JP2021047095A - Failure diagnostic device and method - Google Patents

Abstract

To enable failure diagnosis of a thermal flowmeter while being installed.SOLUTION: A flow stop unit 101 stops the flow of a fluid. A temperature control unit 102 provides control to keep temperature of a heater higher than temperature around the heater. A temperature change measurement unit 103 acquires change in temperature measured by a temperature sensor from a first point in time when the temperature control unit 102 starts controlling the heater temperature to a second point in time when a preset time has elapsed after the first point in time while the flow stop unit 101 is stopping the flow of the fluid and the temperature control unit 102 is controlling the heater temperature. A determination unit 104 determines the presence of a failure involving abnormality in the adhesion state of at least either of the heater and the temperature sensor when the change in temperature measured by the temperature change measurement unit 103 is smaller than a preset reference value.SELECTED DRAWING: Figure 1

Description

The present invention relates to a failure diagnosis device and a method for diagnosing a failure of a thermal flow meter.

Technology for measuring the flow rate and flow velocity of fluid flowing through pipes is widely used in the industrial and medical fields. There are various types of devices for measuring flow rate and flow velocity, such as an electromagnetic flow meter, a vortex flow meter, a Koriori type flow meter, and a thermal flow meter, and they are used properly according to the application. The thermal flow meter has the advantages of being able to detect gas, basically having no pressure loss, and being able to measure mass flow rates. Further, a thermal flow meter capable of measuring the flow rate of a liquid using an organic solvent or a corrosive liquid by forming the pipe from glass is also used (see Patent Document 1). A thermal flow meter that measures the flow rate of such a liquid is suitable for measuring a minute flow rate.

The thermal flow meter measures the flow rate by, for example, the power consumption of the heater. A temperature sensor and a heater are provided in sequence from the upstream to the downstream of the pipe, and the difference between the temperature of the heater and the temperature of the fluid in the upstream that is not affected by the heat of the heater measured by the temperature sensor is set in advance. The heater is controlled so that there is a temperature difference. In this state, the electric power of the heater is measured and used as a sensor value, and the flow rate of the fluid is calculated from this sensor value. The temperature sensor and the heater are adhesively fixed to a portion formed thinner than other parts of the outer wall of the pipe.

By arranging the temperature sensor in such a thin place, the temperature of the fluid flowing through the pipe can be measured favorably. Further, by arranging the heater in such a thin place, the fluid flowing through the pipe can be efficiently heated in a short time. In addition, a heat conductive adhesive is used to improve heat transfer between the piping and the temperature sensor and heater.

As is well known, there is a correlation between the power consumption of the heater described above and the flow rate of the fluid. This correlation is also reproducible at the same fluid / flow rate / temperature. Therefore, the flow rate can be calculated by using a predetermined correlation coefficient (constant) from the power consumption of the heater measured as described above.

2017-101955

By the way, in the above-mentioned thermal flowmeter, it is important that the temperature sensor and the heater are securely adhered and fixed to the outer wall of the pipe and are in close contact with each other. For example, if the temperature sensor or heater does not adhere to the outer wall of the pipe due to deterioration of the adhesive and a gap is partially generated, the fluid cannot be heated efficiently and the temperature of the fluid can be measured accurately. It becomes impossible to measure the flow rate accurately. When measuring with a thermal flow meter, the adhesive may deteriorate due to the influence of humidity in the atmosphere, the influence of temperature, the influence of heat cycle, and the like. When the adhesive deteriorates due to the influence of the usage environment in this way, the above-mentioned problems do not occur at the initial stage when the thermal flowmeter is installed, but problems will occur over time.

However, since it is not easy to remove the thermal flowmeter once attached, it is not easy to confirm the presence or absence of the above-mentioned abnormality (fault diagnosis) by removing and disassembling the flowmeter.

The present invention has been made to solve the above problems, and an object of the present invention is to enable diagnosis of a failure of a thermal flow meter in an installed state.

The failure diagnosis device according to the present invention is adhered and fixed to the outer wall of a pipe that transports a fluid to be measured with an adhesive, and is adhered and fixed to a heater that heats the fluid and an outer wall of a pipe upstream of the heater. When the heater is driven so that the difference between the temperature sensor that measures the temperature of the fluid and the temperature of the fluid at a position that is not affected by the heat of the heater is the set temperature difference. In a failure diagnostic device for diagnosing a failure of a thermal flow meter equipped with a sensor circuit configured to output a sensor value corresponding to the state of thermal diffusion in the fluid heated by the heater, the fluid flow is stopped. A fluid stop unit configured to stop the flow of the fluid, a temperature control unit configured to control the temperature of the heater to a temperature higher than the temperature around the heater, and a fluid stop unit to stop the flow of the fluid, and the temperature control unit. Controls the temperature of the heater, and changes the temperature measured by the temperature sensor from the first time point when the temperature control unit starts controlling the temperature of the heater to the second time point when the set time has elapsed. When the temperature change measured by the temperature change measuring unit configured to measure and the temperature change measuring unit is smaller than the set temperature reference value, there is an abnormality in the adhesion state of at least one of the heater and the temperature sensor. It is provided with a determination unit configured to determine a certain failure state.

