JP2009204538A - Characteristic measuring device and characteristic measuring method of vibration detection sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device and a measuring method capable of measuring efficiently the output and capacitance of a resonance type vibration detection sensor. <P>SOLUTION: The measuring method and the device including a vibration means 11, a means 12 for measuring the output from the resonance type vibration detection sensor 50, a means 13 for measuring the capacitance of the sensor 50, a means 14 for switching so that the sensor 50 is connected to only either of the means 12 and the means 13 between the means 12 and the sensor 50, and between the means 13 and the sensor 50, an acceleration sensor 15, wiring 16 for connecting the sensor 50 to the means 14, wiring 17 for connecting the means 14 to the means 12, wiring 18 for connecting the means 14 to the means 13, and wiring 19 for connecting the acceleration sensor 15 to the means 12, wherein one end 161a on one side 161 of the wiring 16 is connected to a signal terminal 501 of the sensor 50, and one end 162a on the other side 162 of the wiring 16 is connected to a ground 502 of the sensor 50, and the ground of the sensor 50 is insulated from a ground of the acceleration sensor 15. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a characteristic measurement apparatus and characteristic measurement method for a vibration detection sensor including a piezoelectric element. More specifically, the present invention relates to a characteristic measurement apparatus and characteristic measurement method for a vibration detection sensor that measures sensor output and capacitance of a resonance type vibration detection sensor including a piezoelectric element.

  Several types of vibration detection sensors having piezoelectric elements are known depending on the purpose and structure. In particular, a resonance type vibration detection sensor is a vibration detection sensor including a vibration body (vibration body in which a piezoelectric element and a thin metal plate are bonded) that resonates in a frequency band for detection purposes. It is a sensor that can selectively detect vibration. This vibration detection sensor is used, for example, as a knocking sensor for an internal combustion engine.

In addition, when a vibration detection sensor is used as one component in a control system in various systems, in addition to the original function of obtaining a sensor output corresponding to the excited vibration, the inherent characteristics of the vibration detection sensor itself are also provided. It must be accurately controlled. That is, for example, an appropriate capacitance value is required. For this reason, it is necessary to finally inspect the characteristics of the vibration detection sensor which is a finished product by assembling various parts, and to determine whether or not the required characteristics are satisfied. In particular, mass-produced products such as knocking sensors are required to perform this inspection in large quantities and efficiently.
The following Patent Document 1 is known as a resonance type vibration detection sensor provided with the above piezoelectric element, and the following Patent Document 2 is known as an inspection method of the vibration detection sensor.

JP-A-9-269270 JP 2004-239696 A

Although the above Patent Document 1 discloses a structure and the like of a resonance type vibration detection sensor including a piezoelectric element, there is nothing about a method of inspecting sensor characteristics of these resonance type vibration detection sensors and an apparatus therefor. There is no disclosure. Moreover, although the said patent document 2 has described about the measuring method of a sensor output, it is not examined about the measurement of an electrostatic capacitance.
The present invention has been made in view of the above-described conventional technology, and a vibration detection sensor characteristic measuring apparatus capable of efficiently measuring the sensor output and capacitance of a resonance type vibration detection sensor including a piezoelectric element, and characteristics using the same An object is to provide a measurement method.

  Up to now, the inventors have measured the sensor output and capacitance of the vibration detection sensor in different, non-continuous processes using separate devices. That is, as shown in FIG. 9 (apparatus connection outline diagram) and FIG. 10 (measurement flow diagram), the capacitance of the vibration detection sensor 50 is changed to the capacitance measurement means 13 in a state where the vibration detection sensor 50 is not grounded. Use to measure. Thereafter, the vibration detection sensor 50 is removed from the jig for measuring the capacitance, and the jig is for measuring the sensor output. The vibration detection sensor 50 and the acceleration sensor 15 (acceleration sensor amplifier 153 are used in combination). The vibration detection sensor 50 is attached to a jig having a ground (195 in FIG. 9) shared with the robot. Next, the sensor output output from the vibration detection sensor 50 is measured using the output measuring means 12.

  The reason why the above-described characteristics are measured using a separate apparatus and a separate process in such a procedure is that the measurement conditions for sensor output and the measurement conditions for capacitance are contradictory. That is, the vibration detection sensor is designed on the assumption that an assembly object such as an engine block is used as a ground, and the sensor output is measured in a state of being grounded to the ground. On the other hand, the capacitance cannot be measured when the current flowing through the measurement object is grounded to the ground because the measurement current flows to the ground. Thus, the sensor output and the electrostatic capacitance require contradictory measurement conditions.

  It is preferable that the sensor output is not only capable of obtaining an output in a frequency band intended for detection, but also capable of obtaining an output corresponding to the acceleration of vibration that is the purpose of detection. In this case, in the sensor output measurement of the vibration detection sensor, an acceleration sensor (pickup sensor) whose characteristics are guaranteed in advance is vibrated integrally with the vibration detection sensor, and the acceleration of the excited inspection vibration is measured by the acceleration sensor. It is necessary to correct the sensor output from the obtained vibration detection sensor using the pickup output and determine whether the sensor output is appropriate according to the magnitude of acceleration.

  For this reason, in a measuring apparatus in which both the vibration detection sensor and the acceleration sensor are grounded to a common ground, the capacitance cannot be measured even though the sensor output can be measured. For this reason, the present inventors devised a measuring apparatus 10s as shown in FIG. 8 (apparatus connection schematic diagram) prior to the present application. The device is a device in which each means shown in FIG. 9 is connected using two switching means 141 and 142, and sensor output and capacitance can be measured. In this apparatus 10s, by using the two switching means 141 and 142, the sensor output and the capacitance can be continuously measured with one apparatus. However, in this device 10s, the ground wiring 195 used as the ground shared by the vibration detection sensor 50 and the acceleration sensor 15 easily picks up noise (noise is likely to be mixed into the ground wiring), and the sensor output fluctuates and vibration is applied. There is a problem that even if the sensor output is not performed, a behavior as if the sensor output is generated is recognized.

