, the change in the contact resistance, the first particle compared to the conventional one using the piezoresistance effect. Alternatively, the second particle can be selected from a wide range, an internal combustion engine pressure sensor having characteristics corresponding to the specifications can be manufactured, and a low-cost internal combustion engine pressure sensor can be obtained. On the other hand, in the sensor having the above-described structure, holes are formed between the first particles and the second particles, and when pressure is applied, cracks extend from the holes and are easily broken. Therefore, by using the washer, it is possible to prevent an excessive pressure from being applied due to stress concentration and to prevent the pressure sensitive body from being destroyed.

上記説明のように、本発明の内燃機関用圧力センサによれば、それを内燃機関に組み付けるとき又は使用するときに座金を介して感圧体が組付けられるので、感圧体の破壊を解消できる信頼性の高い内燃機関用圧力センサを具現することができる。   As described above, according to the pressure sensor for an internal combustion engine of the present invention, when the pressure sensor is assembled to the internal combustion engine or used, the pressure sensitive body is assembled via the washer, so that the destruction of the pressure sensitive body is eliminated. A highly reliable pressure sensor for an internal combustion engine can be realized.

以下本発明の実施態様について図面を参照しつつ説明する。図１は本発明の第１実施態様の内燃機関用圧力センサ（以下圧力センサと記載する場合がある。）の概略構成を示す斜視図、図２は図１の圧力センサの製造方法を説明する図、図３は図１の圧力センサが内燃機関であるエンジンに取り付けられた状態を示す図、図４は本発明の第２実施態様の圧力センサの概略構成を示す斜視図、図５は本発明の第３実施態様の圧力センサの概略構成を示す斜視図である。なお、以下記載する実施態様及び実施例ではガソリンエンジンに装着される点火プラグのハウジング螺子部に組み込まれる圧力センサを主体として本発明を説明しているが、当該実施態様及び実施例に本発明は限定されず、発明として同一の範囲は本発明に含まれる。   Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing a schematic configuration of a pressure sensor for an internal combustion engine (hereinafter sometimes referred to as a pressure sensor) according to a first embodiment of the present invention, and FIG. 2 illustrates a method for manufacturing the pressure sensor of FIG. 3 is a diagram showing a state in which the pressure sensor of FIG. 1 is attached to an engine which is an internal combustion engine, FIG. 4 is a perspective view showing a schematic configuration of a pressure sensor according to a second embodiment of the present invention, and FIG. It is a perspective view which shows schematic structure of the pressure sensor of 3rd embodiment of invention. In the embodiments and examples described below, the present invention is mainly described with reference to a pressure sensor incorporated in a housing screw portion of a spark plug attached to a gasoline engine. However, the present invention is not limited to the embodiments and examples. Without being limited, the same scope as the invention is included in the present invention.

（第１態様）
本発明の第１実施態様である圧力センサ１について図１に基づき説明する。符号１１は、セラミックスで構成された感圧体である。感圧体１１は、円環の一部を切り欠いて形成した分離部１３を有する、略Ｃ環状をなしている。感圧体１１は、セラミックスからなる第１の粒子を主体とした母材中に前記第１の粒子とは導電性が異なるセラミックスからなる第２の粒子を分散させたものであり、第１の粒子と第２の粒子との加圧による接触状態の変化により電気抵抗が変化する特性を有している。この第１の粒子としては、炭化珪素、窒化珪素、サイアロン、窒化アルミニウム、シリカ、アルミナ、ムライト、ジルコニア、マグネシア、コージェライト、アルミニウムチタネートのいずれか一種またはそれらの二種以上を含むセラミックスを選択することができる。また、第２の粒子としては、カーボン、炭化珪素、酸化錫、酸化インジウム、酸化銀、酸化銅、IV、V、VI族の遷移金属元素の炭化物、窒化物、ホウ化物、珪化物、酸化物及びこれらの化合物で構成される複合化合物の一種、または、それらの二種以上を含むものを選択することができる。導電性が高い材料から第２の粒子を選択することにより、第１の粒子と第２の粒子の差が大きくなり、加圧時に接触抵抗が変化した際の電気抵抗変化率が大きくすることができる。その結果、より圧力感度の高い圧力センサを構成することができる。 (First aspect)
A pressure sensor 1 according to a first embodiment of the present invention will be described with reference to FIG. Reference numeral 11 denotes a pressure sensitive body made of ceramics. The pressure sensitive body 11 has a substantially C ring shape having a separation portion 13 formed by cutting out a part of a ring. The pressure-sensitive body 11 is obtained by dispersing second particles made of ceramics having conductivity different from that of the first particles in a base material mainly composed of first particles made of ceramics. It has the characteristic that the electrical resistance changes due to the change in the contact state caused by the pressurization of the particles and the second particles. As the first particles, silicon carbide, silicon nitride, sialon, aluminum nitride, silica, alumina, mullite, zirconia, magnesia, cordierite, aluminum titanate or a ceramic containing two or more thereof is selected. be able to. Second particles include carbon, silicon carbide, tin oxide, indium oxide, silver oxide, copper oxide, carbides, nitrides, borides, silicides, oxides of group IV, V, and VI transition metal elements. In addition, one of complex compounds composed of these compounds, or one containing two or more of them can be selected. By selecting the second particles from a material having high conductivity, the difference between the first particles and the second particles increases, and the rate of change in electrical resistance when the contact resistance changes during pressurization is increased. it can. As a result, a pressure sensor with higher pressure sensitivity can be configured.

