WO2014136388A1 - Strain-detection device - Google Patents
Strain-detection device Download PDFInfo
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- 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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- detection
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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
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- 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.
Abstract
This strain-detection device is provided with a substrate designed so as to be provided on a strain element, first and second beams supported on the substrate so as to be able to vibrate in a flexing manner, a drive circuit, and a detection circuit. Said detection circuit functions so as to obtain the following: a first squared signal obtained by squaring a first detection signal based on the vibrations of the first beam; and a second squared signal obtained by squaring a second detection signal based on the vibrations of the second beam. The detection circuit also functions so as to obtain a product signal by multiplying the second squared signal by a sensitivity ratio, namely the ratio between the detection sensitivity of the first beam and the detection sensitivity of the second beam. The detection circuit further functions so as to detect a strain amount on the basis of the difference between the product signal and the first squared signal. This strain-detection device has a high degree of detection precision.
Description
本発明は、起歪体に荷重を加えることで生じる歪を検出する歪検出装置に関する。
The present invention relates to a strain detection device that detects strain generated by applying a load to a strain generating body.
特許文献１は、一つの基板内に形成されて互いに直交する２本の梁を備えた従来の歪検出装置を開示している。それぞれの梁を固有振動数で振動させながら、歪に応じた梁の振動周波数の変化を検出することで歪を検出することができる。この歪検出装置では、梁の振動の相互干渉を避けるため２つの梁の振動周波数を異ならせている。この検出装置では検出精度が劣化する場合がある。
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. In this strain detection apparatus, the vibration frequencies of the two beams are made different in order to avoid mutual interference of the vibrations of the beams. In this detection apparatus, the detection accuracy may deteriorate.
歪検出装置は、起歪体上に設けられるように構成されたた基板と、撓むように振動可能に基板に支持されて延伸方向に延びる第１の梁と、撓むように振動可能に基板に支持されるとともに延伸方向と異なる方向に延びる第２の梁と、第１と第２の梁を振動させるように構成された駆動回路と、検出回路とを備える。駆動回路は、第１の梁を第１の振動周波数で基本振動させるとともに第２の梁を第１の振動周波数とは異なる第２の振動周波数で基本振動させるように構成されている。検出回路は、第１の梁の振動に基づく第１の検出信号を自乗して得られた第１の自乗信号と、第２の梁の振動に基づく第２の検出信号を自乗して得られた第２の自乗信号とを得るように動作する。さらに、検出回路は、第１の梁の検出感度と第２の梁の検出感度の比である感度比を第２の自乗信号に積算して積算信号を得るように動作する。さらに、検出回路は、積算信号と第１の自乗信号の差分に基づき歪の量を検出するように動作する。
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.
この歪検出装置は高い検出精度を有する。
This distortion detector has high detection accuracy.
図１は本発明の実施の形態における歪検出装置１００１の斜視図である。図２は図１に示す歪検出装置１００１の線２－２における断面図である。歪検出装置１００１は、例えば車両用ブレーキにおけるブレーキオイルの油圧等の被検出流体の圧力を測定するように構成されている。歪検出装置１００１は、内部に被検出流体９９を収容するように構成された容器１と、容器１の側面に設けられた平坦な平面部１ａに実装された歪検出素子２０２と、歪検出素子２０２の表面に配置された制御回路素子３とを備える。容器１は、開口部１０１ｂを有する筒部１０１ａと、開口部１０１ｂの反対側で筒部１０１ａを塞ぐ底１０１ｃとを有する。容器１の平面部１ａは容器１に収容された被検出流体９９の圧力の増加に伴って変形する起歪体として機能する。歪検出素子２０２は起歪体である平面部１ａの変形を電気信号に変換して出力する。
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.
