JP6830048B2

JP6830048B2 - Knocking sensor

Info

Publication number: JP6830048B2
Application number: JP2017161958A
Authority: JP
Inventors: 克樹青井
Original assignee: NGK Spark Plug Co Ltd
Current assignee: NGK Spark Plug Co Ltd
Priority date: 2017-08-25
Filing date: 2017-08-25
Publication date: 2021-02-17
Anticipated expiration: 2037-08-25
Also published as: JP2019039796A

Description

本発明は、圧電素子を用いたノッキングセンサに関する。 The present invention relates to a knocking sensor using a piezoelectric element.

自動車等の内燃機関のノッキング現象を検出する非共振型のノッキングセンサが知られており、ノッキングセンサの検出に応じて点火プラグの点火時期の遅角制御が行われている。
上記したノッキングセンサとして、内燃機関のシリンダブロック等へ取付けるための取付孔を中心部に有する、いわゆるセンターホール式非共振型のノッキングセンサが知られている。このノッキングセンサは、筒状部と筒状部の一端に位置する鍔部とを有する主体金具を備え、筒状部の外周に鍔部側から順に、それぞれ環状の絶縁部材、圧電素子、ウェイト、及びナットを嵌め込んで構成されている。そして、筒状部の外周面の雄ネジ部にナットを螺合することによりウェイトを係止し、鍔部とウェイトとの間に圧電素子を挟んで固定している。さらに、主体金具に絶縁部材、圧電素子、ウェイト等を組み付けた内部部品全体が樹脂によって被覆されることで、ノッキングセンサは構成されている。なお、筒状部の内面が上記した取付孔となっている。 A non-resonant knocking sensor that detects a knocking phenomenon of an internal combustion engine of an automobile or the like is known, and the retard angle control of the ignition timing of the spark plug is performed according to the detection of the knocking sensor.
As the knocking sensor described above, a so-called center hole type non-resonant knocking sensor having a mounting hole for mounting on a cylinder block or the like of an internal combustion engine at the center is known. This knocking sensor is provided with a main metal fitting having a tubular portion and a flange portion located at one end of the tubular portion, and an annular insulating member, a piezoelectric element, and a weight are provided on the outer periphery of the tubular portion in order from the flange portion side. And a nut is fitted. Then, the weight is locked by screwing a nut into the male screw portion on the outer peripheral surface of the tubular portion, and the piezoelectric element is sandwiched and fixed between the collar portion and the weight. Further, the knocking sensor is configured by covering the entire internal component in which the insulating member, the piezoelectric element, the weight, etc. are assembled to the main metal fitting with the resin. The inner surface of the tubular portion is the mounting hole described above.

特開２０１０−１０１６９６号公報JP-A-2010-101696

ところで、非共振型のノッキングセンサにおいては、エンジンのノッキング振動がウェイトを介して圧電素子を圧縮し、圧電素子の出力信号からノッキングを検出するようになっている。そして、ノッキングセンサは、その構成部品や形状により固有の共振周波数を持っており、この共振周波数を避け、比較的平坦な出力特性を持つ周波数帯にてノッキングを検出している。従来、ノッキング周波数帯は１ｋ〜２０ｋＨｚ程度とされており、ノッキングセンサの共振周波数はこれより高周波の約２８ｋＨｚ以上になるように設計されている。
しかしながら、近年、エンジンの高回転等の理由により、特に２輪エンジンのノッキング周波数帯をより高周波領域に設定したいという要望があり、それに伴ってノッキングセンサの共振周波数を高くすることが必要になってきている。 By the way, in the non-resonant type knocking sensor, the knocking vibration of the engine compresses the piezoelectric element via the weight, and the knocking is detected from the output signal of the piezoelectric element. The knocking sensor has a unique resonance frequency depending on its components and shape, avoids this resonance frequency, and detects knocking in a frequency band having a relatively flat output characteristic. Conventionally, the knocking frequency band is set to about 1 k to 20 kHz, and the resonance frequency of the knocking sensor is designed to be higher than this, about 28 kHz or more.
However, in recent years, there has been a demand to set the knocking frequency band of a two-wheeled engine to a higher frequency region for reasons such as high engine speed, and it has become necessary to increase the resonance frequency of the knocking sensor accordingly. ing.

そこで、本発明は、ノッキングセンサの共振周波数を高くし、より高周波のノッキング周波数帯での測定を可能としたノッキングセンサの提供を目的とする。 Therefore, an object of the present invention is to provide a knocking sensor in which the resonance frequency of the knocking sensor is increased and measurement can be performed in a higher frequency knocking frequency band.

上記課題を解決するため、本発明のノッキングセンサは、筒状部と、該筒状部の一端側に位置し、筒状部の周方向外側に向かって突出する鍔部とを有する主体金具と、前記筒状部の外周に嵌め込まれ、前記鍔部に面する側と反対側に天面を有する環状のウェイトと、前記筒状部の外周に嵌め込まれ、前記鍔部と前記ウェイトとの間に挟まれる環状の圧電素子と、前記ウェイトの天面に接すると共に前記筒状部の外周に固定され、該ウェイトを係止する環状の皿バネからなる係止部材と、前記筒状部の外周から周方向外側に向かって突出し、前記係止部材の上面に接する突出部と、前記鍔部と前記圧電素子との間に介在する絶縁体と、を備えたノッキングセンサであって、前記筒状部の軸方向の断面画像において、前記係止部材は、当該係止部材の内周部の角部から周方向外側にそれぞれ延びる２つの輪郭と前記筒状部の外周面との２つの接点Ｐ１，Ｐ２を結ぶ線分よりも、該筒状部の内部に自身が介在するように前記筒状部の外周面に食い込んでいることを特徴とする。