In one configuration example of the above-mentioned failure diagnosis device, from the first time point when the temperature control unit starts controlling the temperature of the heater while the fluid stop unit stops the flow of the fluid and the temperature control unit controls the temperature of the heater. , The power change measurement unit configured to measure the change in the power of the heater by the second time point when the set time has elapsed, and the power change measured by the power change measurement unit are the set power. Further, it is provided with a heater abnormality determination unit configured to determine a failure state in which there is an abnormality in the adhesion state of the heater when it is smaller than the reference value.

In one configuration example of the failure diagnosis device, the adhesive is a heat conductive adhesive.

In one configuration example of the failure diagnosis device, the thermal flow meter further includes a flow rate calculation unit configured to calculate the flow rate of the fluid from the sensor value.

In one configuration example of the failure diagnosis device, the temperature sensor measures the temperature of the fluid at a position upstream of the heater and not affected by the heat of the heater, and the sensor circuit is the temperature of the heater and the fluid measured by the temperature sensor. The power of the heater when the heater is driven so that the difference from the temperature becomes the set temperature difference is output as the sensor value.

In one configuration example of the failure diagnosis device, the temperature sensor is composed of a first temperature sensor, a second temperature sensor, and a third temperature sensor, and the first temperature sensor is not affected by the heat of the heater on the upstream side of the heater. The temperature of the fluid at the position is measured, the second temperature sensor measures the temperature of the fluid at the position upstream from the heater and is affected by the heat of the heater, and the third temperature sensor measures the temperature of the fluid at the position downstream from the heater. The temperature of the fluid at the receiving position is measured, and the sensor circuit drives the heater so that the difference between the temperature of the heater and the temperature of the fluid measured by the first temperature sensor becomes the set temperature difference. The temperature difference between the temperature of the fluid measured by the second temperature sensor and the temperature of the fluid measured by the third temperature sensor is output as a sensor value.

The failure diagnosis method according to the present invention is adhered and fixed to the outer wall of a pipe that transports a fluid to be measured with an adhesive, and is adhered and fixed to a heater that heats the fluid and an outer wall of a pipe upstream of the heater. When the heater is driven so that the difference between the temperature of the temperature sensor that measures the temperature of the fluid and the temperature of the fluid measured by the temperature sensor is the set temperature difference that is set. It is a failure diagnosis method of a thermal flow meter equipped with a sensor circuit that outputs power as a sensor value. Following the first step of stopping the flow of fluid and the first step, the temperature of the heater is measured around the heater. In the second step of controlling the temperature higher than the temperature, the fluid flow was stopped in the first step, the temperature of the heater was controlled in the second step, and the control of the temperature of the heater was started in the second step. From the first time point to the second time point when the set time has passed, the third step of measuring the temperature change measured by the temperature sensor and the temperature change measured in the third step are set. It is provided with a fourth step of determining a failure state in which there is an abnormality in the adhesion state of at least one of the heater and the temperature sensor when the temperature is smaller than the existing temperature reference value.

In one configuration example of the above failure diagnosis method, from the first time point when the temperature control unit starts controlling the temperature of the heater while the fluid stop unit stops the flow of the fluid and the temperature control unit controls the temperature of the heater. , When the change in the power of the heater is measured in the fifth step and the change in the power measured in the fifth step is smaller than the set power reference value by the second time point when the set time has elapsed. Further, a sixth step of determining a failure state in which the adhesion state of the heater is abnormal is provided.

In one configuration example of the above failure diagnosis method, immediately after the installation of the thermal flow meter, the temperature of the heater is set to a temperature higher than the temperature around the heater in the seventh step of stopping the flow of the fluid and the seventh step. From the third point in time, when the fluid flow was stopped in the eighth step and the seventh step to be controlled, the temperature of the heater was controlled in the eighth step, and the control of the temperature of the heater was started in the eighth step. By the 4th time point when the set time has passed, the change in temperature measured by the temperature sensor or the change in the power of the heater is measured, and the measured value is used as the temperature reference value or the power reference value in the 9th step. Further prepare.

In one configuration example of the above failure diagnosis method, the adhesive is a heat conductive adhesive.