図３は歪検出素子２０２の上面図である。歪検出素子２０２は、シリコンからなる矩形状の基板４と、基板４の中央部分にＴ字状に配置された一対の梁５、６とを有する。梁５は延伸方向１００１Ａに延び、梁６は延伸方向１００１Ａと異なる延伸方向１００１Ｂに延びる。実施の形態１における歪検出装置１００１では延伸方向１００１Bは延伸方向１００１Ａに直角であるが、延伸方向１００１Ａに直角でなくてもよい。梁５は駆動電極１０７ａと検出電極１０８ａと有し、梁６は駆動電極１０７ｂと検出電極１０８ｂとを有する。駆動電極１０７ａ、１０７ｂおよび検出電極１０８ａ、１０８ｂのそれぞれは、ＰＺＴ等の圧電材料よりなる圧電体薄膜と、圧電体薄膜を挟むＰｔ電極とＡｕ電極とを有する積層構造を有する。駆動電極１０７ａ、１０７ｂおよび検出電極１０８ａ、１０８ｂでは、Ｐｔ電極とＡｕ電極との間に電位差を与えることで圧電薄膜を伸縮させことができ、かつ圧電体薄膜が撓むことでＰｔ電極とＡｕ電極との間に電位差を生じさせることができる。
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, and the beam 6 extends in an extending direction 1001B different from the extending direction 1001A. In the strain detection apparatus 1001 in Embodiment 1, 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, and 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. In the drive electrodes 107a and 107b and the detection electrodes 108a and 108b, 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.
基板４は、梁５、６と異なる位置に設けられた制御回路素子３を有している。制御回路素子３は、駆動電極１０７ａ、１０７ｂにそれぞれ印加される駆動信号７ａ、７ｂを形成する駆動回路３ａと、検出電極１０８ａ、１０８ｂからそれぞれ出力される検出信号８ａ、８ｂを処理する検出回路３ｂを備えている。導体７ｃ、７ｄは駆動回路３ａを駆動電極１０７ａ、１０７ｂにそれぞれ電気的に接続する。導体８ｃ、８ｄは検出回路３ｂを検出電極１０８ａ、１０８ｂにそれぞれ電気的に接続する。
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.
次に、歪検出装置１００１の被検出流体９９の圧力を検出する動作について説明する。駆動回路３ａは梁５、６の駆動電極１０７ａ、１０７ｂに梁５、６のそれぞれの固有共振周波数に応じた駆動信号７ａ、７ｂをそれぞれ印加する。これにより、梁５、６は振動周波数で基本振動をする。この状態でブレーキ圧印加などによりブレーキオイルである被検出流体９９の圧力が変化した場合に容器１の平面部１ａは変形し、この変形により歪検出素子２０２は撓む。歪検出素子２０２が撓むと検出電極１０８ａ、１０８ｂからそれぞれ出力される信号の周波数である検出信号８ａ、８ｂが変化する。検出信号８ａ、８ｂの値は梁５、６の振動の周波数である。梁５、６の振動周波数である検出信号８ａ、８ｂの変化は被検出流体９９の圧力の変化に対応する。
Next, an operation for detecting the pressure of the fluid 99 to be detected of the strain detection apparatus 1001 will be described. 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. As a result, the beams 5 and 6 vibrate at a vibration frequency. In this state, when 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. When the strain detection element 202 is bent, 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.
図４は歪検出装置１００１の検出信号８ａ、８ｂの値である梁５、６の振動の周波数１１、１３を示す。図４において、横軸は平面部１ａに印加される圧力である図３に示す外力９の大きさを示し、縦軸は梁５、６の振動周波数を示す。図３に示す側方からの外力９の方向は梁５が延びる延伸方向１００１Ａに一致し、梁６の延伸方向１００１Ｂと直角である。外力９が歪検出素子２０２に加わった場合、梁５を延伸方向１００１Ａで圧縮する圧縮応力１０が梁５に加わり、梁６を延伸方向１００１Ｂで引っ張る引張応力１２が梁６に加わる。図４に示すように、梁５の振動周波数１３は外力９が大きくなると低くなり、梁６の振動周波数１１は外力９が大きくなると高くなる。したがって、検出電極１０８ａ、１０８ｂからそれぞれ出力される検出信号８ａ、８ｂの差分を検出回路３ｂで検出することで、検出回路３ｂは外力９すなわち被検出流体９９の圧力の変化に応じた周波数の変化を効率よく出力することができる。
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. In FIG. 4, 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, and 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. When the external force 9 is applied to the strain detection element 202, a compressive stress 10 that compresses the beam 5 in the extending direction 1001A is applied to the beam 5, and a tensile stress 12 that pulls the beam 6 in the extending direction 1001B is applied to the beam 6. As shown in FIG. 4, the vibration frequency 13 of the beam 5 decreases as the external force 9 increases, and the vibration frequency 11 of the beam 6 increases as the external force 9 increases. Therefore, 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.
