Exhaust gas purification system removal determination device

Abstract

The present invention provides an exhaust gas purification device removal determination device that can suppress the misjudgment of whether or not an exhaust gas purification device has been removed. [Solution] An exhaust purification device removal determination device that determines whether an exhaust purification device is housed inside a casing communicating with the exhaust pipe of an engine, wherein if the input temperature Tin(t) detected by the input temperature sensor within a predetermined period from the start of the engine decreases (Yes in step S4), the device outputs the input temperature Tin(t-1) detected by the input temperature sensor before the decrease, and determines whether or not an exhaust purification device is located inside the casing based on the outputted input temperature Tin(t-1) and the output temperature Tout(t) detected by the output temperature sensor (steps S12 to S14).

Description

Technical Field

[0001] This invention relates to a device for determining whether or not an exhaust gas purification device for an engine has been removed from an exhaust pipe.

Background Art

[0002] Patent Documents 1 to 3 describe devices for determining that an exhaust gas purification device has been removed from an exhaust pipe. The determination device described in Patent Document 1 is configured to determine whether or not the exhaust gas purification device has been removed when the integrated amount of the exhaust gas of the engine reaches a predetermined amount or more. Further, the determination device is configured to determine that the exhaust gas purification device has been removed when the difference between the detected value of the temperature sensor provided upstream of the location where the exhaust gas purification device is provided and the detected value of the temperature sensor provided downstream is less than a predetermined difference.

[0003] The determination device described in Patent Document 2 is configured to determine that the exhaust gas purification device has been removed based on a first integrated value obtained by integrating the amount of change in the temperature of the exhaust gas upstream of the exhaust gas purification device and a second integrated value obtained by integrating the amount of change in the difference between the exhaust gas temperature upstream and downstream of the exhaust gas purification device.

[0004] The determination device described in Patent Document 3 is configured to estimate the temperature downstream of the exhaust gas purification device based on the temperature upstream of the exhaust gas purification device, and to determine that the exhaust gas purification device has been removed by comparing the estimated temperature with the actual temperature. Note that the determination device described in Patent Document 3 is configured to determine whether or not the exhaust gas purification device has been removed when prerequisite conditions such as the temperature of the cooling water of the internal combustion engine being a predetermined temperature or more, the outside air temperature being within a predetermined temperature range, the operation time after the start of the internal combustion engine being a predetermined time or more, the rotational speed of the internal combustion engine being within a predetermined range, and the exhaust gas purification device not being in the regeneration process are satisfied.

Prior Art Documents

Patent Documents

[0005] [[ID=XX]] [Patent Document 1] Japanese Patent Publication No. 2024-036090 [Patent Document 2] Japanese Patent Publication No. 2019-218917 [Patent Document 3] Japanese Patent Publication No. 2019-214952 [Overview of the project] [Problems that the invention aims to solve]

[0006] The determination devices described in Patent Documents 1 to 3 determine whether or not an exhaust gas purification device has been removed based on the exhaust gas temperature upstream of the exhaust gas purification device. On the other hand, since the determination of whether or not an exhaust gas purification device has been removed is based on the rising trend of the exhaust gas temperature detected by the temperature sensor, the process starts from a state where the temperature of the internal combustion engine has sufficiently decreased. Also, when the internal combustion engine is running, water is produced by the reaction of hydrogen and oxygen in the air, and this moisture is contained in the exhaust gas. Therefore, when determining whether or not an exhaust gas purification device is present, the moisture contained in the exhaust gas may condense and change into a liquid phase and flow through the exhaust pipe. In such cases, the detection part of the temperature sensor installed upstream of the exhaust gas purification device may be covered with water. As a result, the heat near the detection part of the temperature sensor is absorbed as heat of vaporization due to the phase change of the liquid water adhering to the detection part into a gaseous phase, and the temperature detected by the temperature sensor may be lower than the actual exhaust gas temperature. Therefore, if the detection unit of the temperature sensor is submerged in water, and the system determines whether or not the exhaust gas purification device has been removed based on the temperature detected by the temperature sensor, there is a possibility of incorrectly determining that the exhaust gas purification device has been removed even though it has not been removed.

