Equipment condition monitoring system

Abstract

To provide a facilities state monitoring system capable of suppressing erroneous determination.SOLUTION: A control unit is configured to perform first abnormality determination and second abnormality determination. In the first abnormality determination, a detection signal is compared with a first threshold range for grasping a state of facilities, and the detection signal is determined to be abnormal when the detection signal is out of the first threshold range. When the detection signal is determined to be abnormal in the first abnormality determination, a characteristics signal indicating characteristics of the sensor device is compared with a second threshold range for grasping a state of the sensor device. In the second abnormality determination, when the characteristics signal is out of the second threshold range, it is determined that the characteristics signal is abnormal and abnormality occurs in the sensor device.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a facility condition monitoring system for detecting abnormalities in facilities.

Background Art

[0002] Conventionally, a piezoelectric device in which a piezoelectric element is disposed in a casing has been proposed (see, for example, Patent Document 1). Specifically, this piezoelectric element has a configuration having a vibration region and transmits a detection signal corresponding to the sound pressure applied to the vibration region. Then, the piezoelectric device as described above is attached to processing equipment, conveyance equipment, etc. as facilities so that the sound pressure generated according to the state of the facilities is applied to the vibration region.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When detecting an abnormality in a facility by attaching the piezoelectric device as described above to the facility, for example, it is conceivable to provide a control unit connected to the piezoelectric element and perform an abnormality determination of the facility based on the detection signal in the control unit. In this case, the control unit compares the detection signal with a predetermined threshold range, and determines that an abnormality has occurred in the facility if the detection signal is outside the threshold range.

[0005] However, the detection signal may be outside the threshold range due to an abnormality occurring in the piezoelectric device itself. Therefore, in such an abnormality determination, there is a possibility of erroneously determining that there is an abnormality even though no abnormality has occurred in the facility.

[0006] In view of the above points, an object of the present invention is to provide a facility condition monitoring system that can suppress false determination. [Means for solving the problem]

[0007] Claim 1, in order to achieve the above objective, provides an equipment status monitoring system comprising: a sensor device (S10) having a sensor element (10) that transmits a detection signal corresponding to the status of equipment (30); and a control unit (210) that performs predetermined processing based on the detection signal, wherein the control unit compares the detection signal with a first threshold range for understanding the status of the equipment and determines that the detection signal is abnormal when the detection signal is outside the first threshold range; and performs a second abnormality determination when the first abnormality determination determines that the sensor device is abnormal, by comparing a characteristic signal, which is a signal indicating the characteristics of the sensor device and is different from the detection signal, with a second threshold range for understanding the status of the sensor device and determining that the characteristic signal is abnormal and that an abnormality has occurred in the sensor device when the characteristic signal is outside the second threshold range. 。

[0008] According to this, if the detected signal is outside the first threshold range, a second abnormality determination is performed to determine whether the characteristic signal based on the characteristics of the sensor device is within the second threshold range. Therefore, it is possible to suppress the determination that the equipment is abnormal when there is an abnormality in the sensor device, and thus suppress the false determination that the equipment is abnormal.

[0009] The reference numerals in parentheses attached to each component indicate an example of the correspondence between that component and the specific components described in the embodiments described later. [Brief explanation of the drawing]

[0010] [Figure 1] This is a block diagram of the equipment status monitoring system in the first embodiment. [Figure 2] This is a cross-sectional view of a piezoelectric element. [Figure 3] This is a plan view of a piezoelectric element. [Figure 4] This is a cross-sectional view of a piezoelectric device. [Figure 5] This is a flowchart of the actions performed by the first determination unit. [Figure 6]This is a flowchart executed by the second determination unit. [Figure 7] This is a block diagram of an equipment status monitoring system in a modified example of the first embodiment. [Figure 8] This is a block diagram of the equipment status monitoring system in the second embodiment. [Figure 9] This is a plan view of a piezoelectric element. [Figure 10] This is a cross-sectional view of a piezoelectric device. [Figure 11] This is a flowchart executed by the second determination unit. [Figure 12] This is a cross-sectional view of a piezoelectric device in a modified example of the second embodiment. [Figure 13] This is a block diagram of the equipment status monitoring system in the third embodiment. [Figure 14] This is a flowchart executed by the second determination unit. [Modes for carrying out the invention]

[0011] The embodiments of the present invention will be described below with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other will be denoted by the same reference numerals.

[0012] (First Embodiment) The first embodiment will be described with reference to the drawings. The equipment condition monitoring system of this embodiment is preferably installed in equipment that manufactures a predetermined product and used to detect abnormalities in the equipment. For example, the equipment condition monitoring system of this embodiment is installed in processing equipment that has cutting tools and is used to detect abnormalities such as wear or breakage of the cutting tools. However, the equipment 30 to be judged can be changed as appropriate and may be conveying equipment, etc.

[0013] As shown in FIG. 1, the equipment state monitoring system S1 includes a circuit unit 20 having a piezoelectric element 10 and a control unit 210, etc. In this embodiment, the piezoelectric element 10 and the circuit unit 20 are both arranged in a casing 300 to be described later and constitute an integrated piezoelectric device S10. Also, in this embodiment, the piezoelectric element 10 corresponds to a sensor element.