感圧体１１としては上記に限定されず圧力に対して電気抵抗が変化するものであれば使用することができるが、本発明の対象となる内燃機関に適用するためには高温においても特性の変化の少ないセラミックスで構成された感圧体１１である必要がある。したがって、ＳｉＣに窒素をドープした材料や、Ｓｉ_３Ｎ_４に導電性物質をドープした材料等ピエゾ抵抗効果を有するセラミックスから構成された感圧体を圧力センサに組み込むことができる。 The pressure-sensitive member 11 is not limited to the above and can be used as long as its electric resistance changes with respect to the pressure. However, the pressure-sensitive member 11 has characteristics even at high temperatures in order to be applied to the internal combustion engine to which the present invention is applied. It is necessary that the pressure sensitive body 11 is composed of ceramics with little change. Therefore, a pressure sensor made of ceramics having a piezoresistance effect, such as a material in which SiC is doped with nitrogen or a material in which Si ₃ N ₄ is doped with a conductive material, can be incorporated into the pressure sensor.

符号１２は、図２にも示すように、感圧体１１の分離部１３の両端の上面及び底面に形成された凹部であり、当該凹部１２にはリード線１４が装着される。なお、リード線１４は、ロウ材を介して当該凹部１２に固定されている。   As shown in FIG. 2, reference numeral 12 denotes concave portions formed on the upper and bottom surfaces of both ends of the separation portion 13 of the pressure sensitive body 11, and lead wires 14 are attached to the concave portion 12. The lead wire 14 is fixed to the concave portion 12 via a brazing material.

符号１５は、感圧体１１の上面及び底面に固定された略円環状の絶縁体である。この絶縁体は、電気的絶縁性を有するものであれば例えば樹脂等で構成してもよいが、検出装置１に負荷される締付圧力に対応するという点からはアルミナやジルコニア等のセラミックスを採用することが好ましい。   Reference numeral 15 denotes a substantially annular insulator fixed to the upper surface and the bottom surface of the pressure sensitive body 11. The insulator may be made of, for example, a resin as long as it has electrical insulation, but ceramics such as alumina and zirconia are used from the viewpoint of corresponding to the clamping pressure applied to the detection device 1. It is preferable to adopt.

符号１６は、上記絶縁体１５を介して感圧体１１に密接される所定のヤング率を有する金属製の座金である。座金１６はヤング率が７０〜２２０ＧＰａであるもの、例えばアルミニウム、真鍮、銅、鋼及びそれらの合金等を主体としたもの適用することができる。   Reference numeral 16 denotes a metal washer having a predetermined Young's modulus that is in close contact with the pressure-sensitive body 11 through the insulator 15. The washer 16 having a Young's modulus of 70 to 220 GPa, for example, aluminum, brass, copper, steel and alloys thereof can be used.

第１態様の圧力センサ１では、上記感圧体１１、絶縁体１５及び座金１６はそれぞれ別体として構成されている。そして、これらは図３に示すように、ガソリンエンジンのシリンダヘッド２００に装着される点火プラグ１００のハウジング螺子部１０２が貫通する状態で、座金１６、絶縁体１５、感圧体１１、絶縁体１５、座金１６の順序でハウジング座面１０１とシリンダヘッド２００の取付面２０１の間に挟み込まれ、所定の締め付けトルクで固定される。   In the pressure sensor 1 of the first aspect, the pressure-sensitive body 11, the insulator 15, and the washer 16 are configured as separate bodies. As shown in FIG. 3, these are the washer 16, the insulator 15, the pressure sensitive body 11, and the insulator 15 with the housing screw portion 102 of the spark plug 100 attached to the cylinder head 200 of the gasoline engine penetrating therethrough. The washer 16 is sandwiched between the housing seat surface 101 and the mounting surface 201 of the cylinder head 200 in the order, and fixed with a predetermined tightening torque.

上記圧力センサ１の実施例１について以下説明する。   A first embodiment of the pressure sensor 1 will be described below.