In order to solve the above problems, the knocking sensor of the present invention includes a main metal fitting having a tubular portion and a flange portion located on one end side of the tubular portion and projecting outward in the circumferential direction of the tubular portion. , Fitted on the outer circumference of the tubular portion and having a top surface on the side opposite to the side facing the flange portion, and fitted on the outer circumference of the tubular portion, between the flange portion and the weight. An annular piezoelectric element sandwiched between the two, a locking member composed of an annular flat spring that is in contact with the top surface of the weight and fixed to the outer circumference of the tubular portion to lock the weight, and an outer circumference of the tubular portion. from toward the circumferential direction outwardly projecting, and the engaging protrusion in contact with the upper surface of the stop member, a knocking sensor comprising an insulating and body, the interposed between said flange portion and the piezoelectric element, the tubular In the axial cross-sectional image of the portion, the locking member has two contours extending outward from the corners of the inner peripheral portion of the locking member and two contact points P1 between the outer peripheral surface of the tubular portion. , P2 is characterized in that it bites into the outer peripheral surface of the tubular portion so as to intervene inside the tubular portion rather than the line segment connecting P2 .

このノッキングセンサによれば、係止部材の内周部の少なくとも一部を筒状部の外周面に食い込ませることで、係止部材、ひいてはウェイトを含む積層構造体（圧電素子、絶縁体等）が筒状部（主体金具）によりしっかりと固定される。これにより、ノッキングセンサの共振周波数が高くなり、より高周波のノッキング周波数帯での測定が可能となる。 According to this knocking sensor, at least a part of the inner peripheral portion of the locking member is made to bite into the outer peripheral surface of the tubular portion, so that the locking member and the laminated structure including the weight (piezoelectric element, insulator, etc.) Is firmly fixed by the tubular part (main metal fitting). As a result, the resonance frequency of the knocking sensor becomes high, and measurement in a higher frequency knocking frequency band becomes possible.

本発明のノッキングセンサにおいて、前記係止部材を前記ウェイトの前記天面側から見たとき、前記内周部は、円環部と、該円環部より径方向外側に位置して前記円環部に繋がる１つ以上の拡径部とを有し、前記拡径部と前記円環部との接続部における前記筒状部の外周面への食い込み量Ｌ１よりも、隣接する前記接続部の間の前記円環部の周方向中央における前記筒状部の外周面への食い込み量Ｌ２が大きくてもよい。
このノッキングセンサによれば、円環部の周方向中央にて、係止部材が筒状部（主体金具）により強固に固定されるので、ノッキングセンサの共振周波数をより一層高くすることができる。 In the knocking sensor of the present invention, when the locking member is viewed from the top surface side of the weight, the inner peripheral portion is located at the annular portion and the annular portion radially outward from the annular portion. It has one or more diameter-expanded portions connected to the portions, and the connecting portion of the connecting portion adjacent to the diameter-expanded portion and the annular portion has a larger amount of biting into the outer peripheral surface of the tubular portion than L1. The amount L2 of biting into the outer peripheral surface of the tubular portion at the center of the annular portion in the circumferential direction may be large.
According to this knocking sensor, since the locking member is firmly fixed by the tubular portion (main metal fitting) at the center in the circumferential direction of the annular portion, the resonance frequency of the knocking sensor can be further increased.

本発明のノッキングセンサにおいて、前記係止部材の厚みが１ｍｍ以上であってもよい。
このノッキングセンサによれば、係止部材の剛性がより高くなるので、ノッキングセンサの共振周波数をより一層高くすることができる。 In the knocking sensor of the present invention, the thickness of the locking member may be 1 mm or more.
According to this knocking sensor, the rigidity of the locking member is increased, so that the resonance frequency of the knocking sensor can be further increased.

この発明によれば、ノッキングセンサの共振周波数を高くし、より高周波のノッキング周波数帯での測定が可能となる。 According to the present invention, the resonance frequency of the knocking sensor is increased, and measurement in a higher frequency knocking frequency band becomes possible.

本発明の実施形態に係るノッキングセンサの外観を示す正面図である。It is a front view which shows the appearance of the knocking sensor which concerns on embodiment of this invention. 本発明の実施形態に係るノッキングセンサの断面図である。It is sectional drawing of the knocking sensor which concerns on embodiment of this invention. 本発明の実施形態に係るノッキングセンサの内部構造の分解図である。It is an exploded view of the internal structure of the knocking sensor which concerns on embodiment of this invention. 図２の部分拡大断面図である。It is a partially enlarged sectional view of FIG. 係止部材の上面図である。It is a top view of the locking member. 本発明の実施形態に係るノッキングセンサの製造方法の一例を示す工程図である。It is a process drawing which shows an example of the manufacturing method of the knocking sensor which concerns on embodiment of this invention. 本発明の実施形態に係るノッキングセンサの製造に用いるプレス治具の上面図である。It is a top view of the press jig used for manufacturing the knocking sensor which concerns on embodiment of this invention. 皿バネを筒状部にネジ締めした場合、及び本実施形態により皿バネを固定した場合のノッキングセンサの共振周波数を示す図である。It is a figure which shows the resonance frequency of the knocking sensor when the disc spring is screw-tightened to the tubular part, and when the disc spring is fixed by this embodiment.