In one configuration example of the above failure diagnosis method, the temperature sensor measures the temperature of the fluid at a position upstream of the heater and not affected by the heat of the heater, and the sensor circuit is the temperature of the heater and the fluid measured by the temperature sensor. The power of the heater when the heater is driven so that the difference from the temperature becomes the set temperature difference is output as a sensor value.

In one configuration example of the above failure diagnosis method, the temperature sensor is composed of a first temperature sensor, a second temperature sensor, and a third temperature sensor, and the first temperature sensor is not affected by the heat of the heater on the upstream side of the heater. The temperature of the fluid at the position is measured, the second temperature sensor measures the temperature of the fluid at the position upstream from the heater and is affected by the heat of the heater, and the third temperature sensor measures the temperature of the fluid at the position downstream from the heater. The temperature of the fluid at the receiving position is measured, and the sensor circuit drives the heater so that the difference between the temperature of the heater and the temperature of the fluid measured by the first temperature sensor becomes the set temperature difference. The temperature difference between the temperature of the fluid measured by the second temperature sensor and the temperature of the fluid measured by the third temperature sensor is output as a sensor value.

As described above, according to the present invention, the temperature sensor is used from the first time point when the control of the heater temperature is started to the second time point when the set time elapses with the fluid flow stopped. Since the measured change in temperature is measured, it is possible to diagnose the failure of the thermal fluid meter in the installed state.

FIG. 1 is a configuration diagram showing a configuration of a failure diagnosis device 100 according to a first embodiment of the present invention. FIG. 2 is a configuration diagram showing the configuration of the thermal flow meter 120. FIG. 3 is a configuration diagram showing the configuration of another thermal flow meter 120. FIG. 4 is a characteristic diagram showing a change in temperature measured by the temperature change measuring unit 103. FIG. 5 is a flowchart for explaining the failure diagnosis method according to the first embodiment of the present invention. FIG. 6 is a configuration diagram showing the configuration of the failure diagnosis device 200 according to the second embodiment of the present invention. FIG. 7 is a flowchart for explaining the failure diagnosis method according to the second embodiment of the present invention. FIG. 8 is a configuration diagram showing a hardware configuration of the failure diagnosis device according to the embodiment.

Hereinafter, the failure diagnosis device according to the embodiment of the present invention will be described.

[Embodiment 1]
First, the failure diagnosis device 100 according to the first embodiment of the present invention will be described with reference to FIG. The failure diagnosis device 100 includes a fluid stop unit 101, a temperature control unit 102, a temperature change measurement unit 103, and a determination unit 104, and diagnoses a failure of the thermal flow meter 120.

Here, the thermal flow meter 120 includes a heater 121, a temperature sensor 122, and a sensor circuit 123. The heater 121 is adhesively fixed to the outer wall of the pipe 151 for transporting the fluid to be measured with an adhesive to heat the fluid.

For example, the heater 121 is adhesively fixed to a counterbore portion 151a formed on the outer wall of the pipe 151 and partially dented and formed thinner than the other portions. The temperature sensor 122 is adhesively fixed to the outer wall of the pipe 151 on the upstream side of the heater 121 with an adhesive to measure the temperature of the fluid. The temperature sensor 122 is adhesively fixed to a counterbore portion 151b formed on the outer wall of the pipe 151 and partially dented and formed thinner than the other portions. The pipe 151 can be made of, for example, glass, sapphire, or the like. By providing the counterbore portion, the heat conduction between the heater or the temperature sensor and the fluid can be further improved. If the pipe wall of the pipe 151 is sufficiently thin, it is not necessary to provide a counterbore portion.

As the adhesive, for example, a thermally conductive adhesive composed of a paste which is a mixture of a conductive filler and a binder resin can be used. As the conductive filler, for example, fine metal powders such as silver, copper, gold, iron, nickel, and aluminum, or carbon black can be used. The binder resin can be a resin such as an epoxy resin, a polyester resin, a urethane resin, a phenol resin, or an imide resin.

The sensor circuit 123 drives the heater 121 so that the difference between the temperature of the heater 121 and the temperature of the fluid at a position not affected by the heat of the heater 121 is a set temperature difference. The sensor value corresponding to the state of heat diffusion in the heated fluid is output.

In the example shown in FIG. 2, the temperature sensor 122 measures the temperature of the fluid at a position upstream of the heater 121 and not affected by the heat of the heater 121, and the sensor circuit 123 measures the temperature of the heater 121 and the temperature sensor 122. The power of the heater 121 when the heater 121 is driven so that the difference from the temperature of the fluid is the set temperature difference is output as a sensor value. The sensor circuit 123 includes a control unit 124 and a power measurement unit 125.