[0014] The piezoelectric device S10 (that is, the piezoelectric element 10) is provided in the equipment 30 and outputs a detection signal corresponding to the sound pressure generated in the equipment 30. The equipment 30 in this embodiment is a processing equipment having a cutting tool as described above.

[0015] Hereinafter, the piezoelectric element 10 of this embodiment will be described with reference to FIGS. 2 and 3. The piezoelectric element 10 includes a support 110 and a vibrating portion 120, and has a rectangular planar shape. The support 110 includes a support substrate 111 having a front surface 111a and a back surface 111b, and an insulating film 112 formed on the front surface 111a of the support substrate 111. The support substrate 111 is made of, for example, a silicon substrate or the like, and the insulating film 112 is made of an oxide film or the like.

[0016] The vibrating portion 120 is arranged on the support 110. A recess 110a is formed in the support 110 to float the inner edge side of the vibrating portion 120. Therefore, the vibrating portion 120 has a configuration including a support region 121a arranged on the support 110 and a floating region 121b that is connected to the support region 121a and floats on the recess 110a. In this embodiment, the recess 110a has a planar rectangular shape at the opening end on the vibrating portion 120 side. Therefore, the entire floating region 121b has a planar rectangular shape.

[0017] A slit 130 is formed in the floating region 121b, penetrating the floating region 121b in the thickness direction. In this embodiment, the slit 130 is formed to divide the floating region 121b into four sections. Specifically, two slits 130 are formed, passing through the center C1 of the floating region 121b and extending toward the opposing corners of the floating region 121b. In other words, the slits 130 extend from each corner of the planar rectangular floating region 121b toward the center C1, and are formed so that each slit 130 intersects at the center C1. As a result, the floating region 121b is separated into four vibration regions 122 that are approximately planar triangular in shape. Although not particularly limited, in this embodiment, the distance between each vibration region 122 (i.e., the width of the slit 130) is approximately 1 μm.

[0018] Each vibration region 122 is a cantilever with a fixed end on the side of the support region 121a and a free end on the opposite side of the support region 121a. In the following description, the side of the vibration region 122 opposite to the support 110 will be referred to as one side 122a of the vibration region 122, and the side of the vibration region 122 on the side of the support 110 will be referred to as the other side 122b of the vibration region 122.

[0019] The vibrating section 120 is configured to have a piezoelectric film 140 and an electrode film 150 connected to the piezoelectric film 140. Specifically, the piezoelectric film 140 has a lower piezoelectric film 141 and an upper piezoelectric film 142 laminated on the lower piezoelectric film 141. The lower piezoelectric film 141 and the upper piezoelectric film 142 are made of lead-free piezoelectric ceramics such as scandium aluminum nitride (ScAlN) or aluminum nitride (AlN).

[0020] The electrode film 150 is formed at a predetermined location in the vibration region 122 so as to be connected to the piezoelectric film 140, and is composed of molybdenum, copper, platinum, titanium, etc. In this embodiment, the electrode film 150 consists of a lower electrode film 151 formed below the lower piezoelectric film 141, an intermediate electrode film 152 formed between the lower piezoelectric film 141 and the upper piezoelectric film 142, and an upper electrode film 153 formed above the upper piezoelectric film 142. The lower electrode film 151 and the intermediate electrode film 152 are arranged to face each other with the lower piezoelectric film 141 in between. The intermediate electrode film 152 and the upper electrode film 153 are arranged to face each other with the upper piezoelectric film 142 in between. The lower electrode film 151, the intermediate electrode film 152, and the upper electrode film 153 have the same shape in the direction normal to one surface 122a of the vibration region 122 (hereinafter also simply referred to as the normal direction). Furthermore, "in the direction normal to one surface 122a of the vibration region 122" can be rephrased as "when viewed from the direction normal to one surface 122a of the vibration region 122."

[0021] Here, as described above, when the vibration region 122 is cantilevered, the stress generated when the vibration region 122 (i.e., the piezoelectric film 140) vibrates tends to be greater on the fixed end side where the vibration region 122 is supported than on the free end side. For this reason, the vibration region 122 is divided into a first region R1 where the stress tends to be large and a second region R2 where the stress tends to be small. In this embodiment, electrode films 150 are formed in both the first region R1 and the second region R2. The electrode film 150 formed in the first region R1 and the electrode film 150 formed in the second region R2 are insulated from each other.

[0022] Furthermore, the electrode film 150 formed in the first region R1 is connected to an electrode section (not shown) via wiring or the like formed in the support region 121a, although this is not shown. In this embodiment, the lower electrode film 151, intermediate electrode film 152, and upper electrode film 153 in each vibration region 122 are connected to the electrode section so that the change in charge in the first region R1 of each vibration region 122 is output as a single detection signal.

[0023] Furthermore, the lower electrode film 151, intermediate electrode film 152, and upper electrode film 153 formed in the second region R2 are not electrically connected to each electrode portion and are in a floating state. For this reason, the lower electrode film 151, intermediate electrode film 152, and upper electrode film 153 formed in the second region R2 are not necessarily required, but in this embodiment they are provided to protect the portions of the lower piezoelectric film 141 and upper piezoelectric film 142 located in the second region R2.

[0024] Furthermore, the lower electrode film 151, intermediate electrode film 152, and upper electrode film 153 formed in the first region R1 and the second region R2 are each formed so as not to reach the slit 130. In other words, the lower electrode film 151, intermediate electrode film 152, and upper electrode film 153 are formed to terminate inside the side surface exposed from the slit 130 in the vibration region 122. To put it another way, the lower electrode film 151, intermediate electrode film 152, and upper electrode film 153 are positioned inside the slit 130 in the direction normal to one surface 122a of the vibration region 122.