以下、図１〜図５を参照し、本発明の実施形態に係るノッキングセンサについて説明する。
図１はノッキングセンサの外観を示し、図２はノッキングセンサを軸方向に破断した断面図を示し、図３はノッキングセンサの内部構造の分解図を示している。又、図４は図２の部分拡大断面図、図５は係止部材（皿バネ）２９の上面図である。
図１において、ノッキングセンサ１は、内燃機関のシリンダブロック等へ取付けるための取付孔１１(図２参照)を中心部に有する、いわゆるセンターホール式非共振型のノッキングセンサである。ノッキングセンサ１は、樹脂モールド材料である合成樹脂（例えばナイロン６６）製のケース３により覆われている。このケース３は、上部がテーパ状に成形された円柱形状の素子収納部５と、図示しない点火時期制御装置からのコネクタを接続するコネクタ部７とから構成されている。 Hereinafter, the knocking sensor according to the embodiment of the present invention will be described with reference to FIGS. 1 to 5.
FIG. 1 shows the appearance of the knocking sensor, FIG. 2 shows a cross-sectional view of the knocking sensor broken in the axial direction, and FIG. 3 shows an exploded view of the internal structure of the knocking sensor. 4 is a partially enlarged cross-sectional view of FIG. 2, and FIG. 5 is a top view of the locking member (belleville spring) 29.
In FIG. 1, the knocking sensor 1 is a so-called center hole type non-resonant knocking sensor having a mounting hole 11 (see FIG. 2) for mounting on a cylinder block or the like of an internal combustion engine at a central portion. The knocking sensor 1 is covered with a case 3 made of a synthetic resin (for example, nylon 66) which is a resin molding material. The case 3 is composed of a cylindrical element accommodating portion 5 having a tapered upper portion and a connector portion 7 for connecting a connector from an ignition timing control device (not shown).

図２及び図３に示すように、ノッキングセンサ１は、金属材料（例えばＳＰＨＤ、ＳＷＣＨ２５Ｋ）からなる主体金具９を備えており、主体金具９は、ボルトを挿通するための取付孔１１を有する円筒形状の筒状部１３と、筒状部１３の一端側（図１の下側）にて外周面から周方向外側に張り出す鍔部１５とを有している。
この主体金具９の鍔部１５の厚み方向の一面（図１の上面）側には、筒状部１３の外周に嵌められる環状（円筒形状）で、圧電セラミックス（例えばＰＺＴ）からなる圧電素子１７が載置されている。
また、圧電素子１７の上面側には、筒状部１３の外周に嵌められる環状（円筒形状）で、錘としての効果を発揮する比重を有する金属材料（例えばＳＭＦ４０５０）からなるウェイト１９が載置されている。 As shown in FIGS. 2 and 3, the knocking sensor 1 includes a main metal fitting 9 made of a metal material (for example, SPHD, SWCH25K), and the main metal fitting 9 is a cylinder having a mounting hole 11 for inserting a bolt. It has a tubular portion 13 having a shape, and a flange portion 15 that projects outward from the outer peripheral surface in the circumferential direction on one end side (lower side of FIG. 1) of the tubular portion 13.
On one surface (upper surface in FIG. 1) of the flange portion 15 of the main metal fitting 9 in the thickness direction, a piezoelectric element 17 made of piezoelectric ceramics (for example, PZT) having an annular shape (cylindrical shape) fitted to the outer circumference of the tubular portion 13. Is placed.
Further, on the upper surface side of the piezoelectric element 17, a weight 19 made of an annular (cylindrical shape) metal material (for example, SMF4050) having a specific gravity that exerts an effect as a weight is placed on the outer circumference of the tubular portion 13. Has been done.

鍔部１５と圧電素子１７との間、及びウェイト１９と圧電素子１７との間、即ち圧電素子１７の厚み方向の両側には、導電材料（例えば黄銅）からなる出力端子２１、２３が、それぞれ圧電素子１７と接するように配置されている。なお、出力端子２１、２３のうち圧電素子１７と接する部分は環状である。
また、鍔部１５と出力端子２１との間、及び出力端子２３とウェイト１９との間には、絶縁性を有するフィルム状の合成樹脂（例えばＰＥＴ）からなる環状の絶縁体２５、２７がそれぞれ配置され、出力端子２１、２３が主体金具９の鍔部１５やウェイト１９と短絡しないようにされている。 Output terminals 21 and 23 made of a conductive material (for example, brass) are provided between the flange portion 15 and the piezoelectric element 17, and between the weight 19 and the piezoelectric element 17, that is, on both sides of the piezoelectric element 17 in the thickness direction. It is arranged so as to be in contact with the piezoelectric element 17. Of the output terminals 21 and 23, the portion in contact with the piezoelectric element 17 is annular.
Further, between the collar portion 15 and the output terminal 21, and between the output terminal 23 and the weight 19, annular insulators 25 and 27 made of a film-like synthetic resin (for example, PET) having insulating properties are respectively. The output terminals 21 and 23 are arranged so as not to short-circuit with the flange portion 15 and the weight 19 of the main metal fitting 9.