In the control unit 124, the difference between the temperature of the heater 121 and the position measured by the temperature sensor 122 that is not affected by the heat of the heater 121, for example, the temperature of the fluid upstream of the heater 121, is a preset temperature difference. The heater 121 is controlled and driven so as to be. The electric power measuring unit 125 measures and outputs the electric power of the heater 121 controlled by the control unit 124. The electric power output from the electric power measuring unit 125 constituting the sensor circuit 123 is the sensor value.

Further, the thermal flow meter 120 includes a flow rate calculation unit 126. The flow rate calculation unit 126 calculates the flow rate of the fluid from the electric power (sensor value) of the heater 121 measured and output by the power measurement unit 125. As is well known, when the heater 121 is driven so that the difference between the temperature of the heater 121 and the temperature of the fluid at a position not affected by the heat of the heater 121 becomes the set temperature difference, the heater 121 There is a correlation between the power consumed and the flow rate of the fluid. This correlation is also reproducible at the same fluid / flow rate / temperature. Therefore, as described above, in the state where the heater 121 is controlled by the control unit 124, the flow rate is calculated by using a predetermined correlation coefficient (constant) in the flow rate calculation unit 126 from the power measured by the power measurement unit 125. Can be calculated.

Further, the thermal flow meter 120 may have the configuration shown in FIG. In the example shown in FIG. 3, the temperature sensor is composed of a temperature sensor (first temperature sensor) 122, a temperature sensor (second temperature sensor) 127, and a temperature sensor (third temperature sensor) 128. In this example, the temperature sensor 127 is adhesively fixed to the counterbore portion 151c formed on the outer wall of the pipe 151 and partially dented and formed thinner than the other portions. .. Further, the temperature sensor 128 is adhesively fixed to the counterbore portion 151d formed on the outer wall of the pipe 151 and partially dented and formed thinner than the other portions.

The temperature sensor 122 measures the temperature of the fluid at a position upstream of the heater 121 and not affected by the heat of the heater 121. The temperature sensor 127 measures the temperature of the fluid at a position upstream of the heater 121 and affected by the heat of the heater 121. The temperature sensor 128 measures the temperature of the fluid at a position downstream of the heater 121 and affected by the heat of the heater 121.

The sensor circuit 123'is the fluid measured by the temperature sensor 127 when the heater 121 is driven so that the difference between the temperature of the heater 121 and the temperature of the fluid measured by the temperature sensor 122 becomes the set temperature difference. The temperature difference between the temperature and the temperature of the fluid measured by the temperature sensor 128 is output as a sensor value. The sensor circuit 123'includes a control unit 124'. The control unit 124'sets a preset temperature at which the difference between the temperature of the heater 121 and the temperature of the fluid measured at a position not affected by the heat of the heater 121 measured by the temperature sensor 122, for example, upstream of the heater 121 is set in advance. The heater 121 is controlled and driven so as to make a difference.

Further, in this example, the flow rate calculation unit 126'is provided. The flow rate calculation unit 126'calculates the flow rate of the fluid from the temperature difference between the temperature of the fluid measured by the temperature sensor 127 and the temperature of the fluid measured by the temperature sensor 128.

As is well known, the heater 121 is driven so that the difference between the temperature of the heater 121 and the temperature of the fluid at a position not affected by the heat of the heater 121 becomes a preset set temperature difference. At that time, there is a correlation between the temperature difference between the temperature of the fluid upstream of the heater 121 and the temperature of the fluid downstream of the heater 121 and the flow rate of the fluid. This correlation is also reproducible at the same fluid / flow rate / temperature. Therefore, as described above, a predetermined phase is obtained from the difference (temperature difference) between the temperature measured by the temperature measuring unit 127 and the temperature measured by the temperature measuring unit 128 while the heater 121 is controlled by the control unit 113. The flow rate can be calculated by using the number of relations (constant).

The fluid stop section 101 stops the flow of the fluid. For example, the fluid stop unit 101 stops the flow of fluid flowing through the pipe 151 by fully closing a valve provided on the upstream side of the pipe 151 shown in FIG. 2 (FIG. 3) (not shown).

The temperature control unit 102 controls the temperature of the heater 121 to a temperature higher than the temperature around (ambient) the heater 121. In the temperature change measurement unit 103, the temperature control unit 102 starts controlling the temperature of the heater 121 while the fluid stop unit 101 stops the flow of the fluid and the temperature control unit 102 controls the temperature of the heater 121. The change in temperature measured by the temperature sensor 122 is measured from the time point to the second time point when the set time has elapsed.

When the temperature change measured by the temperature change measuring unit 103 is smaller than the set temperature reference value, the determination unit 104 determines that the adhesion state of at least one of the heater 121 and the temperature sensor 122 is abnormal. judge.

