JP7284050B2 - Fault diagnosis device and method - Google Patents

Description

The present invention relates to a fault diagnosis device and method for diagnosing faults in thermal flowmeters.

Techniques for measuring the flow rate and velocity of fluid flowing through piping are widely used in the industrial and medical fields. There are various types of devices for measuring flow rates and flow velocities, such as electromagnetic flowmeters, vortex flowmeters, Coriolis flowmeters, and thermal flowmeters. Thermal flowmeters are capable of detecting gases, have basically no pressure loss, and have the advantage of being able to measure mass flow rates. Further, a thermal flow meter is also used, which is capable of measuring the flow rate of a liquid containing an organic solvent or a corrosive liquid by configuring the piping from glass (see Patent Document 1). Such a thermal flow meter that measures the flow rate of liquid is suitable for measuring a very small amount of flow rate.

A thermal flow meter measures the flow rate by, for example, power consumption of a heater. A temperature sensor and a heater are installed sequentially 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, which is not affected by the heat of the heater, measured by the temperature sensor is set in advance. The heater is controlled so as to obtain 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 heater are fixed with an adhesive to a portion of the outer wall of the pipe that is thinner than other portions.

By arranging the temperature sensor at such a thin portion, the temperature of the fluid flowing through the pipe can be measured with good sensitivity. In addition, by arranging the heater at such a thin portion, the fluid flowing through the pipe can be efficiently heated in a short time. Thermally conductive adhesives are also used to improve heat transfer between the piping and the temperature sensors and heaters.

As is well known, there is a correlation between the power consumption of the heater and the flow rate of the fluid. Also, this correlation is repeatable for 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 publication

By the way, in the above-described thermal type 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. If, for example, the temperature sensor or heater does not adhere to the outer wall of the pipe due to deterioration of the adhesive, and a partial gap occurs, the fluid cannot be heated efficiently and the fluid temperature cannot be measured accurately. It becomes impossible to measure the flow rate accurately. When performing measurement with a thermal flow meter, the adhesive may deteriorate due to the effects of ambient humidity, temperature, and heat cycle. In the case where the adhesive deteriorates under the influence of the usage environment in this way, the above-mentioned problems do not occur at the initial stage of installation of the thermal flowmeter, but problems occur over time.

However, since it is not easy to remove the thermal flowmeter once it has been installed, it is not easy to check for the above-described abnormality (failure diagnosis) by removing and disassembling the flowmeter.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-described problems, and to make it possible to diagnose a failure of a thermal flowmeter while it is installed.

A fault diagnosis apparatus according to the present invention is adhesively fixed to the outer wall of a pipe that transports a fluid to be measured with an adhesive, and is adhesively fixed to a heater that heats the fluid and the outer wall of the pipe upstream of the heater. The temperature sensor that measures the temperature of the fluid and the heater are 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 is the set temperature difference. and a sensor circuit configured to output a sensor value corresponding to the state of thermal diffusion in the fluid heated by the heater. a temperature control unit configured to control the temperature of the heater to be higher than the temperature around the heater; and the fluid stop unit stops the flow of the fluid, and the temperature control unit is controlling the temperature of the heater, the change in temperature measured by the temperature sensor from the first time when the temperature control unit starts controlling the temperature of the heater to the second time when the set time has passed A temperature change measuring unit configured to measure temperature change, and if a temperature change measured by the temperature change measuring unit is smaller than a set temperature reference value, an abnormality is detected in the bonding state of at least one of the heater and the temperature sensor. and a determination unit configured to determine a fault condition.

In one configuration example of the above failure diagnosis device, from the first point in time when the temperature control unit starts controlling the temperature of the heater in a state where the fluid stopping 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 a change in the power of the heater by a second point in time after the set time has elapsed; It further comprises a heater abnormality determination unit configured to determine a failure state in which the bonding state of the heater is abnormal when the value is smaller than a reference value.

In one configuration example of the above fault diagnosis device, the adhesive is a thermally conductive adhesive.

In one configuration example of the above fault diagnosis device, the thermal flowmeter further includes a flow rate calculator configured to calculate the flow rate of the fluid from the sensor value.