[0025] Furthermore, the vibrating section 120 of this embodiment has a base film 160 on which the lower piezoelectric film 141 and the lower electrode film 151 are arranged. In other words, the piezoelectric film 140 and the electrode film 150 are arranged on the support 110 via the base film 160. In this embodiment, the other surface 122b of each vibrating region 122 is composed of the base film 160.

[0026] The underlayer film 160 is not strictly necessary, but it is provided to facilitate crystal growth when forming the underlying piezoelectric film 141, etc. In this embodiment, the underlayer film 160 is made of aluminum nitride or the like. The piezoelectric film 140 has a thickness of about 1 μm, and the underlayer film 160 has a thickness of about several tens of nanometers. In other words, the underlayer film 160 is extremely thin compared to the piezoelectric film 140.

[0027] The above describes the configuration of the piezoelectric element 10 in this embodiment. When sound pressure is applied to each vibration region 122 of such a piezoelectric element 10, each vibration region 122 vibrates. In this case, for example, if the free end side of each vibration region 122 is displaced upward, tensile stress is generated in the lower piezoelectric film 141 and compressive stress is generated in the upper piezoelectric film 142, causing the charge of the lower piezoelectric film 141 and the upper piezoelectric film 142 to change. Therefore, the sound pressure applied to the vibration region 122 is detected based on the charge of the lower piezoelectric film 141 and the upper piezoelectric film 142.

[0028] In this case, the stress generated in the vibration region 122 (i.e., the piezoelectric film 140) is greater on the fixed end side than on the free end side because the stress is released on the free end side. In other words, the free end side generates less charge, and the signal-to-noise ratio (SNR), which is the ratio of signal to noise, tends to decrease. For this reason, in the piezoelectric element 10 of this embodiment, each vibration region 122 is divided into a first region R1 where stress tends to be large and a second region R2 where stress tends to be small, as described above. Furthermore, in the piezoelectric element 10, the charge generated in the lower electrode film 141 and upper piezoelectric film 142 located in the first region R1 is extracted from the lower electrode film 151, upper electrode film 153, and intermediate electrode film 152 located in the first region R1. This makes it possible to suppress the influence of noise.

[0029] As shown in Figure 1, the circuit section 20 has a configuration that includes an amplification section 200 and a control section 210, etc.

[0030] In this embodiment, the piezoelectric element 10 and the circuit section 20 are housed together in a casing 300, as shown in Figure 4, to constitute the piezoelectric device S10. Specifically, the casing 300 has a printed circuit board 310 on which the piezoelectric element 10 and the circuit section 20 are mounted, and a lid 320 fixed to the printed circuit board 310 to house the piezoelectric element 10 and the circuit section 20. The printed circuit board 310 can also be called the mounted component.

[0031] The printed circuit board 310, although not shown in the diagram, has a configuration in which wiring sections and through-hole electrodes are appropriately formed, and electronic components such as capacitors (not shown) are mounted as needed. The piezoelectric element 10 is mounted on one side 310a of the printed circuit board 310 via a bonding member 330 such as an adhesive on the other side 111b of the support substrate 111. In this embodiment, a through hole 311 is formed in the part of the printed circuit board 310 that faces the vibration region 122.

[0032] The circuit section 20 is mounted on one side 310a of the printed circuit board 310 via a bonding member 340 made of a conductive material. The piezoelectric element 10 and the circuit section 20 are electrically connected via a bonding wire 301. The cover section 320 is made of metal, plastic, resin, etc., and is fixed to the printed circuit board 310 via a bonding member such as an adhesive (not shown) to house the piezoelectric element 10 and the circuit section 20.

[0033] Such a piezoelectric device S10 is positioned so that sound pressure generated from the equipment 30 is applied to the vibration region 122 through the through-hole 311. The piezoelectric element 10 then transmits a detection signal to the circuit unit 20 corresponding to the sound pressure (i.e., pressure) introduced through the through-hole 311.

[0034] Next, the configuration of the circuit section 20 of this embodiment will be described in detail. The circuit section 20 has a configuration that includes an amplification section 200 and a control section 210, etc., as described above.

[0035] When the amplification unit 200 receives a detection signal from the piezoelectric element 10, it amplifies the detection signal and transmits it to the control unit 210 and the external circuit unit 40.

[0036] The control unit 210 is composed of a microcomputer or the like, which includes a CPU and a storage unit consisting of non-transitional physical storage media such as ROM, RAM, flash memory, and HDD, and has a determination unit 220 and a characteristic acquisition unit 230. CPU stands for Central Processing Unit, ROM stands for Read Only Memory, RAM stands for Random Access Memory, and HDD stands for Hard Disk Drive. Storage media such as ROM are non-transitional physical storage media.

