Anomaly detection device for internal combustion engines, and anomaly detection program for internal combustion engines.

Abstract

To inhibit a wrong determination as to whether or not an exhaust emission control device has been detached from an exhaust passage.SOLUTION: An abnormality determination device for an internal combustion engine executes first processing for acquiring an upstream temperature that is a temperature of exhaust gas upstream of an exhaust emission control device in an exhaust passage. The abnormality determination device executes second processing for acquiring a downstream temperature that is a temperature of exhaust gas downstream of the exhaust emission control device in the exhaust passage. The abnormality determination device executes third processing for acquiring an exhaust gas flow rate that is a flow rate of exhaust gas flowing in the exhaust passage. The abnormality determination device executes fourth processing for determining whether or not an exhaust gas flow rate that is an exhaust gas flow rate during an operation of the internal combustion engine in a previous trip in the state where the upstream temperature is equal to or higher than a predetermined specific temperature is a predetermined reference flow rate or larger (S22). The abnormality determination device executes fifth processing for determining whether or not the exhaust emission control device has been detached from the exhaust passage on the basis of an absolute value of a difference between the upstream temperature and the downstream temperature under the requisite condition that an affirmative determination is made in the fourth processing.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an abnormality determination device for an internal combustion engine and an abnormality determination program for an internal combustion engine.

Background Art

[0002] The system of Patent Document 1 includes an internal combustion engine and an abnormality determination device. The internal combustion engine includes a plurality of cylinders, an exhaust passage, and a PM collection device. A cylinder is a space for burning fuel. The exhaust passage allows the exhaust discharged from each cylinder to flow. The PM collection device is attached in the middle of the exhaust passage. The PM collection device collects particulate matter in the exhaust.

[0003] The abnormality determination device determines whether the PM collection device has been removed from the exhaust passage. Here, in a system such as that of Patent Document 1, on the premise that immediately after the internal combustion engine starts operating, the heat of the exhaust flowing through the exhaust passage is absorbed by the PM collection device. As a result, immediately after the internal combustion engine starts operating, the temperature rise rate on the downstream side of the PM collection device in the exhaust passage is smaller than the temperature rise rate on the upstream side of the PM collection device in the exhaust passage. On the other hand, if the PM collection device has been removed from the exhaust passage, the heat of the exhaust flowing through the exhaust passage is not absorbed by the PM collection device. Therefore, in this case, even immediately after the internal combustion engine starts operating, the difference between the temperature rise rate on the upstream side of the PM collection device in the exhaust passage and the temperature rise rate on the downstream side of the PM collection device in the exhaust passage becomes smaller.

[0004] Therefore, the abnormality determination device of Patent Documentl acquires an upstream temperature which is the temperature of the exhaust on the upstream side of the exhaust purification device in the exhaust passage. Further, the abnormality determination device acquires a downstream temperature which is the temperature of the exhaust on the downstream side of the exhaust purification device in the exhaust passage. Then, the abnormality determination device determines that the exhaust purification device has been removed from the exhaust passage in a situation where the absolute value of the difference between the upstream temperature and the downstream temperature becomes small.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Patent Publication No. 2020-106028 [Overview of the project] [Problems that the invention aims to solve]

[0006] In internal combustion engines like the one described in Patent Document 1, hydrocarbons may accumulate inside the PM collection device. When hydrocarbons accumulate in this way, they can burn during the operation of the internal combustion engine. If hydrocarbons in the PM collection device burn, the downstream temperature, which is the temperature of the exhaust gas downstream of the PM collection device, may rise. In this case, the absolute value of the difference between the upstream and downstream temperatures becomes smaller. Therefore, when this situation occurs, there is a risk of misinterpreting the situation as if the PM collection device has been removed from the exhaust passage, even though the PM collection device is still attached to the exhaust passage. [Means for solving the problem]

[0007] An abnormality detection device for an internal combustion engine to solve the above problems is an abnormality detection device applied to an internal combustion engine comprising a cylinder for burning fuel, an exhaust passage for circulating exhaust gas discharged from the cylinder, and an exhaust gas purification device located in the exhaust passage for purifying the exhaust gas, comprising: a first process of obtaining the upstream temperature, which is the temperature of the exhaust gas upstream of the exhaust gas purification device in the exhaust passage; a second process of obtaining the downstream temperature, which is the temperature of the exhaust gas downstream of the exhaust gas purification device in the exhaust passage; a third process of obtaining the exhaust gas flow rate, which is the flow rate of the exhaust gas circulating in the exhaust passage; a fourth process of determining whether the exhaust gas flow rate during the operation of the internal combustion engine in the previous trip, when the upstream temperature is above a predetermined specified temperature, is above a predetermined standard flow rate; and a condition that the positive determination made in the fourth process is ,before A fifth process is performed to determine whether or not the exhaust gas purification device has been removed from the exhaust passage. In the fifth process, the following are performed: calculate an index value that shows the difference between the integral value of the upstream temperature during the period from when the internal combustion engine starts operating until the downstream temperature reaches or exceeds a predetermined determination temperature, and the integral value of the downstream temperature during the same period; and determine that the exhaust gas purification device has been removed from the exhaust passage if the index value is smaller than a predetermined reference value. . An abnormality detection device for an internal combustion engine to solve the above problems is an abnormality detection device applied to an internal combustion engine comprising a cylinder for burning fuel, an exhaust passage for circulating exhaust gas discharged from the cylinder, and an exhaust gas purification device located in the exhaust passage for purifying the exhaust gas, comprising: a first process of obtaining the upstream temperature, which is the temperature of the exhaust gas upstream of the exhaust gas purification device in the exhaust passage; a second process of obtaining the downstream temperature, which is the temperature of the exhaust gas downstream of the exhaust gas purification device in the exhaust passage; a third process of obtaining the exhaust gas flow rate, which is the flow rate of the exhaust gas circulating in the exhaust passage; and the exhaust gas flow rate during the operation of the internal combustion engine in the previous trip, where the upstream temperature is above a predetermined specified temperature. A fourth process is performed to determine whether the exhaust flow rate is equal to or greater than a predetermined standard flow rate, and a fifth process is performed to determine whether the exhaust purification device has been removed from the exhaust passage, with the positive determination made in the fourth process being a necessary condition. In the fifth process, an index value is calculated that represents the integral of the difference between the rate of change of the upstream temperature per unit time and the rate of change of the downstream temperature per unit time during the period from when the internal combustion engine starts operating until the downstream temperature reaches or exceeds a predetermined determination temperature, and if the index value is smaller than a predetermined standard value, it is determined that the exhaust purification device has been removed from the exhaust passage.