In one configuration example of the above failure diagnosis device, the temperature sensor measures the temperature of the fluid upstream of the heater and is not affected by the heat of the heater, and the sensor circuit measures the temperature of the heater and the temperature of the fluid measured by the temperature sensor. The electric 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 upstream of the heater and is not affected by the heat of the heater. A second temperature sensor measures the temperature of the fluid at a location upstream of the heater and is thermally affected by the heater, and a third temperature sensor is downstream of the heater and is thermally affected by 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 is the set temperature difference. A temperature difference between the fluid temperature measured by the second temperature sensor and the fluid temperature measured by the third temperature sensor is output as a sensor value.

A failure diagnosis method according to the present invention includes a heater that is adhesively fixed to the outer wall of a pipe that transports a fluid to be measured, a heater that heats the fluid, and an outer wall of the pipe upstream of the heater. A temperature sensor that measures the temperature of the fluid and the heater is driven so that the difference between the heater temperature and the fluid temperature measured by the temperature sensor is the set temperature difference. A fault diagnosis method for a thermal flowmeter comprising a sensor circuit that outputs electric power as a sensor value, comprising: a first step of stopping the flow of fluid; a second step of controlling the temperature to be higher than the temperature; and with the flow of the fluid stopped in the first step and the temperature of the heater being controlled in the second step, the control of the temperature of the heater was started in the second step. A third step of measuring a change in the temperature measured by the temperature sensor from the first time to a second time after the set time has elapsed, and the change in the temperature measured in the third step are set. and a fourth step of determining a failure state in which the bonding state of at least one of the heater and the temperature sensor is abnormal when the temperature is lower than the current temperature reference value.

In one configuration example of the above failure diagnosis method, from a first point in time when the temperature control unit starts controlling the temperature of the heater in a state where the fluid stopping unit stops the flow of the fluid and the temperature control unit controls the temperature of the heater. , a fifth step of measuring the change in power of the heater by a second point in time after the set time has elapsed; and a sixth step of judging that there is an abnormality in the bonding state of the heater.

In one configuration example of the above failure diagnosis method, immediately after installation of the thermal flowmeter, the seventh step of stopping the flow of the fluid, and following the seventh step, the temperature of the heater is raised to a temperature higher than the temperature around the heater. In the eighth step of controlling, the flow of the fluid is stopped in the seventh step, the temperature of the heater is controlled in the eighth step, and from the third time when the control of the temperature of the heater is started in the eighth step, a ninth step of measuring a change in the temperature measured by the temperature sensor or a change in the electric power of the heater by a fourth point in time after the set time has elapsed, and using the measured value as the temperature reference value or the electric power reference value; further provide.

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

In one configuration example of the above failure diagnosis method, the temperature sensor measures the temperature of the fluid upstream of the heater and is not affected by the heat of the heater, and the sensor circuit measures the temperature of the heater and the temperature of the fluid measured by the temperature sensor. The electric 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 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 upstream of the heater and is not affected by the heat of the heater. A second temperature sensor measures the temperature of the fluid at a location upstream of the heater and is thermally affected by the heater, and a third temperature sensor is downstream of the heater and is thermally affected by 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 is the set temperature difference. A temperature difference between the fluid temperature measured by the second temperature sensor and the fluid temperature measured by the third temperature sensor is output as a sensor value.

As described above, according to the present invention, in a state where the flow of fluid is stopped, the temperature sensor detects the Since changes in the measured temperature are measured, failures of the thermal flowmeter can be diagnosed while it is installed.

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

A fault diagnosis device according to an embodiment of the present invention will be described below.

[Embodiment 1]
First, a fault diagnosis device 100 according to Embodiment 1 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 failure of the thermal flowmeter 120. FIG.

Here, the thermal flowmeter 120 includes a heater 121 , a temperature sensor 122 and a sensor circuit 123 . The heater 121 is adhered and fixed with an adhesive to the outer wall of the pipe 151 that transports the fluid to be measured, and heats the fluid.

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

As the adhesive, for example, a thermally conductive adhesive composed of a paste that is a mixture of a conductive filler and a binder resin can be used. Examples of conductive fillers that can be used include fine powders of metals such as silver, copper, gold, iron, nickel, and aluminum, and carbon black. The binder resin can also be resins such as epoxy resins, polyester resins, urethane resins, phenolic resins and imide resins.

The sensor circuit 123 detects the temperature of the heater 121 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 a set temperature difference. outputs a sensor value corresponding to the state of heat diffusion in the fluid heated to .