[0037] The determination unit 220 of this embodiment has a first determination unit 221 and a second determination unit 222. The first determination unit 221 performs a first abnormality determination by comparing the amplified detection signal with a predetermined first threshold range. Specifically, the second determination unit 222 determines that the detection signal is normal if the detection signal is within the first threshold range, and determines that the detection signal is abnormal if the detection signal is outside the first threshold range. For example, when detecting the state of a cutting tool in equipment 30, the sound pressure introduced from the through hole 311 increases as the wear of the cutting tool increases. Therefore, the first determination unit 221 determines that the detection signal is abnormal if the detection signal becomes large and falls outside the first threshold range. When the first determination unit 221 determines that the detection signal is abnormal, it transmits a characteristic determination signal to the second determination unit 222. Also, when the first determination unit 221 determines that the detection signal is within the first threshold range, it transmits a normal signal to the external circuit unit 40 because the equipment 30 is normal. The first threshold range is set appropriately based on the material and shape of the cutting tool, for example, so that wear on the cutting tool can be detected.

[0038] When the second determination unit 222 receives a characteristic determination signal from the first determination unit 221, it transmits a characteristic acquisition signal to the characteristic acquisition unit 230. Then, as will be described later, when the second determination unit 222 receives a characteristic signal from the characteristic acquisition unit 230, it performs a second abnormality determination by comparing the characteristic signal with a second threshold range. Specifically, the second determination unit 222 determines that the characteristic signal is normal if it is within the second threshold range, and determines that the characteristic signal is abnormal if it is outside the second threshold range. More specifically, the second determination unit 222 determines that the piezoelectric device S10 is normal and the equipment 30 is abnormal if the characteristic signal is within the second threshold range, and determines that the piezoelectric device S10 is abnormal and the equipment 30 is normal if the characteristic signal is outside the second threshold range. In other words, the second determination unit 222 performs a self-diagnosis of the piezoelectric device S10. For example, in the piezoelectric element 10 described above, if foreign matter adheres to the vibration region 122 or the vibration region 122 is damaged, the mass increases and the resonant frequency changes. Therefore, the second determination unit 222 determines that there is an abnormality when the characteristic signal based on the resonant frequency changes and falls outside the second threshold range. The second threshold range is set appropriately based on the sensitivity of the vibration region 122, etc.

[0039] If the second determination unit 222 determines that the piezoelectric device S10 is functioning normally, it transmits an equipment malfunction signal to the external circuit unit 40 indicating that the equipment 30 is malfunctioning. If the second determination unit 222 determines that the piezoelectric device S10 is malfunctioning, it transmits a piezoelectric device malfunction signal to the external circuit unit 40 indicating that the piezoelectric device S10 is malfunctioning.

[0040] In this embodiment, the characteristic acquisition unit 230 is configured to include an RLC circuit having resistors, coils, capacitors, etc. When the characteristic acquisition unit 230 receives a characteristic acquisition signal from the second determination unit 222, it transmits a characteristic signal indicating the characteristics of the piezoelectric element 10. In this embodiment, the characteristic acquisition unit 230 transmits a characteristic signal based on the resonant frequency of the vibration region 122 in the piezoelectric element 10 to the second determination unit 222. Note that the characteristic signal based on the resonant frequency of the vibration region 122 changes if foreign matter adheres to the vibration region 122 or if the vibration region 122 is damaged, as described above.

[0041] The external circuit unit 40 performs predetermined processing according to the received signal. For example, the external circuit unit 40 is connected to a display device visible to the operator, and the display device displays the status of the equipment 30 and the piezoelectric device S10.

[0042] Specifically, when the external circuit unit 40 receives a normal signal from the first determination unit 221, it displays a message indicating that the equipment 30 and the piezoelectric device S10 are functioning normally. On the other hand, when the external circuit unit 40 receives an equipment malfunction signal from the second determination unit 222, it displays a message indicating that there is a malfunction in the equipment 30 on the display device. Furthermore, when the external circuit unit 40 receives a piezoelectric device malfunction signal from the second determination unit 222, it displays a message indicating that there is a malfunction in the piezoelectric device S10 on the display device.

[0043] The above describes the configuration of the equipment status monitoring system in this embodiment. Next, the operations performed by the control unit 210 will be described. First, the operation of the first determination unit 221 will be described with reference to Figure 5.

[0044] In step S101, the first determination unit 221 receives the detection signal amplified from the amplification unit 200. Next, in step S102, the first determination unit 221 determines whether or not it is a determination timing. For example, the determination timing may be at the start and end of operation of the equipment 30, or at predetermined intervals. However, the determination timing of the first determination unit 221 can be changed as appropriate. If the first determination unit 221 determines that it is not a determination timing (i.e., step S102: NO), it terminates the process.

[0045] If the first determination unit 221 determines that it is time for a determination (i.e., step S102: YES), it performs a first abnormality determination in step S103 by comparing the detected signal with a first threshold range. If the first determination unit 221 determines that the detected signal is within the first threshold range and there is no abnormality in the detected signal (i.e., step S103: NO), it transmits a normal signal to the external circuit unit 40 in step S104 and terminates the process. On the other hand, if the first determination unit 221 determines that the detected signal is outside the first threshold range and there is an abnormality in the detected signal (i.e., step S103: YES), it transmits a characteristic determination signal to the second determination unit 222 in step S105 and terminates the process.

[0046] The above describes the operation of the first determination unit 221. Next, the operation of the second determination unit 222 will be explained with reference to Figure 6.