[0008] The abnormality detection program for an internal combustion engine to solve the above problems is an abnormality detection device applicable to an internal combustion engine comprising a cylinder for burning fuel, an exhaust passage for circulating exhaust gas discharged from the cylinder, and an exhaust gas purification device located in the exhaust passage for purifying the exhaust gas, and the abnormality detection device includes a first process for obtaining the upstream temperature, which is the temperature of the exhaust gas upstream of the exhaust gas purification device in the exhaust passage; a second process for obtaining the downstream temperature, which is the temperature of the exhaust gas downstream of the exhaust gas purification device in the exhaust passage; a third process for obtaining the exhaust gas flow rate, which is the flow rate of the exhaust gas circulating in the exhaust passage; a fourth process for determining whether the exhaust gas flow rate during the operation of the internal combustion engine in the previous trip, when the upstream temperature is above a predetermined specified temperature, is above a predetermined standard flow rate; and a condition that the fourth process has made an affirmative determination. ,before A fifth process is performed to determine whether or not the exhaust gas purification device has been removed from the exhaust passage. In the fifth process, the following are performed: calculate an index value that shows the difference between the integrated value of the upstream temperature during the period from when the internal combustion engine starts operating until the downstream temperature reaches or exceeds a predetermined determination temperature, and the integrated value of the downstream temperature during the same period; and determine that the exhaust gas purification device has been removed from the exhaust passage if the index value is smaller than a predetermined reference value. . The abnormality detection program for an internal combustion engine to solve the above problem is an abnormality detection device applicable to an internal combustion engine comprising a cylinder for burning fuel, an exhaust passage for circulating exhaust gas discharged from the cylinder, and an exhaust gas purification device located in the exhaust passage for purifying the exhaust gas. The abnormality detection device includes a first process for obtaining the upstream temperature, which is the temperature of the exhaust gas upstream of the exhaust gas purification device in the exhaust passage; a second process for obtaining the downstream temperature, which is the temperature of the exhaust gas downstream of the exhaust gas purification device in the exhaust passage; a third process for obtaining the exhaust gas flow rate, which is the flow rate of the exhaust gas circulating in the exhaust passage; and the exhaust gas flow rate during the operation of the internal combustion engine in the previous trip, where the upstream temperature is a predetermined specified temperature. A fourth process is performed to determine whether the exhaust flow rate when the temperature is above a certain level is above a predetermined standard flow rate, and a fifth process is performed to determine whether the exhaust purification device has been removed from the exhaust passage, with the positive determination made in the fourth process being a necessary condition. In the fifth process, an index value is calculated that represents the integral of the difference between the rate of change of the upstream temperature per unit time and the rate of change of the downstream temperature per unit time during the period from when the internal combustion engine starts operating until the downstream temperature reaches a predetermined determination temperature or higher, and the index value is determined to be smaller than a predetermined standard value, and it is determined that the exhaust purification device has been removed from the exhaust passage. [Effects of the Invention]

[0009] In the above configuration, a positive determination in the fourth process indicates that relatively high-temperature exhaust gas flowed into the exhaust purification device during the previous trip. Therefore, if a positive determination is made in the fourth process, there is a high probability that hydrocarbons in the exhaust purification device were burned during the previous trip. Furthermore, according to the above configuration, the fifth process is executed when an excessive amount of hydrocarbons has not accumulated in the exhaust purification device. This allows the fifth process to be executed with a low influence of hydrocarbons, which can cause misdeterminations as to whether or not the exhaust purification device has been removed. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a schematic diagram of the vehicle's configuration. [Figure 2] Figure 2 is a flowchart showing the flag update control. [Figure 3] Figure 3 is a flowchart showing the first decision control. [Figure 4] Figure 4 is a flowchart showing the second decision control. [Modes for carrying out the invention]

[0011] <Outline of the vehicle configuration> An embodiment of the present invention will be described below with reference to Figures 1 to 4. First, the general configuration of the vehicle 100 will be described.

[0012] As shown in Figure 1, the vehicle 100 is equipped with a spark-ignition type internal combustion engine 10. Furthermore, the vehicle 100 is equipped with a first motor-generator 71 and a second motor-generator 72 that combine the functions of both an electric motor and a generator. Therefore, the vehicle 100 is a so-called hybrid vehicle.

[0013] The internal combustion engine 10 comprises multiple cylinders 11, a crankshaft 12, an intake passage 21, a throttle valve 22, and multiple fuel injectors 23. The internal combustion engine 10 also comprises multiple ignition devices 24, an exhaust passage 26, a three-way catalytic converter 27, and a GPF 28.

[0014] Cylinder 11 is a space for burning a mixture of fuel and intake air. The internal combustion engine 10 has four cylinders 11. The crankshaft 12 is connected to pistons (not shown) located in each cylinder 11. The crankshaft 12 rotates due to the combustion of the fuel-intake mixture in the cylinders 11. In this embodiment, an example of fuel is gasoline.

[0015] The intake passage 21 is connected to the cylinder 11. A part including the downstream end in the intake passage 21 branches into four. Each of the branched passages is connected to each cylinder 11. The intake passage 21 introduces intake air from outside the internal combustion engine 10 into each cylinder 11. Note that an intake valve (not shown) is located at the connection point between the intake passage 21 and each cylinder 11. The intake valve opens and closes the connection point between the intake passage 21 and the cylinder 11. The throttle valve 22 is located upstream of the branched portion in the intake passage 21. The throttle valve 22 adjusts the amount of intake air flowing through the intake passage 21.

[0016] The fuel injection valve 23 is located near the downstream end of the intake passage 21. The internal combustion engine 10 includes four fuel injection valves 23 corresponding to the four cylinders 11. The fuel injection valve 23 injects fuel supplied from a fuel tank (not shown) into the intake passage 21. As a result, the fuel from the fuel injection valve 23 is supplied to the cylinder 11. The ignition device 24 is located in the cylinder 11. The internal combustion engine 10 includes four ignition devices 24 corresponding to the four cylinders 11. The ignition device 24 ignites the mixture of fuel and intake air by spark discharge.