(実施例１)
第１の粒子として絶縁性セラミックスであるα‐Ｓｉ_３Ｎ_４粉末（宇部興産製、型番：E１０、平均粒径０．５μｍ）を３８．０ｇ、第２の粒子として導電性のＣ粉末（高純度化学製、型番：ＣＣＥ０１ＰＡ）を３．０ｇ、焼結助剤としてＡｌ_２Ｏ_３（高純度化学製、型番：ＡＬＯ０５ＰＡ）を６．０ｇ、Ｙ_２Ｏ_３（高純度化学製、型番：ＹＹＯ０１ＰＡ）を３．０ｇ秤量し、エタノール中でボールミル混合を２４時間行った。得られたスラリーを乾燥後、Φ３６ｍｍの金型を用い、１００ＭＰａの圧力を加えて、Φ３６ｍｍ、厚さ１０ｍｍの成形体を作製し、次いで、焼結温度１６５０℃、保持時間２時間、加圧力３０ＭＰａ、窒素雰囲気中で、成形体をホットプレスで焼結した。 (Example 1)
As the first particles, 38.0 g of α-Si ₃ N ₄ powder (made by Ube Industries, model number: E10, average particle size 0.5 μm), which is an insulating ceramic, is used as the second particles. 3.0 g of purity chemical, model number: CCE01PA), 6.0 g of Al ₂ O ₃ (made by high purity chemical, model number: ALO05PA) as a sintering aid, Y ₂ O ₃ (made by high purity chemical, model number: YYO01PA) ) Was weighed and ball mill mixed in ethanol for 24 hours. After drying the obtained slurry, using a Φ36 mm mold, a pressure of 100 MPa was applied to produce a molded body having a Φ36 mm and a thickness of 10 mm, and then a sintering temperature of 1650 ° C., a holding time of 2 hours, and an applied pressure of 30 MPa. In a nitrogen atmosphere, the compact was sintered with a hot press.

得られた焼結体から、図２に示すように、外径Φ１９.０ｍｍ、内径Φ１４．０ｍｍ、厚さ２．０ｍｍの円環形状体を切り出し、その円周部の一箇所を０．５ｍｍ幅で切断して分離部１３を形成し、略Ｃ形状をなす感圧体１１を得た。そして、図２（ａ）に示すように、分離部１３の相対する面に０．６ｍｍ×０．６ｍｍ×２．５ｍｍの切込みを入れて凹部１２を形成し、図２（ｂ）に示すように、Φ０．６ｍｍのＣｕリード線１４を凹部１２にロウ材を塗布してそれぞれ配設し、７６５℃、真空度１０^−１Ｐａ以下、加圧力０.１ＭＰaの条件で１５分キープしてロウ付けを行い、感圧体１１とリード線１４とを接合した。次いで、図１に示すように、感圧体１１の上部及び底部に、外径Φ１９.０ｍｍ、内径Φ１４．０ｍｍ、厚さ１．０ｍｍのアルミナからなる円環状の絶縁体１５を配設し、さらにその上部及び底部に外径Φ１９.０ｍｍ、内径Φ１４．０ｍｍ、厚さ２.０ｍｍのＡｌ製の座金１６を配設し、圧力センサ１を得た。なお、上記ロウ材としては、田中貴金属製のＴＫＣ―５９１ペーストを使用した（以下の実施例及び比較例にて同じ）。 As shown in FIG. 2, an annular shaped body having an outer diameter of Φ19.0 mm, an inner diameter of Φ14.0 mm, and a thickness of 2.0 mm was cut out from the obtained sintered body, and one part of the circumference thereof was 0.5 mm. The separation part 13 was formed by cutting with a width to obtain a pressure-sensitive body 11 having a substantially C shape. Then, as shown in FIG. 2A, a recess 12 is formed by making a cut of 0.6 mm × 0.6 mm × 2.5 mm in the opposing surface of the separating portion 13, and as shown in FIG. In addition, a Φ0.6 mm Cu lead wire 14 is applied to the recess 12 by applying a brazing material, respectively, and kept for 15 minutes under conditions of 765 ° C., a vacuum of 10 ⁻¹ Pa or less, and a pressure of 0.1 MPa. The pressure sensitive body 11 and the lead wire 14 were joined. Next, as shown in FIG. 1, an annular insulator 15 made of alumina having an outer diameter of Φ19.0 mm, an inner diameter of Φ14.0 mm, and a thickness of 1.0 mm is disposed on the top and bottom of the pressure sensitive body 11. Further, an Al washer 16 having an outer diameter of Φ19.0 mm, an inner diameter of Φ14.0 mm, and a thickness of 2.0 mm was disposed on the top and the bottom, and the pressure sensor 1 was obtained. As the brazing material, TKC-591 paste made by Tanaka Kikinzoku was used (the same applies to the following examples and comparative examples).