In the example shown in FIG. 2, the temperature sensor 122 measures the temperature of the fluid upstream of the heater 121 and is 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 electric power of the heater 121 when the heater 121 is driven so that the difference from the temperature of the fluid obtained is the set temperature difference is output as the sensor value. The sensor circuit 123 includes a control section 124 and a power measurement section 125 .

The control unit 124 determines that the difference between the temperature of the heater 121 and the position not affected by the heat of the heater 121 measured by the temperature sensor 122, 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 that The power measurement unit 125 measures and outputs the power of the heater 121 controlled by the control unit 124 . The power output from the power measuring section 125 that configures the sensor circuit 123 is the sensor value.

The thermal flowmeter 120 also includes a flow rate calculator 126 . The flow rate calculation unit 126 calculates the flow rate of the fluid from the 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 such 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 being consumed and the flow rate of the fluid. Also, this correlation is repeatable for the same fluid/flow rate/temperature. Therefore, as described above, in a state where the heater 121 is controlled by the control unit 124, the flow rate is can be calculated.

Moreover, the thermal flowmeter 120 can also be configured as shown in FIG. In the example shown in FIG. 3, the temperature sensors are 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 fixed with an adhesive to a countersunk portion 151c formed on the outer wall of the pipe 151 so that a portion thereof is recessed and thinner than the other portions. . Further, the temperature sensor 128 is adhesively fixed to a countersunk portion 151d which is formed on the outer wall of the pipe 151 and which is partially recessed and thinner than the other portions.

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

The sensor circuit 123′ detects the temperature of the fluid measured by the temperature sensor 127 when the heater 121 is driven such 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. A 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' comprises a controller 124'. The control unit 124′ determines that the difference between the temperature of the heater 121 and the temperature of the fluid upstream of the heater 121, which is measured by the temperature sensor 122 and is not affected by the heat of the heater 121, is set to a preset temperature. The heater 121 is controlled and driven so as to make the difference.

Also, in this example, a flow rate calculator 126' is provided. The flow rate calculator 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 temperature difference. 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. Also, this correlation is repeatable for the same fluid/flow rate/temperature. Therefore, as described above, in a state where the heater 121 is controlled by the control unit 113, the difference (temperature difference) between the temperature measured by the temperature measurement unit 127 and the temperature measured by the temperature measurement unit 128 is used to determine a predetermined phase. The flow rate can be calculated by using a relational coefficient (constant).

The fluid stopping part 101 stops the flow of fluid. For example, the fluid stopping unit 101 stops the flow of the fluid through the pipe 151 shown in FIG.

The temperature control unit 102 controls the temperature of the heater 121 to be higher than the temperature around the heater 121 (surroundings). The temperature change measuring unit 103 measures the temperature of the heater 121 when the temperature control unit 102 starts controlling the temperature of the heater 121 in a state where the fluid stopping unit 101 stops the flow of the fluid and the temperature control unit 102 controls the temperature of the heater 121 . A change in the temperature measured by the temperature sensor 122 is measured from the time point to a second time point after the set time has elapsed.

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

When the heater 121 starts heating, the heat is transferred from the heater 121 to the pipe 151 through the adhesive layer. The heat transferred through the pipe 151 is transferred from the pipe 151 to the fluid, and part of the heat reaches the temperature sensor 122 via the pipe 151 . This heat is transferred to the temperature sensor 122 through the layer of adhesive. This change in heat transfer causes a change in the measurement of temperature sensor 122 .

If a defect such as peeling occurs in the adhesive of the heater 121 or the adhesive of the temperature sensor 122 or both of them, the temperature sensor 122 and the outer wall of the pipe 151 may be damaged. A gap will be formed somewhere in between. The thermal conductivity in this gap is less than that of the adhesive. For this reason, it is considered that the heat transfer from the heater 121 to the temperature sensor 122 is reduced when the gap is formed.

The change in heat transfer described above 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 temperature change 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 indicated by the solid line is measured by the temperature change measuring unit 103 when there is an abnormality indicated by the dotted line. The temperature change ΔT1 becomes smaller. If ΔT0 is used as a temperature reference value and ΔT1 is compared with the temperature reference value ΔT0 for determination, it becomes possible to diagnose a failure due to a defective adhesive agent or the like.

