JP6319034B2 - Filter inspection device and filter inspection method - Google Patents

Description

  The present invention relates to inspection of filters.

  A technique of using a differential pressure before and after the DPF is known for detecting an abnormality of a DPF (Diesel Particulate Filter). Specifically, when the differential pressure is smaller than the threshold value, it is determined that an abnormality such as a crack or a hole has occurred in the DPF (Patent Document 1).

JP 2006-283748 A

  The above prior art inspection utilizes the fact that if the DPF is cracked or perforated, the pressure loss due to the DPF is reduced, and if the pressure loss due to the DPF is reduced, the differential pressure before and after the DPF is also reduced. . However, even if the DPF is not cracked or perforated, the differential pressure may be smaller than the threshold value. This is because the differential pressure before and after the DPF is not determined only by the pressure loss due to the DPF.

  Therefore, when the differential pressure before and after the DPF becomes small, if it is immediately determined that the DPF is abnormal, there is a risk of erroneous detection. In view of the above-described prior art, the present invention has an object to solve erroneous detection in DPF abnormality detection using differential pressure.

  SUMMARY An advantage of some aspects of the invention is to solve the above-described problems, and the invention can be implemented as the following forms.

(1) According to one aspect of the present invention, a filter inspection apparatus is provided. The filter inspection apparatus includes: an abnormality detection unit that detects an abnormality of the filter based on a differential pressure before and after the filter for collecting particulates; an inflow temperature that is a temperature of the gas before flowing into the filter; and an outflow from the filter And a prohibition unit that prohibits the detection when the outflow temperature, which is the temperature of the gas after being deviated, deviates. According to this form, erroneous detection is suppressed. This is because the above divergence affects the differential pressure before and after the filter.

(2) In the above aspect, the prohibition unit may execute the prohibition when a ratio between the inflow temperature and the outflow temperature is not included in a predetermined range. According to this form, the prohibition of inspection can be appropriately executed. The method based on the above ratio is appropriate from the theoretical relationship between pressure and temperature.

(3) In the above aspect, the prohibition unit may execute the prohibition when a difference between the inflow temperature and the outflow temperature is not included in a predetermined range. You may implement | achieve the said form like this form.

(4) In the above aspect, the abnormality detection unit may perform the detection based on a relationship between the differential pressure and a volume flow rate of the gas before flowing into the filter. According to this form, it can test | inspect more appropriately.

  The present invention can be realized in various forms other than the above. For example, the present invention can be realized in the form of an inspection method, a computer program for realizing the method, a non-temporary storage medium storing the computer program, and the like.

The schematic block diagram of a diesel engine. The flowchart which shows a DPF inspection process. The flowchart which shows an acquisition permission decision processing. The graph for demonstrating abnormality detection based on a differential pressure-flow volume relationship. The graph which shows a mode that temperature ratio changes with progress of time. 9 is a flowchart showing acquisition permission / denial determination processing according to the second embodiment. The graph which shows a mode that a temperature difference changes with progress of time. 10 is a flowchart illustrating acquisition permission determination processing according to the third embodiment. The graph which shows a mode that inflow temperature and outflow temperature change with progress of time.

  Embodiment 1 will be described. FIG. 1 shows a schematic configuration of a diesel engine 10. The diesel engine 10 is mounted on an automobile and is a four-stroke engine having four cylinders. When air is supplied to each combustion chamber via the intake pipe 12 and fuel is injected from the fuel injection valve 14 provided in each combustion chamber, combustion occurs in the combustion chamber. The exhaust gas generated by the combustion is discharged into the atmosphere from the exhaust pipe 17 through the exhaust collecting pipe 16.

  A supercharger 20 is provided in the middle of the exhaust pipe 17. The supercharger 20 includes a turbine 21 provided in the exhaust pipe 17, a compressor 22 provided in the intake pipe 12, and a shaft 23. The shaft 23 connects the turbine 21 and the compressor 22.

  An air cleaner 26 is provided on the upstream side of the compressor 22. When the exhaust gas discharged from the combustion chambers rotates the turbine 21 of the supercharger 20, the compressor 22 rotates through the shaft 23, compresses the air, and supplies the compressed air to each combustion chamber. Since the air temperature rises when compressed by the compressor 22, an intercooler 24 for cooling the air is provided downstream of the compressor 22. The compressed air is cooled by the intercooler 24, and after the pressure is reduced, the compressed air is supplied into the combustion chamber.