図３に示すように、圧力センサ１が、点火プラグ１００（ＮＧＫ製：ＢＰＲ６ＥＳ）のハウジング螺子部１０２を貫通するように、ヤマハ製オートバイＳＲ４００のエンジンのシリンダヘッド２００に組み付けた。この時のプラグの絞めつけトルクは、安全率を考慮し規定の締め付けトルクの２倍の５ｋｇｆ・ｍとした。このときにシリンダヘッド２００の取付面２０１に加わる面圧を感圧フィルム（フジフィルム製：プレスケール高圧用）を用いて計測したところ、約１６０ＭＰaであった。次いで圧力センサ１から取り出したリード線１４を測定回路に接続し、特性を評価した。   As shown in FIG. 3, the pressure sensor 1 was assembled to the cylinder head 200 of the engine of the Yamaha motorcycle SR400 so as to penetrate the housing screw portion 102 of the spark plug 100 (manufactured by NGK: BPR6ES). The tightening torque of the plug at this time was 5 kgf · m, which is twice the specified tightening torque in consideration of the safety factor. The surface pressure applied to the mounting surface 201 of the cylinder head 200 at this time was measured using a pressure-sensitive film (manufactured by Fuji Film: for prescale high pressure), and was about 160 MPa. Next, the lead wire 14 taken out from the pressure sensor 1 was connected to a measurement circuit, and the characteristics were evaluated.

圧力センサ１の特性評価方法について説明する。エンジンを作動させて、得られた圧力センサ１の出力からシリンダの内圧を計測し、アイドリング時の信号出力とノイズの比率（以下ＳＮ比）を算出した。エンジンを１時間連続で作動させた後、圧力センサ１を外して、その感圧体１１のクラックの数を目視にて計測した。（以下の実施例及び比較例で同じ）。得られた結果を表１に示す。ＳＮ比は１１０と高い値が得られた。感圧体１１にクラックは観察されなかった。   A method for evaluating the characteristics of the pressure sensor 1 will be described. The engine was operated, the internal pressure of the cylinder was measured from the output of the obtained pressure sensor 1, and the signal output to noise ratio (hereinafter referred to as SN ratio) during idling was calculated. After the engine was operated continuously for 1 hour, the pressure sensor 1 was removed, and the number of cracks in the pressure sensitive body 11 was visually measured. (The same applies to the following examples and comparative examples). The obtained results are shown in Table 1. A high S / N ratio of 110 was obtained. No cracks were observed in the pressure sensitive body 11.

（第２態様）
本発明の第２態様の圧力センサ２について図４を参照し説明する。なお、図４において、上記第１態様の圧力センサ１と同様な構成要素については同一符号を付し、詳細な説明を省略する。 (Second aspect)
The pressure sensor 2 according to the second aspect of the present invention will be described with reference to FIG. In FIG. 4, the same components as those of the pressure sensor 1 of the first aspect are denoted by the same reference numerals, and detailed description thereof is omitted.

第２態様の圧力センサ２は、座金１６が絶縁体１５を介して感圧体１１と接合されて一体となっている点で第１態様の圧力センサ１と相異し、その他の構成は同一である。なお、絶縁体１５、感圧体１１及び座金１６は、ロウ付け又は耐熱性を有する接着剤などで接合することができる。   The pressure sensor 2 according to the second aspect is different from the pressure sensor 1 according to the first aspect in that the washer 16 is joined to the pressure-sensitive body 11 via the insulator 15, and the other configurations are the same. It is. Note that the insulator 15, the pressure sensitive body 11, and the washer 16 can be joined by brazing or a heat-resistant adhesive.

上記第２態様の圧力センサ２の実施例２〜１３について以下説明する。   Examples 2 to 13 of the pressure sensor 2 of the second aspect will be described below.

（実施例２）
実施例１と同様の方法で感圧体１１を作製した。そして、図２（ａ）に示すように、分離部１３の相対する面に０．６ｍｍ×０．６ｍｍ×２．５ｍｍの切込みを入れて凹部１２を形成し、凹部１２にロウ材を塗布し、Φ０．６ｍｍのＣｕリード線１４を凹部１２に配設し、その上面と底面に外径Φ１９.０ｍｍ、内径Φ１４．０ｍｍ、厚さ１．０ｍｍのアルミナからなる絶縁体１５の凹部１２と接触する部位のみにロウ材を塗布してそれぞれ重ね合わせ、７６５℃、真空度１０^−１Ｐａ以下、加圧力０.１ＭＰaの条件で１５分キープしてロウ付けを行い、感圧体１１、リード線１４及び絶縁体１５を接合した。次いで、さらにその上下に外径Φ１９.０ｍｍ、内径Φ１４．０ｍｍ、厚さ２.０ｍｍのＡｌ製の座金１６を絶縁体１５と接触する全面に耐熱性接着剤セラマボンド（８３５Ｍ）を塗布して重ね合わせ、２００℃、３０分の条件で乾燥させて接合し、圧力センサ２を得た。得られたセンサを実施例１と同様の方法でエンジンに組み付け、特性評価を行った。得られた結果を表１に示す。 (Example 2)
A pressure-sensitive body 11 was produced in the same manner as in Example 1. Then, as shown in FIG. 2A, a recess 12 is formed by making a notch of 0.6 mm × 0.6 mm × 2.5 mm on the opposing surface of the separation portion 13, and a brazing material is applied to the recess 12. A lead wire 14 having a diameter of 0.6 mm is disposed in the concave portion 12, and the upper surface and the bottom surface thereof are in contact with the concave portion 12 of the insulator 15 made of alumina having an outer diameter of Φ19.0 mm, an inner diameter of Φ14.0 mm, and a thickness of 1.0 mm. Apply the brazing material only to the parts to be soldered and superimpose each other, and brazing is performed for 15 minutes under the conditions of 765 ° C., vacuum degree of 10 ⁻¹ Pa or less, and applied pressure of 0.1 MPa, and pressure sensitive body 11 and lead wire 14 and the insulator 15 were joined. Next, an Al washer 16 having an outer diameter of Φ19.0 mm, an inner diameter of Φ14.0 mm, and a thickness of 2.0 mm is applied to the upper and lower surfaces of the insulating layer 15 by applying a heat-resistant adhesive ceramer bond (835M) to the entire surface. In addition, the pressure sensor 2 was obtained by drying and bonding at 200 ° C. for 30 minutes. The obtained sensor was assembled to the engine in the same manner as in Example 1, and the characteristics were evaluated. The obtained results are shown in Table 1.