[0017] The exhaust passage 26 is connected to the cylinder 11. A part including the upstream end in the exhaust passage 26 branches into four. Each of the branched passages is connected to each cylinder 11. The exhaust passage 26 discharges exhaust from each cylinder 11 to the outside of the internal combustion engine 10. Note that an exhaust valve (not shown) is located at the connection point between the exhaust passage 26 and each cylinder 11. The exhaust valve opens and closes the connection point between the exhaust passage 26 and the cylinder 11.

[0018] The three-way catalyst 27 is located downstream of the branched portion in the exhaust passage 26. The three-way catalyst 27 purifies the exhaust flowing through the exhaust passage 26. Specifically, the three-way catalyst 27 has a function of purifying hydrocarbons, carbon monoxide, and nitrogen oxides in the exhaust. Further, the three-way catalyst 27 has a function of storing oxygen in the exhaust.

[0019] The GPF 28 is located on the downstream side with respect to the three-way catalyst 27 in the exhaust passage 26. In the present embodiment, the GPF 28 is a filter on which a three-way catalyst is supported. Therefore, the GPF 28 can collect particulate matter contained in the exhaust flowing through the exhaust passage 26. Note that "GPF" is an abbreviation for Gasoline Particulate Filter. In the present embodiment, the GPF 28 is an example of an exhaust purification device that is located in the exhaust passage 26 and purifies the exhaust.

[0020] The vehicle 100 includes a first planetary gear mechanism 40, a ring gear shaft 45, a second planetary gear mechanism 50, a reduction mechanism 62, a differential mechanism 63, and a plurality of drive wheels 64. The first planetary gear mechanism 40 includes a sun gear 41, a ring gear 42, a plurality of pinion gears 43, and a carrier 44. The sun gear 41 is an external gear. The sun gear 41 is connected to the first motor generator 71. The ring gear 42 is an internal gear and is located coaxially with the sun gear 41. Each pinion gear 43 is located between the sun gear 41 and the ring gear 42. Each pinion gear 43 meshes with both the sun gear 41 and the ring gear 42. The carrier 44 supports the pinion gears 43. The pinion gears 43 are rotatable about their own axes and are revolvable by rotating together with the carrier 44. The carrier 44 is connected to the crankshaft 12. Therefore, the first motor generator 71 is connected to the crankshaft 12 via the first planetary gear mechanism 40.

[0021] The ring gear shaft 45 is connected to the ring gear 42. Further, the ring gear shaft 45 is connected to the drive wheels 64 via the reduction mechanism 62 and the differential mechanism 63. The reduction mechanism 62 reduces the rotational speed of the ring gear shaft 45 and outputs it. The differential mechanism 63 allows a difference in rotational speed to occur between the left and right drive wheels 64.

[0022] The second planetary gear mechanism 50 comprises a sun gear 51, a ring gear 52, a plurality of pinion gears 53, a carrier 54, and a case 55. The sun gear 51 is an external gear. The sun gear 51 is connected to the second motor generator 72. The ring gear 52 is an internal gear and is located coaxially with the sun gear 51. The ring gear 52 is connected to the ring gear shaft 45. Each pinion gear 53 is located between the sun gear 51 and the ring gear 52. Each pinion gear 53 meshes with both the sun gear 51 and the ring gear 52. The carrier 54 supports the pinion gears 53. The pinion gears 53 are capable of rotation. The carrier 54 is fixed to the case 55. Therefore, the pinion gears 53 are not capable of orbiting.

[0023] Vehicle 100 is equipped with a battery 75, a first inverter 76, and a second inverter 77. Battery 75 is a secondary battery. The first inverter 76 performs AC-DC power conversion between the first motor generator 71 and the battery 75. The first inverter 76 also adjusts the amount of power exchanged between the first motor generator 71 and the battery 75. The second inverter 77 performs AC-DC power conversion between the second motor generator 72 and the battery 75. The second inverter 77 adjusts the amount of power exchanged between the second motor generator 72 and the battery 75.

[0024] Vehicle 100 is equipped with an airflow meter 81, a water temperature sensor 82, an intake air temperature sensor 83, and a crank angle sensor 84. Vehicle 100 is also equipped with an accelerator pedal input sensor 85, a vehicle speed sensor 86, an upstream temperature sensor 87, and a downstream temperature sensor 88.

[0025] The airflow meter 81 detects the intake air volume GA, which is the amount of intake air flowing through the intake passage 21 per unit time. The water temperature sensor 82 detects the coolant temperature THW, which is the temperature of the coolant flowing through each part of the internal combustion engine 10. The intake air temperature sensor 83 detects the intake air temperature THA, which is the temperature of the intake air flowing through the intake passage 21. The crank angle sensor 84 detects the crank angle SC, which is the rotational position of the crankshaft 12. The accelerator pedal operation amount sensor 85 detects the accelerator pedal operation amount ACC, which is the amount of accelerator pedal operation performed by the driver. The vehicle speed sensor 86 detects the vehicle speed SP, which is the speed of the vehicle 100.

[0026] The upstream temperature sensor 87 is located downstream of the three-way catalyst 27 and upstream of the GPF 28 in the exhaust passage 26. The upstream temperature sensor 87 detects the upstream temperature Tin, which is the temperature of the exhaust gas upstream of the GPF 28 in the exhaust passage 26. The downstream temperature sensor 88 is located downstream of the GPF 28 in the exhaust passage 26. The downstream temperature sensor 88 detects the downstream temperature Tout, which is the temperature of the exhaust gas downstream of the GPF 28 in the exhaust passage 26.

[0027] Vehicle 100 is equipped with a control device 90. The control device 90 acquires signals indicating various values ​​from various sensors. Specifically, the control device 90 can perform a first process to acquire the upstream temperature Tin. The control device 90 can also perform a second process to acquire the downstream temperature Tout.

[0028] The control device 90 comprises an execution unit 91 and a storage unit 92. An example of the execution unit 91 is a CPU. The storage unit 92 includes a ROM that is read-only, a volatile RAM that is read-and-write, and a non-volatile storage that is read-and-write. The storage unit 92 pre-stores a control program 92A as one of various programs. The execution unit 91 implements various processes described later by executing the control program 92A. In other words, the execution unit 91 implements various processes related to abnormality detection of the internal combustion engine 10 by executing the control program 92A. In this embodiment, the control device 90 is an example of an abnormality detection device for the internal combustion engine 10. The control program 92A is an example of an abnormality detection program for the internal combustion engine 10.