  An electric throttle valve 28 is provided in the intake pipe 12. The electric throttle valve 28 is opened under normal operating conditions. The amount of air flowing into the combustion chamber can be limited by closing the electric throttle valve 28 as necessary.

  The intake pipe 12 and the exhaust collecting pipe 16 are connected by an EGR passage 60. EGR means exhaust gas recirculation. An EGR valve 62 is provided in the EGR passage 60, and the amount of exhaust gas introduced into the intake pipe 12 can be controlled by adjusting the opening degree of the EGR valve 62.

  The ECU 30 acquires values such as the engine speed and the accelerator opening, and controls the fuel supply pump 18, the fuel injection valve 14, the electric throttle valve 28, the EGR valve 62, and the like according to the acquired values.

  The exhaust gas generated by the combustion of fuel in the combustion chamber contains carbon-containing suspended particulates such as soot. A DPF 100 is provided in the exhaust pipe 17 on the downstream side of the turbine 21 in order to purify the carbon-containing suspended fine particles in the exhaust gas.

  The thermometer 70 measures the temperature of the exhaust gas before flowing into the DPF 100 (hereinafter referred to as “inflow temperature Tin”). The thermometer 75 measures the temperature of the exhaust gas after flowing in from the DPF 100 (hereinafter referred to as “outflow temperature Tout”). The pressure gauge 80 measures the pressure Pin of the exhaust gas before flowing into the DPF 100. The differential pressure gauge 90 measures the differential pressure of exhaust gas around the DPF 100 (hereinafter referred to as “differential pressure ΔP”). These measured values are input to the ECU 30.

  FIG. 2 is a flowchart showing the DPF inspection process. The DPF inspection process is a process for detecting an abnormality of the DPF 100, and is executed by the ECU 30 when the ignition key of the automobile is turned on.

  First, it is determined whether all the sensors are normal (step S200). Here, the sensor or the like is a device that should operate normally when executing each step described later. For example, an atmospheric pressure sensor (not shown), an air flow meter (not shown), a thermometer 70, a temperature The total 75, the differential pressure gauge 90, and the like. In step S200, it is also determined whether the fuel injection valve 14 is normal. If all the sensors are normal (step S200, YES), an acquisition permission / inhibition decision process is executed (step S300).

  FIG. 3 is a flowchart showing acquisition permission / denial determination processing. First, it is determined whether various parameters are within the standard (step S310). Specifically, whether the inflow flow rate Fin is within a predetermined range (whether the flow rate is F1 to F2 shown in FIG. 4), the number of times the DPF 100 is regenerated is less than the predetermined number, or the measured value by the differential pressure gauge 90 is stable. It is determined whether or not all of them are satisfied. The regeneration of the DPF 100 is to temporarily raise the DPF 100 to a high temperature and remove soot and the like by combustion. The number of times affects the pressure loss by the DPF 100. If the number of reproductions is too large, for example, even if it is normal, the differential pressure tends to increase.

The inflow flow rate Fin is a volume flow rate at the time of inflow into the DPF 100. The inflow flow rate Fin is calculated by the following equation (1).
Fin = (R / M) × Fm × Tin / Pin (1)

  Fm in Formula (1) shows the mass flow rate (kg / s) of exhaust gas. The mass flow rate Fm is calculated based on the sum of the intake air amount and the fuel injection amount from the fuel injection valve 14. The intake air amount is obtained from an air flow meter. R in the formula (1) is a gas constant (J / (K · mol)), and M is an average molar mass (kg / mol) of exhaust gas. The average molar mass is considered to be a constant for this embodiment. Of course, M may be handled as a variable by measuring the molecular composition of the exhaust gas. When the average molar mass is a constant, R / M becomes a constant, and the calculation of formula (1) is simplified.

  If the various parameters are within the standard (step S310, YES), it is determined whether the temperature ratio Tr is equal to or higher than the lower limit threshold ThL1 (step S320). The temperature ratio Tr is a quotient obtained by dividing the inflow temperature Tin by the outflow temperature Tout (Tin / Tout). The lower limit threshold ThL1 and the upper limit threshold ThU1 described later will be described later together with FIG.