When the heating by the heater 121 is started, this heat is transferred from the heater 121 to the pipe 151 via the layer of the adhesive. The heat transferred through the pipe 151 is transferred from the pipe 151 to the fluid, but a part of the heat is transferred to the temperature sensor 122 via the pipe 151. This heat is transferred to the temperature sensor 122 through the layer of adhesive. Due to this change in heat transfer, the measurement result of the temperature sensor 122 changes.

If a defect such as peeling occurs in the adhesive of the heater 121, the adhesive of the temperature sensor 122, or both of them, the temperature sensor 122 and the outer wall of the pipe 151 are separated from each other between the heater 121 and the outer wall of the pipe 151. A gap will be formed in one of the spaces. The thermal conductivity in this gap is smaller than the thermal conductivity of the adhesive. Therefore, it is considered that the heat transfer from the heater 121 to the temperature sensor 122 described above becomes small when the gap is formed.

The above-mentioned change in heat transfer appears in the change in temperature measured by the temperature change measuring unit 103. As described above, the smaller the heat transfer, the smaller the change in temperature measured by the temperature change measuring unit 103. For example, as shown in FIG. 3, the temperature change ΔT0 measured by the temperature change measuring unit 103 when there is no abnormality shown by the solid line is measured by the temperature change measuring unit 103 when there is an abnormality shown by the dotted line. The temperature change ΔT1 becomes smaller. If ΔT0 is used as the temperature reference value and ΔT1 is compared with the temperature reference value ΔT0, it is possible to diagnose a failure due to a defect in the adhesive or the like.

Here, the above-mentioned temperature reference value is the above-mentioned fluid stop unit 101, temperature control unit 102, and temperature change measurement carried out immediately after the manufacture of the failure diagnosis device 100 that can determine that no abnormality has occurred in the adhesive. The measured value of the temperature change by the unit 103 can be used. It should be noted that the liquid type to be measured can be diagnosed by the above-mentioned temperature change measured in a normal state in which the heater 121 and the temperature sensor 122 are in close contact with the outer wall of the pipe 151 without any abnormality in the adhesive.

Next, the operation (fault diagnosis method) of the failure diagnosis device according to the embodiment of the present invention will be described with reference to FIG.

First, in step S101, the fluid stop unit 101 stops the flow of the fluid flowing through the pipe 151 (first step). Next, in step S102, the temperature control unit 102 controls the temperature of the heater 121 to a temperature higher than the temperature around the heater 121 (second step).

As described above, when the flow of the fluid is stopped and the temperature of the heater 121 is controlled, the temperature change measuring unit 103 starts controlling the temperature of the heater 121 by the temperature control unit 102 in step S103. The change in temperature measured by the temperature sensor 122 is measured from the time point to the second time point when the set time has elapsed (third step).

Next, in step S104, the determination unit 104 determines whether or not the change in temperature measured in the third step is smaller than the set temperature reference value (fourth step). When the measured temperature change is smaller than the set temperature reference value (yes in step S104), in step S105, the determination unit 104 has an abnormality in the adhesion state of at least one of the heater 121 and the temperature sensor 122. Judge as a failure status. Further, when the determination unit 104 determines the failure, the determination unit 104 notifies the user by displaying this fact on, for example, a display unit (not shown). On the other hand, when the measured temperature change is larger than the set temperature reference value (no in step S104), the diagnostic operation is terminated.

Here, the above-mentioned temperature reference value can be obtained in advance by the following. First, immediately after the installation of the thermal flow meter 120, the fluid flow is stopped by the fluid stop section 101 (7th step). Subsequently, the temperature control unit 102 controls the temperature of the heater 121 to a temperature higher than the temperature around the heater 121 (8th step). In this way, with the fluid flow stopped and the temperature of the heater 121 controlled, from the third time point when the temperature control of the heater 121 is started to the fourth time point when the set time has elapsed. , The change in temperature measured by the temperature sensor 122 is measured, and the measured value is used as the temperature reference value (9th step).

[Embodiment 2]
Next, the failure diagnosis device 200 according to the second embodiment of the present invention will be described with reference to FIG. The failure diagnosis device 200 includes a fluid stop unit 101, a temperature control unit 102, a temperature change measurement unit 103, a determination unit 104, a power change measurement unit 203, and a heater abnormality determination unit 204, and diagnoses a failure of the thermal flow meter 120. .. The fluid stop unit 101, the temperature control unit 102, the temperature change measurement unit 103, the determination unit 104, and the thermal flow meter 120 are the same as those in the first embodiment described above, and the description thereof will be omitted below.

