JPH0511772B2 - - Google Patents
Info
- Publication number
- JPH0511772B2 JPH0511772B2 JP23999385A JP23999385A JPH0511772B2 JP H0511772 B2 JPH0511772 B2 JP H0511772B2 JP 23999385 A JP23999385 A JP 23999385A JP 23999385 A JP23999385 A JP 23999385A JP H0511772 B2 JPH0511772 B2 JP H0511772B2
- Authority
- JP
- Japan
- Prior art keywords
- piezoelectric element
- piezoelectric
- conditions
- pressure
- deterioration
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 230000032683 aging Effects 0.000 description 12
- 230000006866 deterioration Effects 0.000 description 9
- 230000007423 decrease Effects 0.000 description 6
- 230000010287 polarization Effects 0.000 description 5
- 230000000694 effects Effects 0.000 description 4
- 239000000446 fuel Substances 0.000 description 2
- 238000002347 injection Methods 0.000 description 2
- 239000007924 injection Substances 0.000 description 2
- 230000000087 stabilizing effect Effects 0.000 description 2
- 238000001514 detection method Methods 0.000 description 1
- 230000002542 deteriorative effect Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000002203 pretreatment Methods 0.000 description 1
- 230000001360 synchronised effect Effects 0.000 description 1
Landscapes
- Transmission And Conversion Of Sensor Element Output (AREA)
- Measurement Of Mechanical Vibrations Or Ultrasonic Waves (AREA)
Description
【発明の詳細な説明】
〈産業上の利用分野〉
本発明は、ノツキングや燃料の噴出によつて振
動を生じるエンジンのシリンダーブロツク等の振
動体の表面に設けて、その振動を検知する圧電セ
ンサーに関する。[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a piezoelectric sensor that is provided on the surface of a vibrating body such as an engine cylinder block that generates vibrations due to knocking or fuel injection to detect the vibrations. Regarding.
〈従来技術〉
この種の圧電センサーｓのもつとも単純なもの
は、環状の圧電素子ａの表裏に電極ｂ，ｂを設け
てなり、第１図に示すように、シリンダーブロツ
ク等の振動体ｃの表面に突成した螺子杆ｄに、挟
圧用ワツシヤーｅ，ｅを当てて嵌着し、さらにそ
の上部から前記螺子杆ｄに締付けナツトｆを螺締
て、振動体ｃの表面と、前記締付けナツトｆとで
圧電素子ｃを挟持するようにして装着される。か
かる装着状態において、前記振動体ｃの、ノツキ
ングや燃料噴射等に伴つて発生する被検出振動に
より、前記圧電素子ｃに圧縮歪が生じ、該圧電素
子ｃから前記振動に同期する出力信号が発生す
る。<Prior art> A very simple piezoelectric sensor s of this type has electrodes b, b provided on the front and back sides of a ring-shaped piezoelectric element a, and as shown in FIG. Apply pressure washers e and e to the screw rod d protruding from the surface and fit them, and then screw the tightening nut f onto the screw rod d from above, so that the surface of the vibrating body c and the tightening nut The piezoelectric element c is sandwiched between the piezoelectric element f and the piezoelectric element c. In this installed state, compressive strain is generated in the piezoelectric element c due to detected vibrations of the vibrating body c that occur due to knocking, fuel injection, etc., and an output signal synchronized with the vibrations is generated from the piezoelectric element c. do.
前記圧電センサーｓは、点火栓の螺装部に外嵌
して取付けられる場合もある。 The piezoelectric sensor s may be attached to the threaded part of the ignition plug by fitting it onto the outside.
〈発明が解決しようとする問題点〉
ところで、前記したエンジンのシリンダーブロ
ツクに適用する場合のように、圧電素子を高温、
高圧下におくと、該圧電素子の経時変化速度が加
速され、劣化し易くなる。<Problems to be Solved by the Invention> By the way, as in the case where the piezoelectric element is applied to the cylinder block of the engine described above, the piezoelectric element is exposed to high temperatures,
When placed under high pressure, the rate of change over time of the piezoelectric element is accelerated, making it more likely to deteriorate.
すなわち、圧電素子は、圧電性を得るため、あ
らかじめ直流電圧を印加して、分極処理をする。
かかる分極処理により、前記素子を構成する微結
晶粒は反転して、単一の分域となる。このよう
に、分極方向に揃つた状態で、圧電素子は、分極
方向に延び、それと垂直な方向に収縮する歪を生
じ、圧電性を示すこととなる。ところでこの状態
にある圧電素子は、エネルギー的に不安定な状態
にあり、外部から熱、圧力等のエネルギーが加わ
ると、前記した歪が取り除かれ易い状態となる。
而て、前述のように、劣化を生じ易くなるのであ
る。 That is, in order to obtain piezoelectricity, a piezoelectric element is polarized by applying a DC voltage in advance.