[0007] This invention was made in view of the above-mentioned technical problems, and the object of this invention is to provide an exhaust gas purification device removal determination device that can suppress misjudgments of whether or not an exhaust gas purification device has been removed. [Means for solving the problem]

[0008] To achieve the above objective, this invention provides an exhaust gas purification device removal determination device for determining whether an exhaust gas purification device is housed inside a casing communicating with the exhaust pipe of an engine, comprising: an input temperature sensor for detecting the temperature on the upstream side of the casing; an output temperature sensor for detecting the temperature on the downstream side of the casing; and a controller for determining the presence or absence of the exhaust gas purification device inside the casing, wherein the controller comprises: a noise reduction processing unit that outputs the input temperature detected by the input temperature sensor before the decrease occurs when the input temperature detected by the input temperature sensor decreases within a predetermined period from the start of the engine; and a determination unit that determines whether or not the exhaust gas purification device is located inside the casing based on the input temperature output from the noise reduction processing unit and the output temperature detected by the output temperature sensor.

[0009] Furthermore, in this invention, the predetermined period may include the period from the start of the engine until the output temperature reaches a predetermined temperature.

[0010] Furthermore, in this invention, the determination unit may determine that the exhaust gas purification device is located inside the casing if the ratio of the integrated value of the input temperature output from the noise reduction processing unit during the predetermined period to the integrated value of the output temperature during the predetermined period is equal to or greater than a predetermined value.

[0011] Furthermore, in this invention, the controller further comprises an engine stop time acquisition unit that acquires the time from when the engine stops until it starts, and the determination unit may determine whether or not the exhaust gas purification device is located inside the casing if the time from when the engine stops until it starts is equal to or greater than a predetermined time. [Effects of the Invention]

[0012] The exhaust gas purification device removal determination device in this invention outputs the input temperature detected by the input temperature sensor located upstream of the exhaust gas purification device if the input temperature detected by the input temperature sensor located upstream of the exhaust gas purification device decreases within a predetermined period from the start of the engine. In other words, the input temperature detected by the input temperature sensor before the temperature decreased is set as the lower limit guard value. Then, based on the input temperature detected by the input temperature sensor before the temperature decreased and the output temperature detected by the output temperature sensor located downstream of the exhaust gas purification device, it is determined whether or not an exhaust gas purification device is installed. Therefore, even if the input temperature detected by the input temperature sensor decreases due to the input temperature sensor being exposed to water or the like, it is possible to suppress the influence of the decrease in input temperature on the determination value for determining the presence or absence of an exhaust gas purification device. As a result, it is possible to suppress misdetermining the presence or absence of an exhaust gas purification device, or in other words, to improve the accuracy of determining the presence or absence of an exhaust gas purification device. [Brief explanation of the drawing]

[0013] [Figure 1] Figure 1 is a schematic diagram illustrating an example of an engine equipped with an exhaust gas purification device according to an embodiment of the present invention. [Figure 2] Figure 2 is a block diagram illustrating the functional configuration of the controller. [Figure 3] Figure 3 is a flowchart illustrating an example of the control performed by the removal determination device in this embodiment of the invention. [Figure 4] Figure 4 is a time chart illustrating the changes in input and output temperatures when the detection unit of the input temperature sensor is submerged in water. [Figure 5] Figure 5 is a time chart showing the changes in input and output temperatures when the GPF is removed from the casing. [Modes for carrying out the invention]

[0014] This invention will be described based on the embodiments shown in the drawings. Note that the embodiments described below are merely examples of the case where this invention is embodied, and do not limit this invention.

[0015] An example of an engine and an exhaust purification device to which the removal determination device in the embodiment of this invention is applied is schematically shown in FIG. 1. The engine 1 shown in FIG. 1 is configured to generate power by burning a mixture of fuel such as gasoline or diesel and air, similar to a conventional engine. Specifically, in the engine 1, a plurality of cylinders 2 for burning the mixture are formed in the engine block 3. Each cylinder 2 is provided with a spark plug 4 for igniting the mixture.

[0016] An intake pipe 5 for taking in outside air is connected to the engine block 3 via an intake manifold 6. In addition to various members such as an air cleaner (not shown), this intake pipe 5 is provided with a throttle valve 7 for controlling the amount of air flowing in the intake pipe 5 based on the driver's accelerator operation amount and the like. The intake pipe 5 is provided with a throttle opening sensor 8 for detecting the opening degree of the throttle valve 7.

[0017] An exhaust pipe 9 for discharging the exhaust generated by burning the mixture in each cylinder 2 to the outside of the vehicle is connected to the engine block 3 via an exhaust manifold 10.