  When the temperature ratio Tr is equal to or higher than the lower limit threshold ThL1 (step S320, YES), it is determined whether the temperature ratio Tr is equal to or lower than the upper limit threshold ThU1 (step S330). When the temperature ratio Tr is equal to or lower than the upper limit threshold ThU1 (step S330, YES), the acquisition of the relationship between the differential pressure ΔP and the inflow flow rate Fin (hereinafter referred to as “differential pressure-flow rate relationship”) is permitted (step S340). The acceptance / rejection determination process is terminated. The acquisition of the differential pressure-flow rate relationship means that the values of the differential pressure ΔP and the inflow flow rate Fin are associated with each other and stored in a storage medium built in the ECU 30 in order to detect an abnormality of the DPF 100.

  On the other hand, if NO is determined in any one of steps S310 to S330, acquisition of the differential pressure-flow rate relationship is prohibited (step S350), and the acquisition permission / inhibition determination process is terminated.

  When the acquisition permission / denial determination process ends, as shown in FIG. 2, it is determined whether acquisition of the differential pressure-flow rate relationship is permitted (step S400). When permitted (step S400, YES), a differential pressure-flow rate relationship is acquired (step S500). After that, the value that holds the memory is selected by deleting the more normal acquired value in the differential pressure-flow rate relationship acquired here and the differential pressure-flow rate relationship acquired in the past (step S600). The more normal acquired value is an acquired value having a larger value of ΔP / Fin.

  Next, it is determined whether the ignition key is on (step S700). If the ignition key is on (step S700, YES), the process returns to step S200 and the process is repeated.

  When the ignition key is off (step S700, NO), it is determined whether the DPF 100 is normal or abnormal (step S800). This determination is performed based on whether or not the acquired value stored in the storage medium is included in the abnormal area (see FIG. 4). Finally, the determination result is stored (step S900), and the DPF inspection process is terminated.

  On the other hand, when acquisition of the differential pressure-flow rate relationship is prohibited (step S400, NO), steps S500 and S600 are skipped and step S700 is executed. If the sensor or the like is not normal (step S200, NO), steps S300 to S600 are skipped and step S700 is executed.

  When the stored determination result indicates that the DPF 100 is abnormal, the ECU 30 displays that fact on a display in the vehicle. The display timing may be the timing when the ignition switch is turned off, or may be the timing after the timing when the ignition key is turned on next time.

  FIG. 4 is a graph for explaining abnormality determination based on the differential pressure-flow rate relationship. The vertical axis of the graph represents the differential pressure ΔP, and the horizontal axis of the graph represents the inflow flow rate Fin. The curve shown in FIG. 4 will be described later.

  As shown in FIG. 4, when the inflow flow rate Fin is less than the flow rate F1 and exceeds the flow rate F2, there is no abnormal region. This is because abnormality detection is prohibited by step S310 unless the inflow flow rate Fin is not less than the flow rate F1 and not more than the flow rate F2. The reason for this prohibition is that erroneous detection is likely to occur if the inflow flow rate Fin is too small or too large.

  When the inflow flow rate Fin is not less than the flow rate F1 and not more than the flow rate F2, if the differential pressure ΔP is smaller than the reference, it is determined to be abnormal. As shown in FIG. 4, this standard is determined by the relationship with the inflow flow rate Fin. The relationship in this embodiment employs a straight line having a positive slope. Of course, this relationship is not limited to such a straight line, and may be changed to a curve or the like based on an experiment or the like.

  When the acquired differential pressure-flow rate relationship is included in the abnormal region, it is determined that the DPF 100 is abnormal. However, as described above, while acquisition of the differential pressure-flow rate relationship is prohibited, even if the differential pressure-flow rate relationship is actually included in the abnormal region, it is determined to be abnormal based on the differential pressure-flow rate relationship. It will never be done.

  FIG. 5 is a graph showing an example of how the temperature ratio Tr changes with time. The first axis on the vertical axis represents temperature (unit is Kelvin), the second axis on the vertical axis represents the temperature ratio Tr, and the horizontal axis represents time. Hereinafter, a description will be given with reference to FIGS.

  The graph of FIG. 5 shows a case where the diesel engine 10 is started at time t0. When the diesel engine 10 starts, both the inflow temperature Tin and the outflow temperature Tout gradually increase as shown in FIG. However, as shown in FIG. 5, the inflow temperature Tin has a higher rising speed than the outflow temperature Tout. As a result, the temperature ratio Tr gradually increases from 1. At time ta1, the temperature ratio reaches the upper limit threshold ThU1. Therefore, at time ta1, acquisition of the differential pressure-flow rate relationship is prohibited.