  As a result of further studies on the above-described apparatus, the present inventors have found an apparatus 10a having the configuration shown in the present invention (illustrated in FIG. 1 and the like) and a measurement method associated therewith. With this apparatus 10a, the sensor output and the capacitance can be measured with one apparatus, and the present invention has been completed by knowing that the sensor output and the capacitance can be continuously and efficiently measured without causing the above-mentioned problems due to noise. I came to let you.

That is, the present invention is as follows.
(1) A vibration detection sensor characteristic measuring apparatus for measuring a sensor output and capacitance of a resonance type vibration detection sensor having a piezoelectric element,
Vibration means for vibrating inspection vibration to the vibration detection sensor;
Output measuring means for measuring the sensor output from the vibration detection sensor;
Capacitance measuring means for measuring the capacitance of the vibration detection sensor;
The vibration detection sensor is disposed between the output measurement unit and the vibration detection sensor and between the capacitance measurement unit and the vibration detection sensor, and the vibration detection sensor is connected to the output measurement unit and the capacitance measurement unit. Switching means for switching so that only one of them is connected;
An acceleration sensor that is vibrated by the vibration means together with the vibration detection sensor, and outputs a pickup output corresponding to the acceleration of the inspection vibration when the vibration is applied;
A pair of first wires connecting the vibration detection sensor and the switching means;
A pair of second wires connecting the switching means and the output measuring means;
A pair of third wires connecting the switching means and the capacitance measuring means; and
A pair of fourth wires connecting the acceleration sensor and the output measuring means,
When the vibration detection sensor is arranged in a measurable state, one end of one of the first wires is connected to a signal terminal of the vibration detection sensor, and the other of the first wires One end of the wiring is connected to the ground of the vibration detection sensor, and the ground of the vibration detection sensor is insulated from the ground of the acceleration sensor.
(2) The output measuring unit includes a correcting unit that corrects the sensor output of the vibration detection sensor to a value corresponding to the acceleration of the inspection vibration based on the pickup output of the acceleration sensor. Vibration detection sensor characteristics measurement device.
(3) A fixing jig for fixing both the vibration detection sensor and the acceleration sensor is provided.
The vibration detection sensor characteristic measurement device according to (1) or (2), wherein the ground of the vibration detection sensor and the ground of the acceleration sensor are insulated in the fixing jig.
(4) A characteristic measurement method for a vibration detection sensor using the vibration detection sensor characteristic measurement device according to any one of (1) to (3) above,
A capacitance measuring step of measuring the capacitance of the vibration detection sensor using the capacitance measuring means;
An output measuring step of measuring the sensor output of the vibration detection sensor when the inspection vibration is vibrated using the output measuring means;
A switching step of switching the output measuring means or the capacitance measuring means connected to the vibration detection sensor to the other using the switching means,
After performing one of the capacitance measurement step and the output measurement step, the switching step is performed, and then the other step of the capacitance measurement step and the output measurement step is performed. A method for measuring characteristics of a vibration detection sensor, characterized in that:
(5) A method for measuring characteristics of a vibration detection sensor using the vibration detection sensor characteristic measurement device according to (2) above,
A capacitance measuring step of measuring the capacitance of the vibration detection sensor using the capacitance measuring means;
Using the output measuring means, the output measuring step of correcting the sensor output of the vibration detection sensor when the inspection vibration is vibrated and correcting the sensor output based on the pickup output of the acceleration sensor; and
A switching step of switching the output measuring means or the capacitance measuring means connected to the vibration detection sensor to the other using the switching means,
After performing one of the capacitance measurement step and the output measurement step, the switching step is performed, and then the other step of the capacitance measurement step and the output measurement step is performed. A method for measuring characteristics of a vibration detection sensor, characterized in that:

According to the characteristic measuring apparatus for vibration detection sensor of (1) above, the sensor output and the capacitance of the vibration detection sensor can be continuously measured without causing the problem due to the noise even though it is a single apparatus. In particular, after the vibration detection sensor is set on the jig of the characteristic measurement device, the sensor output and the capacitance can be measured efficiently and continuously without removing the vibration detection sensor from the jig.
In the vibration measuring sensor characteristic measuring apparatus according to (2) above, when the output measuring means includes a correcting means for correcting the sensor output to a value corresponding to the acceleration of the inspection vibration based on the pickup output, it corresponds to the acceleration. Thus, the vibration detection sensor whose sensor output changes can also be inspected.
The vibration measuring sensor characteristic measuring apparatus according to (3), further comprising a fixing jig for fixing both the vibration detecting sensor and the acceleration sensor, wherein the ground of the vibration detecting sensor and the ground of the acceleration sensor are within the fixing jig. When insulated, both characteristics of sensor output and capacitance can be efficiently measured with a particularly simple apparatus and operation.
According to the characteristic measurement method of the vibration detection sensor of (4) above, the sensor output and the capacitance of the vibration detection sensor can be continuously measured without causing the problem due to the noise. In particular, after the vibration detection sensor is set on the jig of the characteristic measurement device, the sensor output and the capacitance can be measured efficiently and continuously without removing the vibration detection sensor from the jig.
According to the characteristic measurement method of the vibration detection sensor of the above (5), the sensor output and the capacitance of the vibration detection sensor whose sensor output changes according to the acceleration can be measured with one device, and the problem due to the noise occurs. The sensor output and the capacitance can be measured continuously. In particular, after the vibration detection sensor is set on the jig of the characteristic measurement device, the sensor output and the capacitance can be measured efficiently and continuously without removing the vibration detection sensor from the jig.