（実施例３〜６）
表１に示すように、実施例３〜６は、座金の材質を変更した以外は実施例２と同様の方法で圧力センサ２を作製し、特性評価を行った。得られた結果を表１に示す。 (Examples 3 to 6)
As shown in Table 1, in Examples 3 to 6, the pressure sensor 2 was produced by the same method as in Example 2 except that the material of the washer was changed, and the characteristics were evaluated. The obtained results are shown in Table 1.

(実施例７)
第１の粒子として絶縁性セラミックスであるα‐Ｓｉ_３Ｎ_４粉末（宇部興産製、型番：E１０、平均粒径０．５μｍ）を３８．０ｇ、第２の粒子として導電性のＳｉＣ粉末（屋久島電工製、型番：ＳＨ−７）を３．０ｇ、焼結助剤としてＡｌ_２Ｏ_３（高純度化学製、型番：ＡＬＯ０５ＰＡ）を６．０ｇ、Ｙ_２Ｏ_３（高純度化学製、型番：ＹＹＯ０１ＰＡ）を３．０ｇ秤量し、エタノール中でボールミル混合を２４時間行った。得られたスラリーを乾燥後、Φ３６ｍｍの金型を用い、１００ＭＰａの圧力を加えて、Φ３６ｍｍ、厚さ１０ｍｍの成形体を作製し、次いで、焼結温度１６５０℃、保持時間２時間、加圧力３０ＭＰａ、窒素雰囲気中で、成形体をホットプレスで焼結した。得られた焼結体から実施例２と同様の方法で圧力センサ２を作製し、特性評価を行った。得られた結果を表1に示す。 (Example 7)
As the first particles, 38.0 g of α-Si ₃ N ₄ powder (made by Ube Industries, model number: E10, average particle size 0.5 μm), which is an insulating ceramic, and conductive SiC powder (Yakushima) as the second particles 3.0 g of Denko, model number: SH-7), 6.0 g of Al ₂ O ₃ (manufactured by high purity chemical, model number: ALO05PA) as a sintering aid, Y ₂ O ₃ (manufactured by high purity chemical, model number: 3.0 g of YYO01PA) was weighed and ball milled in ethanol for 24 hours. After drying the obtained slurry, using a Φ36 mm mold, a pressure of 100 MPa was applied to produce a molded body having a Φ36 mm and a thickness of 10 mm, and then a sintering temperature of 1650 ° C., a holding time of 2 hours, and an applied pressure of 30 MPa. In a nitrogen atmosphere, the compact was sintered with a hot press. The pressure sensor 2 was produced from the obtained sintered body by the same method as in Example 2, and the characteristics were evaluated. The results obtained are shown in Table 1.