In the power change measurement unit 203, the temperature control unit 102 starts controlling the temperature of the heater 121 while the fluid stop unit 101 stops the flow of the fluid and the temperature control unit 102 controls the temperature of the heater 121. The change in the power consumption (power consumption) of the heater 121 is measured from the time point to the second time point when the set time has elapsed. For example, in the thermal flow meter 120 illustrated with reference to FIG. 2, the change in the electric power of the heater 121 measured and output by the electric power measuring unit 125 is measured by the electric power change measuring unit 203.

When the change in power measured by the power change measuring unit 203 is smaller than the set power reference value, the heater abnormality determination unit 204 determines that the adhesion state of the heater 121 is abnormal. The failure diagnosis device 200 of the second embodiment measures the power change when the temperature change measurement unit 103 and the determination unit 104 determine that the adhesion state of at least one of the heater 121 and the temperature sensor 122 is abnormal. By determining the abnormality of the bonding state of the heater 121 by the unit 203 and the heater abnormality determination unit 204, it is determined whether the abnormality occurring is both the heater 121 and the temperature sensor 122, or one of them.

When the heating by the heater 121 is started, this heat is transferred from the heater 121 to the pipe 151 via the layer of the adhesive. The heat transferred through the pipe 151 is transferred from the pipe 151 to the fluid, but a part of the heat is transferred to the temperature sensor 122 via the pipe 151. This heat is transferred to the temperature sensor 122 through the layer of adhesive. Due to this change in heat transfer, the power consumption of the heater 121 changes.

When a defect such as peeling occurs in the adhesive of the heater 121, a gap is formed between the heater 121 and the outer wall of the pipe 151. If there is a gap, the heat generated by the heater 121 is less likely to be transmitted in the direction of the pipe 151, the heater 121 is easily heated, and the power consumption of the heater 121 is smaller than that when there is no gap. Here, when the adhesive of the heater 121 has no defect and the adhesive of the temperature sensor 122 has a defect, the above-mentioned change in the power consumption of the heater 121 does not occur. Therefore, by determining the change in the power consumption of the heater 121, it is possible to distinguish between the abnormality in the adhesive of the heater 121 and the abnormality in the adhesive of the temperature sensor 122.

The change in the operating state of the heater 121 described above appears in the change in power measured by the power change measuring unit 203. As described above, in a state where the sound is easily muted due to the presence of a gap, the change in power measured by the power change measuring unit 203 becomes smaller than the power reference value. For example, the change ΔT1 of the power measured by the power change measuring unit 203 when there is an abnormality is smaller than the change ΔT1 of the power measured by the power change measuring unit 203 when there is no abnormality. If ΔT0 is set as the power reference value and ΔT1 is compared with the power reference value ΔT0, it is possible to diagnose a failure due to a defect in the adhesive of the heater 121 or the like.

Here, the power reference value described above is the fluid stop unit 101, the temperature control unit 102, and the temperature control unit 102 described above, which were carried out immediately after the manufacture of the failure diagnosis device 200 that can determine that no abnormality has occurred in the adhesive of the heater 121. The measured value of the power change by the power change measuring unit 203 can be used.

Next, the operation (fault diagnosis method) of the failure diagnosis device according to the second embodiment of the present invention will be described with reference to FIG. 7. Here, the operation (fault diagnosis method) shown below can be performed after the failure diagnosis according to the first embodiment described above is performed.

First, in step S101, the fluid stop unit 101 stops the flow of the fluid flowing through the pipe 151 (first step). Next, in step S102, the temperature control unit 102 controls the temperature of the heater 121 to a temperature higher than the temperature around the heater 121 (second step).

As described above, when the flow of the fluid is stopped and the temperature of the heater 121 is controlled, in step S203, the power change measuring unit 203 starts controlling the temperature of the heater 121 by the temperature control unit 102. From the time point to the second time point when the set time has elapsed, the change in the power of the heater 121 measured by the power measurement unit 125 is measured (fifth step).

Next, in step S204, the heater abnormality determination unit 204 determines whether or not the change in power measured in the third step is smaller than the set power reference value (sixth step). When the change in the measured power is smaller than the set power reference value (yes in step S204), in step S205, the heater abnormality determination unit 204 has an abnormality in the adhesion state of at least one of the heater 121 and the temperature sensor 122. It is determined that there is a failure state. Further, when the heater abnormality determination unit 204 determines the failure, the heater abnormality determination unit 204 notifies the user, for example, by displaying this on a display unit (not shown). On the other hand, when the change in the measured power is larger than the set power reference value (no in step S204), the diagnostic operation is terminated.

Here, the above-mentioned power reference value can be obtained in advance by the following. First, immediately after the installation of the thermal flow meter 120, the fluid flow is stopped by the fluid stop section 101 (7th step). Subsequently, the temperature control unit 102 controls the temperature of the heater 121 to a temperature higher than the temperature around the heater 121 (8th step). In this way, with the fluid flow stopped and the temperature of the heater 121 controlled, from the third time point when the control of the temperature of the heater 121 is started to the fourth time point when the set time has elapsed. , The change in the electric power of the heater 121 measured by the electric power measuring unit 125 is measured, and the measured value is used as the electric power reference value (9th step).