Hereinafter, the present invention will be described with reference to FIGS.
[1] Vibration Detection Sensor Characteristic Measurement Device The vibration detection sensor characteristic measurement devices 10a to 10d (see FIGS. 1 to 3 and FIG. 5) are sensor outputs of a resonance type vibration detection sensor 50 (see FIG. 7) including a piezoelectric element 511. And a vibration detection sensor characteristic measuring device for measuring capacitance,
Vibration means 11 for vibrating inspection vibration to the vibration detection sensor 50;
Output measuring means 12 for measuring the sensor output from the vibration detection sensor 50;
Capacitance measuring means 13 for measuring the capacitance of the vibration detection sensor 50;
The vibration detection sensor 50 is disposed between the output measurement unit 12 and the vibration detection sensor 50 and between the capacitance measurement unit 13 and the vibration detection sensor 50. Switching means 14 for switching so that only one of the capacitance measuring means 13 is connected;
An acceleration sensor 15 that is vibrated by the vibration means 11 together with the vibration detection sensor 50 and outputs a pickup output corresponding to the acceleration of the inspection vibration when the vibration is applied;
A pair of first wires 16 connecting the vibration detection sensor 50 and the switching means 14;
A pair of second wirings 17 connecting the switching means 14 and the output measuring means 12;
A pair of third wires 18 connecting the switching means 14 and the capacitance measuring means 13; and
A pair of fourth wirings 19 for connecting the acceleration sensor 15 and the output measuring means 12,
When the vibration detection sensor 50 is arranged in a measurable state, one end 161a of one wiring 161 of the first wiring 16 is connected to the signal terminal 501 of the vibration detection sensor 50, and the first One end 162a of the other wiring 162 of one wiring 16 is connected to the ground 502 of the vibration detection sensor 50, and the ground 502 of the vibration detection sensor 50 and the ground 152 of the acceleration sensor 15 are insulated. It is characterized by that.

  The “excitation means (11)” is a means for exciting the vibration detection sensor 50 with inspection vibration. This vibration means is preferably capable of changing the frequency and acceleration of vibration to be vibrated for the purpose of measuring (analyzing) the sensor output of the vibration detection sensor 50 for a plurality of frequencies. The control method of the vibration means 11 is not limited, and the start and end of vibration may be controlled manually or electrically. When electrically controlling, various means such as the output measuring means 12 may be performed (see FIGS. 3 and 4), or the control means using the integrated control means 30 (see FIGS. 5 and 6). 30 may be performed. In any case, an instruction signal is formed by various means, and this instruction signal is transmitted to the vibration means 11 for control.

  The “output measuring means (12)” is a means for measuring the sensor output from the vibration detection sensor 50. The configuration and characteristics of the output measuring means 12 are not particularly limited, and an oscilloscope or the like can be used. However, the sensor output from the vibration detection sensor is subjected to frequency analysis, and the presence / absence and magnitude of the sensor output at each vibration frequency is determined. It is preferable that it is a means which can output. Therefore, the output measuring means 12 is preferably a device having a fast Fourier transform function, and is preferably a fast Fourier transformer (hereinafter also simply referred to as “FFT”).

Since the output measuring means 12 has an input / output function, a calculation function (CPU), a memory function, and the like, an operation instruction of the vibration means 11 can be given to the output measuring means 12 (see FIGS. 3 and 4). .
Further, the output measuring unit 12 corrects the sensor output of the vibration detection sensor 50 to a value corresponding to the acceleration of the inspection vibration based on the pickup output of the acceleration sensor 15 (FIGS. 2, 3 and 5). 5). Thereby, it is possible to determine whether or not an accurate sensor output corresponding to the acceleration of vibration by the vibration means 11 is obtained.

  The “capacitance measurement means (13)” is a means for measuring the capacitance of the vibration detection sensor 50. The capacitance measuring unit 13 only needs to be connected to the vibration detection sensor 50 and measure (calculate) the capacitance of the entire vibration detection sensor 50. Moreover, it is preferable that the electrostatic capacity can be measured with an AC power source and the frequency characteristics thereof can be measured. Therefore, it is preferable to have an alternating current supply function, a voltage measurement function, and a phase measurement function. For example, an LCR meter, an impedance analyzer, a network analyzer, or the like can be used.

  The “switching means (14)” is disposed between the output measurement means 12 and the vibration detection sensor 50 and between the capacitance measurement means 13 and the vibration detection sensor 50, and the vibration detection sensor 50 performs output measurement. This is means for switching so that only one of the means 12 and the capacitance measuring means 13 is connected. The configuration and characteristics of the switching unit 14 are not particularly limited, and examples of the switching unit 14 include a relay and a switch. Relays and electrical switches can be electrically controlled, and manual switches can be controlled manually. Of these, relays are preferred. The relay control method is not particularly limited, and may be performed by various units such as the output measuring unit 12 or may be performed by the control unit 30 using the integrated control unit 30 (FIGS. 3 to 6). reference). In any case, control is performed by forming an instruction signal by various means and transmitting the instruction signal to the switching means 14.

The “acceleration sensor (15)” is a sensor that is vibrated by the vibration means together with the vibration detection sensor 50 and outputs a pickup output corresponding to the acceleration of the inspection vibration when the vibration is applied. The acceleration sensor 15 is usually used in combination with an acceleration sensor amplifier 153 (see FIGS. 2, 3 and 5). The acceleration sensor 15 may be a charge output type or a voltage output type. Among these, the charge output type performs sensor output by charge, and converts it into voltage data via the charge-voltage conversion amplifier 153 as the acceleration sensor amplifier 153 and outputs it. On the other hand, in the voltage output type, the sensor output is directly performed by voltage, and voltage data is directly output. Usually, a constant current supply amplifier 153 is used in combination as the acceleration sensor amplifier 153 that supplies a constant current to the acceleration sensor.
Among these, the former, that is, the acceleration detection means including the charge output type acceleration sensor 15 and the charge voltage conversion amplifier 153 is preferable. When the acceleration sensor amplifier 153 is used, the amplifier is disposed between the acceleration sensor 15 and the output measuring means 12 (see FIGS. 2, 3 and 5).