なお、圧電素子１７とウェイト１９と出力端子２１、２３（環状部分）と絶縁体２５、２７との内周部と、筒状部１３の外周面との間には、環状の空間２０が形成されており、この環状の空間２０にも上記合成樹脂が充填されている。更に、主体金具９には、金属材料（例えばＳＫ−５Ｍ）からなり、ウェイト１９を鍔部１５方向（同図下方）へ押圧する環状の皿バネ（座金）２９が取り付けられている。図３に示すように、皿バネ２９は、外周面から円錐台状に斜めに立ち上がり、径方向内側へ向かって水平に延びる形状になっていて、この水平部の中央が開口している。
なお、ウェイト１９の上面（図１の上面）１９ａに皿バネ２９の下面の少なくとも一部が接しており、ウェイト１９の上面１９ａが特許請求の範囲の「天面」に相当する。又、皿バネ２９が特許請求の範囲の「係止部材」に相当する。又、鍔部１５と出力端子２１との間の絶縁体２５が特許請求の範囲の「絶縁体」に相当する。 An annular space 20 is formed between the inner peripheral portion of the piezoelectric element 17, the weight 19, the output terminals 21, 23 (annular portion), the insulators 25, 27, and the outer peripheral surface of the tubular portion 13. The annular space 20 is also filled with the synthetic resin. Further, the main metal fitting 9 is attached with an annular disc spring (washer) 29 made of a metal material (for example, SK-5M) and pressing the weight 19 in the flange portion 15 direction (lower part of the figure). As shown in FIG. 3, the disc spring 29 has a shape that rises diagonally from the outer peripheral surface in a truncated cone shape and extends horizontally inward in the radial direction, and the center of the horizontal portion is open.
At least a part of the lower surface of the disc spring 29 is in contact with the upper surface (upper surface of FIG. 1) 19a of the weight 19, and the upper surface 19a of the weight 19 corresponds to the "top surface" of the claims. Further, the disc spring 29 corresponds to the "locking member" in the claims. Further, the insulator 25 between the flange portion 15 and the output terminal 21 corresponds to the "insulator" in the claims.

さらに、皿バネ２９の上側の位置において、筒状部１３の外周面には、筒状部１３の内面１３ａから周方向外側に向かって塑性変形して突出する突出部１３ｐが設けられている。又、突出部１３ｐに対応する筒状部１３の内面１３ａには凹部１３ｒが形成されている。
そして、突出部１３ｐが皿バネ２９の上面に接することによって、皿バネ２９が下方に押圧され、さらに皿バネ２９の弾性力によりウェイト１９が係止され、ウェイト１９と鍔部１５との間の積層構造体（圧電素子１７、出力端子２１、２３、絶縁体２５、２７）が主体金具９に固定される。
つまり、突出部１３ｐが皿バネ２９を介してウェイト１９の天面１９ａに接し、主体金具９の鍔部１５に向けてウェイト１９を押圧するようにして、ウェイト１９を間接的に主体金具９に係止している。
なお、突出部１３ｐは、筒状部１３の外周面から０．１〜０．２ｍｍ程度突出していればよい。 Further, at the position above the disc spring 29, the outer peripheral surface of the tubular portion 13 is provided with a protruding portion 13p that is plastically deformed and protrudes outward in the circumferential direction from the inner surface 13a of the tubular portion 13. Further, a recess 13r is formed on the inner surface 13a of the tubular portion 13 corresponding to the protruding portion 13p.
Then, when the protruding portion 13p comes into contact with the upper surface of the disc spring 29, the disc spring 29 is pressed downward, and the weight 19 is further locked by the elastic force of the disc spring 29, and the weight 19 is between the weight 19 and the flange portion 15. The laminated structure (piezoelectric element 17, output terminals 21, 23, insulators 25, 27) is fixed to the main metal fitting 9.
That is, the protruding portion 13p comes into contact with the top surface 19a of the weight 19 via the disc spring 29 and presses the weight 19 toward the flange portion 15 of the main metal fitting 9, thereby indirectly making the weight 19 into the main metal fitting 9. It is locked.
The protruding portion 13p may protrude by about 0.1 to 0.2 mm from the outer peripheral surface of the tubular portion 13.

さらに、図２、図４に示すように、皿バネ２９の内周部２９ｉの上側の部位２９ｓが筒状部１３の外周面１３ｂに食い込んでいる。
このように、皿バネ２９の内周部２９ｉの一部（部位２９ｓ）を筒状部１３の外周面１３ｂに食い込ませることで、皿バネ２９、ひいてはウェイト１９を含む積層構造体（圧電素子１７、出力端子２１、２３、絶縁体２５、２７）が筒状部１３（主体金具９）によりしっかりと固定される。これにより、ノッキングセンサ１の共振周波数が高くなり、より高周波のノッキング周波数帯での測定が可能となる。
特に、皿バネ２９の厚みが１ｍｍ以上であると、皿バネ２９の剛性がより高くなるので、ノッキングセンサ１の共振周波数をより一層高くすることができる。
皿バネ２９としては、上述のＳＫ−５Ｍの他、例えばＳ２５Ｃ等の炭素鋼を用いることができる。 Further, as shown in FIGS. 2 and 4, the upper portion 29s of the inner peripheral portion 29i of the disc spring 29 bites into the outer peripheral surface 13b of the tubular portion 13.
In this way, a part (part 29s) of the inner peripheral portion 29i of the disc spring 29 is made to bite into the outer peripheral surface 13b of the tubular portion 13, so that the laminated structure (piezoelectric element 17) including the disc spring 29 and the weight 19 is included. , Output terminals 21, 23, insulators 25, 27) are firmly fixed by the tubular portion 13 (main metal fitting 9). As a result, the resonance frequency of the knocking sensor 1 becomes high, and measurement in a higher frequency knocking frequency band becomes possible.
In particular, when the thickness of the disc spring 29 is 1 mm or more, the rigidity of the disc spring 29 becomes higher, so that the resonance frequency of the knocking sensor 1 can be further increased.
As the disc spring 29, in addition to the above-mentioned SK-5M, carbon steel such as S25C can be used.