As shown in FIG. 8, the failure diagnosis device according to the above-described embodiment includes a CPU (Central Processing Unit) 301, a main storage device 302, an external storage device 303, a network connection device 304, and the like. It is also possible to realize each of the above-mentioned functions (fault diagnosis method) by operating the CPU 301 (execution of the program) by the program expanded in the main storage device 302. The above program is a program for a computer to execute the failure diagnosis method shown in the above-described embodiment. The network connection device 304 connects to the network 305. In addition, each function can be distributed to a plurality of computer devices.

Further, the failure diagnosis device in the above-described embodiment can also be configured by a programmable logic device (PLD: Programmable Logic Device) such as an FPGA (field-programmable gate array). For example, by providing each of the storage unit, the fluid stop unit, the temperature control unit, the temperature change measurement unit, and the determination unit (power change measurement unit, heater abnormality determination unit) as circuits in the logic element of the FPGA, it can be used as a failure diagnosis device. Can be made to work. Each of the storage circuit, the fluid stop circuit, the temperature control circuit, the temperature measurement circuit, and the determination circuit (power change measurement circuit, heater abnormality determination circuit) can be written to the FPGA by connecting a predetermined writing device. Further, each of the above circuits written in the FPGA can be confirmed by a writing device connected to the FPGA.

As described above, according to the present invention, the temperature sensor is from the first time point when the control of the heater temperature is started to the second time point when the set time elapses with the fluid flow stopped. Since the change in temperature measured in is measured, it becomes possible to diagnose the failure of the thermal fluid meter in the installed state.

The present invention is not limited to the embodiments described above, and many modifications and combinations can be carried out by a person having ordinary knowledge in the art within the technical idea of the present invention. That is clear.

100 ... Failure diagnosis device, 101 ... Fluid stop unit, 102 ... Temperature control unit, 103 ... Temperature change measurement unit, 104 ... Judgment unit, 120 ... Thermal flow meter, 121 ... Heater, 122 ... Temperature sensor, 123 ... Sensor circuit , 124 ... control unit, 125 ... power measurement unit, 126 ... flow rate calculation unit, 151 ... piping, 151a, 151b ... counterbore unit.

Claims (12)