[0047] In step S201, the second determination unit 222 determines whether or not it has received a characteristic determination signal. If it determines that it has not received a characteristic determination signal (i.e., step S201: NO), it terminates the process. On the other hand, if the second determination unit 222 determines that it has received a characteristic determination signal (i.e., step S201: YES), it transmits a characteristic acquisition signal to the characteristic acquisition unit 230 in step S202. As a result, the characteristic acquisition unit 230 transmits a characteristic signal based on the resonant frequency of the vibration region 122 in the piezoelectric element 10 to the second determination unit 222. As described above, the characteristic signal based on the vibration region 122 changes if foreign matter adheres to the vibration region 122 or if the vibration region 122 is damaged.

[0048] Next, in step S203, the second determination unit 222 determines whether or not a characteristic signal has been received. If it determines that a characteristic signal has not been received (i.e., step S203: NO), it executes the process in step S203 again. In other words, the second determination unit 222 waits until a characteristic signal is received.

[0049] If the second determination unit 222 determines that it has received a characteristic signal (i.e., step S203: YES), it performs a second abnormality determination in step S204 by comparing the characteristic signal with the second threshold range. In other words, it performs a self-diagnosis of the piezoelectric device S10. If the second determination unit 222 determines that the characteristic signal is not within the second threshold range (i.e., step S204: YES), it determines that the characteristic signal is abnormal and transmits a piezoelectric device abnormality signal to the external circuit unit 40 in step S205, indicating that the piezoelectric device S10 is abnormal. On the other hand, if the second determination unit 222 determines that the characteristic signal is within the second threshold range (i.e., step S204: NO), it determines that the equipment 30 is abnormal because the characteristic signal is normal and transmits an equipment abnormality signal to the external circuit unit 40 in step S206, indicating that the equipment 30 is abnormal.

[0050] According to the embodiment described above, if the detection signal is outside the first threshold range, a second abnormality determination is performed to determine whether the characteristic signal based on the characteristics of the piezoelectric device S10 is within the second threshold range. Therefore, it is possible to suppress the determination that the equipment 30 is abnormal even though there is an abnormality in the piezoelectric device S10. In other words, it is possible to suppress the false determination that the equipment 30 is abnormal.

[0051] (Modified version of the first embodiment) A modified version of the first embodiment will now be described. In the first embodiment described above, as shown in Figure 7, a characteristic operating unit 240 may be provided, which is composed of a sound source that generates sound pressure and is connected to the characteristic acquisition unit 230. The characteristic operating unit 240 is configured to generate sound pressure of multiple different frequencies so that it can correspond to the resonant frequencies in the vibration region 122. In this case, when the characteristic acquisition unit 230 receives the characteristic acquisition signal, it may be configured to derive a characteristic signal based on the resonant frequency of the piezoelectric element 10 based on the detection signal generated by operating the characteristic operating unit 240, and to transmit the derived characteristic signal to the second determination unit 222. In this way, the resonant frequency may be acquired mechanically as a characteristic signal.

[0052] (Second Embodiment) A second embodiment will now be described. This embodiment adds a return operation to the first embodiment. Other aspects are the same as the first embodiment, so a detailed explanation will be omitted here.

[0053] In this embodiment, as shown in Figure 8, the equipment status monitoring system S1 further includes an element return unit 250, a casing return unit 260, and a return operation unit 270.

[0054] Specifically, in this embodiment, as shown in Figure 9, the piezoelectric element 10 has a temperature detection element 251 that outputs a temperature detection signal according to the temperature and a heating element 252 that generates heat when energized, arranged in each vibration region 122 as a return section 250 for the element. In this embodiment, the temperature detection element 251 and the heating element 252 are formed in the second region R2 of each vibration region 122. More specifically, in this embodiment, the intermediate electrode film 152 is not formed in the second region R2. The temperature detection element 251 and the heating element 252 are formed in the portion located between the lower piezoelectric film 141 and the upper piezoelectric film 142. In other words, the temperature detection element 251 and the heating element 252 are formed in the portion where the intermediate electrode film 152 was formed in the first embodiment.

[0055] The temperature detection element 251 is configured using, for example, a thermosensitive resistor whose resistance changes according to temperature, and the heating element 252 is configured using, for example, a heat-generating resistor that generates heat when an electric current is passed through it. In this embodiment, the temperature detection element 251 and the heating element 252 are made of, for example, platinum.

[0056] Furthermore, as shown in Figure 10, the casing 300 is equipped with a casing return section 260, which includes a temperature detection section 261, a heat generation section 262, and a vibration section 263.

[0057] The heating element 262 is composed of, for example, a resistance heater. The temperature detection element 261 is composed of a thermistor. The vibration element 263 is composed of a piezoelectric element. Although not shown in the diagram, the temperature detection element 261, the heating element 262, and the vibration element 263 are each electrically connected to the circuit element 20 via wires or the like.

[0058] Figure 10 shows an example where the vibrating unit 263 is located inside the casing 300, and the temperature detection unit 261 and heat-generating unit 262 are located outside the casing 300. However, the location of these components is not particularly limited; the vibrating unit 263 may be located outside the casing 300, or the temperature detection unit 261 and heat-generating unit 262 may be located inside the casing 300.

[0059] The reset operation unit 270 is connected to the element reset unit 250 and the casing reset unit 260, and as will be described later, when it receives a reset start signal from the second determination unit 222, it activates the element reset unit 250 and the casing reset unit 260.