なお、特開２０１３−７６１２号公報に記載されているように、ウェイトの内周面に設けられた凸部を筒状部の外周面に押し付けることにより固定する方法では、固定力が十分ではない。又、筒状部の外周面に予め切り欠きや凹部を形成し、その切り欠きや凹部にバネ部材を嵌めて固定することや、係止部材の一部を配置して固定する方法もある。しかし、これらの方法は、予め切り欠きや凹部を形成し、その部分に嵌る寸法の部材を準備した上で、それらを嵌合するよう制御する工程が必要となり、生産性及びコストの問題がある。
これに対し、本実施形態のように、予め切り欠きや凹部が形成されていない筒状部１３の外周面１３ｂに皿バネ２９を食い込ませることで、容易に皿バネ２９、ひいてはウェイト１９を含む積層構造体（圧電素子１７、出力端子２１、２３、絶縁体２５、２７）を筒状部１３（主体金具９）により確りと固定できる。
As described in Japanese Patent Application Laid-Open No. 2013-7612, the fixing force is not sufficient in the method of fixing by pressing the convex portion provided on the inner peripheral surface of the weight against the outer peripheral surface of the tubular portion. .. Further, there is also a method in which a notch or a recess is formed in advance on the outer peripheral surface of the tubular portion and a spring member is fitted and fixed in the notch or the recess, or a part of the locking member is arranged and fixed. However, these methods require a step of forming notches and recesses in advance, preparing members having dimensions to fit the portions, and then controlling them to fit, which causes problems of productivity and cost. ..
On the other hand, as in the present embodiment, by allowing the disc spring 29 to bite into the outer peripheral surface 13b of the tubular portion 13 in which the notch or the recess is not formed in advance, the disc spring 29 and thus the weight 19 are easily included. The laminated structure (piezoelectric element 17, output terminals 21, 23, insulators 25, 27) can be securely fixed by the tubular portion 13 (main metal fitting 9).

なお、皿バネ２９の内周部２９ｉの一部２９ｓが筒状部１３の外周面１３ｂに食い込んでいるか否かは、皿バネ２９を含む筒状部１３の軸方向の断面画像により判定する。つまり、図４に示すように、皿バネ２９の輪郭と筒状部１３の外周面１３ｂとの２つの接点Ｐ１，Ｐ２を求め、Ｐ１，Ｐ２を結ぶ線分よりも筒状部１３の内部に皿バネ２９（部位２９ｓ）が介在していれば、「食い込んでいる」とみなす。もちろん、接点が１つしかない場合は、食い込んでいない。 Whether or not a part 29s of the inner peripheral portion 29i of the disc spring 29 bites into the outer peripheral surface 13b of the tubular portion 13 is determined from a cross-sectional image of the tubular portion 13 including the disc spring 29 in the axial direction. That is, as shown in FIG. 4, two contact points P1 and P2 between the contour of the disc spring 29 and the outer peripheral surface 13b of the tubular portion 13 are obtained, and the inside of the tubular portion 13 is located inside the tubular portion 13 rather than the line segment connecting P1 and P2. If the disc spring 29 (part 29s) is present, it is considered to be "biting". Of course, if there is only one contact, it is not biting.

図８は、従来のように皿バネ２９を筒状部の外周面の雄ネジ部にナットでネジ締めした場合、及び本実施形態において皿バネ２９の厚みを変えたときのノッキングセンサ１の共振周波数をそれぞれ示す。
本実施形態のように皿バネ２９の一部を筒状部１３の外周面１３ｂに食い込ませることで、従来のネジ締め法よりも共振周波数が高くなることがわかる。又、皿バネ２９の厚みが厚くなるほど、共振周波数も高くなる。 FIG. 8 shows the resonance of the knocking sensor 1 when the disc spring 29 is screwed to the male screw portion on the outer peripheral surface of the tubular portion with a nut as in the conventional case, and when the thickness of the disc spring 29 is changed in the present embodiment. The frequencies are shown respectively.
It can be seen that by having a part of the disc spring 29 bite into the outer peripheral surface 13b of the tubular portion 13 as in the present embodiment, the resonance frequency becomes higher than that of the conventional screw tightening method. Further, the thicker the disc spring 29, the higher the resonance frequency.

図５に示すように、本実施形態では、皿バネ２９の内周部２９ｉは、円環部２９ｉ１と、円環部２９ｉ１より径方向外側に位置して円環部２９ｉ１に繋がる３つの拡径部２９ｉ２とを有している。３つの拡径部２９ｉ２は半円形状であり、それぞれ周方向に等間隔に離間している。
ここで、拡径部２９ｉ２と円環部２９ｉ１との接続部Ｃ１，Ｃ２における筒状部１３の外周面１３ｂへの食い込み量Ｌ１よりも、隣接する接続部Ｃ１，Ｃ２の間の円環部２９ｉ１の周方向中央Ｃｅにおける筒状部１３の外周面１３ｂへの食い込み量Ｌ２が大きい。
これにより、円環部２９ｉ１の周方向中央Ｃｅにて、皿バネ２９が筒状部１３（主体金具９）により強固に固定されるので、ノッキングセンサ１の共振周波数をより一層高くすることができる。 As shown in FIG. 5, in the present embodiment, the inner peripheral portion 29i of the disc spring 29 is located radially outside the annular portion 29i1 and the annular portion 29i1 and is connected to the annular portion 29i1. It has a part 29i2. The three enlarged diameter portions 29i2 have a semicircular shape and are spaced apart at equal intervals in the circumferential direction.
Here, the annular portion 29i1 between the adjacent connecting portions C1 and C2 is larger than the biting amount L1 of the tubular portion 13 into the outer peripheral surface 13b of the connecting portions C1 and C2 between the enlarged diameter portion 29i2 and the annular portion 29i1. The amount L2 of the tubular portion 13 biting into the outer peripheral surface 13b at the center Ce in the circumferential direction is large.
As a result, the disc spring 29 is firmly fixed by the tubular portion 13 (main metal fitting 9) at the center Ce in the circumferential direction of the annular portion 29i1, so that the resonance frequency of the knocking sensor 1 can be further increased. ..