図５は制御回路素子３の検出回路３ｂのブロック図である。検出回路３ｂは、積算器１４、１５、１６と差分器１７とを備える。積算器１４は梁５から出力された検出信号８ａを自乗して自乗信号１４ａを得る。積算器１５は梁６から出力された検出信号８ｂを自乗して自乗信号１５ａを得る。梁５、６の検出感度は梁５、６に単位歪を印加した場合の自乗信号１４ａ、１５ａの変化量と定義する。梁５の検出感度の梁６の検出感度に対する比を感度比ｋと定義する。積算器１６は自乗信号１５ａに感度比ｋを積算し積算信号１６ａを得る。差分器１７は積算信号１６ａと自乗信号１４ａとの差分である差分信号１７ａを得る。歪検出装置１００１は差分信号１７ａにより外力９すなわち起歪体である容器１の平面部１ａの歪を検出することができる。このように、検出回路３ｂは、梁５の振動に基づく検出信号８ａを自乗して得られた自乗信号１４ａと、梁６の振動に基づく検出信号８ｂを自乗して得られた自乗信号１５ａとを得る。さらに検出回路３ｂは、梁５の検出感度と梁６の検出感度の比である感度比を自乗信号１５ａに積算して積算信号１６ａを得る。さらに検出回路３ｂは、積算信号１６ａと自乗信号１４ａの差分（差分信号１７ａ）に基づき歪の量を検出するように動作する。
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. As described above, 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. Further, 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.
２つの梁の振動周波数を異ならせた場合、それぞれの梁における歪に対する周波数変化や温度特性に相違が生じる場合があるので、特許文献１に記載の従来の歪検出装置では歪の検出精度が低下する場合がある。
When the vibration frequencies of the two beams are made different, there may be a difference in frequency change or temperature characteristics with respect to the strain in each beam, so that the strain detection accuracy of the conventional strain detection device described in Patent Document 1 is reduced. There is a case.
歪検出装置１００１は上記の処理により、温度特性を良化し検出精度を高めることが出来る。上記の処理について、以下、詳細に説明する。
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.
一般に、延伸方向に延びる梁に印加された歪εと梁の振動周波数ｆは、その梁のヤング率Ｅと、その梁の密度ρと、その梁の延伸方向の長さＬと、その梁の延伸方向と直角の方向の厚みｈと、その梁の延伸方向と直角の方向の断面積Ａと、その梁の断面２次係数Ｉとにより（数１）で表される。
In general, the strain ε 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 ρ 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).
（数１）における定数Ｓは（数２）で定義される。
The constant S in (Equation 1) is defined by (Equation 2).
（数１）の両辺を自乗することで（数３）が得られる。
(Equation 3) is obtained by squaring both sides of (Equation 1).
（数３）における定数Ｃは（数４）で定義する。
The constant C in (Equation 3) is defined by (Equation 4).
（数３）は歪εを変数とする１次方程式である。梁の検出感度は歪εに乗じられている係数Ｃ２・Ｓである。
(Equation 3) is a linear equation with the strain ε as a variable. The detection sensitivity of the beam is a coefficient C 2 · S multiplied by the strain ε.
梁５、６にそれぞれ印加された歪ε１、ε２による検出信号８ａ、８ｂの周波数である梁５、６の振動周波数ｆ１、ｆ２は（数３）に基づきそれぞれ（数５）および（数６）で表すことができる。
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 ε 1 and ε 2 applied to the beams 5 and 6, respectively, are based on (Equation 3) and (Expression 6).
梁５、６のヤング率Ｅ１、Ｅ２と、梁５、６の密度ρ１、ρ２と、梁５、６の延伸方向１００１Ａ、１００１Ｂの長さＬ１、Ｌ２と、梁５、６の延伸方向１００１Ａ，１００１Ｂと直角の方向の厚みｈ１、ｈ２と、梁５、６の延伸方向１００１Ａ，１００１Ｂと直角の方向の断面積Ａ１、Ａ２と、梁５、６の断面２次係数Ｉ１、Ｉ１とにより、（数５）（数６）の定数Ｓ１、Ｃ１、Ｓ２、Ｃ２は（数７）～（数１０）で表される。
Young's modulus E 1 , E 2 of the beams 5, 6, density ρ 1 , ρ 2 of the beams 5, 6, lengths L 1 , L 2 of the extending directions 1001A, 1001B of the beams 5, 6, 6, the thicknesses h 1 and h 2 in the direction perpendicular to the extending directions 1001A and 1001B, the cross-sectional areas A 1 and A 2 in the direction perpendicular to the extending directions 1001A and 1001B of the beams 5 and 6, and the cross sections of the beams 5 and 6. The constants S 1 , C 1 , S 2 , and C 2 of (Equation 5) and (Equation 6) are expressed by (Equation 7) to (Equation 10) by the secondary coefficients I 1 and I 1 .
