WO2014136388A1 - Dispositif de détection de contrainte - Google Patents

Dispositif de détection de contrainte Download PDF

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Publication number
WO2014136388A1
WO2014136388A1 PCT/JP2014/000849 JP2014000849W WO2014136388A1 WO 2014136388 A1 WO2014136388 A1 WO 2014136388A1 JP 2014000849 W JP2014000849 W JP 2014000849W WO 2014136388 A1 WO2014136388 A1 WO 2014136388A1
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WO
WIPO (PCT)
Prior art keywords
detection
strain
signal
equation
sensitivity
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Application number
PCT/JP2014/000849
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English (en)
Japanese (ja)
Inventor
孔明 藤田
基樹 緒方
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パナソニック株式会社
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Publication date
Application filed by パナソニック株式会社 filed Critical パナソニック株式会社
Publication of WO2014136388A1 publication Critical patent/WO2014136388A1/fr

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L1/00—Measuring force or stress, in general
    • G01L1/10—Measuring force or stress, in general by measuring variations of frequency of stressed vibrating elements, e.g. of stressed strings
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L9/00—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means
    • G01L9/0001—Transmitting or indicating the displacement of elastically deformable gauges by electric, electro-mechanical, magnetic or electro-magnetic means
    • G01L9/0008—Transmitting or indicating the displacement of elastically deformable gauges by electric, electro-mechanical, magnetic or electro-magnetic means using vibrations
    • G01L9/0013—Transmitting or indicating the displacement of elastically deformable gauges by electric, electro-mechanical, magnetic or electro-magnetic means using vibrations of a string