[0018] Various devices for purifying unburned gases (carbon monoxide (CO) and hydrocarbons (HC)) and nitrogen oxides (NOx) contained in the exhaust and collecting particulate matter are provided in this exhaust pipe 9. In the example shown in FIG. 1, a catalyst device 11 such as an oxidation catalyst (two-way catalyst) or a three-way catalyst for purifying unburned gases and NOx is provided in the exhaust pipe 9, and a PM collection device 12 for collecting particulate matter is provided downstream of the catalyst device 11.

[0019] In an embodiment of the present invention, a wall-flow type filter 13 is adopted as a PM collection device 12 of an exhaust gas purification device. Specifically, the PM collection device 12 is a filter 13 called a GPF (Gasoline Particulate Filter), and a three-way catalyst is supported on the filter 13. Therefore, unburned gas and NOx contained in the exhaust gas discharged from the catalyst device 11 can be effectively purified by the PM collection device 12. In the following description, the filter 13 is simply referred to as GPF13.

[0020] The GPF13 has an outer diameter substantially the same as the inner diameter of a casing 14 formed by expanding a part of the diameter of the exhaust pipe 9, and is assembled inside the casing 14. That is, the casing 14 is provided in communication with the exhaust pipe 9, and is configured such that all of the exhaust gas flowing to the casing 14 passes through the inside of the GPF13.

[0021] In order to detect the temperature of the exhaust gas flowing into the GPF13, an input temperature sensor 15 is provided between the catalyst device 11 and the GPF13. In addition, an output temperature sensor 16 is provided on the downstream side of the GPF13 in order to detect the temperature of the exhaust gas flowing out of the GPF13. In other words, the input temperature sensor 15 detects the temperature on the upstream side of the casing 14, and the output temperature sensor 16 detects the temperature on the downstream side of the casing 14. Note that a detection unit 15a for detecting the temperature of the exhaust gas in the input temperature sensor 15 is provided to protrude a predetermined amount into the exhaust pipe 9, and similarly, a detection unit 16a for detecting the temperature of the exhaust gas in the output temperature sensor 16 is provided to protrude a predetermined amount into the exhaust pipe 9.

[0022] The throttle opening sensor 8, the temperature sensors 15 and 16, and the soak timer 17 are connected to an electronic control unit (hereinafter referred to as ECU) 18 corresponding to the "controller" in the embodiment of the present invention. The soak timer 17 is configured to measure the elapsed time (soak time) since the ignition was turned off.

[0023] The ECU18, like conventional ECUs, is primarily composed of a microcomputer and is configured to determine the presence or absence of the GPF13 based on the input signals and pre-stored maps and calculation formulas. The ECU18 can also receive signals from other sensors, such as the engine speed sensor.

[0024] Figure 2 shows a block diagram illustrating the functional configuration of the ECU 18. The ECU 18 shown in Figure 2 comprises a soak time acquisition unit 19, a temperature acquisition unit 20, a noise reduction processing unit 21, a determination value calculation unit 22, and a GPF determination unit 23.

[0025] The soak time acquisition unit 19 functions as an "engine stop time acquisition unit" that acquires the time from when the engine 1 is stopped until it is started. In this embodiment of the invention, the soak time measured by the soak timer 17 is transmitted to the soak time acquisition unit 19.

[0026] The temperature acquisition unit 20 is configured to acquire the temperature detected by the input temperature sensor 15 and the output temperature sensor 16, and output it to the noise reduction processing unit 21 and the determination value calculation unit 22.

[0027] The noise reduction processing unit 21 suppresses the detection value from being lower than the actual exhaust temperature due to factors such as the detection unit 15a of the input temperature sensor 15 being exposed to water. Specifically, if the input temperature detected by the input temperature sensor 15 decreases within a predetermined period from the start of the engine 1, the unit is configured to output the input temperature detected by the input temperature sensor before the input temperature decreased. More specifically, if the input temperature detected by the input temperature sensor 15 decreases, the unit is configured to suppress the decrease in the input temperature output from the noise reduction processing unit 21 by setting the temperature at the point when the input temperature begins to decrease as the lower limit guard value. A signal is output from this noise reduction processing unit 21 to the determination value calculation unit 22.

[0028] The determination value calculation unit 22 calculates a determination value for determining whether or not a GPF 13 is provided, based on the exhaust temperature input from the temperature acquisition unit 20 and the noise reduction processing unit 21. In this example, the determination value is calculated as the ratio of the integrated value of the input temperature input from the noise reduction processing unit 21 to the integrated value of the output temperature input from the temperature acquisition unit 20 within a predetermined period.