  The “first wiring (16)”, the “second wiring (17)”, the “third wiring (18)”, and the “fourth wiring (19)” are shown in FIG. 3 and FIG. 5), each of which has at least a pair of wires, but may be a set of wires each having three or more wires. Each wiring may be a pair of independent wirings (single wires), a twisted wiring such as a twin cable, or the like, and a plurality of cables in one cable such as a coaxial cable. The coaxial wiring in the form in which the conductor is disposed may be used. Further, each wiring may be directly connected to each means or the like, or may be indirectly connected via a necessary circuit element such as a filter.

Furthermore, when the vibration detection sensor 50 is arranged in a state where the vibration detection sensor 50 can be measured, the vibration detection sensor characteristic measurement devices 10a to 10d have the following conditions <1> to <3> (FIGS. 1 to 3 and FIG. 5). That is,
<1> One end 161 a of one wiring 161 of the first wiring 16 is connected to the signal terminal 501 of the vibration detection sensor 50. This signal terminal 501 is a terminal on the side where the sensor output is output in the vibration detection sensor 50, and means that it is connected to the terminal 52 in the knocking sensor (vibration detection sensor) of FIG.
<2> One end 162 a of the other wiring 162 of the first wiring 16 is connected to the ground 502 of the vibration detection sensor 50. This ground 502 means that it is electrically connected to the casing 54 in the knocking sensor (vibration detection sensor) of FIG.
<3> The ground 502 of the vibration detection sensor 50 and the ground 152 of the acceleration sensor 15 are insulated (in other words, both the grounds 502 and 152 are provided independently).

The vibration detection sensor characteristic measuring apparatus of the present invention can include other means such as other means and equipment in addition to the above means and sensors. As another part, the fixing jig 21 (FIGS. 2, 3 and 5) for fixing the vibration detection sensor 50 can be cited. The fixing jig 21 may fix only the vibration detection sensor 50, but is preferably a jig that fixes the acceleration sensor 15 together with the vibration detection sensor 50. Furthermore, it is more preferable that the ground 502 of the vibration detection sensor 50 and the ground 152 of the acceleration sensor 15 are insulated in the fixing jig 21.
The fixing jig 21 can fix the vibration detection sensor 50 and the acceleration sensor 15 together (integrally) and is coaxial in the vertical direction with respect to the excitation direction (both with respect to the excitation direction of the inspection vibration). It is preferable that the center of gravity of the sensor can be fixed (located coaxially). Thereby, more accurate correction of the sensor output can be performed.

  Furthermore, the vibration detection sensor characteristic measuring apparatus of the present invention can further include a control means 30 (FIGS. 3 and 5) that can control the entire apparatus in an integrated manner. The control means 30 can include an input / output unit (I / O) 31, a CPU 32, a memory 33, and the like. In this configuration, the input / output unit 31 is a part where data is input from various means and data is output from the control means. Examples of the input to the input / output unit include capacitance data from the capacitance measuring means 13, sensor output data from the output measuring means 12, acceleration data from the acceleration sensor 15, and the like. Examples of the output from the input / output unit include a switching instruction signal to the switching means 14 and an instruction signal for operating the vibration means 11.

The CPU 32 can execute the program recorded in the memory 33. As this program, for example, an acquired value such as a calculation program (for example, a program for correcting sensor output using a pickup output) or a comparison program (for example, sensor output input from the output measuring device 12) is defined in advance. And a signal output program (for example, a program for outputting a signal when a value higher or lower than the threshold is obtained in the comparison program).
The memory 33 is a storage medium capable of storing data, and can record measurement values measured by each means, preset threshold values, various data generated in the process of the CPU 32, various programs, and the like.

  Furthermore, the vibration detection sensor characteristic measuring apparatus of the present invention can include image acquisition means for acquiring images such as the lot number and product number of each vibration detection sensor 50. In addition to the video acquisition means, when the integrated control means 30 described above is provided, the video acquired by the video acquisition means is transmitted to the control means 30, and the control means 30 extracts the lot number, product number, and the like.・ Can be recorded. Furthermore, the electrostatic capacity data and the sensor output data corresponding to the vibration detection sensor 50 of each lot number and product number can be stored and utilized by the control means 30 in association with each other.

[2] Method for Measuring Characteristics of Vibration Detection Sensor <1> Method for Measuring Characteristics of Vibration Detection Sensor of (4) (see FIGS. 4 and 6)
The characteristic measurement method of the vibration detection sensor (4) is a characteristic measurement method of the vibration detection sensor using the vibration detection sensor characteristic measurement device of the present invention,
A capacitance measuring step of measuring the capacitance of the vibration detection sensor using the capacitance measuring means;
An output measuring step of measuring the sensor output of the vibration detection sensor when the inspection vibration is vibrated using the output measuring means;
A switching step of switching the output measuring means or the capacitance measuring means connected to the vibration detection sensor to the other using the switching means,
After performing one of the capacitance measurement step and the output measurement step, the switching step is performed, and then the other step of the capacitance measurement step and the output measurement step is performed. It is characterized by performing.

  That is, the method (4) includes a <capacitance measurement step>, an <output measurement step>, and a <switching step>. Among these steps, the <Capacitance measurement step> may be performed before the <Output measurement step>, or may be performed after the <Output measurement step>. In addition, in each step, when the above combination is one cycle, the cycle is usually performed once for one vibration detection sensor, but can be performed twice or more for one vibration detection sensor. . When performing two or more times, the dispersion | variation in a measured value can be investigated and the average value of each measured value can be measured.

Further, when continuously measuring a plurality of vibration detection sensors, after at least one cycle of the first vibration detection sensor is completed, the vibration detection sensor is replaced, and the second vibration detection sensor , Do the same cycle.
When continuously measuring a plurality of vibration detection sensors, <output measurement step, switching step, capacitance measurement step>, <capacitance measurement step, switching step, output capacitance measurement step>, <output measurement Steps, switching steps, capacitance measuring steps>,... In this case, the number of switching steps can be reduced.