（実施例８〜１０）
第１の粒子として絶縁性セラミックスであるＺｒＯ_２粉末（東ソー製、型番：ＴＺ−３Ｙ−Ｅ、平均粒径０．０７μｍ）を７７．２ｇ、第２の粒子として導電性のＣ粉末（高純度化学製、型番：ＣＣＥ０１ＰＡ）を２．８ｇ秤量し、エタノール中でボールミル混合を２４時間行った。得られたスラリーを乾燥後、Φ３６ｍｍの金型を用い、１００ＭＰａの圧力を加えて、Φ３６ｍｍ、厚さ１０ｍｍの成形体を作製し、次いで、焼結温度１３００℃、保持時間２時間、加圧力３０ＭＰａ、窒素雰囲気中で、成形体をホットプレスで焼結した。得られた焼結体から実施例２と同様の方法で感圧体１１を作製した。その感圧体１１と表１に示すように材質を種々変更した座金１６とを組み合わせた圧力センサ２を作製し、特性評価を行った。得られた結果を表１に示す。 (Examples 8 to 10)
77.2 g of ZrO ₂ powder (made by Tosoh, model number: TZ-3Y-E, average particle size 0.07 μm) as insulating ceramics as the first particles, conductive C powder (high purity) as the second particles 2.8 g of Chemical Model No .: CCE01PA) was weighed and ball milled in ethanol for 24 hours. After drying the obtained slurry, using a Φ36 mm mold, a pressure of 100 MPa was applied to produce a molded body having a Φ36 mm and a thickness of 10 mm, and then a sintering temperature of 1300 ° C., a holding time of 2 hours, and an applied pressure of 30 MPa. In a nitrogen atmosphere, the compact was sintered with a hot press. A pressure sensitive body 11 was produced from the obtained sintered body in the same manner as in Example 2. A pressure sensor 2 was produced by combining the pressure-sensitive body 11 and a washer 16 having various materials changed as shown in Table 1, and the characteristics were evaluated. The obtained results are shown in Table 1.

（実施例１１〜１３）
α-ＳｉＣ粉末（屋久島電工製、型番：ＳＨ−７）を３８．０ｇ、Ｃ粉末（高純度化学製、型番：ＣＣＥ０１ＰＡ）を３．０ｇ、焼結助剤としてＡｌ_２Ｏ_３（高純度化学製、型番：ＡＬＯ０５ＰＡ）を６．０ｇ、Ｙ_２Ｏ_３（高純度化学製、型番：ＹＹＯ０１ＰＡ）を３．０ｇ秤量し、エタノール中でボールミル混合を行った。混合粉を乾燥した後、Φ３６ｍｍ、厚さ１０ｍｍの成形体を作成した。その成形体を、ホットプレスにて、焼結温度１８００℃、保持時間２時間、加圧力５０ＭＰａ、窒素雰囲気中で焼結した。得られた焼結体から実施例２と同様の方法で感圧体１１を作製した。その感圧体１１と表１に示すように材質を種々変更した座金１６とを組み合わせた圧力検出センサ２を作製し、特性評価を行った。得られた結果を表１に示す。 (Examples 11 to 13)
38.0 g of α-SiC powder (manufactured by Yakushima Denko, model number: SH-7), 3.0 g of C powder (manufactured by high purity chemical, model number: CCE01PA), Al ₂ O ₃ (high purity chemical) as a sintering aid Made, model number: ALO05PA) and 3.0 g of Y ₂ O ₃ (manufactured by Koyo Chemical Co., model number: YYO01PA) were weighed and mixed in a ball mill in ethanol. After the mixed powder was dried, a molded body having a diameter of 36 mm and a thickness of 10 mm was prepared. The compact was sintered in a nitrogen atmosphere in a hot press at a sintering temperature of 1800 ° C., a holding time of 2 hours, a pressing force of 50 MPa. A pressure sensitive body 11 was produced from the obtained sintered body in the same manner as in Example 2. A pressure detection sensor 2 was produced by combining the pressure-sensitive body 11 and a washer 16 having various materials changed as shown in Table 1, and the characteristics were evaluated. The obtained results are shown in Table 1.

（第３態様）
本発明の第３態様の圧力センサ３について図５を参照し説明する。なお、図５において、上記第１態様の圧力センサ１と同様な構成要素については同一符号を付し、詳細な説明を省略する。 (Third aspect)
A pressure sensor 3 according to a third aspect of the present invention will be described with reference to FIG. In FIG. 5, the same components as those of the pressure sensor 1 of the first aspect are denoted by the same reference numerals, and detailed description thereof is omitted.

第３態様の圧力センサ３は、感圧体３１の上面と底面に電極部３７が形成されており、その電極部３７からリード線３４が取り出されている点で上記第１態様又は第２態様の圧力センサ１，２と相異し、その他の構成は同一である。ここで、電極部３７としては、銅又は銀等の導電性を有する金属を使用することができる。電極部３７として金属片を使用する場合には、ロウ付け又は導電性接着剤などで感圧体３１の上面と底面に金属片を接合することにより電極部３７を形成することができる。また、感圧体３１の上面及び底面に銀ペースト等を塗布し、焼成して電極部３７を形成するようにしてもよい。   The pressure sensor 3 according to the third aspect has the electrode part 37 formed on the upper surface and the bottom surface of the pressure-sensitive body 31, and the lead wire 34 is taken out from the electrode part 37. Unlike the pressure sensors 1 and 2, the other configurations are the same. Here, as the electrode part 37, the metal which has electroconductivity, such as copper or silver, can be used. When a metal piece is used as the electrode part 37, the electrode part 37 can be formed by joining the metal piece to the upper surface and the bottom surface of the pressure-sensitive body 31 with brazing or a conductive adhesive. Alternatively, the electrode part 37 may be formed by applying a silver paste or the like to the top and bottom surfaces of the pressure-sensitive body 31 and baking it.