[0029] The GPF determination unit 23 is configured to determine that the GPF 13 is installed inside the casing 14 if the determination value calculated by the determination value calculation unit 22 is equal to or greater than a predetermined value, and to determine that the GPF 13 has been removed from the casing 14 if the determination value is less than the predetermined value. This GPF determination unit 23 corresponds to the "determination unit" in this embodiment of the invention.

[0030] Figure 3 shows a flowchart illustrating an example of control performed by the ECU 18. This control example is executed repeatedly with each control cycle of the ECU 18. In step S1, it is determined whether the soak time is equal to or greater than a predetermined time. This predetermined time is set based on experimental and simulation results to the time required for the temperature inside the engine 1 and exhaust pipe 9 to decrease to the same temperature as the outside air. In this embodiment, if the removal determination device is applied to a hybrid vehicle that can run on a motor as another power source after stopping the engine 1, in step S1, instead of determining the soak time, it may be determined whether the elapsed time since the engine 1 was stopped is equal to or greater than a predetermined time. Thus, in step S1, it is determined whether the time from stopping the engine 1 to starting it is equal to or greater than a predetermined time.

[0031] In this control example, the presence or absence of the GPF 13 is determined based on the exhaust temperature detected by the input temperature sensor 15 and the output temperature sensor 16. Therefore, if the exhaust temperature inside the engine 1 or exhaust pipe 9 is relatively high, such as immediately after the engine 1 has been stopped, it may not be possible to accurately determine the presence or absence of the GPF 13. For this reason, if a negative determination is made in step S1 because the soak time is not longer than a predetermined time, this routine is terminated.

[0032] Conversely, if the soak time is longer than a predetermined time, and the result is positive in step S1, the process proceeds to step S2 to determine whether or not it is within a predetermined time since engine start. Specifically, it is determined whether or not it is within the period from when the engine 1 is started until the output temperature detected by the output temperature sensor 16 reaches a predetermined temperature. This step S2 is a step to determine whether or not it is within the period for determining whether or not the GPF 13 is provided, and the predetermined time may be a time predetermined by experimentation or the like, or it may be determined by the cumulative amount of intake air.

[0033] If step S2 is negatively determined because it is not within a predetermined time since engine start, this routine is terminated. Conversely, if step S2 is positively determined because it is within a predetermined time since engine start, the process proceeds to step S3, where the exhaust temperature (hereinafter referred to as input temperature) Tin(t) detected by the input temperature sensor 15 is obtained. Next, the process proceeds to step S4, where it is determined whether the input temperature Tin(t) detected in step S3 is greater than or equal to the input temperature Tin(t-1) used in the previous routine. In other words, it is determined whether the input temperature has decreased.

[0034] If the input temperature Tin(t) detected in step S3 is greater than or equal to the input temperature Tin(t-1) used in the previous routine, and this is judged positively in step S4, the process proceeds to step S5, and the input temperature Tin(t) detected in step S3 is output. Conversely, if the input temperature Tin(t) detected in step S3 is less than the input temperature Tin(t-1) used in the previous routine, and this is judged negatively in step S4, it is presumed that the input temperature has decreased because the detection unit 15a of the input temperature sensor 15 has been exposed to water. This is because, within a predetermined time from engine startup, the exhaust temperature in the exhaust pipe 9 is expected to gradually increase with the combustion of the engine 1; in other words, the exhaust temperature in the exhaust pipe 9 is not expected to decrease. Therefore, if this is judged negatively in step S4, the process proceeds to step S6, and the input temperature Tin(t-1) used in the previous routine is output.

[0035] Following steps S5 and S6, in step S7, the input temperature Tin(t) output from step S5 or the input temperature Tin(t-1) output from step S6 is integrated to obtain the cumulative input temperature Sin. In other words, the input temperature from the time of engine startup is sequentially accumulated. Next, in step S8, the exhaust temperature (hereinafter referred to as output temperature) Tout detected by the output temperature sensor 16 is detected, and in step S9, this output temperature Tout is integrated to obtain the cumulative output temperature Sout. In other words, the output temperature from the time of engine startup is sequentially accumulated.

[0036] As shown in Figure 1, in the engine 1, the GPF 13 heats up after the input temperature Tin(t) rises, and then the output temperature Tout(t) heats up. That is, if the GPF 13 is installed in the exhaust pipe 9, the output temperature Tout(t) heats up later than the input temperature Tin(t) according to the heat capacity of the GPF 13. In this control example, the presence or absence of the GPF 13 is determined after the input temperature Tin(t) and output temperature Tout(t) have increased. Therefore, in step S10 following step S9, it is determined whether the output temperature Tout(t) is above a predetermined temperature. The predetermined temperature in step S10 can be set to, for example, above the dew point temperature of water.