<2> Method for Measuring Characteristics of Vibration Detection Sensor of (5) The method of measuring characteristics of the vibration detection sensor of (5) is the characteristics of the vibration detection sensor using the vibration detection sensor characteristic measuring device described in (2). A measuring method,
A capacitance measuring step of measuring the capacitance of the vibration detection sensor using the capacitance measuring means;
Using the output measuring means, the output measuring step of correcting the sensor output of the vibration detection sensor when the inspection vibration is vibrated and correcting the sensor output based on the pickup output of the acceleration sensor; and
A switching step of switching the output measuring means or the capacitance measuring means connected to the vibration detection sensor to the other using the switching means,
After performing one of the capacitance measurement step and the output measurement step, the switching step is performed, and then the other step of the capacitance measurement step and the output measurement step is performed. It is characterized by performing.

  The method (5) differs from the method (4) in that the “correction” is performed in the <output measurement step>, but the <capacitance measurement step>, <output measurement step>, and < Switching step> is the same. Therefore, the order of the steps in the method (4) can be applied to the method (5) as it is.

  In the method (5), since the output measuring means has the correcting means as described above, the correction is performed in the output measuring step. However, as described above, the integrated control means 30 is used. In the case of using a vibration detection sensor characteristic measuring apparatus having the above, correction can be performed by background processing in a PC or the like used as the control means 30 independently of each process.

[3] Resonance-type vibration detection sensor A resonance-type vibration detection sensor including a piezoelectric element to be used in the characteristic measurement apparatus and characteristic measurement method of the present invention will be described below with reference to FIG.
FIG. 7 is a partial cross-sectional view of a knocking sensor that is an example of a resonance type vibration detection sensor 50 including a piezoelectric element 511. A knocking sensor is used for the purpose of detecting knocking of an engine by being disposed in an engine block or the like of an automobile, and has a structure for that purpose. The vibration detection sensor (knocking sensor) 50 includes a vibrating body 51, a terminal 52, a terminal holder 53, a casing 54, and a cover member 55.

  The vibrating body 51 includes a thin metal plate 512 having a disk shape having a first through hole in the central portion, and a disk shape having a through hole having a diameter larger than the first through hole in the central portion, and a pair of front and back surfaces. A piezoelectric element 511 on which electrodes are formed, and the metal thin plate 512 and the piezoelectric element 511 are stacked and bonded so that the central axis of the first through hole and the central axis of the second through hole coincide with each other. . One electrode of the pair of electrodes constituting the piezoelectric element 511 is grounded to the engine block via the casing 54 when the vibration detection sensor 50 is disposed on the engine block, as will be described later. These electrodes are connected to the outside of the vibration detection sensor 50 via a terminal 52.

  The terminal 52 is a conductor made of a strip-shaped metal plate formed in a substantially L shape, and is integrated with a resin terminal holder 53 by injection molding. On the other hand, the terminal holder 53 has an opening 531, has a circular planar shape formed in an inverted dish shape whose center portion bulges upward, and is arranged so as to cover the vibration detection element 51 together with the terminal 52 from above. The The terminal 52 is disposed in the terminal holder 53, and one end side thereof protrudes from the terminal holder 53 so as to be located in the connector portion 551 of the cover member 55, and the other end side is located in the opening portion 531. It protrudes from the terminal holder 53. The other end of the terminal 52 is electrically connected to one end of the connection wire 56. The other end of the connection wire 56 is joined and electrically connected to one electrode (upper electrode) of the piezoelectric element 511 located above the vibrating body 51.

The casing 54 has an accommodating portion 541 that accommodates the vibrating body 51 in the upper portion, and a mounting portion 542 in which a screw portion 547 for screwing with the engine block is formed in the lower portion. Further, the center of the inner bottom of the accommodating portion 541 has a screw hole that enters the attachment portion 542.
Then, the vibrating body 51 is screwed into the screw hole with the screw member 543 inserted through the through holes (through holes formed in the piezoelectric element 511 and the metal thin plate 512, respectively), and uses a washer 544, a nut 545, and the like. The fixed portion is stored at a predetermined height spaced from the inner bottom of the storage portion 541. The other electrode (lower electrode) of the piezoelectric element 511 constituting the vibrating body 51 is electrically connected to the engine block via the metal thin plate 512, the washer 544, the nut 545, the screw member 547, and the mounting portion 542. Connected and grounded.

  The cover member 55 is a resin molded body having a connector, is disposed so as to cover the terminal holder 53 from above, and is supported in the casing 54 via a seal member 57 such as an O-ring. The upper outer edge portion 546 of the casing 54 is caulked inward to suppress the upper surface of the cover member 55, so that the casing 54, the vibrating body 51, the terminal 52, the terminal holder 53, and the cover member 55 are integrated and caulked. The

In the vibration detection sensor 50, when the screw part 547 formed on the outer surface of the attachment part 542 is screwed into the attachment hole screwed into the engine block and knocking occurs in the engine, the vibration body 51 is Due to the vibration, the piezoelectric element 511 constituting the vibrating body 51 is distorted to generate a charge, and this charge is output from the terminal 52 to the outside of the vibration detection sensor 50 as an electric signal.
The terminal 52 is connected to the signal terminal 501 in the present apparatus, and the casing 54 is connected to the ground 502 in the present apparatus.

Hereinafter, the present invention will be described more specifically.
[First Embodiment]
[1] Device for Measuring Characteristics of Vibration Detection Sensor A first embodiment of the present invention will be described with reference to FIG. 3, FIG. 4, and FIG.
The vibration detection sensor characteristic measurement device 10c of the vibration detection sensor according to the present embodiment is a device for measuring two characteristics of the capacitance of the resonance type knocking sensor 50 and the sensor output. The vibration detection sensor characteristic measuring apparatus 10c includes an excitation means 11, an output measurement means (FFT) 12, a correction means 121, a capacitance measurement means (LCR meter) 13, a switching means (relay) 14, and an acceleration sensor amplifier. (Charge-voltage conversion amplifier) 153, fixing jig 21 and control means 30 are provided.