[0029] The control device 90 calculates the required vehicle driving force, which is the required driving force necessary for the vehicle 100 to run, based on the accelerator pedal input amount ACC and the vehicle speed SP. Based on the required vehicle driving force, the control device 90 determines the torque distribution of the internal combustion engine 10, the first motor generator 71, and the second motor generator 72. Based on the torque distribution of the internal combustion engine 10, the first motor generator 71, and the second motor generator 72, the control device 90 controls the output of the internal combustion engine 10 and the traction and regeneration of the first motor generator 71 and the second motor generator 72. Specifically, the control device 90 controls the opening degree of the throttle valve 22, the amount of fuel injected from the fuel injector 23, the ignition timing of the ignition device 24, etc., by outputting a control signal to the internal combustion engine 10. The control device 90 also controls the first motor generator 71 via the first inverter 76 by outputting a control signal to the first inverter 76. Furthermore, the control device 90 controls the second motor generator 72 via the second inverter 77 by outputting a control signal to the second inverter 77.

[0030] Furthermore, when the vehicle 100 is in motion, the control device 90 selects either EV mode or HV mode as the driving mode for the vehicle 100. Here, EV mode is a driving mode in which the vehicle 100 is driven by driving one or more motor generators selected from the first motor generator 71 and the second motor generator 72 while the internal combustion engine 10 is stopped. Therefore, in EV mode, the vehicle 100 is driven by the driving force of the first motor generator 71 and the driving force of the second motor generator 72. HV mode is a driving mode for the vehicle 100 in which the vehicle 100 is driven by driving the internal combustion engine 10 in addition to the first motor generator 71 and the second motor generator 72. Therefore, in HV mode, the vehicle 100 is driven by the driving force of the internal combustion engine 10 in addition to the driving force of the first motor generator 71 and the second motor generator 72.

[0031] The control device 90 selects EV mode, for example, when there is sufficient reserve in the charge level of the battery 75 and the vehicle's required driving force is small. Examples of situations where the vehicle's required driving force is small include when the vehicle 100 is starting up and when the vehicle 100 is driving under light load with low acceleration. On the other hand, the control device 90 selects HV mode, for example, when there is not sufficient reserve in the charge level of the battery 75.

[0032] <Flag update control> Next, with reference to Figure 2, the flag update control performed by the control device 90 will be described. This flag update control is for updating the prohibition flag FA. The prohibition flag FA is a flag that prohibits the determination of whether or not the GPF 28 has been removed from the exhaust passage 26. In this embodiment, the prohibition flag FA is ON when the system of the vehicle 100 is started by operating a start switch (not shown). In this embodiment, the control device 90 starts the flag update control when the internal combustion engine 10 is in operation.

[0033] As shown in Figure 2, when the execution unit 91 of the control device 90 starts flag update control, it executes the process in step S11. In step S11, the execution unit 91 determines whether the upstream temperature Tin is equal to or greater than a predetermined specified temperature A. Here, the specified temperature A is a temperature predetermined as the temperature of the exhaust gas at which hydrocarbons begin to burn in the GPF28. The specified temperature A is predetermined by experiments and simulations, etc. An example of a specified temperature A is several hundred degrees Celsius. If the execution unit 91 determines in step S11 that the upstream temperature Tin is equal to or greater than the specified temperature A (S11: YES), the execution unit 91 proceeds to step S21.

[0034] In step S21, the execution unit 91 calculates the high-temperature exhaust flow rate FH, which is the flow rate of exhaust gases circulating through the exhaust passage 26 during the operation of the internal combustion engine 10 for the current trip, and is the flow rate of exhaust gases when the upstream temperature Tin is at or above the specified temperature A. Specifically, the high-temperature exhaust flow rate FH is the accumulated amount of exhaust gases with an upstream temperature Tin at or above the specified temperature A from the start of the current trip until the processing time of step S21. For example, the execution unit 91 calculates the high-temperature exhaust flow rate FH based on the intake air amount GA and the fuel injection amount from the fuel injection valve 23. A trip is defined as the period from when the system of the vehicle 100 is started until when the system of the vehicle 100 is shut down. In this embodiment, the processing in step S21 is an example of a third processing. After step S21, the execution unit 91 proceeds to step S22.

[0035] In step S22, the execution unit 91 determines whether the high-temperature exhaust flow rate FH is equal to or greater than a predetermined reference flow rate ZA. Here, the reference flow rate ZA is a predetermined threshold value, for example, the flow rate of exhaust gas in which the hydrocarbons in the GPF28 are expected to be completely burned out, even if the hydrocarbons in the GPF28 are at their maximum value, by the inflow of exhaust gas with an upstream temperature Tin equal to or greater than a specified temperature A into the GPF28. The reference flow rate ZA is predetermined by experiments and simulations. In this embodiment, the process in step S22 is an example of the fourth process. In step S22, if the execution unit 91 determines that the high-temperature exhaust flow rate FH is less than the reference flow rate ZA (S22: NO), the execution unit 91 terminates the current flag update control. Then, the execution unit 91 proceeds to step S11 again.

[0036] On the other hand, if the execution unit 91 determines in step S22 that the high-temperature exhaust flow rate FH is equal to or greater than the reference flow rate ZA (S22: YES), the execution unit 91 proceeds to step S23. In step S23, the execution unit 91 sets the prohibition flag FA to OFF. After step S23, the execution unit 91 terminates the current flag update control. Then, the execution unit 91 proceeds to step S11 again.

[0037] On the other hand, if the execution unit 91 determines in step S11 that the upstream temperature Tin is less than the specified temperature A (S11:NO), the execution unit 91 proceeds to step S31.

[0038] In step S31, the execution unit 91 calculates the low-temperature exhaust flow rate FL, which is the flow rate of exhaust gases circulating through the exhaust passage 26 during the operation of the internal combustion engine 10 for the current trip, when the upstream temperature Tin is below the specified temperature A. Specifically, the low-temperature exhaust flow rate FL is the cumulative amount of exhaust gases where the upstream temperature Tin is below the specified temperature A from the start of the current trip until the processing time of step S31. For example, the execution unit 91 calculates the low-temperature exhaust flow rate FL based on the intake air amount GA and the fuel injection amount from the fuel injection valve 23. In this embodiment, the processing in step S31 is an example of a third processing. After step S31, the execution unit 91 proceeds to step S32.