By such polarization treatment, the microcrystalline grains constituting the element are inverted and become a single domain. In this way, in a state where the piezoelectric elements are aligned in the polarization direction, the piezoelectric element exhibits a strain that extends in the polarization direction and contracts in a direction perpendicular to the polarization direction, and exhibits piezoelectricity. By the way, the piezoelectric element in this state is in an energetically unstable state, and when energy such as heat or pressure is applied from the outside, the above-described strain is easily removed.
Therefore, as mentioned above, deterioration is more likely to occur.
この特性の劣化を生ずると、圧電センサーｓの
出力が低下し、ノツキング等の被検出振動が発生
しても、信号処理装置で設定された閾値以下とな
つて、振動検知が不能となる。 When this characteristic deteriorates, the output of the piezoelectric sensor s decreases, and even if a detected vibration such as knocking occurs, the output falls below a threshold set by the signal processing device, making it impossible to detect the vibration.
本発明は、かかる特性劣化による影響を可及的
に除去する構成を備えた圧電センサーｓの提供を
目的とするものである。 An object of the present invention is to provide a piezoelectric sensor s having a configuration that eliminates as much as possible the influence of such characteristic deterioration.
〈問題点を解決するための手段〉
本発明は、適用する圧電素子に、あらかじめ、
その使用条件よりも高い温度と圧力を所定時間加
えて、前処理（エージング処理）するようにした
ものである。<Means for Solving the Problems> The present invention provides the piezoelectric element to be applied with the following steps:
Pretreatment (aging treatment) is performed by applying a temperature and pressure higher than the usage conditions for a predetermined period of time.
〈作用〉
圧電素子の劣化（出力低下）と時間との関係
は、最初急速に降下し、徐々に緩慢となる低下曲
線を描く。すなわち、分極後に、外部から熱、圧
力等のエネルギーを加えると、最初はこの影響を
強く受け、急速に劣化するが、徐々に劣化速度が
低下し安定化する。例えば、最初の100時間経過
時の圧電定数の低下量は、次の1000時間経過時の
低下量にほぼ相当する。<Operation> The relationship between the deterioration (reduction in output) of the piezoelectric element and time depicts a decline curve that first drops rapidly and then gradually slows down. That is, when energy such as heat and pressure is applied from the outside after polarization, the material is initially strongly affected and rapidly deteriorates, but the deterioration rate gradually decreases and becomes stable. For example, the amount of decrease in the piezoelectric constant after the first 100 hours approximately corresponds to the amount of decrease after the next 1000 hours.
そこで、実際の使用に先立つて、あらかじめ、
その使用条件よりも高い温度と圧力を所定時間加
えて前処理（エージング処理）をし、強制的に劣
化させることにより、使用時の出力低下量を減少
でき、経時変化速度を低下することができること
となる。 Therefore, before actual use,
By applying pre-treatment (aging treatment) to a temperature and pressure higher than the operating conditions for a predetermined period of time and forcibly deteriorating the product, it is possible to reduce the amount of output decrease during use and reduce the rate of deterioration over time. becomes.
〈実施例〉
第２図は、エージング処理を施すために用いら
れる装置の一例を示す。<Example> FIG. 2 shows an example of an apparatus used for performing aging treatment.
ここで、１は恒温槽であつて、その内部は任意
の温度調整を施し得るようになつている。前記恒
温槽１下には、上下方向に伸縮するピストン２を
槽内に突出させたシリンダー３が配設される。前
記ピストン２は、筒枠４に覆われている。また前
記恒温槽１外には、前記シリンダー３に油圧力を
作用させるための油圧発生器５が設けられ、ウエ
イト６を適宜に選定することにより、油圧の調整
を任意に施し得るようになつている。 Here, 1 is a constant temperature bath, and the temperature inside thereof can be arbitrarily adjusted. A cylinder 3 having a piston 2 that extends and contracts in the vertical direction protrudes into the bath is disposed below the constant temperature bath 1. The piston 2 is covered by a cylinder frame 4. Further, a hydraulic pressure generator 5 for applying hydraulic pressure to the cylinder 3 is provided outside the constant temperature bath 1, and by appropriately selecting a weight 6, the hydraulic pressure can be adjusted as desired. There is.