Definitions

  • the present invention relates to a strain detection device that detects strain generated by applying a load to a strain generating body.
  • Patent Document 1 discloses a conventional strain detection device including two beams formed in one substrate and orthogonal to each other. The strain can be detected by detecting the change in the vibration frequency of the beam according to the strain while vibrating each beam at the natural frequency.
  • the vibration frequencies of the two beams are made different in order to avoid mutual interference of the vibrations of the beams.
  • the detection accuracy may deteriorate.
  • the strain detection device includes a substrate configured to be provided on the strain body, a first beam supported on the substrate so as to be able to vibrate and extending in the extending direction, and supported on the substrate so as to be able to vibrate. And a second beam extending in a direction different from the extending direction, a drive circuit configured to vibrate the first and second beams, and a detection circuit.
  • the drive circuit is configured to cause the first beam to vibrate at a first vibration frequency and to cause the second beam to vibrate at a second vibration frequency different from the first vibration frequency.
  • the detection circuit is obtained by squaring the first square signal obtained by squaring the first detection signal based on the vibration of the first beam and the second detection signal based on the vibration of the second beam.
  • the second square signal is obtained. Further, the detection circuit operates to integrate a sensitivity ratio, which is a ratio between the detection sensitivity of the first beam and the detection sensitivity of the second beam, to the second square signal to obtain an integrated signal. Further, the detection circuit operates to detect the amount of distortion based on the difference between the integrated signal and the first square signal.
  • a sensitivity ratio which is a ratio between the detection sensitivity of the first beam and the detection sensitivity of the second beam
  • This distortion detector has high detection accuracy.
  • FIG. 1 is a perspective view of a strain detection apparatus according to an embodiment of the present invention.
  • 2 is a cross-sectional view taken along line 2-2 of the strain detection apparatus shown in FIG.
  • FIG. 3 is a top view of the strain detection element of the strain detection apparatus according to the embodiment.
  • FIG. 4 is a diagram illustrating a detection signal of a strain detection element of the strain detection apparatus according to the embodiment.
  • FIG. 5 is a block diagram of a detection circuit of the distortion detection apparatus according to the embodiment.
  • FIG. 6 is a diagram illustrating the vibration frequency of the beam in the strain detection apparatus according to the embodiment.
  • FIG. 1 is a perspective view of a strain detection apparatus 1001 according to an embodiment of the present invention.
  • FIG. 2 is a sectional view taken along line 2-2 of the strain detection apparatus 1001 shown in FIG.
  • the strain detection device 1001 is configured to measure the pressure of a fluid to be detected such as the hydraulic pressure of brake oil in a vehicle brake, for example.
  • the strain detection device 1001 includes a container 1 configured to accommodate the fluid 99 to be detected therein, a strain detection element 202 mounted on a flat flat portion 1a provided on a side surface of the container 1, and a strain detection element. And a control circuit element 3 disposed on the surface of 202.
  • the container 1 has a cylindrical portion 101a having an opening 101b and a bottom 101c that closes the cylindrical portion 101a on the opposite side of the opening 101b.
  • the flat surface portion 1a of the container 1 functions as a strain generating body that deforms as the pressure of the fluid 99 to be detected contained in the container 1 increases.
  • the strain detection element 202 converts the deformation of the planar portion 1a, which is a strain generating body, into an electric signal and outputs it.
  • FIG. 3 is a top view of the strain detection element 202.
  • the strain detection element 202 includes a rectangular substrate 4 made of silicon, and a pair of beams 5 and 6 arranged in a T shape at the center of the substrate 4.
  • the beam 5 extends in the extending direction 1001A
  • the beam 6 extends in an extending direction 1001B different from the extending direction 1001A.
  • the stretching direction 1001B is perpendicular to the stretching direction 1001A, but may not be perpendicular to the stretching direction 1001A.
  • the beam 5 has a drive electrode 107a and a detection electrode 108a
  • the beam 6 has a drive electrode 107b and a detection electrode 108b.
  • Each of the drive electrodes 107a and 107b and the detection electrodes 108a and 108b has a laminated structure including a piezoelectric thin film made of a piezoelectric material such as PZT, and a Pt electrode and an Au electrode sandwiching the piezoelectric thin film.
  • the piezoelectric thin film can be expanded and contracted by applying a potential difference between the Pt electrode and the Au electrode, and the Pt electrode and the Au electrode can be expanded by bending the piezoelectric thin film. A potential difference can be generated between the two.
  • the substrate 4 has a control circuit element 3 provided at a position different from the beams 5 and 6.
  • the control circuit element 3 includes a drive circuit 3a that forms drive signals 7a and 7b applied to the drive electrodes 107a and 107b, respectively, and a detection circuit 3b that processes detection signals 8a and 8b output from the detection electrodes 108a and 108b, respectively. It has.
  • the conductors 7c and 7d electrically connect the drive circuit 3a to the drive electrodes 107a and 107b, respectively.
  • Conductors 8c and 8d electrically connect detection circuit 3b to detection electrodes 108a and 108b, respectively.
  • the drive circuit 3a applies drive signals 7a and 7b corresponding to the natural resonance frequencies of the beams 5 and 6 to the drive electrodes 107a and 107b of the beams 5 and 6, respectively.
  • the beams 5 and 6 vibrate at a vibration frequency.
  • the pressure of the fluid 99 to be detected which is brake oil, changes due to application of brake pressure or the like
  • the flat portion 1a of the container 1 is deformed, and the strain detecting element 202 is bent by this deformation.
  • detection signals 8a and 8b which are frequencies of signals output from the detection electrodes 108a and 108b, change.
  • the values of the detection signals 8a and 8b are the vibration frequencies of the beams 5 and 6. Changes in the detection signals 8 a and 8 b that are the vibration frequencies of the beams 5 and 6 correspond to changes in the pressure of the fluid 99 to be detected.