上記第３態様の圧力センサ３の実施例１４〜１６について以下説明する。   Examples 14 to 16 of the pressure sensor 3 of the third aspect will be described below.

（実施例１４〜１６）
実施例１と同様の方法で焼結体を作成し、得られた焼結体から、外径Φ１９.０ｍｍ、内径Φ１４．０ｍｍ、厚さ２．０ｍｍの円環形状体を切り出し感圧体３１を作製した。次いで、感圧体３１の上面と底面に外径Φ１９.０ｍｍ、内径Φ１４．０ｍｍ、厚さ０．５ｍｍの両面にロウ材を塗布した円環状のＣｕ片を配設して電極部３７を形成し、さらに、各電極部３７の上面と底面にアルミナからなる絶縁体１５をそれぞれ配設し、さらに絶縁体１５の上面と底面にロウ材を塗布してＡｌ製の座金１６をそれぞれ配設し、７６５℃、真空度１０^−１Ｐａ以下、加圧力０.１ＭＰaの条件で１５分キープしてロウ付けを行い、感圧体３１、電極部３７、絶縁体１５及び座金１６を接合した。そして電極部３７にΦ０．３ｍｍのＣｕ線３４をスポット溶接で接合し、図５に示した構造の圧力センサ３を得た。得られた圧力センサ３の特性評価を行った。なお、実施例１４〜１６で使用した座金１６は、表１に示すように３種である。得られた結果を表１に示す。 (Examples 14 to 16)
A sintered body was prepared in the same manner as in Example 1. From the obtained sintered body, a ring-shaped body having an outer diameter of Φ19.0 mm, an inner diameter of Φ14.0 mm, and a thickness of 2.0 mm was cut out. Was made. Next, an electrode part 37 is formed by arranging annular Cu pieces each coated with a brazing material on both sides of an outer diameter Φ19.0 mm, an inner diameter Φ14.0 mm, and a thickness 0.5 mm on the top and bottom surfaces of the pressure-sensitive body 31. Furthermore, an insulator 15 made of alumina is disposed on the top and bottom surfaces of each electrode portion 37, and a brazing material is applied to the top and bottom surfaces of the insulator 15, and an aluminum washer 16 is disposed. The pressure sensitive body 31, the electrode part 37, the insulator 15 and the washer 16 were joined by keeping brazing for 15 minutes under the conditions of 765 ° C., a vacuum of 10 ⁻¹ Pa or less, and a pressure of 0.1 MPa. Then, a Cu wire 34 having a diameter of 0.3 mm was joined to the electrode portion 37 by spot welding to obtain the pressure sensor 3 having the structure shown in FIG. The characteristics of the obtained pressure sensor 3 were evaluated. In addition, as shown in Table 1, there are three types of washers 16 used in Examples 14 to 16. The obtained results are shown in Table 1.

（比較例１〜６）
比較例１〜６は表１に示すように、座金をヤング率７０ＧＰa未満の材質と、２２０ＧＰaより高い材質を用いた例である。その他感圧体の製造方法や、圧力センサの構成、特性評価の方法は基本的に実施例２と同じである。使用した座金の種類と得られた結果を表１に示した。 (Comparative Examples 1-6)
As shown in Table 1, Comparative Examples 1 to 6 are examples in which the washer is made of a material having a Young's modulus of less than 70 GPa and a material having a higher than 220 GPa. Other methods for manufacturing the pressure-sensitive body, the configuration of the pressure sensor, and the method for evaluating the characteristics are basically the same as those in the second embodiment. Table 1 shows the types of washers used and the results obtained.

実施例１〜１６では、座金のヤング率が７０〜２２０ＧＰaの範囲であれば、組付け及び使用の際に感圧体が破壊することなく、ＳＮ比が１００以上の高い感度が得られる圧力センサを実現できることが判る。また、実施例１４〜１６では、感圧体に電極部を設けることによりＳＮ比がさらに改善できることが判る。比較例１〜３では座金のヤング率が７０ＧＰa以下であると、組み付け時の感圧体の破壊は防止できるが、座金が圧力を吸収することによりＳＮ比が１００以下となり高い感度が得られないことが判る。また、比較例４〜６では座金のヤング率が２５０以上になると、座金が硬すぎて感圧体の破壊を防げないことが判る。さらに実施例１〜７、８〜１０、１１〜１３から、座金のヤング率が７０〜２２０ＧＰaの範囲であれば感圧体の材質を変えても、ＳＮ比が１００以上の感度の高い圧力検出センサが得られることが判る。   In Examples 1 to 16, if the Young's modulus of the washer is in the range of 70 to 220 GPa, the pressure sensor can obtain a high sensitivity with an S / N ratio of 100 or more without destroying the pressure sensitive body during assembly and use. Can be realized. Moreover, in Examples 14-16, it turns out that SN ratio can further be improved by providing an electrode part in a pressure sensitive body. In Comparative Examples 1 to 3, if the Young's modulus of the washer is 70 GPa or less, the pressure-sensitive body can be prevented from being destroyed during assembly, but the SN ratio becomes 100 or less and high sensitivity cannot be obtained by absorbing the pressure of the washer. I understand that. In Comparative Examples 4 to 6, it can be seen that when the Young's modulus of the washer is 250 or more, the washer is too hard to prevent the pressure-sensitive body from being destroyed. Furthermore, from Examples 1 to 7, 8 to 10, and 11 to 13, if the Young's modulus of the washer is in the range of 70 to 220 GPa, even if the material of the pressure sensitive body is changed, the S / N ratio is 100 or more and highly sensitive pressure detection. It can be seen that a sensor is obtained.