[0060] Specifically, the reset operation unit 270 controls the temperature detection element 251 and the heating element 252 of the piezoelectric element 10 so that the temperature of the temperature detection element 251 (i.e., the piezoelectric element 10) reaches a predetermined temperature. This allows foreign matter such as water to evaporate if it is adhering to the vibration region 122. The reset operation unit 270 also applies a predetermined voltage to the piezoelectric element 10 to vibrate the vibration region 122. This allows foreign matter to be brushed off if it is adhering to the vibration region 122. In this embodiment, the target object for the element reset unit 250 is the piezoelectric element 10.

[0061] Similarly, the reset operation unit 270 controls the temperature detection unit 261 and the heating unit 262 located in the casing 300 to ensure that the temperature of the temperature detection unit 261 (i.e., the casing 300) reaches a predetermined temperature. This allows any foreign matter such as water adhering to the casing 300 to evaporate. The reset operation unit 270 also applies a predetermined voltage to the vibration unit 263 located in the casing 300, causing the casing 300 to vibrate. This allows any foreign matter such as water adhering to the casing 300 to be brushed off. It should be noted that foreign matter adhering to the casing 300, especially if it is adhering to the through-hole 311 of the casing 300, will change the sound pressure introduced, thus having a greater impact on the detection signal. In this embodiment, the target object for the casing reset unit is the casing 300.

[0062] When the second determination unit 222 receives the characteristic determination signal, it transmits a recovery start signal to the recovery operation unit 270. As a result, the recovery operation unit 270 performs the above operation. The second determination unit 222 then performs a second abnormality determination by comparing the characteristic signal after the recovery process with the second threshold range.

[0063] The above describes the configuration of the equipment status monitoring system S1 in this embodiment. Next, the operation of the second determination unit 222 in this embodiment will be explained with reference to Figure 11. Note that the same parts as in the first embodiment will not be explained.

[0064] If the second determination unit 222 determines in step S201 that it has received a characteristic determination signal (i.e., S201: YES), it transmits a reset start signal to the reset operation unit 270 in step S210. As a result, the reset operation unit 270 activates the element reset unit 250 and the casing reset unit 260, and performs an operation to remove any foreign matter that is attached.

[0065] Subsequently, in step S211, it is determined whether a predetermined recovery time has elapsed. That is, it is determined whether the recovery operation has been completed. If it is determined that the recovery time has not elapsed (i.e., step S211: NO), the process of step S211 is repeated. In other words, the system waits until the recovery time has elapsed.

[0066] If the second determination unit 222 determines that the recovery time has elapsed (i.e., step S211: YES), it performs the processing in steps S202 to S206. In this case, in the processing in step S204, the characteristic signal after the recovery operation is performed is compared with the second threshold. That is, the characteristic signal, which suppresses the presence of foreign matter, is compared with the second threshold. Therefore, the accuracy of abnormality detection for the characteristic signal can be improved.

[0067] According to the embodiment described above, if the detection signal is outside the first threshold range, a second abnormality determination is performed to determine whether the characteristic signal based on the characteristics of the piezoelectric device S10 is within the second threshold range. Therefore, the same effects as in the first embodiment can be obtained.

[0068] (1) In this embodiment, the piezoelectric device S10 is reset before the second abnormality determination is made. Therefore, abnormalities caused by foreign matter etc. adhering to the piezoelectric device S10 can be eliminated, and furthermore, the false determination that the piezoelectric device S10 is abnormal can be suppressed.

[0069] (Modified version of the second embodiment) A modified version of the second embodiment described above will now be explained. In the second embodiment, if the second determination unit 222 has not transmitted a recovery start signal, it may transmit an adjustment signal to the recovery operation unit 270 to control the temperature detection element 251 and the heating element 252 so that the vibration region 122 remains constant at a predetermined temperature. Similarly, if the second determination unit 222 has not transmitted a recovery start signal, it may transmit an adjustment signal to the recovery operation unit 270 to control the temperature detection unit 261 and the heating element 262 so that the casing 300 remains constant at a predetermined temperature. As a result, the detection signal from the piezoelectric element 10 will be a signal from a state maintained at a predetermined temperature. Therefore, variations in detection accuracy can be suppressed.

[0070] Furthermore, the configurations of the element return section 250 and the casing return section 260 can be changed as appropriate. For example, the casing return section 260 may be composed of an air blow device 264 that applies a predetermined air pressure to the through hole 311 of the casing 300, as shown in Figure 12. Also, although not specifically shown, an air blow device that applies air pressure to the piezoelectric element 10 may be arranged in the casing 300. Furthermore, the element return section 250 may be configured to have only the heating element 252 of the temperature detection element 251 and heating element 252, and the casing return section 260 may be configured to have only the heating element 262 of the temperature detection section 261 and heating section 262.

[0071] Furthermore, although the second embodiment described above includes an example in which the return section comprises an element return section 250 and a casing return section 260, it is also possible to have a configuration that includes only one of the element return section 250 and the casing return section 260.

[0072] (Third embodiment) A third embodiment will now be described. This embodiment is modified from the first embodiment to detect the surrounding conditions of the equipment 30. Other aspects are the same as in the first embodiment, so further explanation will be omitted here.

[0073] As shown in Figure 13, the equipment status monitoring system S1 of this embodiment includes an ambient temperature detection unit 280 as an ambient detection unit. The ambient temperature detection unit 280 is composed of a thermistor or the like and is connected to a second determination unit 222. The ambient temperature detection unit 280 is, for example, placed near the equipment 30 and transmits a status signal to the second determination unit 222 according to the ambient conditions (i.e., temperature) around the equipment 30.