歪は外力による歪と温度の変化による熱歪との和である。熱歪は等方性を有する。外力９により梁５に歪ε１σが生じ、梁６に歪ε２σが生じる。温度の変化により梁５、６に熱歪εＴが生じる。この場合、（数５）および（数６）は（数１１）、（数１２）にそれぞれ変形できる。
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 ε T occurs in the beams 5 and 6 due to a change in temperature. In this case, (Equation 5) and (Equation 6) can be transformed into (Equation 11) and (Equation 12), respectively.
検出信号８ａ、８ｂの差分値Δｆａ
２は、２つの梁５、６から検出された検出信号８ａ、８ｂの値である振動周波数ｆ１、ｆ２並びに感度比ｋにより（数１３）で定義される。
The difference value Δf 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.
なお、梁５の検出感度梁６の検出感度の比である感度比ｋは（数１４）で表される。
Note that 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).
（数１３）の周波数ｆ１、ｆ２に（数１１）、（数１２）を代入すると、差分値Δｆａ
２は（数１５）で表される。
When (Equation 11) and (Equation 12) are substituted into the frequencies f 1 and f 2 of (Equation 13), the difference value Δf a 2 is expressed by (Equation 15).
（数１５）の第３項は感度比ｋに（数１４）の右辺を代入すると０になるので、（数１５）は（数１６）に変形できる。
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).
歪ε１σおよび歪ε２σはポアソン比νにより（数１７）を満たす。
The strain ε 1σ and the strain ε 2σ satisfy ( Equation 17) by the Poisson ratio ν.
（数１６）は（数１７）により（数１８）に変形できる。
(Equation 16) can be transformed into (Equation 18) by (Equation 17).
（数１８）は外力９により梁５に生じる歪ε１σの１次関数である。言い換えると（数１８）は歪ε１σに対して線形である。したがって、歪検出装置１００１は容易に信号処理を行うことができる。（数１８）は熱歪εＴを含んでおらず熱歪εＴの影響を受けないので、歪検出装置１００１は温度特性を改善し高い検出精度で差分値Δｆａ
２により外力９の大きさすなわち起歪体である容器１の平面部１ａの歪の大きさを検出することができる。
(Equation 18) is a linear function of strain ε 1σ generated in the beam 5 by the external force 9. In other words, ( Equation 18) is linear with respect to the strain ε 1σ . Therefore, the distortion detection apparatus 1001 can easily perform signal processing. Since (Equation 18) does not include the thermal strain ε T and is not affected by the thermal strain ε T , the strain detection device 1001 improves the temperature characteristics and the magnitude of the external force 9 by the difference value Δf 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.
歪検出装置１００１は温度の変化等の環境変化の影響によってヒステリシスの影響を受ける。一般にヒステリシスは、測定精度を低下させる。
The strain detection device 1001 is affected by hysteresis due to environmental changes such as temperature changes. In general, hysteresis reduces measurement accuracy.
図６は、歪検出装置１００１の周囲の温度に対する梁５、６の振動周波数ｆ１、ｆ２の変化を示す。図６において、横軸は温度を示し、縦軸は梁５、６の振動の周波数ｆ１、ｆ２を示す。ヒステリシスの影響を考慮すると、（数３）は定数Ｃ２の変化分αと定数Ｓの変化分βにより（数１９）で表される。
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. In FIG. 6, the horizontal axis represents temperature, and the vertical axis represents the vibration frequencies f 1 and f 2 of the beams 5 and 6. Considering the influence of hysteresis, (Equation 3) is expressed by (Equation 19) by the change α of the constant C 2 and the change β of the constant S.
すなわち変化分α、βを用いてヒステリシスの影響を考慮すると、（数５）、（数６）で示す周波数ｆ１、ｆ２は（数２０）、（数２１）で表される。
That is, when the influence of hysteresis is taken into account using the changes α and β, the frequencies f 1 and f 2 shown in (Equation 5) and (Equation 6) are expressed by (Equation 20) and (Equation 21).