[0039] In step S32, the execution unit 91 determines whether the low-temperature exhaust flow rate FL is greater than or equal to a predetermined flow rate ZB. Here, the predetermined flow rate ZB is a predetermined threshold value that represents the flow rate of exhaust gas in which hydrocarbons are expected to accumulate in the GPF28, even if the amount of hydrocarbons in the GPF28 is at its minimum, due to the inflow of exhaust gas with an upstream temperature Tin below a specified temperature A into the GPF28. The predetermined flow rate ZB is predetermined by experiments and simulations. Note that the rate at which hydrocarbons in the GPF28 decrease when exhaust gas with an upstream temperature Tin above a specified temperature A flows into the GPF28 is less than the rate at which hydrocarbons in the GPF28 increase when exhaust gas with an upstream temperature Tin below a specified temperature A flows into the GPF28. Therefore, the predetermined flow rate ZB is predetermined to be a value greater than the reference flow rate ZA. In this embodiment, the process in step S32 is an example of the sixth process. In step S32, if the execution unit 91 determines that the low-temperature exhaust flow rate FL is less than a predetermined flow rate ZB (S32: NO), the execution unit 91 terminates the current flag update control. Then, the execution unit 91 proceeds to step S11 again.

[0040] On the other hand, if the execution unit 91 determines in step S32 that the low-temperature exhaust flow rate FL is equal to or greater than a predetermined flow rate ZB (S32: YES), the execution unit 91 proceeds to step S33. In step S33, the execution unit 91 sets the prohibition flag FA to ON. After step S33, the flag update control for this step ends. Then, the execution unit 91 proceeds to step S11 again.

[0041] <First Decision Control> Next, with reference to Figure 3, the first determination control performed by the control device 90 will be described. This first determination control is the first control to determine whether or not the GPF 28 has been removed from the exhaust passage 26. In this embodiment, the control device 90 starts the first determination control each time the internal combustion engine 10 is operating.

[0042] As shown in Figure 3, when the execution unit 91 of the control device 90 starts the first determination control, it executes the process in step S41. In step S41, the execution unit 91 determines whether or not predetermined preconditions are met. For example, the execution unit 91 determines that the preconditions are met if all of the following requirements (1) to requirements (3) are met.

[0043] Requirement (1): All sensors must be functioning correctly. Requirement (2): The cooling water temperature THW must be above the predetermined first low-temperature threshold. Requirement (3): The intake air temperature (THA) must be above the predetermined second low-temperature threshold.

[0044] Here, an example of the first low-temperature threshold is "-15°C". Also, an example of the second low-temperature threshold is "-15°C". If the execution unit 91 determines in step S41 that the preconditions are met (S41:YES), the execution unit 91 proceeds to step S42.

[0045] In step S42, the execution unit 91 determines whether predetermined cooling conditions are met. For example, the execution unit 91 determines that the cooling conditions are met if all of the following requirements (4) to (6) are met.

[0046] Requirement (4): The soak time Tsoak must be equal to or greater than the predetermined specified period. Requirement (5): The upstream temperature Tin must be below the predetermined first permitted temperature. Requirement (6): The downstream temperature Tout must be below the predetermined second permitted temperature.

[0047] Here, the soak time Tsoak is the period from the end of operation of the internal combustion engine 10 until the start of operation of the internal combustion engine 10 again. The specified period is defined as a threshold for determining whether, for example, enough soak time Tsoak has elapsed for the GPF 28 to be sufficiently cooled. An example of a specified period is several hours to more than ten hours. The first permitted temperature is a threshold for determining whether the upstream temperature Tin is sufficiently low. An example of a first permitted temperature is several tens of degrees Celsius. The second permitted temperature is a threshold for determining whether the downstream temperature Tout is sufficiently low. An example of a second permitted temperature is several tens of degrees Celsius. If the execution unit 91 determines in step S42 that the cooling conditions are met (S42: YES), the execution unit 91 proceeds to step S43.

[0048] In step S43, the execution unit 91 accesses the storage unit 92 to determine whether the prohibition flag FA was OFF at the end of the previous trip. If the execution unit 91 determines in step S43 that the prohibition flag FA was OFF at the end of the previous trip (S43:YES), the execution unit 91 proceeds to step S51. As described above, in this embodiment, the prohibition flag FA is set to OFF if the execution unit 91 makes a positive determination in the process of step S22 and does not make a positive determination in the process of step S32. Therefore, the execution unit 91 proceeds to step S51, with the necessary conditions that it made a positive determination in the process of step S22 and did not make a positive determination in the process of step S32 during the previous trip.

[0049] In step S51, the execution unit 91 sets the upstream temperature Tin at the time of processing in step S51 as the starting upstream temperature TSin. After step S51, the execution unit 91 proceeds to step S52.

[0050] In step S52, the execution unit 91 sets the downstream temperature Tout at the time of processing in step S52 as the starting downstream temperature TSout. After step S52, the execution unit 91 terminates the current first determination control.

[0051] On the other hand, if the execution unit 91 determines in step S41 above that the preconditions are not met (S41: NO), the execution unit 91 terminates the current first determination control. Similarly, if the execution unit 91 determines in step S42 above that the cooling conditions are not met (S42: NO), the execution unit 91 terminates the current first determination control. Also, if the execution unit 91 determines in step S43 above that the prohibition flag FA was ON at the end of the previous trip (S43: NO), the execution unit 91 terminates the current first determination control.

[0052] <Second Decision Control> Next, with reference to Figure 4, the second decision control performed by the control device 90 will be described. This second decision control is a second control for determining whether or not the GPF 28 has been removed from the exhaust passage 26. In this embodiment, the control device 90 starts the second decision control each time the initial upstream temperature TSin and initial downstream temperature TSout are set by the first decision control.

[0053] As shown in Figure 4, when the execution unit 91 of the control device 90 starts the second decision control, it executes the process of step S61. In step S61, the execution unit 91 calculates the upstream change amount ΔTin, which is the value obtained by subtracting the initial upstream temperature TSin from the upstream temperature Tin at the time of processing in step S61. After step S61, the execution unit 91 proceeds to step S62.

[0054] In step S62, the execution unit 91 calculates the upstream integral value ΣΔTin, which is the value obtained by integrating the upstream change amount ΔTin from the start of the second decision control to the processing time of step S62. That is, in this step S62, the execution unit 91 calculates a new upstream integral value ΣΔTin by adding the upstream change amount ΔTin to the upstream integral value ΣΔTin calculated in the previous step S62. In this embodiment, the upstream integral value ΣΔTin is an example of the integral value of the upstream temperature Tin. After step S62, the execution unit 91 proceeds to step S63.