[0074] When the second determination unit 222 receives a characteristic determination signal, it performs a third abnormality determination by comparing the status signal with a third threshold range. Specifically, the second determination unit 222 determines that the status signal is normal if it is within the third threshold range, and determines that the status signal is abnormal if it is outside the third threshold range. More specifically, the second determination unit 222 determines that the surrounding conditions of the equipment 30 are normal if the status signal is within the third threshold range, and determines that the surrounding conditions are abnormal if the status signal is outside the third threshold range. If the second determination unit 222 determines that the status signal is outside the third threshold range, it transmits an ambient abnormality signal to the external circuit unit 40 because the surrounding conditions are abnormal.

[0075] An abnormal condition in the surrounding environment of equipment 30 refers to situations such as when equipment 30 or the devices surrounding equipment 30 are abnormally hot. The third threshold range is set based on the range of temperatures that can occur around equipment 30 during normal use.

[0076] When the external circuit unit 40 receives an ambient abnormality signal from the second determination unit 222, it causes the display device to show that the ambient temperature of the equipment 30 is abnormal.

[0077] The above describes the configuration of the equipment status monitoring system S1 in this embodiment. Next, the operation of the second determination unit 222 in this embodiment will be explained with reference to Figure 14. Note that the same parts as in the first embodiment will not be explained.

[0078] When the second determination unit 222 receives the characteristic determination signal in step S201, it performs a third abnormality determination in step S220 by comparing the status signal with the third threshold range.

[0079] Then, if the second determination unit 222 determines that the status signal is not within the third threshold range (i.e., step S220: YES), it determines that the surrounding condition of the equipment 30 is abnormal, and therefore transmits an abnormal surrounding signal to the external circuit unit 40 in step S221. On the other hand, if the second determination unit 222 determines that the status signal is within the third value range (i.e., step S200: NO), it determines that the surrounding condition of the equipment 30 is normal, and performs the processing in steps S202 to S206.

[0080] According to the embodiment described above, if the detection signal is outside the first threshold range, a second abnormality determination is performed to determine whether the characteristic signal based on the characteristics of the piezoelectric device S10 is within the second threshold range. Therefore, the same effects as in the first embodiment can be obtained.

[0081] (1) In this embodiment, if there is an abnormality in the detection signal, the surrounding conditions are determined. Therefore, the influence of the surroundings can be taken into account, and the possibility of misjudgment can be suppressed.

[0082] (Modified version of the third embodiment) A modified example of the third embodiment described above will now be explained. In the third embodiment described above, an example was described in which an ambient temperature detection unit 280 is provided as the ambient detection unit. However, the configuration of the ambient detection unit can be changed as appropriate, and for example, it may be composed of a humidity detection unit for detecting ambient humidity, a vibration detection unit for detecting ambient vibration, a sound detection unit for detecting ambient sound, and an illuminance detection unit for detecting ambient illuminance.

[0083] Furthermore, in the third embodiment described above, an example was described in which the ambient temperature detection unit 280, which serves as the ambient detection unit, is arranged around the equipment 30. However, the ambient detection unit may also be arranged inside the piezoelectric device S10. The piezoelectric device S10 outputs a detection signal according to the state of the equipment 30 and is arranged around the equipment 30. Therefore, even if the ambient temperature detection unit 280 is arranged inside the piezoelectric device S10, it can be said that the ambient temperature detection unit 280 transmits a state signal according to the state of the surroundings of the equipment 30.

[0084] Furthermore, although the third embodiment described above illustrates an example in which the third abnormality determination is performed before the second abnormality determination, the third abnormality determination may also be performed after the second abnormality determination.

[0085] (Other embodiments) This disclosure is described in accordance with embodiments, but it is understood that this disclosure is not limited to such embodiments or structures. This disclosure also includes various modifications and variations within the scope of equivalents. In addition, various combinations and forms, as well as other combinations and forms that include only one, more, or fewer of those elements, fall within the scope and concept of this disclosure.

[0086] For example, in each of the above embodiments, the control unit 210 was described as having a configuration in which a first determination unit 221 and a second determination unit 222 are included, but the first determination unit 221 and the second determination unit 222 may be integrated.

[0087] Furthermore, although the above embodiments describe an example in which the control unit 210 is mounted on the circuit unit 20, the control unit 210 may be provided in, for example, an external circuit unit 40. Moreover, the circuit unit 20 may be located outside the casing 300.

[0088] Furthermore, although the above embodiments described examples having a piezoelectric element 10 as a sensor element, the sensor element may consist of an acceleration detection element, an angular velocity detection element, a temperature detection element, a light detection element, a humidity detection element, and the like. Also, multiple sensor elements may be provided so that detection signals corresponding to different physical quantities are transmitted. For example, a piezoelectric element and a humidity detection element may be provided, and the above determination may be made by combining the detection signals. This further reduces the likelihood of misjudgment.

[0089] The control unit and its method described herein may be implemented by a dedicated computer provided by configuring a processor and memory programmed to perform one or more functions embodied by a computer program. Alternatively, the control unit and its method described herein may be implemented by a dedicated computer provided by configuring a processor by one or more dedicated hardware logic circuits. Alternatively, the control unit and its method described herein may be implemented by one or more dedicated computers configured by a combination of a processor and memory programmed to perform one or more functions and a processor configured by one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions executed by the computer on a computer-readable non-transitional tangible recording medium.