食い込み量Ｌ２が食い込み量Ｌ１よりも大きい理由は、拡径部２９ｉ２と筒状部１３との間に隙間が生じるため、皿バネ２９を筒状部１３へ押圧したとき、円環部２９ｉ１の周方向中央Ｃｅから拡径部２９ｉ２へ筒状部１３の材料Ｍが流動し易く、周方向中央Ｃｅで食い込み易くなるためである。
又、食い込み量Ｌ１、Ｌ２は径方向への食い込み長さである。
なお、図５では、押圧して変形する前の皿バネ２９の形状を表したが、実際には、周方向中央Ｃｅが筒状部１３へより一層食い込むので、周方向中央Ｃｅが径方向内側へ縮径し、円環部２９ｉ１が真円よりも歪んでいる。 The reason why the bite amount L2 is larger than the bite amount L1 is that a gap is generated between the enlarged diameter portion 29i2 and the tubular portion 13, so that when the disc spring 29 is pressed against the tubular portion 13, the circumference of the annular portion 29i1 This is because the material M of the tubular portion 13 easily flows from the central Ce in the direction to the enlarged diameter portion 29i2, and easily bites into the central Ce in the circumferential direction.
Further, the bite amounts L1 and L2 are the bite lengths in the radial direction.
In FIG. 5, the shape of the disc spring 29 before being pressed and deformed is shown, but in reality, the circumferential center Ce bites further into the tubular portion 13, so that the circumferential center Ce is radially inside. The diameter is reduced to, and the annular portion 29i1 is distorted more than a perfect circle.

又、本実施形態では、ナットを用いず、筒状部１３に設けた突出部１３ｐによって皿バネ２９を主体金具９に固定するので、ナットの部品コストを削減し、ノッキングセンサ１のコストを低下することができる。
但し、筒状部１３の外周面１３ｂに雄ネジを切り、ナットを用いてナットの下面側の皿バネ２９を主体金具９に固定してもよいが、ナットと皿バネ２９の２つの部材が必要で、部品コストはアップする傾向にある。
なお、突出部１３ｐは、筒状部１３の内面１３ａから周方向外側に向かって加工（塑性変形）を施して形成してもよく、筒状部１３の外周面に直接プレス加工等を行って形成してもよい。 Further, in the present embodiment, since the disc spring 29 is fixed to the main metal fitting 9 by the protruding portion 13p provided on the tubular portion 13 without using the nut, the cost of the nut parts is reduced and the cost of the knocking sensor 1 is reduced. can do.
However, a male screw may be cut on the outer peripheral surface 13b of the tubular portion 13 and the disc spring 29 on the lower surface side of the nut may be fixed to the main metal fitting 9 using a nut, but the nut and the disc spring 29 are two members. It is necessary, and the cost of parts tends to increase.
The protruding portion 13p may be formed by processing (plastic deformation) from the inner surface 13a of the tubular portion 13 toward the outside in the circumferential direction, and the outer peripheral surface of the tubular portion 13 may be directly pressed. It may be formed.

次に、図６、図７を参照し、本実施形態のノッキングセンサ１の製造方法の一例を説明する。
まず、主体金具粗形材９ｘを用意する。この主体金具粗形材９ｘは、内面１３ａに凹部１３ｒが形成されず、外周面に突出部１３ｐが形成されていない筒状部１３ｘと、筒状部１３ｘの一端側（下側）に上述の鍔部１５とを有している(図３参照)。そして、筒状部１３ｘの外周側に嵌めるようにして、鍔部１５上に、絶縁部材２５、出力端子２１、圧電素子１７、出力端子２３、絶縁部材２７、ウェイト１９、皿バネ２９を順次載置する。さらに、筒状部１３ｘの内面に、鍔部１５側（下方）からプレス治具１１０を挿入する(図６（ａ）)。プレス治具１１０は、後述する４つの切り欠き部１１０ｓによって４つに分割された個片から構成され、各個片の下端側に位置する張出部１１０ｆを１つの環状保持リング１４０によって保持させた集合体より形成されており、内側に後述するピストン１３０を内挿可能な略円形の孔を有する略円筒状の形態をなしている。なお、プレス治具１１０を構成する各個片の張出部１１０ｆが鍔部１５の下面に当接して挿入深さを位置決めするようになっている。 Next, an example of the manufacturing method of the knocking sensor 1 of the present embodiment will be described with reference to FIGS. 6 and 7.
First, the main metal fitting rough material 9x is prepared. The main metal fitting rough material 9x has a tubular portion 13x in which a recess 13r is not formed on the inner surface 13a and a protruding portion 13p is not formed on the outer peripheral surface, and the above-mentioned one end side (lower side) of the tubular portion 13x. It has a collar 15 (see FIG. 3). Then, the insulating member 25, the output terminal 21, the piezoelectric element 17, the output terminal 23, the insulating member 27, the weight 19, and the disc spring 29 are sequentially placed on the flange portion 15 so as to be fitted on the outer peripheral side of the tubular portion 13x. Place. Further, the press jig 110 is inserted into the inner surface of the tubular portion 13x from the flange portion 15 side (lower side) (FIG. 6A). The press jig 110 is composed of individual pieces divided into four by four notch portions 110s described later, and the overhanging portion 110f located on the lower end side of each individual piece is held by one annular holding ring 140. It is formed of an aggregate and has a substantially cylindrical shape having a substantially circular hole into which a piston 130 described later can be inserted. The overhanging portion 110f of each piece constituting the press jig 110 abuts on the lower surface of the flange portion 15 to position the insertion depth.