本発明の第１態様の内燃機関用圧力センサの概略構成を示す斜視図である。It is a perspective view showing a schematic structure of a pressure sensor for internal combustion engines of the 1st mode of the present invention. 図１の内燃機関用圧力センサの製造方法を示す斜視図である。It is a perspective view which shows the manufacturing method of the pressure sensor for internal combustion engines of FIG. 図１の内燃機関用圧力センサが内燃機関に取り付けられた状態を示す斜視図である。FIG. 2 is a perspective view showing a state in which the internal combustion engine pressure sensor of FIG. 1 is attached to the internal combustion engine. 本発明の第２実施態様の内燃機関用圧力センサの概略構成を示す斜視図である。It is a perspective view which shows schematic structure of the pressure sensor for internal combustion engines of the 2nd embodiment of this invention. 本発明の第３実施態様の内燃機関用圧力センサの概略構成を示す斜視図である。It is a perspective view which shows schematic structure of the pressure sensor for internal combustion engines of the 3rd embodiment of this invention.

符号の説明Explanation of symbols

１（２、３） 内燃機関用圧力センサ
１１（３１） 感圧体
１２ 凹部
１３ 分離部
１４ （３４） リード線
１５ 絶縁体
１６ 座金
３７ 電極部
１００ 点火プラグ
１０１ ハウジング座面
１０２ ハウジング螺子部
２００ シリンダヘッド
２０１ 取付面
DESCRIPTION OF SYMBOLS 1 (2, 3) Pressure sensor for internal combustion engines 11 (31) Pressure sensitive body 12 Recessed part 13 Separating part 14 (34) Lead wire 15 Insulator 16 Washer 37 Electrode part 100 Spark plug 101 Housing seat surface 102 Housing screw part 200 Cylinder Head 201 Mounting surface

Claims (4)

内燃機関に取り付けられた器具に組み込まれ当該内燃機関のシリンダ内の圧力を検出する圧力センサであって、前記器具のハウジング座面と当該器具が取り付けられた前記内燃機関の取付面との間に、前記器具のハウジング螺子部が貫通する状態で組み込まれた略円環状のセラミックスを主体としてなる感圧体と、絶縁体を介して前記感圧体の上面と底面に密接して設けられたヤング率が７０〜２２０ＧＰaである座金とを有する内燃機関用圧力センサ。 A pressure sensor incorporated in an instrument attached to an internal combustion engine to detect a pressure in a cylinder of the internal combustion engine, between a housing seat surface of the instrument and an attachment surface of the internal combustion engine to which the instrument is attached A pressure-sensitive body mainly composed of a substantially annular ceramic incorporated in a state where the housing screw portion of the instrument penetrates, and a Young provided in close contact with the top and bottom surfaces of the pressure-sensitive body via an insulator A pressure sensor for an internal combustion engine having a washer with a rate of 70 to 220 GPa. 前記絶縁体を介して感圧体と座金とが一体化されている請求項１に記載の内燃機関用圧力センサ。 The pressure sensor for an internal combustion engine according to claim 1, wherein the pressure sensitive body and the washer are integrated with each other through the insulator. 前記感圧体の上面と底面には、電極部が形成されていることを特徴とする請求項１及び２に記載の内燃機関用圧力センサ。 The pressure sensor for an internal combustion engine according to claim 1 or 2, wherein electrodes are formed on an upper surface and a bottom surface of the pressure sensitive body. セラミックスからなる第１の粒子を主体とした母材中に前記第１の粒子とは導電性が異なるセラミックスからなる第２の粒子が分散し、前記第１の粒子と第２の粒子との加圧による接触状態の変化により電気抵抗が変化する特性を有する感圧体を備えた請求項１〜３に記載の内燃機関用圧力センサ。 In the base material mainly composed of the first particles made of ceramics, the second particles made of ceramics having different conductivity from the first particles are dispersed, and the first particles and the second particles are added. The pressure sensor for an internal combustion engine according to any one of claims 1 to 3, further comprising a pressure-sensitive body having a characteristic that electric resistance changes due to a change in a contact state due to pressure.

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