[0037] If the output temperature Tout(t) is below a predetermined temperature and therefore judged negatively in step S10, the presence or absence of GPF13 cannot be accurately determined, so this routine is terminated. That is, the input temperature Tin(t) or input temperature Tin(t-1) is accumulated along with the output temperature Tout(t) until the output temperature Tout(t) becomes above the predetermined temperature and judged positively in step S10. Conversely, if the output temperature Tout(t) is above the predetermined temperature and judged positively in step S10, the process proceeds to step S11 to calculate the judgment value Sin / Sout. Specifically, the cumulative input temperature Sin is calculated for the cumulative output temperature Sout.

[0038] Then, in step S12, it is determined whether the judgment value Sin / Sout calculated in step S11 is greater than or equal to a predetermined value determined by experiments or simulations. If the judgment value is greater than or equal to the predetermined value and therefore judged positively in step S12, step S13 determines that it is normal and terminates this routine. In other words, it is determined that the GPF13 is installed inside the casing 14. Conversely, if the judgment value is less than the predetermined value and therefore judged negatively in step S12, step S14 determines that it is abnormal and terminates this routine. In other words, it is determined that the GPF13 has been removed from the casing 14. In this case, it is preferable to notify the driver by illuminating the instrument panel or similar means. Note that if steps S13 and S14 are executed, the cumulative input temperature Sin and cumulative output temperature Sout described above are cleared.

[0039] Figure 4 shows a time chart illustrating the changes in input temperature Tin and output temperature Tout when the detection unit 15a of the input temperature sensor 15 is temporarily submerged in condensed water after the engine 1 is started. The input temperature Tin detected by the input temperature sensor 15 is shown by a solid line, the accumulated input temperature is shown by a thick line, the output temperature Tout detected by the output temperature sensor 16 is shown by a dashed line, and the input temperature when the detection unit 15a of the input temperature sensor 15 is not submerged in water, in other words, the actual exhaust temperature, is shown by a dotted line.

[0040] In the example shown in Figure 4, engine 1 begins to start at time t0. Engine 1 starts by increasing its rotational speed to a predetermined speed, then igniting the air-fuel mixture. Subsequently, the exhaust gas, which has become hot from the combustion of the mixture, reaches the input temperature sensor 15. Therefore, in the example shown in Figure 4, the input temperature Tin begins to increase with a delay from time t0.

[0041] On the other hand, immediately after engine startup, the air inside engine 1 and exhaust pipe 9 contains moisture, so the exhaust temperature is absorbed as heat of vaporization of water. As a result, the input temperature Tin gradually increases or remains near the dew point temperature until point t1, when the exhaust temperature reaches a predetermined temperature higher than the dew point temperature. Then, when the exhaust temperature rises above the dew point temperature, the input temperature Tin begins to increase as the exhaust temperature starts to rise.

[0042] In the example shown in Figure 4, at point t2, after the input temperature Tin(t) has started to increase, the temperature detected by the input temperature sensor 15 begins to decrease due to water exposure to the detection unit 15a of the input temperature sensor 15. Therefore, as a negative judgment is made in step S4 in Figure 3, the input temperature Tin(t-1) used in the previous routine is accumulated. That is, the input temperature Tin(t-1) continues to accumulate until t3, when the moisture adhering to the detection unit 15a of the input temperature sensor 15 vaporizes and the input temperature Tin(t) detected by the input temperature sensor 15 becomes equal to or greater than the input temperature Tin(t-1).

[0043] Furthermore, in the example shown in Figure 4, the output temperature Tout detected by the output temperature sensor 16 begins to increase at time t4, and the output temperature Tout reaches a predetermined temperature at time t5.

[0044] Therefore, the cumulative input temperature Sin corresponds to the amount of heat corresponding to the area shown by the dots, while the cumulative output temperature Sout corresponds to the amount of heat corresponding to the area shown by the hatching. As a result, the determination value, which is the ratio of the cumulative input temperature Sin to the cumulative output temperature Sout (Sin / Sout), is a relatively large value. Consequently, if the determination value is greater than a predetermined value, it is determined that the GPF13 is installed inside the casing 14.