又、図７に示すように、プレス治具１１０（各個片）の上端側には周方向外側に突出する凸部１１０ｐと、軸方向に延びる４つの切り欠き部１１０ｓとが形成されており、凸部１１０ｐは切り欠き部１１０ｓで周方向に４つに分離されている。従って、切り欠き部１１０ｓが閉じたり開いたりすることにより、凸部１１０ｐが周方向に縮径及び拡径可能になっていて、プレス治具１１０を筒状部１３ｘの内面に挿入した際には筒状部１３ｘの内面に押圧されて凸部１１０ｐが周方向に縮径する。 Further, as shown in FIG. 7, a convex portion 110p protruding outward in the circumferential direction and four notched portions 110s extending in the axial direction are formed on the upper end side of the press jig 110 (each piece). The convex portion 110p is separated into four in the circumferential direction by the notch portion 110s. Therefore, when the notch portion 110s is closed or opened, the convex portion 110p can be reduced in diameter and expanded in the circumferential direction, and when the press jig 110 is inserted into the inner surface of the tubular portion 13x, Pressed against the inner surface of the tubular portion 13x, the convex portion 110p is reduced in diameter in the circumferential direction.

次に、円筒ピン１２０を上方から下ろし、円筒ピン１２０の下面にて皿バネ２９を押圧し、皿バネ２９の内周部２９ｉの少なくとも一部が、筒状部１３ｘの外周面に食い込むように弾性変形させる(図６（ｂ）)。なお、皿バネ２９を押圧した際、内周部２９ｉが筒状部１３ｘの外周面に届くよう、内周部２９ｉの直径が筒状部１３ｘの外径に近くなる（筒状部１３ｘの外径よりやや大きくなる）ように設定する。 Next, the cylindrical pin 120 is lowered from above, and the disc spring 29 is pressed by the lower surface of the cylindrical pin 120 so that at least a part of the inner peripheral portion 29i of the disc spring 29 bites into the outer peripheral surface of the tubular portion 13x. It is elastically deformed (FIG. 6 (b)). When the disc spring 29 is pressed, the diameter of the inner peripheral portion 29i becomes close to the outer diameter of the tubular portion 13x so that the inner peripheral portion 29i reaches the outer peripheral surface of the tubular portion 13x (outside the tubular portion 13x). Set so that it is slightly larger than the diameter).

次に、円筒ピン１２０を下ろした状態で、プレス治具１１０の上端側（プレス治具１１０の内側の孔）に、上方からピストン１３０を挿入する(図６（ｃ）)。ピストン１３０は先端に向かって狭まるテーパ状をなし、プレス治具１１０にピストン１３０を挿入すると、プレス治具１１０の上端側が押し広げられ、各個片が周方向外側に向かって移動し、凸部１１０ｐが拡径する(図６（ｄ）)。このため、凸部１１０ｐに接する筒状部１３ｘの内面が周方向外側に向かって塑性変形して突出し、凹部１３ｒを形成する。この際、凹部１３ｒの位置（すなわち、凸部１１０ｐの位置）は、押圧された状態の皿バネ２９の上面とほぼ同一であるので、皿バネ２９の上面側に突出部１３ｐが形成される。そして、円筒ピン１２０を離すと、皿バネ２９が弾性的に戻り、突出部１３ｐに接しながら皿バネ２９の弾性力によりウェイト１９の天面１９ａを鍔部１５側へ押圧し、上述の積層構造体が主体金具９に固定される。
又、皿バネ２９の内周部２９ｉの少なくとも一部が筒状部１３ｘの外周面に食い込んだ状態が維持される。
このようにしてノッキングセンサ１を組み立てた後、主体金具９を含む上述の積層構造体を覆うように樹脂モールド材料（合成樹脂）を射出し固化させることにより、ケース３を形成し、ノッキングセンサ１が完成する。 Next, with the cylindrical pin 120 lowered, the piston 130 is inserted from above into the upper end side (hole inside the press jig 110) of the press jig 110 (FIG. 6 (c)). The piston 130 has a tapered shape that narrows toward the tip, and when the piston 130 is inserted into the press jig 110, the upper end side of the press jig 110 is expanded, each piece moves outward in the circumferential direction, and the convex portion 110p. Expands the diameter (Fig. 6 (d)). Therefore, the inner surface of the tubular portion 13x in contact with the convex portion 110p is plastically deformed and protrudes outward in the circumferential direction to form the concave portion 13r. At this time, since the position of the concave portion 13r (that is, the position of the convex portion 110p) is substantially the same as the upper surface of the disc spring 29 in the pressed state, the protruding portion 13p is formed on the upper surface side of the disc spring 29. Then, when the cylindrical pin 120 is released, the disc spring 29 elastically returns, and the top surface 19a of the weight 19 is pressed toward the flange portion 15 by the elastic force of the disc spring 29 while being in contact with the protruding portion 13p, and the above-mentioned laminated structure is formed. The body is fixed to the main metal fitting 9.
Further, at least a part of the inner peripheral portion 29i of the disc spring 29 is maintained in a state of being bitten into the outer peripheral surface of the tubular portion 13x.
After assembling the knocking sensor 1 in this way, the case 3 is formed by injecting and solidifying a resin mold material (synthetic resin) so as to cover the above-mentioned laminated structure including the main metal fitting 9, and the knocking sensor 1 is formed. Is completed.