In FIG. 4, the state from time t0 to time ta1 described above corresponds to the locus of the curve J from t0 to ta1. On the other hand, the curve C is a curve obtained by correcting the curve J with the temperature ratio Tr. Curve C is shown for reference as a comparison object for visualizing the effect of temperature ratio Tr on differential pressure ΔP. The following equation (2) is used for correction.
C = Pin− (Pin−J) / Tr (2)

By the way, Pin> ΔP (= J) always holds. Therefore, the equation (2) indicates that the curve C and the curve J deviate as the difference between the inflow temperature Tin and the outflow temperature Tout increases, that is, as the temperature ratio Tr increases. For example, when the divergence between the curve C and the curve J is represented by a difference, the difference (C−J) is represented by Expression (3).
C−J = (Pin−ΔP) (1-1 / Tr) (3)

  After the time ta1, the outflow temperature Tout follows the inflow temperature Tin as shown in FIG. Along with this, the temperature ratio Tr peaks. And at time tb1, it falls below the upper limit threshold ThU1. As a result, acquisition of the differential pressure-flow rate relationship is permitted.

  As shown in FIG. 4, between the time ta1 and the time tb1, the curve C and the curve J greatly deviate due to the large temperature ratio Tr. And in the curve J which shows an actual measurement value, most of the differential pressure-flow rate relationship is included in the abnormal region. However, as described above, since the acquisition of the differential pressure-flow rate relationship is prohibited in step S350 from time ta1 to time tb1, it is determined that there is an abnormality based on the differential pressure-flow rate relationship during this period. Absent.

  After time tb1, as shown in FIG. 5, the temperature ratio Tr is stable, and the state where the acquisition of the differential pressure-flow rate relationship is allowed continues.

  Thus, when the temperature ratio Tr is equal to or higher than the upper limit threshold ThU1, erroneous detection is suppressed by prohibiting acquisition of the differential pressure-flow rate relationship. The abnormality detection based on the differential pressure-flow rate relationship is a method for determining whether or not the pressure loss due to the DPF 100 is normal, and the differential pressure ΔP and the inflow flow rate Fin are used for this determination.

  On the other hand, when factors other than the pressure loss due to the DPF 100 have a non-negligible influence on the differential pressure ΔP, the above determination lacks accuracy. Therefore, in the present embodiment, attention is paid to the temperature ratio Tr as a factor affecting the differential pressure ΔP. The temperature ratio Tr has a value slightly larger than 1 due to the influence of the expansion of the throttle caused by passing through the DPF 100 in a steady operation state.

  On the other hand, when the temperature ratio Tr deviates from this value, it can be considered from the gas equation of state that the temperature ratio Tr has a non-negligible effect on the differential pressure ΔP. For example, as illustrated in FIGS. 4 and 5, the cause that the differential pressure-flow rate relationship is included in the abnormal region at time ta1 to time tb1 is not an abnormality of the DPF 100 but an inflow temperature Tin and an outflow temperature Tout. It is thought that this is a divergence. Therefore, by prohibiting abnormality detection in such a case, it is possible to suppress erroneous detection of the normal DPF 100 as being abnormal.

  Thus, even if there is a time zone in which the acquisition of the differential pressure-flow rate relationship is prohibited, there is almost no hindrance to abnormality detection, and it can be said that it is rather convenient. This is because an abnormality in the DPF 100 does not immediately affect traveling and does not need to be detected so frequently. Therefore, it can be said that the method of detecting the abnormality only when the influence of the temperature ratio Tr can be ignored is reasonable in that the detection of the abnormality with an unnecessary frequency can be avoided in addition to the improvement of the detection accuracy.

  A second embodiment will be described. The second embodiment is the same as the first embodiment in the hardware configuration and the point that the DPF inspection process is executed. The difference is a part of the acquisition permission / denial determination process.

  FIG. 6 is a flowchart illustrating acquisition permission / denial determination processing according to the second embodiment. The difference from the first embodiment is that steps S322 and S332 are executed as shown in FIG. 6 instead of steps S320 and S330. Since the other steps are the same, description thereof is omitted.

  As shown in FIG. 6, step S322 is a determination step for prohibiting the acquisition of the differential pressure-flow rate relationship when the temperature difference Td is less than the lower limit threshold ThL2. The temperature difference Td is a difference obtained by subtracting the outflow temperature Tout from the inflow temperature Tin (Tin−Tout). Step S332 is a determination step for prohibiting acquisition of the differential pressure-flow rate relationship when the temperature difference Td exceeds the upper limit threshold ThU2.