図６では、例えば、最初に周囲の温度が温度Ｔ０のときに周波数ｆ１、ｆ２は周波数ｆ２１である。温度を温度Ｔ０から温度ＴＵまで上昇させると図６の矢印の方向に周波数が変化する。その後、温度を温度ＴＵから低下させると、温度が上昇したときとは異なる線上で周波数が変化し、温度が再び温度Ｔ０になったときには周波数ｆ１、ｆ２は最初の周波数ｆ２１とは異なる周波数ｆ２２となる。
In Figure 6, for example, 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. Then, 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.
（数１９）を用いてヒステリシスを考慮した検出信号８ａ、８ｂの差分値Δｆｂ
２は（数２２）で表すことができる。
The difference value Δf b 2 between the detection signals 8a and 8b in consideration of the hysteresis using (Equation 19) can be expressed by (Equation 22).
歪検出装置１００１は（数１５）で歪を検出するので、ヒステリシスによる誤差は（数１５）と（数２２）との差であり、（数２３）で表される。
Since the strain detection apparatus 1001 detects strain by (Equation 15), the error due to hysteresis is the difference between (Equation 15) and (Equation 22), and is represented by (Equation 23).
（数２３）の第３項に（数１４）に示す感度比ｋを代入すると第３項が消えるので、（数２３）は（数２４）に変形できる。
When the sensitivity ratio k shown in (Equation 14) is substituted into the third term of (Equation 23), the third term disappears, so that (Equation 23) can be transformed into (Equation 24).
（数２４）では（数２３）の第３項が消去されているので、（数２３）の第３項の影響を除去することができる。即ち、歪検出装置１００１は感度比ｋを導入することでヒステリシスの影響を低減して高い検出精度で差分値Δｆａ
２により外力９すなわち起歪体である容器１の平面部１ａの歪を検出することができる。
In (Equation 24), since the third term of (Equation 23) is deleted, the influence of the third term of (Equation 23) can be eliminated. That is, the strain detection apparatus 1001 reduces the influence of hysteresis by introducing the sensitivity ratio k, and detects the external force 9, that is, the strain of the planar portion 1 a of the container 1 that is a strain generating body, with high detection accuracy by the difference value Δf a 2. can do.
本発明に係る歪検出装置は検出精度を高めることができ、特に、車両用ブレーキ等の被検出流体の圧力を測定する歪検出装置において有用である。
The strain detection apparatus according to the present invention 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.
１ａ 平面部（起歪体）
３ａ 駆動回路
３ｂ 検出回路
４ 基板
５ 梁（第１の梁）
６ 梁（第２の梁）
８ａ，８ｂ 検出信号
１４ａ，１５ａ 自乗信号
１６ａ 積算信号
ｋ 感度比 1a Plane portion (distortion body)
3a Drive circuit 3b Detection circuit 4 Substrate 5 Beam (first beam)
6 Beam (second beam)
8a, 8b Detection signals 14a, 15a Square signal 16a Integration signal k Sensitivity ratio
３ａ 駆動回路
３ｂ 検出回路
４ 基板
５ 梁（第１の梁）
６ 梁（第２の梁）
８ａ，８ｂ 検出信号
１４ａ，１５ａ 自乗信号
１６ａ 積算信号
ｋ 感度比 1a Plane portion (distortion body)
6 Beam (second beam)
8a,
Claims (3)
- 歪が印加されるように構成された起歪体と共に用いられるように構成された歪検出装置であって、
前記起歪体上に設けられるように構成された基板と、
撓むように振動可能に前記基板に支持されて延伸方向に延びる第１の梁と、
撓むように振動可能に前記基板に支持されるとともに前記延伸方向とと異なる方向に延びる第２の梁と、
前記第１の梁を第１の振動周波数で基本振動させるとともに前記第２の梁を前記第１の振動周波数とは異なる第２の振動周波数で基本振動させるように構成された駆動回路と、
前記第１の梁の振動に基づく第１の検出信号を自乗して得られた第１の自乗信号と、前記第２の梁の振動に基づく第２の検出信号を自乗して得られた第２の自乗信号とを得て、
前記第１の梁の検出感度と前記第２の梁の検出感度の比である感度比を前記第２の自乗信号に積算して積算信号を得て、
前記積算信号と前記第１の自乗信号の差分に基づき前記歪の量を検出する、
ように動作する検出回路と、
を備えた歪検出装置。 A strain detection device configured to be used with a strain generating body configured to be applied with strain,
A substrate configured to be provided on the strain body;
A first beam supported in the substrate so as to be vibrated so as to bend and extending in a stretching direction;
A second beam supported by the substrate so as to vibrate so as to bend and extending in a direction different from the extending direction;
A drive circuit configured to fundamentally vibrate the first beam at a first vibration frequency and to fundamentally vibrate the second beam at a second vibration frequency different from the first vibration frequency;
A first squared signal obtained by squaring the first detection signal based on the vibration of the first beam and a second squared signal obtained by squaring the second detection signal based on the vibration of the second beam. With a squared signal of 2,