[0055] In step S63, the execution unit 91 calculates the downstream change ΔTout, which is the value obtained by subtracting the initial downstream temperature TSout from the downstream temperature Tout at the time of processing in step S63. After step S63, the execution unit 91 proceeds to step S64.

[0056] In step S64, the execution unit 91 calculates a downstream integral value ΣΔTout, which is the value obtained by integrating the downstream change amount ΔTout from the start of the second decision control to the processing time of step S64. That is, in this step S64, the execution unit 91 calculates a new downstream integral value ΣΔTout by adding the downstream change amount ΔTout to the downstream integral value ΣΔTout calculated in the previous step S64. In this embodiment, the downstream integral value ΣΔTout is an example of the integral value of the downstream temperature Tout. After step S64, the execution unit 91 proceeds to step S65.

[0057] In step S65, the execution unit 91 sets the determination temperature TF based on the initial downstream temperature TSout. In this embodiment, the execution unit 91 sets the determination temperature TF as a value obtained by adding a predetermined constant temperature to the initial downstream temperature TSout. Here, an example of a constant temperature is several tens of degrees Celsius. After step S65, the execution unit 91 proceeds to step S66.

[0058] In step S66, the execution unit 91 determines whether the downstream temperature Tout is equal to or greater than the determination temperature TF. If the execution unit 91 determines in step S66 that the downstream temperature Tout is less than the determination temperature TF (S66: NO), the execution unit 91 terminates the current second determination control. The execution unit 91 then proceeds to step S61 again. On the other hand, if the execution unit 91 determines in step S66 that the downstream temperature Tout is equal to or greater than the determination temperature TF (S66: YES), the execution unit 91 proceeds to step S71.

[0059] In step S71, the execution unit 91 calculates the quotient Q by dividing the upstream integral value ΣΔTin by the downstream integral value ΣΔTout. In this embodiment, the quotient Q is an example of an index value that shows the difference between the integral value of the upstream temperature Tin during the period from when the internal combustion engine 10 starts operation until the downstream temperature Tout becomes equal to or greater than a predetermined determination temperature TF, and the integral value of the downstream temperature Tout during the same period. After step S71, the execution unit 91 proceeds to step S72.

[0060] In step S72, the execution unit 91 determines whether the quotient Q is greater than or equal to a predetermined diagnostic threshold QA. Here, the diagnostic threshold QA is defined as a value that is a certain amount smaller than the minimum value of the quotient Q calculated when the GPF 28 is attached to the exhaust passage 26. The diagnostic threshold QA is determined in advance through experiments and simulations. In step S72, if the execution unit 91 determines that the quotient Q is greater than or equal to the diagnostic threshold QA (S72: YES), the execution unit 91 proceeds to step S81.

[0061] In step S81, the execution unit 91 determines that the GPF 28 is attached to the exhaust passage 26. That is, the execution unit 91 determines that the internal combustion engine 10 is functioning normally. After step S81, the execution unit 91 terminates the second determination control.

[0062] On the other hand, if the execution unit 91 determines in step S72 above that the quotient Q is less than the diagnostic threshold QA (S72:NO), the execution unit 91 proceeds to step S82. In other words, the execution unit 91 proceeds to step S82 if the index value is smaller than a predetermined standard value.

[0063] In step S82, the execution unit 91 determines that the GPF 28 has been removed from the exhaust passage 26. That is, the execution unit 91 determines that the internal combustion engine 10 is abnormal. At this time, the execution unit 91 outputs a control signal to a display (not shown) to inform the driver of the vehicle 100 that the GPF 28 has been removed from the exhaust passage 26. In this embodiment, the processing in steps S61 to S82 is an example of a fifth process that determines whether or not the GPF 28 has been removed from the exhaust passage 26 based on the absolute value of the difference between the upstream temperature Tin and the downstream temperature Tout. After step S82, the execution unit 91 terminates the second determination control.

[0064] <Operation of this embodiment> In vehicle 100, for example, the period during which the internal combustion engine 10 operates may be shorter during the previous trip. When the period during which the internal combustion engine 10 operates is relatively short during the previous trip, the upstream temperature Tin is often below the specified temperature A, so a relatively large amount of hydrocarbons accumulate in the GPF 28 at the end of the previous trip. In this case, during the flag update control for the previous trip, the control device 90 makes a negative determination in step S11, or even if it makes a positive determination in step S11, it makes a negative determination in step S22. As a result, the prohibition flag FA is ON at the end of the previous trip. Then, during the first determination control for the current trip, the control device 90 makes a negative determination in step S43. In this case, the control device 90 does not perform the second determination control for the current trip.

[0065] On the other hand, for example, if the internal combustion engine 10 was operating for a relatively long period during the previous trip, the upstream temperature Tin is often above the specified temperature A. When exhaust gas with an upstream temperature Tin above the specified temperature A flows into the GPF 28, the hydrocarbons in the GPF 28 are burned. Therefore, it is unlikely that hydrocarbons have accumulated in the GPF 28 at the end of the previous trip. In this case, the control device 90 repeatedly performs flag update control during the previous trip, and in step S22, it makes a positive determination, that is, it determines that the high-temperature exhaust gas flow rate FH is above the standard flow rate ZA. As a result, the prohibition flag FA is turned OFF at the end of the previous trip. Then, in the first determination control of the current trip, the control device 90 makes a positive determination in step S43. The control device 90 then performs a second determination control during the current trip. That is, in the second determination control, the control device 90 determines whether or not the GPF 28 has been removed from the exhaust passage 26.

[0066] <Effects of this embodiment> (1) In this embodiment, the control device 90 executes the second determination control in the current trip, provided that the prohibition flag FA was OFF at the end of the previous trip, i.e., the control device 90 determined that the high-temperature exhaust gas flow rate FH was equal to or greater than the reference flow rate ZA in the previous trip. As described above, in the situation where the high-temperature exhaust gas flow rate FH was equal to or greater than the reference flow rate ZA in the previous trip, it is unlikely that hydrocarbons in the GPF28 have accumulated in the GPF28 due to combustion. In other words, the control device 90 executes the second determination control when there is no excessive amount of hydrocarbons accumulated in the GPF28. This makes it possible to determine whether or not the GPF28 has been removed from the exhaust passage 26 in a state where the influence of hydrocarbons, which can cause a misdetermination of whether or not the GPF28 has been removed from the exhaust passage 26, is low.