Here, the above-described temperature reference value is obtained by measuring the above-described fluid stop unit 101, temperature control unit 102, and temperature change measurement performed immediately after manufacturing the failure diagnosis device 100 that can determine that no abnormality has occurred in the adhesive. Temperature change measurements by unit 103 can be used. It should be noted that the type of liquid to be measured can be diagnosed based on the above-described temperature change measured in a normal state in which the adhesive is normal and the heater 121 and temperature sensor 122 are in close contact with the outer wall of the pipe 151 .

Next, the operation (failure 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 stopping unit 101 stops the flow of 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 be 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 S103, the temperature change measuring unit 103 detects the first temperature at which the temperature control unit 102 starts controlling the temperature of the heater 121. A change in the temperature measured by the temperature sensor 122 is measured from the point in time to a second point in time after 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). If the measured change in temperature is smaller than the set temperature reference value (yes in step S104), in step S105, the determination unit 104 determines that at least one of the heater 121 and the temperature sensor 122 is in an abnormal bonding state. Judged as a failure state. Further, when determining a failure, the determining unit 104 notifies the user of this fact by, for example, displaying it on a display unit (not shown). On the other hand, if the measured change in temperature is greater than the set temperature reference value (no in step S104), the diagnostic operation is terminated.

Here, the above-described temperature reference value can be obtained in advance as follows. First, immediately after installation of the thermal flow meter 120, the flow of the fluid is stopped by the fluid stop portion 101 (seventh step). Subsequently, the temperature control unit 102 controls the temperature of the heater 121 to be higher than the temperature around the heater 121 (eighth step). In this way, in a state in which the flow of fluid is stopped and the temperature of the heater 121 is controlled, from the third time when the temperature control of the heater 121 is started to the fourth time when the set time has passed, , 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, a fault diagnosis device 200 according to Embodiment 2 of the present invention will be described with reference to FIG. The failure diagnosis device 200 includes a fluid stopping 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 flowmeter 120. . The fluid stopping unit 101, the temperature control unit 102, the temperature change measuring unit 103, the determining unit 104, and the thermal flow meter 120 are the same as those in the above-described first embodiment, and descriptions thereof are omitted below.

The power change measuring unit 203 measures the temperature of the heater 121 when the temperature control unit 102 starts controlling the temperature of the heater 121 in a state where the fluid stopping unit 101 stops the flow of the fluid and the temperature control unit 102 controls the temperature of the heater 121 . A change in the power (power consumption) of the heater 121 is measured from the time point to the second time point after the set time has elapsed. For example, in the thermal flow meter 120 illustrated using FIG.

The heater abnormality determination unit 204 determines that the adhesion state of the heater 121 is abnormal when the change in power measured by the power change measurement unit 203 is smaller than the set power reference value. When temperature change measurement unit 103 and determination unit 104 determine that at least one of heater 121 and temperature sensor 122 is in a failure state in which there is an abnormality in the bonding state of heater 121 and temperature sensor 122, failure diagnosis apparatus 200 according to the second embodiment measures power change. Based on the abnormality determination of the adhesion state of the heater 121 by the unit 203 and the heater abnormality determination unit 204, it is determined whether the abnormality occurs in both the heater 121 and the temperature sensor 122, or in one of them.

When the heater 121 starts heating, the heat is transferred from the heater 121 to the pipe 151 through the adhesive layer. The heat transferred through the pipe 151 is transferred from the pipe 151 to the fluid, and part of the heat reaches the temperature sensor 122 via the pipe 151 . This heat is transferred to the temperature sensor 122 through the layer of adhesive. This change in heat transfer causes a change in power consumption of the heater 121 .

If 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 . When there is a gap, the heat generated by the heater 121 is less likely to be conducted in the direction of the pipe 151, the heater 121 is easily heated, and the power consumption of the heater 121 is smaller than when there is no gap. Here, when there is no defect in the adhesive of the heater 121 and there is a defect in the adhesive of the temperature sensor 122, the power consumption of the heater 121 does not change as described above. Therefore, by determining a change in the power consumption of the heater 121 , it is possible to distinguish between an abnormality in the adhesive of the heater 121 and an abnormality in the adhesive of the temperature sensor 122 .

A change in the operating state of the heater 121 described above appears in a change in power measured by the power change measuring unit 203 . As described above, in a state where noise is likely to be silenced due to the presence of a gap, the power change measured by the power change measuring unit 203 is smaller than the power reference value. For example, the power change ΔT1 measured by the power change measuring unit 203 when there is an abnormality is smaller than the power change ΔT0 measured by the power change measuring unit 203 when there is no abnormality. If ΔT0 is used as a power reference value and ΔT1 is compared with the power reference value ΔT0 for determination, it is possible to diagnose a failure due to a defect in the adhesive of the heater 121 or the like.