  FIG. 7 is a graph showing an example of how the temperature difference Td changes over time. The first axis on the vertical axis represents temperature, the second axis on the vertical axis represents the temperature difference Td, and the horizontal axis represents time. FIG. 7 shows a state when the diesel engine 10 is started as in the first embodiment. Therefore, the inflow temperature Tin and the outflow temperature Tout exhibit the same behavior as that described in the first embodiment.

  The temperature difference Td is substantially zero at time t0. When time elapses from time t0, the temperature difference Td gradually increases from zero because the inflow temperature Tin has a higher rising speed than the outflow temperature Tout.

  At time ta2, the temperature difference Td reaches the upper limit threshold ThU2. Therefore, at time ta2, acquisition of the differential pressure-flow rate relationship is prohibited. Thereafter, the temperature difference Td peaks and falls below the upper limit threshold ThU2 at time tb2. Therefore, after time tb2, acquisition of the differential pressure-flow rate relationship is permitted.

  Even if the temperature difference Td is used as in the second embodiment, whether to acquire the differential pressure-flow rate relationship can be set appropriately.

  A third embodiment will be described. The third embodiment is the same as the first embodiment in the hardware configuration and the point that the DPF inspection process is executed. The difference is a part of the acquisition permission / denial determination process.

  FIG. 8 is a flowchart showing acquisition permission / denial determination processing according to the third embodiment. The difference from the first embodiment is that steps S323 and S333 are executed as shown in FIG. 8 instead of steps S320 and S330. Since the other steps are the same, description thereof is omitted.

  As shown in FIG. 8, step S323 is a determination step for prohibiting acquisition of the differential pressure-flow rate relationship when the inflow temperature Tin is lower than the lower limit threshold ThL3. Step S333 is a determination step for prohibiting acquisition of the differential pressure-flow rate relationship when the outflow temperature Tout is lower than the lower limit threshold ThL3.

  FIG. 9 is a graph showing an example of how the inflow temperature Tin and the outflow temperature Tout change with time. The vertical axis represents temperature, and the horizontal axis represents time. FIG. 9 shows a state when the diesel engine 10 is started, as in the first and second embodiments. Therefore, the inflow temperature Tin and the outflow temperature Tout exhibit the same behavior as that described in the first embodiment.

  As shown in FIG. 9, the inflow temperature Tin exceeds the lower limit threshold ThL3 at time ta3. However, since the outflow temperature Tout is lower than the lower limit threshold ThL3 at time ta3, acquisition of the differential pressure-flow rate relationship is prohibited in step S333.

  At time tb3, since the inflow temperature Tin and the outflow temperature Tout both exceed the lower limit threshold ThL3, acquisition of the differential pressure-flow rate relationship is permitted.

  When each of the inflow temperature Tin and the outflow temperature Tout is equal to or higher than the lower limit threshold ThL3, it is considered that the exhaust gas is stable. Therefore, even with the method of the third embodiment, abnormality detection can be performed in a state where the exhaust gas is stable.

  In the first, second, and third embodiments, the acquisition of the differential pressure-flow rate relationship is not limited to the time when the diesel engine 10 described above is started. That is, the prohibition is determined based on the inflow temperature Tin and the outflow temperature Tout regardless of the history of the inflow temperature Tin, the outflow temperature Tout, the differential pressure ΔP, the inflow flow rate Fin, and the like. For example, the acquisition may be prohibited at the time of stopping, at the time of rapid acceleration or deceleration, or when an external factor (external temperature or the like) changes suddenly, and the effect is exhibited.

  The present invention is not limited to the embodiments, examples, and modifications of the present specification, and can be implemented with various configurations without departing from the spirit of the present invention. For example, the technical features in the embodiments, examples, and modifications corresponding to the technical features in the embodiments described in the summary section of the invention are to solve some or all of the above-described problems, or In order to achieve part or all of the effects described above, replacement or combination can be performed as appropriate. If the technical feature is not described as essential in this specification, it can be deleted as appropriate. For example, the following are exemplified.

  The content prohibited based on the inflow temperature and the outflow temperature may not be acquisition of the differential pressure-flow rate relationship. For example, the prohibited content may be determined as abnormal based on the differential pressure-flow rate relationship when the inflow temperature and the outflow temperature deviate. This way of grasping the prohibited content is a concept including the technique of the above-described embodiment. As a specific method different from the embodiment, for example, a method of executing the acquisition of the differential pressure-flow rate relationship even if the inflow temperature and the outflow temperature are different can be considered. However, in the case of this method, it is obtained by distinguishing whether it is acquired when the inflow temperature and the outflow temperature are different from each other, or is acquired when there is no difference. In determining whether the temperature is normal or abnormal, an effect equivalent to that of the embodiment can be obtained by ignoring what is acquired when the inflow temperature and the outflow temperature are different.