(1) Vibration detection sensor, acceleration sensor, and fixing jig As the vibration detection sensor 50, a knocking sensor having the structure shown in FIG. 7 (that is, described in [3] above) was used. As the acceleration sensor 15, a charge output type acceleration sensor was used. The acceleration sensor 15 uses a charge-voltage conversion amplifier 153 as the acceleration sensor amplifier 153.

The fixing jig 21 is used to hold the vibration detection sensor 50 and the acceleration sensor 15 together. The fixing jig 21 is a metal jig having an upper stage 211 and a lower stage 213 and having a structure insulated by the upper stage 211 and the lower stage 213. The upper portion 211 has a screw hole for fixing the vibration detection sensor 50, and the screw portion 547 provided in the attachment portion 542 of the vibration detection sensor 50 is fixed and fixed similarly to the case where the vibration detection sensor 50 is attached to the engine block. The vibration detection sensor 50 is fixed to the fixing jig 21 by being screwed into the screw hole of the tool 21. On the other hand, the acceleration sensor 15 has a housing portion formed in a shape corresponding to the lower stage 213 of the fixing jig 21, and is bonded and fixed in the housing portion.
Further, in the fixing jig 21, the upper stage 211 and the lower stage 213 are insulated via a resin insulating plate 212, whereby the vibration detection sensor 50 fixed to the upper stage 211 and the lower stage 213 are fixed. Accordingly, the ground terminal 502 of the vibration detection sensor and the ground terminal 152 of the acceleration sensor are insulated.
Furthermore, the vibration detection sensor 50 and the acceleration sensor 15 are integrally fixed by a fixing jig 21 and are coaxially arranged in the vertical direction with respect to the excitation direction (both of the two sensors with respect to the excitation direction of the inspection vibration). The center of gravity is arranged coaxially).

  The vibration detection sensor 50 is connected to the relay (switching means) 14 by the first wiring 16. One end (the end on the vibration detection sensor side) 161a of one of the first wirings 16 is connected to the connector portion 551 of the vibration detection sensor 50 and connected to the terminal 52 (that is, the signal terminal 501). On the other hand, one end 162 a of the other wiring 162 of the first wiring 16 is connected to a connection portion fixed to the fixing jig 21 and connected to the attachment portion 542 via the fixing jig 21. Each other end of the first wiring 16 is connected to the relay 14.

  The acceleration sensor 15 is connected to a pair of fourth wires 19 made of a coaxial cable. One wiring 191 of the fourth wiring 19 is connected to the ground 152 of the acceleration sensor 15, and the other wiring 192 of the fourth wiring 19 is connected to the signal terminal 151 in the acceleration sensor 15. Each other end of the fourth wiring 19 is connected to the FFT (output measuring means) 12 via the charge-voltage conversion amplifier 153.

(2) Excitation means 11
As the vibration means 11, a vibration exciter 11 capable of scanning the vibration frequency and acceleration within a predetermined range was used. The vibrator 11 is operated at each frequency and each acceleration programmed in advance, and vibrates the vibration detection sensor 50 and the acceleration sensor 15.
Further, as shown in FIG. 3, the vibrator 11 is controlled by the following output measuring means (FFT) 12.

(3) Output measuring means 12
As the output measuring means 12, a fast Fourier transformer (also simply referred to as "FFT") 12 was used. The FFT 12 includes a correction unit 121 and is connected so as to be able to output a signal to the vibration exciter 11, and is connected to a coaxial cable via an acceleration sensor 15 and an acceleration sensor amplifier (charge-voltage conversion amplifier) 153. Are connected by a fourth wiring 19 composed of
Further, in connection with the acceleration sensor 15 by the fourth wiring 19, one wiring 191 of the fourth wiring 19 and the signal terminal 151 of the acceleration sensor 15 are connected, and the other of the fourth wiring 19 is connected. The wiring 192 and the ground 152 of the acceleration sensor 15 are connected.
The correction means 121 receives the pickup output of the acceleration sensor 15 and corrects the sensor output of the knocking sensor 50 received by the FFT 12 to a value corresponding to the acceleration of the inspection vibration based on the pickup output. To do.
Further, the FFT 12 is connected to a relay (switching means) 14 by a second wiring 17.
The FFT 12 is connected so that sensor output data can be output to the control means 30.

(4) Capacitance measuring means 13
An LCR meter 13 was used as the capacitance measuring means 13. The LCR meter is connected to a relay (switching means) 14 through a third wiring 18. Further, the LCR meter 13 is connected so that capacitance data can be output to the control means 30.

(5) Switching means 14
As the switching means 14, a relay 14 having two input contacts and four output contacts was used. Further, the two input contacts are connected to the vibration detection sensor 50 by the first wiring 16 as described in (1) above. Further, two of the four output contacts are connected to the LCR meter 13 and the remaining two of the four output contacts are connected to the FFT 12.
The switching operation of the relay 14 is switched so as to connect two input contacts and two output contacts. That is, the vibration detection sensor 50 and the LCR meter 13 are connected, the vibration detection sensor 50 and the FFT 12 are not connected, and the vibration detection sensor 50 and the LCR meter 13 are not connected. The state is switched to either the second state in which the FFT 12 is connected. Further, this switching operation is performed by the control means 30.

(6) Control means 30
As the control means 30, a computer having an input / output unit (I / O) 31, a CPU 32, and a memory 33 (including two memories of HDD and RAM) was used. The I / O 31 of the control means 30 is connected to the relay 14 so that output is possible. Further, the I / O 31 is connected to the FFT 12 and the LCR meter 13 so as to be input.