[0045] Figure 5 shows the changes in input temperature Tin and output temperature Tout when the GPF 13 is removed from the casing 14. In the example shown in Figure 5, the output temperature Tout begins to increase at t4', slightly later than at t1, and reaches the predetermined temperature at t5'. This is because, with the GPF 13 removed from the casing 14, the heat from the exhaust is not absorbed by the GPF 13, and the exhaust temperature is measured by the output temperature sensor 16 with a delay corresponding to the exhaust flow velocity. Therefore, when the GPF 13 is removed from the casing 14, the output temperature Tout reaches the predetermined temperature when the increase in input temperature Tin is small, resulting in a smaller difference between the cumulative input temperature Sin and the cumulative output temperature Sout. As a result, the judgment value becomes smaller than the predetermined value, and it can be determined that the GPF 13 has been removed from the casing 14.

[0046] As described above, if the input temperature Tin(t) detected by the input temperature sensor 15 decreases within a predetermined period from engine startup, the cumulative input temperature Sin can be calculated using the input temperature Tin(t-1) used in the previous routine. This suppresses a decrease in the judgment value and prevents the system from mistakenly determining that the GPF 13 has been removed from the casing 14. In other words, even if the input temperature Tin(t) decreases due to the detection unit 15a of the input temperature sensor 15 being exposed to water, it is possible to accurately determine whether or not the GPF 13 is installed inside the casing 14.

[0047] In this embodiment of the invention, the removal determination device only needs to use the input temperature Tin(t-1) before the input temperature Tin(t) detected by the input temperature sensor 15 decreases to determine whether or not the GPF 13 is present, and the determination means is not limited. That is, when determining whether or not the GPF 13 is present based on the temperature difference between the input temperature and the output temperature at a predetermined timing, or the temperature difference between the estimated output temperature based on the input temperature at a predetermined timing and the actual output temperature, the input temperature Tin(t-1) before the input temperature decreases may be used to determine whether or not the GPF 13 is present. [Explanation of symbols]

[0048] 1 Engine 2-cylinder 3 Engine Block 4 spark plugs 5. Intake pipe 6. Intake Manifold 7. Throttle valve 8. Throttle position sensor 9 Exhaust pipe 10 Exhaust Manifold 11. Catalytic converter 12 Collection device 13. Filter (GPF) 14 Casing 15 Input temperature sensor 15a, 16a Detection unit 16 Output temperature sensor 17 Soak Timer 18 Electronic Control Unit (ECU) 19. Sorting time acquisition unit 20 Temperature acquisition section 21. Noise Reduction Processing Unit 22 Judgment Value Calculation Unit 23 GPF Judging Section

Claims

1. An exhaust gas purification device removal determination device that determines whether an exhaust gas purification device is housed inside a casing that communicates with the exhaust pipe of an engine, An input temperature sensor for detecting the temperature on the upstream side of the casing, An output temperature sensor for detecting the temperature downstream of the casing, The system includes a controller that determines whether or not the exhaust gas purification device is present inside the casing, The aforementioned controller, A noise reduction processing unit outputs the input temperature detected by the input temperature sensor before the decrease in the input temperature detected by the input temperature sensor within a predetermined period from the start of the engine, The system includes a determination unit that determines whether or not the exhaust gas purification device is located inside the casing, based on the input temperature output from the noise reduction processing unit and the output temperature detected by the output temperature sensor. A device for determining whether an exhaust gas purification system should be removed, characterized by the above features.

2. A device for determining the removal of an exhaust gas purification device according to claim 1, The predetermined period includes the period from the start of the engine until the output temperature reaches a predetermined temperature. A device for determining whether an exhaust gas purification system should be removed, characterized by the above features.

3. A device for determining the removal of an exhaust gas purification device according to claim 1, The determination unit determines that the exhaust gas purification device is located inside the casing if the ratio of the integrated value of the input temperature output from the noise reduction processing unit during the predetermined period to the integrated value of the output temperature during the predetermined period is equal to or greater than a predetermined value. A device for determining whether an exhaust gas purification system should be removed, characterized by the above features.

4. A device for determining the removal of an exhaust gas purification device according to claim 1, The aforementioned controller, The engine further includes an engine stop time acquisition unit that acquires the time from when the engine stops until it starts again. The determination unit determines whether or not the exhaust gas purification device is located inside the casing if the time from when the engine stops until it starts is equal to or greater than a predetermined time. A device for determining whether an exhaust gas purification system should be removed, characterized by the above features.

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