Integrating a sensitivity ratio that is a ratio of detection sensitivity of the first beam and detection sensitivity of the second beam to the second square signal to obtain an integrated signal;
Detecting the amount of distortion based on a difference between the integrated signal and the first square signal;
A detection circuit that operates as follows:
A strain detection apparatus comprising: - 前記第１の検出信号の値は前記第１の振動周波数であり、前記第２の検出信号の値は前記第２の振動周波数である、請求項１に記載の歪検出装置。 The strain detection apparatus according to claim 1, wherein a value of the first detection signal is the first vibration frequency, and a value of the second detection signal is the second vibration frequency.
- 前記第２の梁は前記延伸方向と直角の方向に延びる、請求項１に記載の歪検出装置。 The strain detection apparatus according to claim 1, wherein the second beam extends in a direction perpendicular to the extending direction.
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| Application Number | Priority Date | Filing Date | Title |
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| JP2013046312A JP2016102649A (en) | 2013-03-08 | 2013-03-08 | Strain detector |
| JP2013-046312 | 2013-03-08 |
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| WO2014136388A1 true WO2014136388A1 (en) | 2014-09-12 |
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| PCT/JP2014/000849 WO2014136388A1 (en) | 2013-03-08 | 2014-02-19 | Strain-detection device |
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| WO (1) | WO2014136388A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106108907A (en) * | 2016-06-17 | 2016-11-16 | 合肥工业大学 | A kind of sole pressure distribution detector |
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| JPS62144036A (en) * | 1985-12-02 | 1987-06-27 | ザ シンガ− コンパニ↓− | Device and method of analyzing pair of frequency related to natural frequency as function of force applied to system |
| JPH09500726A (en) * | 1993-07-20 | 1997-01-21 | ハネウエル・インコーポレーテッド | Static pressure compensation of resonant integrated microbeam sensor |
| JP2011085407A (en) * | 2009-10-13 | 2011-04-28 | Yokogawa Electric Corp | Vibrating pressure sensor |
| JP2012242188A (en) * | 2011-05-18 | 2012-12-10 | Panasonic Corp | Physical quantity sensor |
| WO2013132842A1 (en) * | 2012-03-07 | 2013-09-12 | パナソニック株式会社 | Load sensor |
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2013
- 2013-03-08 JP JP2013046312A patent/JP2016102649A/en active Pending
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- 2014-02-19 WO PCT/JP2014/000849 patent/WO2014136388A1/en active Application Filing
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS62144036A (en) * | 1985-12-02 | 1987-06-27 | ザ シンガ− コンパニ↓− | Device and method of analyzing pair of frequency related to natural frequency as function of force applied to system |
| JPH09500726A (en) * | 1993-07-20 | 1997-01-21 | ハネウエル・インコーポレーテッド | Static pressure compensation of resonant integrated microbeam sensor |
| JP2011085407A (en) * | 2009-10-13 | 2011-04-28 | Yokogawa Electric Corp | Vibrating pressure sensor |
| JP2012242188A (en) * | 2011-05-18 | 2012-12-10 | Panasonic Corp | Physical quantity sensor |
| WO2013132842A1 (en) * | 2012-03-07 | 2013-09-12 | パナソニック株式会社 | Load sensor |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106108907A (en) * | 2016-06-17 | 2016-11-16 | 合肥工业大学 | A kind of sole pressure distribution detector |
| CN106108907B (en) * | 2016-06-17 | 2022-12-06 | 合肥工业大学 | Plantar pressure distribution detection device |
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| JP2016102649A (en) | 2016-06-02 |
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