A heater that is fixed to the outer wall of the pipe that transports the fluid to be measured with an adhesive to heat the fluid, and
A temperature sensor that is adhesively fixed to the outer wall of the pipe on the upstream side of the heater to measure the temperature of the fluid, and
The heater was heated when the heater was driven so that the difference between the temperature of the heater and the temperature of the fluid at a position not affected by the heat of the heater was a set temperature difference. In a failure diagnosis device for diagnosing a failure of a thermal flow meter including a sensor circuit configured to output a sensor value corresponding to a state of heat diffusion in the fluid.
A fluid stop unit configured to stop the flow of the fluid,
A temperature control unit configured to control the temperature of the heater to a temperature higher than the temperature around the heater.
It is set from the first time point when the temperature control unit starts controlling the temperature of the heater while the fluid stop unit stops the flow of the fluid and the temperature control unit controls the temperature of the heater. A temperature change measuring unit configured to measure the temperature change measured by the temperature sensor by the second time point after the lapse of time.
When the temperature change measured by the temperature change measuring unit is smaller than the set temperature reference value, it is configured to determine that there is an abnormality in the adhesion state of at least one of the heater and the temperature sensor. A failure diagnosis device including a determined determination unit. In the failure diagnosis device according to claim 1,
It is set from the first time point when the temperature control unit starts controlling the temperature of the heater while the fluid stop unit stops the flow of the fluid and the temperature control unit controls the temperature of the heater. A power change measuring unit configured to measure the change in the power of the heater by the second time point after the lapse of time.
When the change in power measured by the power change measuring unit is smaller than the set power reference value, the heater abnormality determining unit is configured to determine that the heater has an abnormality in the adhesion state and is in a faulty state. A failure diagnosis device characterized by further comprising. In the failure diagnosis device according to claim 1 or 2.
The adhesive is a failure diagnosis device, characterized in that it is a heat conductive adhesive. In the failure diagnosis device according to any one of claims 1 to 3.
The thermal flow meter is a failure diagnosis device further comprising a flow rate calculation unit configured to calculate the flow rate of the fluid from the sensor value. In the failure diagnosis device according to any one of claims 1 to 4.
The temperature sensor measures the temperature of the fluid at a position upstream of the heater and not affected by the heat of the heater.
The sensor circuit measures the power of the heater when the heater is driven so that the difference between the temperature of the heater and the temperature of the fluid measured by the temperature sensor becomes the set temperature difference. A failure diagnosis device characterized by outputting as. In the failure diagnosis device according to any one of claims 1 to 4.
The temperature sensor is composed of a first temperature sensor, a second temperature sensor, and a third temperature sensor.
The first temperature sensor measures the temperature of the fluid at a position upstream of the heater and not affected by the heat of the heater.
The second temperature sensor measures the temperature of the fluid at a position upstream of the heater and affected by the heat of the heater.
The third temperature sensor measures the temperature of the fluid at a position downstream of the heater and affected by the heat of the heater.
The sensor circuit is the second temperature sensor when the heater is driven so that the difference between the temperature of the heater and the temperature of the fluid measured by the first temperature sensor becomes the set temperature difference. A failure diagnosis device, characterized in that the temperature difference between the temperature of the fluid measured by the third temperature sensor and the temperature of the fluid measured by the third temperature sensor is output as the sensor value. A heater that is fixed to the outer wall of the pipe that transports the fluid to be measured with an adhesive to heat the fluid, and
A temperature sensor that is adhesively fixed to the outer wall of the pipe on the upstream side of the heater to measure the temperature of the fluid, and
The heater was heated when the heater was driven so that the difference between the temperature of the heater and the temperature of the fluid at a position not affected by the heat of the heater was a set temperature difference. A method for diagnosing a failure of a thermal flow meter including a sensor circuit configured to output a sensor value corresponding to a state of heat diffusion in the fluid.
The first step of stopping the flow of the fluid and
Following the first step, a second step of controlling the temperature of the heater to a temperature higher than the temperature around the heater, and
The setting is made from the first time point in which the flow of the fluid is stopped in the first step, the temperature of the heater is controlled in the second step, and the temperature control of the heater is started in the second step. The third step of measuring the change in temperature measured by the temperature sensor by the second time point when the time has passed, and
When the change in temperature measured in the third step is smaller than the set temperature reference value, the fourth step determines that there is an abnormality in the adhesion state of at least one of the heater and the temperature sensor. Failure diagnosis method with and. In the failure diagnosis method according to claim 7,
It is set from the first time point when the temperature control unit starts controlling the temperature of the heater while the fluid stop unit stops the flow of the fluid and the temperature control unit controls the temperature of the heater. The fifth step of measuring the change in the electric power of the heater by the second time point after the lapse of time, and
When the change in power measured in the fifth step is smaller than the set power reference value, the sixth step is further provided to determine that the state of failure is such that the adhesion state of the heater is abnormal. Failure diagnosis method. In the failure diagnosis method according to claim 7 or 8.
Immediately after installing the thermal flow meter, the seventh step of stopping the flow of the fluid and
Following the seventh step, the eighth step of controlling the temperature of the heater to a temperature higher than the temperature around the heater,
The setting is made from the third time point in which the flow of the fluid is stopped in the seventh step, the temperature of the heater is controlled in the eighth step, and the temperature control of the heater is started in the eighth step. By the fourth time point when the time has elapsed, the change in temperature measured by the temperature sensor or the change in power of the heater is measured, and the measured value is used as the temperature reference value or the power reference value. A failure diagnosis method characterized by further providing steps. In the failure diagnosis method according to any one of claims 7 to 9,
A failure diagnosis method, wherein the adhesive is a heat conductive adhesive. In the failure diagnosis method according to any one of claims 7 to 10.
The temperature sensor measures the temperature of the fluid at a position upstream of the heater and not affected by the heat of the heater.
The sensor circuit measures the electric power of the heater when the heater is driven so that the difference between the temperature of the heater and the temperature of the fluid measured by the temperature sensor becomes the set temperature difference. A failure diagnosis method characterized by outputting as. In the failure diagnosis method according to any one of claims 7 to 10.
The temperature sensor is composed of a first temperature sensor, a second temperature sensor, and a third temperature sensor.
The first temperature sensor measures the temperature of the fluid at a position upstream of the heater and not affected by the heat of the heater.
The second temperature sensor measures the temperature of the fluid at a position upstream of the heater and affected by the heat of the heater.
The third temperature sensor measures the temperature of the fluid at a position downstream of the heater and affected by the heat of the heater.
The sensor circuit is the second temperature sensor when the heater is driven so that the difference between the temperature of the heater and the temperature of the fluid measured by the first temperature sensor becomes the set temperature difference. A failure diagnosis method, characterized in that the temperature difference between the temperature of the fluid measured by the third temperature sensor and the temperature of the fluid measured by the third temperature sensor is output as the sensor value.

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