[0090] (Features of the present invention) [Claim 1] A system for monitoring the condition of equipment, A sensor device (S10) having a sensor element (10) that transmits a detection signal according to the state of the equipment (30), The system includes a control unit (210) that performs predetermined processing based on the detection signal, The control unit performs a first abnormality determination, in which it compares the detection signal with a first threshold range for determining the state of the equipment and determines that the detection signal is abnormal when the detection signal is outside the first threshold range; and a second abnormality determination, in which it compares a characteristic signal indicating the characteristics of the sensor device with a second threshold range for determining the state of the sensor device when it determines that the sensor device is abnormal in the first abnormality determination, and determines that the characteristic signal is abnormal and that an abnormality has occurred in the sensor device when the characteristic signal is outside the second threshold range. [Claim 2] The sensor device has a return section (250, 260), The equipment status monitoring system according to claim 1, wherein when the control unit determines that there is an abnormality in the first abnormality determination, it controls the recovery unit to perform a recovery operation to restore the state of the sensor device before performing the second abnormality determination, and performs the second abnormality determination after the recovery operation is completed. [Claim 3] The sensor device comprises the sensor element and a casing (300) that houses the sensor element. The equipment status monitoring system according to claim 1 or 2, wherein the resetting unit is a sensor element resetting unit (250) provided on the sensor element for restoring the state of the sensor element. [Claim 4] The sensor device comprises the sensor element and a casing (300) that houses the sensor element. The equipment condition monitoring system according to claim 1 or 2, wherein the return unit is a casing return unit (260) provided in the casing for restoring the state of the casing. [Claim 5] The equipment status monitoring system according to claim 3 or 4, wherein the recovery unit generates heat to heat the target object. [Claim 6] The equipment status monitoring system according to any one of claims 3 to 5, wherein the return unit vibrates the target object. [Claim 7] The equipment condition monitoring system according to any one of claims 3 to 6, wherein the return unit applies air pressure to the target object. [Claim 8] The equipment has an ambient detection unit (270) that transmits a status signal corresponding to the surrounding environment, The equipment status monitoring system according to any one of claims 1 to 7, wherein the control unit, when it determines in the first abnormality determination that there is an abnormality, compares the status signal with a third threshold range for understanding the surrounding conditions of the equipment, and performs a third abnormality determination when the status signal is outside the third threshold range, in which it determines that the surrounding conditions of the equipment are abnormal. [Claim 9] The equipment status monitoring system according to any one of claims 1 to 8, wherein the sensor element comprises a plurality of sensors and transmits a detection signal corresponding to a different physical quantity. [Explanation of symbols]

[0091] 10. Piezoelectric element (sensor element) 30 Equipment 220 Control Unit S10 Piezoelectric device (sensor device)

Claims

1. A system for monitoring the condition of equipment, A sensor device (S10) having a sensor element (10) that transmits a detection signal according to the state of the equipment (30), The system includes a control unit (210) that performs predetermined processing based on the detection signal, The control unit performs a first abnormality determination, in which it compares the detection signal with a first threshold range for determining the state of the equipment and determines that the detection signal is abnormal when the detection signal is outside the first threshold range; and a second abnormality determination, in which it compares a characteristic signal, which is a signal indicating the characteristics of the sensor device and is different from the detection signal, with a second threshold range for determining the state of the sensor device and determines that the characteristic signal is abnormal and that an abnormality has occurred in the sensor device when the characteristic signal is outside the second threshold range.

2. The sensor device has a return section (250, 260), The equipment status monitoring system according to claim 1, wherein when the control unit determines that there is an abnormality in the first abnormality determination, it controls the recovery unit to perform a recovery operation to restore the state of the sensor device before performing the second abnormality determination, and performs the second abnormality determination after the recovery operation is completed.

3. The sensor device comprises the sensor element and a casing (300) that houses the sensor element. The equipment status monitoring system according to claim 2, wherein the resetting unit is a sensor element resetting unit (250) provided on the sensor element for restoring the state of the sensor element.

4. The sensor device comprises the sensor element and a casing (300) that houses the sensor element. The equipment condition monitoring system according to claim 2, wherein the return unit is a casing return unit (260) provided in the casing for restoring the state of the casing.

5. The equipment status monitoring system according to claim 3 or 4, wherein the recovery unit generates heat to heat the target object.

6. The equipment status monitoring system according to claim 3 or 4, wherein the return unit vibrates the target object.

7. The equipment condition monitoring system according to claim 3 or 4, wherein the return unit applies air pressure to the target object.

8. The equipment has an ambient detection unit (270) that transmits a status signal corresponding to the surrounding environment, The equipment status monitoring system according to any one of claims 1 to 4, wherein the control unit, when it determines in the first abnormality determination that there is an abnormality, compares the status signal with a third threshold range for understanding the surrounding state of the equipment, and performs a third abnormality determination when the status signal is outside the third threshold range, in which it determines that the surrounding state of the equipment is abnormal.

9. The equipment status monitoring system according to any one of claims 1 to 4, wherein the sensor element comprises a plurality of sensors and transmits a detection signal corresponding to a different physical quantity.

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