  • FIG. 4 shows the vibration frequencies 11 and 13 of the beams 5 and 6, which are the values of the detection signals 8a and 8b of the strain detection apparatus 1001.
  • the horizontal axis indicates the magnitude of the external force 9 shown in FIG. 3 that is the pressure applied to the flat portion 1 a
  • the vertical axis indicates the vibration frequency of the beams 5 and 6.
  • the direction of the external force 9 from the side shown in FIG. 3 coincides with the extending direction 1001A in which the beam 5 extends, and is perpendicular to the extending direction 1001B of the beam 6.
  • the detection circuit 3b detects the difference between the detection signals 8a and 8b output from the detection electrodes 108a and 108b, respectively, so that the detection circuit 3b changes the frequency according to the change in the external force 9, that is, the pressure of the fluid 99 to be detected. Can be output efficiently.
  • FIG. 5 is a block diagram of the detection circuit 3 b of the control circuit element 3.
  • the detection circuit 3 b includes integrators 14, 15, 16 and a subtractor 17.
  • the integrator 14 squares the detection signal 8a output from the beam 5 to obtain a square signal 14a.
  • the integrator 15 squares the detection signal 8b output from the beam 6 to obtain a square signal 15a.
  • the detection sensitivity of the beams 5 and 6 is defined as the amount of change of the square signals 14a and 15a when a unit strain is applied to the beams 5 and 6.
  • the ratio of the detection sensitivity of the beam 5 to the detection sensitivity of the beam 6 is defined as a sensitivity ratio k.
  • the integrator 16 adds the sensitivity ratio k to the square signal 15a to obtain an integrated signal 16a.
  • the differentiator 17 obtains a difference signal 17a that is a difference between the integrated signal 16a and the square signal 14a.
  • the strain detection apparatus 1001 can detect the external force 9, that is, the strain of the flat portion 1 a of the container 1 that is a strain generating body, based on the difference signal 17 a.
  • the detection circuit 3b includes the square signal 14a obtained by squaring the detection signal 8a based on the vibration of the beam 5, and the square signal 15a obtained by squaring the detection signal 8b based on the vibration of the beam 6. Get.
  • the detection circuit 3b integrates a sensitivity ratio, which is a ratio of the detection sensitivity of the beam 5 and the detection sensitivity of the beam 6, to the square signal 15a to obtain an integrated signal 16a. Further, the detection circuit 3b operates to detect the amount of distortion based on the difference (difference signal 17a) between the integrated signal 16a and the square signal 14a.
  • the strain detection apparatus 1001 can improve the temperature characteristics and improve the detection accuracy by the above processing.
  • the above processing will be described in detail below.
  • the strain ⁇ applied to the beam extending in the extending direction and the vibration frequency f of the beam are the Young's modulus E of the beam, the density ⁇ of the beam, the length L of the beam in the extending direction, The thickness h in the direction perpendicular to the stretching direction, the cross-sectional area A in the direction perpendicular to the stretching direction of the beam, and the cross-sectional secondary coefficient I of the beam are expressed by (Equation 1).
  • Equation 3 is obtained by squaring both sides of (Equation 1).
  • Equation 3 is a linear equation with the strain ⁇ as a variable.
  • the detection sensitivity of the beam is a coefficient C 2 ⁇ S multiplied by the strain ⁇ .
  • the vibration frequencies f 1 and f 2 of the beams 5 and 6, which are the frequencies of the detection signals 8a and 8b caused by the strains ⁇ 1 and ⁇ 2 applied to the beams 5 and 6, respectively, are based on (Equation 3) and (Expression 6).
  • Strain is the sum of strain due to external force and thermal strain due to temperature change.
  • Thermal strain is isotropic.
  • Strain epsilon 1 [sigma occurs in the beam 5 by an external force 9
  • strain epsilon 2 [sigma] is generated in the beam 6.
  • a thermal strain ⁇ T occurs in the beams 5 and 6 due to a change in temperature.
  • (Equation 5) and (Equation 6) can be transformed into (Equation 11) and (Equation 12), respectively.
  • the difference value ⁇ f a 2 between the detection signals 8 a and 8 b is defined by (Equation 13) by the vibration frequencies f 1 and f 2 that are the values of the detection signals 8 a and 8 b detected from the two beams 5 and 6 and the sensitivity ratio k. Is done.
  • the sensitivity ratio k which is the ratio of the detection sensitivity of the beam 5 to the detection sensitivity of the beam 6, is expressed by (Expression 14).
  • Equation 15 Since the third term of (Equation 15) is 0 when the right side of (Equation 14) is substituted into the sensitivity ratio k, (Equation 15) can be transformed into (Equation 16).
  • the strain ⁇ 1 ⁇ and the strain ⁇ 2 ⁇ satisfy ( Equation 17) by the Poisson ratio ⁇ .
  • Equation 16 can be transformed into (Equation 18) by (Equation 17).
  • Equation 18 is a linear function of strain ⁇ 1 ⁇ generated in the beam 5 by the external force 9. In other words, ( Equation 18) is linear with respect to the strain ⁇ 1 ⁇ . Therefore, the distortion detection apparatus 1001 can easily perform signal processing. Since (Equation 18) does not include the thermal strain ⁇ T and is not affected by the thermal strain ⁇ T , the strain detection device 1001 improves the temperature characteristics and the magnitude of the external force 9 by the difference value ⁇ f a 2 with high detection accuracy. That is, it is possible to detect the magnitude of strain of the flat portion 1a of the container 1 that is a strain generating body.
  • the strain detection device 1001 is affected by hysteresis due to environmental changes such as temperature changes. In general, hysteresis reduces measurement accuracy.
  • FIG. 6 shows changes in the vibration frequencies f 1 and f 2 of the beams 5 and 6 with respect to the ambient temperature of the strain detection apparatus 1001.
  • the horizontal axis represents temperature
  • the vertical axis represents the vibration frequencies f 1 and f 2 of the beams 5 and 6.
  • frequencies f1, f2 at the first temperature of the ambient temperature T 0 is the frequency f 21.
  • Raising the temperature from the temperature T 0 to the temperature T U is the frequency in the direction of the arrow in FIG. 6 changes.
  • lowering the temperature from the temperature T U the frequency changes in different lines than when the temperature rises, the frequency f 1, f 2 when the temperature reaches the temperature T 0 again the first frequency f 21 the frequency f 22 which is different.
  • the strain detection apparatus can improve detection accuracy, and is particularly useful in a strain detection apparatus that measures the pressure of a fluid to be detected such as a vehicle brake.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Measuring Fluid Pressure (AREA)