本発明は上記実施形態に限定されず、本発明の思想と範囲に含まれる様々な変形及び均等物に及ぶことはいうまでもない。
絶縁体の種類としては、上述のフィルム状の合成樹脂の他、セラミック材でもよく、絶縁性接着剤を塗布してもよい。
又、係止部材の形状は、皿バネ２９に限られない。 It goes without saying that the present invention is not limited to the above embodiments and extends to various modifications and equivalents included in the ideas and scope of the present invention.
As the type of the insulator, in addition to the above-mentioned film-like synthetic resin, a ceramic material may be used, or an insulating adhesive may be applied.
Further, the shape of the locking member is not limited to the disc spring 29.

１ノッキングセンサ
９主体金具
１３筒状部
１３ｂ筒状部の外周面
１５鍔部
１７圧電素子
１９ウェイト
１９ａウェイトの天面
２５絶縁体
２９係止部材
２９ｉ係止部材の内周部
２９ｉ１円環部
２９ｉ２内周部の拡径部
２９ｓ係止部材の内周部の一部 1 Knocking sensor 9 Main metal fittings 13 Cylindrical part 13b Outer peripheral surface of tubular part 15 Collar 17 Piezoelectric element 19 Weight 19a Top surface of weight 25 Insulator 29 Locking member 29i Inner peripheral part of locking member 29i1 Circumferential part 29i2 Diameter expansion part of inner circumference 29s Part of inner circumference of locking member

Claims

筒状部と、該筒状部の一端側に位置し、筒状部の周方向外側に向かって突出する鍔部とを有する主体金具と、
前記筒状部の外周に嵌め込まれ、前記鍔部に面する側と反対側に天面を有する環状のウェイトと、
前記筒状部の外周に嵌め込まれ、前記鍔部と前記ウェイトとの間に挟まれる環状の圧電素子と、
前記ウェイトの天面に接すると共に前記筒状部の外周に固定され、該ウェイトを係止する環状の皿バネからなる係止部材と、
前記筒状部の外周から周方向外側に向かって突出し、前記係止部材の上面に接する突出部と、
前記鍔部と前記圧電素子との間に介在する絶縁体と、を備えたノッキングセンサであって、
前記筒状部の軸方向の断面画像において、前記係止部材は、当該係止部材の内周部の角部から周方向外側にそれぞれ延びる２つの輪郭と前記筒状部の外周面との２つの接点Ｐ１，Ｐ２を結ぶ線分よりも、該筒状部の内部に自身が介在するように前記筒状部の外周面に食い込んでいることを特徴とするノッキングセンサ。 A main metal fitting having a tubular portion and a flange portion located on one end side of the tubular portion and projecting outward in the circumferential direction of the tubular portion.
An annular weight that is fitted on the outer circumference of the tubular portion and has a top surface on the side opposite to the side facing the flange portion.
An annular piezoelectric element fitted on the outer circumference of the tubular portion and sandwiched between the flange portion and the weight.
A locking member made of an annular disc spring that is in contact with the top surface of the weight and is fixed to the outer periphery of the tubular portion to lock the weight.
A protruding portion that protrudes outward in the circumferential direction from the outer circumference of the tubular portion and is in contact with the upper surface of the locking member.
A knocking sensor including an insulator interposed between the flange portion and the piezoelectric element.
In the axial cross-sectional image of the tubular portion, the locking member has two contours extending outward in the circumferential direction from the corners of the inner peripheral portion of the locking member and two outer peripheral surfaces of the tubular portion. A knocking sensor characterized in that it bites into the outer peripheral surface of the tubular portion so as to intervene inside the tubular portion rather than a line segment connecting the two contacts P1 and P2 .

前記係止部材を前記ウェイトの前記天面側から見たとき、前記内周部は、円環部と、該円環部より径方向外側に位置して前記円環部に繋がる１つ以上の拡径部とを有し、
前記拡径部と前記円環部との接続部における前記筒状部の外周面への食い込み量Ｌ１よりも、隣接する前記接続部の間の前記円環部の周方向中央における前記筒状部の外周面への食い込み量Ｌ２が大きい請求項１記載のノッキングセンサ。 When the locking member is viewed from the top surface side of the weight, the inner peripheral portion is located at the annular portion and radially outward from the annular portion, and is connected to the annular portion. It has an enlarged diameter part and
The tubular portion at the center of the circumferential direction between the adjacent connecting portions, rather than the amount L1 of the tubular portion biting into the outer peripheral surface at the connecting portion between the enlarged diameter portion and the annular portion. The knocking sensor according to claim 1, wherein the amount of biting into the outer peripheral surface L2 is large.

前記係止部材の厚みが１ｍｍ以上である請求項１又は２記載のノッキングセンサ。 The knocking sensor according to claim 1 or 2, wherein the thickness of the locking member is 1 mm or more.