[0067] (2) In the vehicle 100, during the previous trip, for example, the internal combustion engine 10 may repeatedly switch between being in operation and not being in operation. In such situations, not only will the upstream temperature Tin be above the specified temperature A, but the upstream temperature Tin may also be below the specified temperature A. In this case, even if hydrocarbons in the GPF 28 are burned when exhaust gas with an upstream temperature Tin above the specified temperature A flows into the GPF 28, hydrocarbons may be deposited again in the GPF 28 when exhaust gas with an upstream temperature Tin below the specified temperature A flows into the GPF 28. In this regard, the control device 90 sets the prohibition flag FA to ON when it determines in step S32 that the low-temperature exhaust flow rate FL is above the specified flow rate ZB. Therefore, if the control device 90 determines that hydrocarbons may be deposited again in the GPF 28 when exhaust gas with an upstream temperature Tin below the specified temperature A flows into the GPF 28, it does not execute the second determination control during the current trip. In other words, the control device 90 executes the second determination control, requiring that in the previous trip, it made a positive determination in step S22 and did not make a positive determination in step S32. This allows for a more accurate determination of the situation in which hydrocarbons have not accumulated in the GPF28. The second determination control can then be executed after accurately determining that hydrocarbons have not accumulated in the GPF28.

[0068] (3) For example, depending on the operating conditions of the internal combustion engine 10, the absolute value of the difference between the upstream temperature Tin and the downstream temperature Tout may temporarily become large. Therefore, if the system is configured to determine that the GPF 28 has been removed from the exhaust passage 26 when the absolute value of the difference between the upstream temperature Tin and the downstream temperature Tout becomes large, misjudgments are likely to occur depending on the operating conditions of the internal combustion engine 10.

[0069] In this regard, in the second determination control, the control device 90 calculates an upstream integral value ΣΔTin, which is the value obtained by integrating the upstream change amount ΔTin based on the upstream temperature Tin. The control device 90 also calculates a downstream integral value ΣΔTout, which is the value obtained by integrating the downstream change amount ΔTout based on the downstream temperature Tout. The control device 90 then determines that the GPF 28 has been removed from the exhaust passage 26 if the quotient Q calculated from the upstream integral value ΣΔTin and the downstream integral value ΣΔTout is less than the diagnostic threshold QA. In other words, according to this embodiment, since the integral values ​​of the upstream temperature Tin and the downstream temperature Tout are used, the possibility that the determination result will change simply because the absolute value of the difference between the upstream temperature Tin and the downstream temperature Tout temporarily becomes large can be reduced.

[0070] (4) In this embodiment, the vehicle 100 is a so-called hybrid vehicle, which is equipped with a first motor generator 71 and a second motor generator 72 as drive sources in addition to the internal combustion engine 10 as a drive source. In such a vehicle 100, the operating period of the internal combustion engine 10 tends to be shorter compared to a configuration in which only the internal combustion engine 10 is equipped as a drive source. Therefore, it is particularly preferable to apply the present technology to such a vehicle 100.

[0071] <Example of changes> This embodiment can be implemented with the following modifications. This embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically.

[0072] In the above embodiment, the flag update control may be modified. For example, the configuration for taking into account the effect of exhaust gas when the upstream temperature Tin is below the specified temperature A may be changed. Specifically, in order to take into account the effect of exhaust gas when the upstream temperature Tin is below the specified temperature A, the execution unit 91 may increase the reference flow rate ZA in step S22 the more times a negative determination is made in step S11. In this case, the processing in steps S31 to S33 may be omitted. Note that depending on the configuration of the internal combustion engine 10, there may be cases where the possibility of hydrocarbons accumulating in the GPF 28 is low because exhaust gas with an upstream temperature Tin below the specified temperature A flows into the GPF 28. In such cases, the effect of omitting the processing in steps S31 to S33 in a configuration where the reference flow rate ZA is a fixed value is small.

[0073] In the above embodiment, the first decision control and the second decision control may be modified. For example, the process in step S71 may be modified. Specifically, in step S71, the execution unit 91 may calculate an index value obtained by subtracting the downstream integral value ΣΔTout from the upstream integral value ΣΔTin, instead of the quotient Q. In this case, in step S72, the execution unit 91 only needs to determine whether the index value calculated in step S71 is greater than or equal to a predetermined diagnostic threshold QA.

[0074] Furthermore, as a specific example, in step S71, the execution unit 91 may calculate the integral of the difference between the rate of change per unit time of the upstream temperature Tin and the rate of change per unit time of the downstream temperature Tout as the index value, instead of the quotient Q. In this case, in step S72, the execution unit 91 only needs to determine whether the index value calculated in step S71 is equal to or greater than a predetermined diagnostic threshold QA. This configuration produces the same effect as (3) above. Note that if this configuration is adopted, the processing in steps S61 to S64 may be omitted.

[0075] As a specific example, in step S71, the execution unit 91 may calculate the absolute value of the difference between the upstream temperature Tin and the downstream temperature Tout as the index value instead of the quotient Q. In this case, in step S72, the execution unit 91 only needs to determine whether the index value calculated in step S71 is equal to or greater than a predetermined diagnostic threshold QA.

[0076] • In the above embodiment, the configuration of the vehicle 100 may be changed. For example, vehicle 100 may be equipped with only the internal combustion engine 10, a first motor generator 71, and a second motor generator 72. In other words, the present technology can be applied to any vehicle 100 equipped with an internal combustion engine 10.