圧電素子ａは筒枠４の上壁と、ピストン２の上
端間に配置される。而て、恒温槽１を所定の高温
にしてから、指定された重さのウエイト６を、油
圧発生器５に装着すると、シリンダ３に所定油圧
が作用し、圧電素子ａはピストン２の伸張によ
り、筒枠４の上壁下で挟圧力を受ける。これによ
り該圧電素子ａは、高温下で、高圧力を受けて、
エージング処理が施されることとなる。 The piezoelectric element a is arranged between the upper wall of the cylinder frame 4 and the upper end of the piston 2. After heating the constant temperature bath 1 to a predetermined high temperature, when a weight 6 of a specified weight is attached to the hydraulic pressure generator 5, a predetermined hydraulic pressure is applied to the cylinder 3, and the piezoelectric element a is activated by the expansion of the piston 2. , receives a clamping force under the upper wall of the cylinder frame 4. As a result, the piezoelectric element a receives high pressure under high temperature,
Aging treatment will be performed.
・エージング条件の設定
エンジンのシリンダーブロツクに適用する圧力
センサーに用いられる圧電素子のエージング条件
を設定するために、前記装置を用いて、圧電素子
ａに2600Kg／cm2の圧力を加え、かつ恒温槽１内の
温度を230℃、250℃の二種類の温度に設定し、該
温度下における圧電定数d33の変化を検出して、
その経時特性を調べた。・Setting of aging conditions In order to set the aging conditions of the piezoelectric element used in the pressure sensor applied to the cylinder block of the engine, a pressure of 2600 kg/cm 2 was applied to the piezoelectric element a using the above device, and a constant temperature bath was applied. 1 is set at two temperatures, 230°C and 250°C, and the change in piezoelectric constant d 33 is detected under these temperatures.
We investigated its characteristics over time.
尚、前記圧電センサーは、その実際の使用状態
で、温度約200℃、圧力1000Kg／cm2程度が加わる
ものと予想される。 It is expected that the piezoelectric sensor will be subjected to a temperature of about 200° C. and a pressure of about 1000 kg/cm 2 in actual use.
この結果を第３図に示す。この図にあつて、特
性の低下は、最初急速に下降し、時間経過ととも
に徐々に緩慢となる低下曲線を描くことから、該
特性変化の把握を容易とするために経過時間は対
数目盛をとつている。 The results are shown in FIG. In this figure, since the deterioration of the characteristics draws a curve that initially drops rapidly and then gradually slows down as time passes, the elapsed time is shown on a logarithmic scale to make it easier to understand the changes in characteristics. It's on.
圧電センサーをエンジンのシリンダーブロツク
に適用した場合には、約500時間使用するとセン
サー出力の劣化は５〜10％程度となる。この程度
の劣化を生じさせる条件を第３図から選定する
と、250℃−2600Kg／cm2−２時間となる。そこで、
該条件をエージング条件とした。尚 230℃では、
５〜10％の劣化を生じるまでに10時間を要し、作
業能率上適当ではない。 When a piezoelectric sensor is applied to an engine cylinder block, the sensor output deteriorates by about 5 to 10% after approximately 500 hours of use. When the conditions that cause this degree of deterioration are selected from FIG. 3, they are 250° C. - 2600 Kg/cm 2 - 2 hours. Therefore,
These conditions were defined as aging conditions. Furthermore, at 230℃,
It takes 10 hours to cause 5 to 10% deterioration, which is not appropriate in terms of work efficiency.
尚エージング条件は、使用条件等に対応して
種々設定され得る。ただし、あまり過剰な条件と
すると、圧電特性が低下し過ぎて、所要特性を得
ることができなくなるから、その条件には限界が
ある。 Note that the aging conditions can be set in various ways depending on the usage conditions and the like. However, if the conditions are too excessive, the piezoelectric characteristics will deteriorate too much, making it impossible to obtain the required characteristics, so there is a limit to these conditions.
・特性比較
前記したエージング処理の効果を確かめるため
に、エージングをしていない製品と、エージング
処理製品の特性を同一条件で検出し、比較した。- Comparison of characteristics In order to confirm the effect of the aging treatment described above, the characteristics of a non-aged product and an aged product were detected under the same conditions and compared.
第４図は、該特性を検知するために用いた装置
である。 FIG. 4 shows the device used to detect this characteristic.
ここで、１０は、杆部の先端に螺子部１１を有
するボルトであつて、該ボルト１０に金属ブロツ
ク１２、ワツシヤー１３、被験物となる圧電素子
ａ、ワツシヤー１３及びロードワツシヤー１４が
夫々外嵌され、しかる後に、螺子部１１にナツト
１５が螺合される。かかる構成にあつて、圧電素
子ａは該ナツト１５の締付けにより挟持され、そ
の両面に圧力を受ける。この挟圧力は、ロードワ
ツシヤー１４により検知される。このためナツト
１５の締付けトルクを調整することにより、任意
圧力の設定が可能となる。 Here, 10 is a bolt having a threaded part 11 at the tip of the rod part, and a metal block 12, a washer 13, a piezoelectric element a to be tested, a washer 13, and a load washer 14 are attached to the bolt 10, respectively. After that, the nut 15 is screwed onto the threaded portion 11. In this configuration, the piezoelectric element a is held by tightening the nut 15 and receives pressure on both sides thereof. This clamping force is detected by the load washer 14. Therefore, by adjusting the tightening torque of the nut 15, it is possible to set an arbitrary pressure.