[2] Vibration Detection Sensor Characteristic Measuring Method The vibration detection sensor characteristic measurement was performed using the vibration detection sensor characteristic measurement device 10c of the first embodiment (see FIG. 4).
First, the control means 30 outputs an instruction signal to connect the vibration detection sensor 50 and the LCR meter 13 to the relay (switching means) 14 to switch the relay 14 (switching process).

  Thereafter, the capacitance of the vibration detection sensor 50 is measured using an LCR meter. The obtained capacitance data is output to the control means 30 (capacitance measurement step).

  Next, the control means 30 outputs an instruction signal so as to connect the vibration detection sensor 50 and the FFT (output measurement means) 12 to the relay (switching means) 14 to switch the relay 14 (switching step). .

  Thereafter, the vibrator 12 is operated by the FFT 12 to vibrate the vibration detection sensor 50 and the acceleration sensor 15. Excitation is performed while changing the frequency and acceleration. Meanwhile, the sensor output acquired by the vibration detection sensor 50 is output to the FFT 12. The pickup output acquired by the acceleration sensor 15 is also output to the FFT 12. Then, the sensor output from the vibration detection sensor 50 is corrected by the correction means 121 in the FFT 12 to a sensor output corresponding to the acceleration value by the pickup output from the acceleration sensor 15 and output to the control means 30 (output measurement). Process).

Next, the control unit 30 compares the capacitance data input from the LCR meter 13 with the first allowable range data set in a predetermined range stored in the memory 33 provided in the control unit 30, and If the capacitance data is within the range of the first allowable range data, the control means 30 outputs an OK determination (assuming the vibration detection sensor is an acceptable product). On the other hand, when the capacitance data is outside the range of the first allowable range data, an NG determination (the vibration detection sensor is regarded as a rejected product) is output.
Further, the sensor output data input from the FFT 12 and the second allowable range data set in a predetermined range stored in the memory 33 provided in the control means 30 are compared, and the sensor output data is the second allowable range data. If it is within the range, the control means 30 outputs an OK determination (the vibration detection sensor is regarded as a pass product). On the other hand, when the sensor output data is outside the range of the second allowable range data, an NG determination (a vibration detection sensor is determined as a rejected product) is output.
By repeating this routine, the capacitances and sensor outputs of the plurality of vibration detection sensors 50 are continuously and efficiently measured.

[Second Embodiment]
[1] Device for Measuring Characteristics of Vibration Detection Sensor A second embodiment of the present invention will be described with reference to FIGS.
The vibration detection sensor characteristic measurement device 10d of the vibration detection sensor according to the present embodiment includes the vibration detection sensor characteristic measurement device 10c (see FIG. 3) of the first embodiment and the following four points <1> to <4>. Different. That is,
<1> In the apparatus 10c, the FFT 12 includes the correcting unit 121, whereas in the apparatus 10d, the FFT 12 does not include the correcting unit.
<2> In the apparatus 10c, the correction unit 121 in the FFT 12 performs data correction, whereas in the apparatus 10d, the control unit 30 performs data correction.
<3> While the pickup output of the acceleration sensor 15 is output to the FFT 12 in the device 10c, the pickup output of the acceleration sensor 15 is output to the control means 30 in the device 10d.
<4> In the apparatus 10c, the FFT 12 instructs the operation of the vibrator 11, whereas in the apparatus 10d, the control means 30 instructs the operation of the vibrator 11.

[2] Method for Measuring Characteristics of Vibration Detection Sensor Using the vibration detection sensor characteristic measurement apparatus 10d of the second embodiment, the characteristics of the vibration detection sensor were measured (see FIG. 6).
First, the control means 30 outputs an instruction signal to connect the vibration detection sensor 50 and the LCR meter 13 to the relay (switching means) 14 to switch the relay 14 (switching process).

  Thereafter, the capacitance of the vibration detection sensor 50 is measured using an LCR meter. The obtained capacitance data is output to the control means 30 (capacitance measurement step).

  Next, the control means 30 outputs an instruction signal so as to connect the vibration detection sensor 50 and the FFT (output measurement means) 12 to the relay (switching means) 14 to switch the relay 14 (switching step). . Furthermore, the vibration exciter 11 is operated by the control means 30 thereafter.

  The vibrator 11 vibrates the vibration detection sensor 50 and the acceleration sensor 15. Excitation is performed while changing the frequency and acceleration. Meanwhile, the sensor output acquired by the vibration detection sensor 50 is output to the FFT 12 and subjected to frequency analysis, and then output to the control means 30 (output measurement process). The pickup output acquired by the acceleration sensor 15 is output to the control means 30.

Next, the control unit 30 compares the capacitance data input from the LCR meter 13 with the first allowable range data set in a predetermined range stored in the memory 33 provided in the control unit 30, and If the capacitance data is within the range of the first allowable range data, the control means 30 outputs an OK determination (assuming the vibration detection sensor is an acceptable product). On the other hand, when the capacitance data is outside the range of the first allowable range data, an NG determination (the vibration detection sensor is regarded as a rejected product) is output.
Further, sensor output data input from the FFT 12 and pickup output input from the acceleration sensor 15 are used as corrected sensor output data obtained by correcting the sensor output data to an output value corresponding to the acceleration. Then, the second allowable range data set in a predetermined range stored in the memory 33 provided in the control means 30 is compared with the corrected sensor output data, and the sensor output data is within the range of the second allowable range data. In some cases, the control means 30 outputs an OK determination (makes the vibration detection sensor an acceptable product). On the other hand, when the sensor output data is outside the range of the second allowable range data, an NG determination (a vibration detection sensor is determined as a rejected product) is output.
By repeating this routine, the capacitances and sensor outputs of the plurality of vibration detection sensors 50 are continuously and efficiently measured.