Here, the above-described power reference value is determined by the above-described fluid stop unit 101, temperature control unit 102, and the above-described fluid stop unit 101, temperature control unit 102, and the like, which were performed immediately after manufacturing the failure diagnosis device 200 that can determine that the adhesive of the heater 121 has no abnormality. A power change measurement value obtained by the power change measuring unit 203 can be used.

Next, the operation (fault diagnosis method) of the fault diagnosis device according to Embodiment 2 of the present invention will be described with reference to FIG. Here, the operation (failure diagnosis method) described below can be performed after performing the failure diagnosis in the first embodiment described above.

First, in step S101, the fluid stopping unit 101 stops the flow of 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 be 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 measurement unit 203 detects the first temperature at which the temperature control unit 102 starts controlling the temperature of the heater 121. A change in the electric power of the heater 121 measured by the electric power measuring unit 125 is measured from the time to the second time when the set time has elapsed (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). If the measured power change is smaller than the set power reference value (yes in step S204), the heater abnormality determination unit 204 determines that the bonding state of at least one of the heater 121 and the temperature sensor 122 is abnormal in step S205. It is determined that there is a certain failure state. Further, when the heater abnormality determination unit 204 determines that there is a failure, the heater abnormality determination unit 204 notifies the user of this fact by, for example, displaying it on a display unit (not shown). On the other hand, if the measured power change is greater than the set power reference value (no in step S204), the diagnostic operation is terminated.

Here, the power reference value described above can be obtained in advance as follows. First, immediately after installation of the thermal flow meter 120, the flow of the fluid is stopped by the fluid stop portion 101 (seventh step). Subsequently, the temperature control unit 102 controls the temperature of the heater 121 to be higher than the temperature around the heater 121 (eighth step). In this way, in a state in which the flow of fluid is stopped and the temperature of the heater 121 is controlled, from the third time when the temperature control of the heater 121 is started to the fourth time when the set time has passed, , 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 (ninth step).

As shown in FIG. 8, the fault diagnosis apparatus 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. , and the CPU 301 operates (executes the program) according to the program developed in the main storage device 302, so that each function (failure diagnosis method) described above can be realized. The above program is a program for a computer to execute the fault diagnosis method shown in the above-described embodiment. A network connection device 304 connects to a network 305 . Also, functions may be distributed among multiple computing devices.

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

As described above, according to the present invention, from the first point in time when control of the temperature of the heater is started in a state where the flow of the fluid is stopped, until the second point in time after the elapse of the set time, the temperature sensor Since the change in temperature measured by is measured, it becomes possible to diagnose the failure of the thermal flowmeter while it is installed.

It should be noted that the present invention is not limited to the embodiments described above, and many modifications and combinations can be implemented by those skilled in the art within the technical concept of the present invention. It is clear.

DESCRIPTION OF SYMBOLS 100... Fault diagnosis apparatus 101... Fluid stop part 102... Temperature control part 103... Temperature change measurement part 104... Judgment part 120... Thermal flow meter 121... Heater 122... Temperature sensor 123... Sensor circuit , 124... control section, 125... electric power measurement section, 126... flow rate calculation section, 151... piping, 151a, 151b... spot facing section.

Claims (12)