Abstract

La présente invention concerne un dispositif de détection de contrainte comprenant un substrat conçu pour être installé sur un élément de contrainte, une première et une seconde tige supportées par le substrat afin d'être en mesure de dévier de façon vibrante, un circuit d'attaque et un circuit de détection. Ledit circuit de détection fonctionne de manière à obtenir ce qui suit : un premier signal au carré obtenu en élevant au carré un premier signal de détection basé sur les vibrations de la première tige ; et un second signal au carré obtenu en élevant au carré un second signal de détection basé sur les vibrations de la seconde tige. Le circuit de détection fonctionne également de manière à obtenir un signal de produit en multipliant le second signal au carré par un rapport de sensibilité, c'est-à-dire le rapport entre la sensibilité de détection de la première tige et la sensibilité de détection de la seconde tige. Le circuit fonctionne en outre de manière à détecter une quantité de contrainte sur la base de la différence entre le signal de produit et le premier signal au carré. La précision de détection du dispositif de détection de contrainte selon l'invention est élevée.
PCT/JP2014/000849 2013-03-08 2014-02-19 Dispositif de détection de contrainte WO2014136388A1 (fr)

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Application Number Priority Date Filing Date Title
JP2013-046312 2013-03-08
JP2013046312A JP2016102649A (ja) 2013-03-08 2013-03-08 歪検出装置

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WO2014136388A1 true WO2014136388A1 (fr) 2014-09-12

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106108907A (zh) * 2016-06-17 2016-11-16 合肥工业大学 一种足底压力分布检测装置

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS62144036A (ja) * 1985-12-02 1987-06-27 ザ　シンガ−　コンパニ↓− 系に加えられる力の関数として固有振動数に関連させられる一対の周波数を解析する装置および方法
JPH09500726A (ja) * 1993-07-20 1997-01-21 ハネウエル・インコーポレーテッド 共振型集積マイクロビームセンサの静圧補償
JP2011085407A (ja) * 2009-10-13 2011-04-28 Yokogawa Electric Corp 振動式圧力センサ
JP2012242188A (ja) * 2011-05-18 2012-12-10 Panasonic Corp 物理量センサ
WO2013132842A1 (fr) * 2012-03-07 2013-09-12 パナソニック株式会社 Capteur de charge

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS62144036A (ja) * 1985-12-02 1987-06-27 ザ　シンガ−　コンパニ↓− 系に加えられる力の関数として固有振動数に関連させられる一対の周波数を解析する装置および方法
JPH09500726A (ja) * 1993-07-20 1997-01-21 ハネウエル・インコーポレーテッド 共振型集積マイクロビームセンサの静圧補償
JP2011085407A (ja) * 2009-10-13 2011-04-28 Yokogawa Electric Corp 振動式圧力センサ
JP2012242188A (ja) * 2011-05-18 2012-12-10 Panasonic Corp 物理量センサ
WO2013132842A1 (fr) * 2012-03-07 2013-09-12 パナソニック株式会社 Capteur de charge

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106108907A (zh) * 2016-06-17 2016-11-16 合肥工业大学 一种足底压力分布检测装置
CN106108907B (zh) * 2016-06-17 2022-12-06 合肥工业大学 一种足底压力分布检测装置

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