It is explanatory drawing which shows the connection state of each means in an example (Embodiment 1) of the characteristic measuring apparatus of the vibration detection sensor of this invention. It is explanatory drawing which shows the connection state in the example (Embodiment 1) of the characteristic measuring apparatus of the vibration detection sensor of this invention when a correction means and the amplifier for acceleration sensors are used. It is explanatory drawing which shows the connection state in the example (Embodiment 1) of the characteristic measuring apparatus of the vibration detection sensor of this invention when a correction means, the amplifier for acceleration sensors, and a control means are used. It is a flowchart explaining the characteristic measuring method using an example (Embodiment 1) of the characteristic measuring apparatus of the vibration detection sensor of this invention. It is explanatory drawing which shows the connection state of each means in the other example (Embodiment 2) of the characteristic measuring apparatus of the vibration detection sensor of this invention. It is a flowchart explaining the characteristic measuring method using the other example (Embodiment 2) of the characteristic measuring apparatus of the vibration detection sensor of this invention. It is a typical partial sectional view showing an example of a vibration detection sensor. It is explanatory drawing which shows the connection state of each means in the characteristic measuring apparatus of the vibration detection sensor of a reference example. It is explanatory drawing explaining the characteristic measuring apparatus and method of the conventional vibration detection sensor. It is a flowchart explaining the characteristic measuring apparatus and method of the conventional vibration detection sensor.

Explanation of symbols

10a to 10c; vibration detection sensor characteristic measuring device of the present invention,
10 s; vibration detection sensor characteristic measuring device of reference example,
11: Excitation means,
12; Output measuring means,
13; capacitance measuring means,
14; switching means, 141; switching means, 142; switching means,
15; acceleration sensor, 152; ground, 153; acceleration sensor amplifier (charge-voltage conversion amplifier),
16; 1st wiring, 161; 1 wiring of 1st wiring, 161a; 1 end of 1 wiring of 1st wiring, 162; 2 wirings of 1st wiring, 162a; 2 of 1st wiring One end of the wiring,
17; second wiring,
18; third wiring,
19; fourth wiring, 195; shared ground wiring,
21; Fixing jig 211; Fixing jig upper stage 212; Insulating plate 213; Fixing jig lower stage;
30; control means; 31; input / output unit; 33; memory;
50; Vibration detection sensor, 501; Signal terminal, 502; Ground,
51; vibrator, 511; piezoelectric element, 512; metal thin plate,
52; terminal,
53; terminal holder, 531; opening,
54; casing, 541; housing portion, 542; attachment portion, 543; screw member, 544; washer, 545; nut, 546; upper outer edge portion, 547;
55; cover member, 551; connector,
56; wire for connection,
57; a sealing member.

Claims (5)

A vibration detection sensor characteristic measurement device for measuring a sensor output and capacitance of a resonance type vibration detection sensor including a piezoelectric element,
Vibration means for vibrating inspection vibration to the vibration detection sensor;
Output measuring means for measuring the sensor output from the vibration detection sensor;
Capacitance measuring means for measuring the capacitance of the vibration detection sensor;
The vibration detection sensor is disposed between the output measurement unit and the vibration detection sensor and between the capacitance measurement unit and the vibration detection sensor, and the vibration detection sensor is connected to the output measurement unit and the capacitance measurement unit. Switching means for switching so that only one of them is connected;
An acceleration sensor that is vibrated by the vibration means together with the vibration detection sensor, and outputs a pickup output corresponding to the acceleration of the inspection vibration when the vibration is applied;
A pair of first wires connecting the vibration detection sensor and the switching means;
A pair of second wires connecting the switching means and the output measuring means;
A pair of third wires connecting the switching means and the capacitance measuring means; and
A pair of fourth wires connecting the acceleration sensor and the output measuring means,
When the vibration detection sensor is arranged in a measurable state, one end of one of the first wires is connected to a signal terminal of the vibration detection sensor, and the other of the first wires One end of the wiring is connected to the ground of the vibration detection sensor, and the ground of the vibration detection sensor is insulated from the ground of the acceleration sensor.   2. The vibration detection sensor according to claim 1, wherein the output measurement unit includes a correction unit that corrects the sensor output of the vibration detection sensor to a value corresponding to the acceleration of the inspection vibration based on a pickup output of the acceleration sensor. Characteristic measuring device. A fixing jig for fixing both the vibration detection sensor and the acceleration sensor;
The vibration detection sensor characteristic measuring apparatus according to claim 1, wherein a ground of the vibration detection sensor and a ground of the acceleration sensor are insulated in the fixing jig. A method for measuring characteristics of a vibration detection sensor using the vibration detection sensor characteristic measurement device according to any one of claims 1 to 3,
A capacitance measuring step of measuring the capacitance of the vibration detection sensor using the capacitance measuring means;
An output measuring step of measuring the sensor output of the vibration detection sensor when the inspection vibration is vibrated using the output measuring means;
A switching step of switching the output measuring means or the capacitance measuring means connected to the vibration detection sensor to the other using the switching means,
After performing one of the capacitance measurement step and the output measurement step, the switching step is performed, and then the other step of the capacitance measurement step and the output measurement step is performed. A method for measuring characteristics of a vibration detection sensor, characterized in that: A method for measuring characteristics of a vibration detection sensor using the vibration detection sensor characteristic measurement device according to claim 2,
A capacitance measuring step of measuring the capacitance of the vibration detection sensor using the capacitance measuring means;
Using the output measuring means, the output measuring step of correcting the sensor output of the vibration detection sensor when the inspection vibration is vibrated and correcting the sensor output based on the pickup output of the acceleration sensor; and
A switching step of switching the output measuring means or the capacitance measuring means connected to the vibration detection sensor to the other using the switching means,
After performing one of the capacitance measurement step and the output measurement step, the switching step is performed, and then the other step of the capacitance measurement step and the output measurement step is performed. A method for measuring characteristics of a vibration detection sensor, characterized in that:

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