a heater that is adhered and fixed with an adhesive to the outer wall of the pipe that transports the fluid to be measured and that heats the fluid;
a temperature sensor that is adhesively fixed to the outer wall of the pipe on the upstream side of the heater and measures the temperature of the fluid;
When the heater is driven such 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 becomes a set temperature difference, and a sensor circuit configured to output a sensor value corresponding to the state of heat diffusion in the fluid.
a fluid stop configured to stop the flow of said fluid;
a temperature control unit configured to control the temperature of the heater to be higher than the temperature around the heater;
In a state where the fluid stop unit stops the flow of the fluid and the temperature control unit controls the temperature of the heater, the temperature control unit starts controlling the temperature of the heater from a first time point. a temperature change measuring unit configured to measure a change in the temperature measured by the temperature sensor by a second point in time after a certain period of time has elapsed;
When the change in temperature measured by the temperature change measuring unit is smaller than a set temperature reference value, it is determined that the bonding state of at least one of the heater and the temperature sensor is faulty. and a fault diagnosis device comprising: In the failure diagnosis device according to claim 1,
In a state where the fluid stop unit stops the flow of the fluid and the temperature control unit controls the temperature of the heater, the temperature control unit starts controlling the temperature of the heater from a first time point. a power change measuring unit configured to measure a change in power of the heater by a second point in time after a certain period of time has elapsed;
a heater abnormality determination unit configured to determine that the heater is in a state of failure in which an adhesion state of the heater is abnormal when a change in power measured by the power change measurement unit is smaller than a set power reference value; A fault diagnosis device further comprising: The fault diagnosis device according to claim 1 or 2,
The failure diagnosis device, wherein the adhesive is a thermally conductive adhesive. In the failure diagnosis device according to any one of claims 1 to 3,
The fault diagnosis device, wherein the thermal type flowmeter further includes a flow rate calculator 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 thermally affected by the heater;
The sensor circuit detects the electric power of the heater when the heater is driven such that the difference between the temperature of the heater and the temperature of the fluid measured by the temperature sensor is equal to 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 thermally affected by the heater;
The second temperature sensor measures the temperature of the fluid at a position on the upstream side of the heater that is thermally affected by the heater,
the third temperature sensor measures the temperature of the fluid at a location downstream of the heater and is thermally affected by the heater;
The sensor circuit controls the second temperature sensor when driving 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. a temperature difference between the temperature of the fluid measured by and the temperature of the fluid measured by the third temperature sensor as the sensor value. a heater that is adhered and fixed with an adhesive to the outer wall of the pipe that transports the fluid to be measured and that heats the fluid;
a temperature sensor that is adhesively fixed to the outer wall of the pipe on the upstream side of the heater and measures the temperature of the fluid;
When the heater is driven such 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 becomes a set temperature difference, and a sensor circuit configured to output a sensor value corresponding to the state of heat diffusion in the fluid, wherein:
a first step of stopping the flow of said fluid;
a second step of controlling the temperature of the heater to be higher than the temperature around the heater, following the first step;
With the flow of the fluid stopped in the first step and the temperature of the heater controlled in the second step, the temperature control of the heater is started in the second step. a third step of measuring a change in the temperature measured by the temperature sensor by a second point in time after the predetermined time has elapsed;
A fourth step of determining that there is an abnormality in the bonding state of at least one of the heater and the temperature sensor when the change in temperature measured in the third step is smaller than a set temperature reference value. and . In the failure diagnosis method according to claim 7,
In a state where the fluid stop unit stops the flow of the fluid and the temperature control unit controls the temperature of the heater, the temperature control unit starts controlling the temperature of the heater from a first time point. a fifth step of measuring a change in power of the heater by a second point in time after the elapse of a certain time;
and a sixth step of determining that the heater is in a state of failure in which the bonding state of the heater is abnormal when the change in power measured in the fifth step is smaller than a set power reference value. failure diagnosis method. In the failure diagnosis method according to claim 7 or 8,
a seventh step of stopping the flow of the fluid immediately after installation of the thermal flow meter;
an eighth step of controlling the temperature of the heater to be higher than the temperature around the heater, following the seventh step;
In the state where the flow of the fluid is stopped in the seventh step and the temperature of the heater is controlled in the eighth step, from the third time when the temperature control of the heater is started in the eighth step, setting A ninth step of measuring a change in the temperature measured by the temperature sensor or a change in the power of the heater by a fourth point in time after the predetermined time has elapsed, and using the measured value as the temperature reference value or the power reference value A fault diagnosis method, further comprising: In the failure diagnosis method according to any one of claims 7 to 9,
A failure diagnosis method, wherein the adhesive is a thermally 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 thermally affected by the heater;
The sensor circuit detects the electric power of the heater when the heater is driven such that the difference between the temperature of the heater and the temperature of the fluid measured by the temperature sensor is equal to 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 thermally affected by the heater;
The second temperature sensor measures the temperature of the fluid at a position on the upstream side of the heater that is thermally affected by the heater,
the third temperature sensor measures the temperature of the fluid at a location downstream of the heater and is thermally affected by the heater;
The sensor circuit controls the second temperature sensor when driving 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. outputting as the sensor value a temperature difference between the temperature of the fluid measured by and the temperature of the fluid measured by the third temperature sensor.

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