  When the differential pressure-flow rate relationship is acquired only when the inflow temperature and the outflow temperature deviate, two or more acquired differential pressure-flow rate relationships may be stored, or may be stored. And in the determination, you may detect abnormality based on the presence or absence of the relationship included in an abnormal area | region.

  The method of using the inflow temperature and the outflow temperature may not be as described above. For example, the differential pressure may be corrected using the inflow temperature and the outflow temperature as described in the first embodiment, and the abnormality detection may be performed using the corrected differential pressure. In this way, even if the inflow temperature and the outflow temperature are different, abnormality detection can be performed with high accuracy. In addition, the differential pressure-flow rate relationship can be acquired with high frequency.

  Any two or three of the methods described as the first, second, and third embodiments may be combined. For example, both the temperature ratio and the temperature difference may be monitored, and acquisition of the differential pressure-flow rate relationship may be prohibited when at least one of them is out of a predetermined range.

  The inspection may not be performed by the ECU mounted on the automobile. For example, a person or an external device may be used. For example, when performed by a person, the person monitors the measured values of differential pressure, inflow temperature, and outflow temperature using an instrument. Then, when the inflow temperature and the outflow temperature are stable and the temperature ratio becomes about 1, the differential pressure is read, and if the read differential pressure is within a predetermined range, it is normal, otherwise it is determined abnormal. Good. In the case of using an external device, the same method may be used.

  As a modification of the third embodiment, only one of the inflow temperature and the outflow temperature may be monitored. For example, the outflow temperature may be ignored and acquisition of the differential pressure-flow rate relationship may be prohibited when the inflow temperature is less than a threshold value.

  When the DPF is new, the value of the flow rate F1 (the lower limit flow rate for performing abnormality detection) may be increased.

  The filter to be inspected may not be a DPF for automobiles. For example, it may be applied to a filter for another type of internal combustion engine (gasoline engine, Stirling engine, etc.), or applied to a DPF mounted on other transportation equipment (motorcycle, diesel locomotive, etc.). Also good.

DESCRIPTION OF SYMBOLS 10 ... Diesel engine 12 ... Intake pipe 14 ... Fuel injection valve 16 ... Exhaust collecting pipe 17 ... Exhaust pipe 18 ... Fuel supply pump 20 ... Supercharger 21 ... Turbine 22 ... Compressor 23 ... Shaft 24 ... Intercooler 26 ... Air cleaner 28 ... Electric throttle valve 30 ... ECU
60 ... EGR passage 62 ... EGR valve 70 ... Thermometer 75 ... Thermometer 80 ... Pressure gauge 90 ... Differential pressure gauge 100 ... DPF

Claims (4)

A measuring instrument for measuring a value indicating a differential pressure before and after the filter for collecting particulates, a thermometer for measuring an inflow temperature which is a temperature of the gas before flowing into the filter, and a temperature of the gas after flowing out from the filter It is a filter inspection device that acquires a measurement value from a thermometer that measures the outflow temperature,
It said differential pressure, and the abnormality detecting unit for detecting an abnormality of the filter based on the relationship between the volume flow rate of the previous gas flowing into the filter,
The flow and inlet temperature, when said flow exit temperature deviates, the filter testing device comprising a prohibition unit that prohibits the detection. The filter inspection device according to claim 1, wherein the prohibition unit executes the prohibition when a ratio between the inflow temperature and the outflow temperature is not included in a predetermined range. The filter inspection device according to claim 1, wherein the prohibition unit executes the prohibition when a difference between the inflow temperature and the outflow temperature is not included in a predetermined range. A measuring instrument for measuring a value indicating a differential pressure before and after the filter for collecting particulates, a thermometer for measuring an inflow temperature which is a temperature of the gas before flowing into the filter, and a temperature of the gas after flowing out from the filter It is a method executed by a filter inspection device that acquires a measurement value from a thermometer that measures an outflow temperature,
Said pressure difference, to detect the abnormality of the filter based on the relationship between the volume flow rate of the previous gas flowing into the filter,
With the flow inlet temperature, if the temperature leaving the flow is deviated, filter inspection method for inhibiting the detection.

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