[0077] For example, the exhaust gas purification device may be changed. Specifically, the GPF28 may be equipped with either a filter or a three-way catalyst. In this case, the filter or the three-way catalyst in the GPF28 is the exhaust gas purification device. Also, specifically, the exhaust gas purification device may be a three-way catalyst 27 instead of the GPF28. In this case, the upstream temperature sensor 87 should be located upstream of the three-way catalyst 27 in the exhaust passage 26. Similarly, the downstream temperature sensor 88 should be located downstream of the three-way catalyst 27 in the exhaust passage 26. [Explanation of Symbols]

[0078] 10...Internal combustion engine 11...Cylinder 12...Crankshaft 21...Intake passage 22...Throttle valve 23...Fuel injector 24...Ignition system 26...Exhaust passage 27...Three-way catalytic converter 28...GPF 40...First planetary gear mechanism 50...Second planetary gear mechanism 62...Reduction mechanism 63...Differential mechanism 64...Drive wheels 71...First motor generator 72...Second motor generator 75...Battery 87...Upstream temperature sensor 88...Downstream temperature sensor 90...Control device 91...Execution unit 92...Memory unit 92A...Control program 100...Vehicle

Claims

1. An abnormality detection device applicable to an internal combustion engine comprising a cylinder for burning fuel, an exhaust passage for circulating exhaust gas discharged from the cylinder, and an exhaust gas purification device located in the exhaust passage for purifying the exhaust gas, A first process for obtaining the upstream temperature, which is the temperature of the exhaust gas upstream of the exhaust gas purification device in the exhaust passage, A second process for obtaining the downstream temperature, which is the temperature of the exhaust gas downstream of the exhaust gas purification device in the exhaust passage, A third process for obtaining the exhaust flow rate, which is the flow rate of exhaust gas flowing through the aforementioned exhaust passage, A fourth process for determining whether the exhaust flow rate during the operation of the internal combustion engine in the previous trip, when the upstream temperature is above a predetermined specified temperature, is above a predetermined standard flow rate, A fifth process, which determines whether or not the exhaust gas purification device has been removed from the exhaust passage, is performed, with the positive determination in the fourth process being a necessary condition. Execute, In the fifth process described above, The process involves calculating the integral value of the upstream temperature during the period from when the internal combustion engine starts operating until the downstream temperature reaches a predetermined threshold temperature, and an index value indicating the difference between the integral values ​​of the downstream temperature during the same period. If the aforementioned index value is smaller than a predetermined standard value, it is determined that the exhaust gas purification device has been removed from the exhaust passage. Execute An internal combustion engine malfunction detection device.

2. An abnormality detection device applicable to an internal combustion engine comprising a cylinder for burning fuel, an exhaust passage for circulating exhaust gas discharged from the cylinder, and an exhaust gas purification device located in the exhaust passage for purifying the exhaust gas, A first process for obtaining the upstream temperature, which is the temperature of the exhaust gas upstream of the exhaust gas purification device in the exhaust passage, A second process for obtaining the downstream temperature, which is the temperature of the exhaust gas downstream of the exhaust gas purification device in the exhaust passage, A third process for obtaining the exhaust flow rate, which is the flow rate of exhaust gas flowing through the aforementioned exhaust passage, A fourth process for determining whether the exhaust flow rate during the operation of the internal combustion engine in the previous trip, when the upstream temperature is above a predetermined specified temperature, is above a predetermined standard flow rate, A fifth process, which determines whether or not the exhaust gas purification device has been removed from the exhaust passage, is performed, with the positive determination in the fourth process being a necessary condition. Execute, In the fifth process described above, The process involves calculating an index value that represents the rate of change per unit time of the upstream temperature during the period from when the internal combustion engine starts operating until the downstream temperature reaches a predetermined determination temperature, and the integral value of the difference between the rate of change per unit time of the downstream temperature during the same period. If the aforementioned index value is smaller than a predetermined standard value, it is determined that the exhaust gas purification device has been removed from the exhaust passage. Execute An internal combustion engine malfunction detection device.

3. A sixth process can be further performed to determine whether the exhaust flow rate during the operation of the internal combustion engine in the previous trip, when the upstream temperature is below the specified temperature, is greater than or equal to a predetermined flow rate that is greater than the standard flow rate. The fifth process is executed, provided that the fourth process results in a positive determination and the sixth process does not result in a positive determination. An abnormality detection device for an internal combustion engine according to claim 1 or claim 2.

4. This invention relates to an abnormality detection device applied to an internal combustion engine that comprises a cylinder for burning fuel, an exhaust passage for circulating exhaust gas discharged from the cylinder, and an exhaust gas purification device located in the exhaust passage for purifying the exhaust gas. The abnormality detection device, A first process for obtaining the upstream temperature, which is the temperature of the exhaust gas upstream of the exhaust gas purification device in the exhaust passage, A second process for obtaining the downstream temperature, which is the temperature of the exhaust gas downstream of the exhaust gas purification device in the exhaust passage, A third process for obtaining the exhaust flow rate, which is the flow rate of exhaust gas flowing through the aforementioned exhaust passage, A fourth process for determining whether the exhaust flow rate during the operation of the internal combustion engine in the previous trip, when the upstream temperature is above a predetermined specified temperature, is above a predetermined standard flow rate, A fifth process, which determines whether or not the exhaust gas purification device has been removed from the exhaust passage, is performed, with the positive determination in the fourth process being a necessary condition. Make it run, In the fifth process described above, The process involves calculating the integral value of the upstream temperature during the period from when the internal combustion engine starts operating until the downstream temperature reaches a predetermined threshold temperature, and an index value indicating the difference between the integral values ​​of the downstream temperature during the same period. If the aforementioned index value is smaller than a predetermined standard value, it is determined that the exhaust gas purification device has been removed from the exhaust passage. Make it run An internal combustion engine abnormality detection program.

5. This invention relates to an abnormality detection device applied to an internal combustion engine that comprises a cylinder for burning fuel, an exhaust passage for circulating exhaust gas discharged from the cylinder, and an exhaust gas purification device located in the exhaust passage for purifying the exhaust gas. The abnormality detection device, A first process for obtaining the upstream temperature, which is the temperature of the exhaust gas upstream of the exhaust gas purification device in the exhaust passage, A second process for obtaining the downstream temperature, which is the temperature of the exhaust gas downstream of the exhaust gas purification device in the exhaust passage, A third process for obtaining the exhaust flow rate, which is the flow rate of exhaust gas flowing through the aforementioned exhaust passage, A fourth process for determining whether the exhaust flow rate during the operation of the internal combustion engine in the previous trip, when the upstream temperature is above a predetermined specified temperature, is above a predetermined standard flow rate, A fifth process, which determines whether or not the exhaust gas purification device has been removed from the exhaust passage, is performed, with the positive determination in the fourth process being a necessary condition. Make it run, In the fifth process described above, The process involves calculating an index value that represents the rate of change per unit time of the upstream temperature during the period from when the internal combustion engine starts operating until the downstream temperature reaches a predetermined determination temperature, and the integral value of the difference between the rate of change per unit time of the downstream temperature during the same period. If the aforementioned index value is smaller than a predetermined standard value, it is determined that the exhaust gas purification device has been removed from the exhaust passage. Make it run An internal combustion engine abnormality detection program.

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