前記装置で圧電素子ａを締付けた状態で、230
℃下に置いて、時間経過に伴う圧電定数d33の変
化を検出した。その結果を第５図イ，ロに示す。
ここで経過時間は対数目盛をとる。 With the piezoelectric element a tightened in the above device, 230
℃, and changes in the piezoelectric constant d33 over time were detected. The results are shown in Figure 5 A and B.
Here, the elapsed time is on a logarithmic scale.
この第５図イで明らかなように、エージングを
していない製品は、時間の経過にともなう特性低
下が著しいことが示された。一方、第５図ロのよ
うにエージング処理製品の場合の特性の低下は、
第５図イに比して緩勾配であつた。 As is clear from FIG. 5A, it was shown that the properties of the unaged product significantly deteriorated over time. On the other hand, as shown in Figure 5 (b), the characteristics of aging-treated products deteriorate due to
The slope was gentler than that in Figure 5A.
このことから、エージング処理の効果が確認さ
れた。 From this, the effect of aging treatment was confirmed.
〈発明の効果〉
本発明は、上述のように、圧電素子ａに、その
使用条件よりも高い温度と圧力を所定時間加え
て、あらかじめ劣化させ、使用の際にその劣化の
割合を小さくするようにしたから、圧電センサー
ｓの出力が安定し、信号処理装置に設定された閾
値を長時間に渡つて有効とする等、圧電センサー
ｓの特性を安定下できる優れた効果がある。<Effects of the Invention> As described above, the present invention applies a temperature and pressure higher than the usage conditions to the piezoelectric element a for a predetermined period of time to deteriorate the piezoelectric element a in advance, so as to reduce the rate of deterioration during use. This has an excellent effect of stabilizing the characteristics of the piezoelectric sensor s, such as stabilizing the output of the piezoelectric sensor s and making the threshold value set in the signal processing device valid for a long time.
第１図は圧電センサーｓの一例を示す縦断側面
図、第２図はエージング処理装置の一例を示す縦
断側面図、第３図は圧電定数d33の経時変化を示
すグラフ、第４図は特性検知装置の縦断側面図、
第５図イはエージングをしていない製品の圧電定
数d33の経時変化を示すグラフ、第５図ロはエー
ジング処理製品の同グラフである。
ｓ……圧電センサー、ａ……圧電素子。
Fig. 1 is a longitudinal side view showing an example of a piezoelectric sensor s, Fig. 2 is a longitudinal side view showing an example of an aging treatment device, Fig. 3 is a graph showing changes over time in the piezoelectric constant d 33 , and Fig. 4 is a characteristic Vertical side view of the detection device,
Figure 5A is a graph showing the change over time in the piezoelectric constant d33 of a product that has not been aged, and Figure 5B is the same graph for an aged product. s...Piezoelectric sensor, a...Piezoelectric element.
Claims (1)
圧電センサーにおいて、前記圧電素子として、あ
らかじめ、その使用条件よりも高い温度と圧力を
所定時間加えたものを用いたことを特徴とする圧
電センサー。1. A piezoelectric sensor equipped with a piezoelectric element that converts vibration into an electrical signal, characterized in that the piezoelectric element is previously subjected to a temperature and pressure higher than the conditions of use for a predetermined period of time.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP23999385A JPS62100618A (en) | 1985-10-26 | 1985-10-26 | Piezoelectric sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP23999385A JPS62100618A (en) | 1985-10-26 | 1985-10-26 | Piezoelectric sensor |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS62100618A JPS62100618A (en) | 1987-05-11 |
| JPH0511772B2 true JPH0511772B2 (en) | 1993-02-16 |
Family
ID=17052875
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP23999385A Granted JPS62100618A (en) | 1985-10-26 | 1985-10-26 | Piezoelectric sensor |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS62100618A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9020158B2 (en) | 2008-11-20 | 2015-04-28 | Harman International Industries, Incorporated | Quiet zone control system |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2802133B1 (en) * | 1999-12-13 | 2002-02-15 | Ct Tech Des Ind Mecaniques | CONTAINER CRIMPING CAM CAM WITH LOAD CELLS |
-
1985
- 1985-10-26 JP JP23999385A patent/JPS62100618A/en active Granted
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9020158B2 (en) | 2008-11-20 | 2015-04-28 | Harman International Industries, Incorporated | Quiet zone control system |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS62100618A (en) | 1987-05-11 |
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