Control device of internal combustion engine, control method of internal combustion engine, and storage medium

Abstract

The present application provides a control device of an internal combustion engine, a control method of an internal combustion engine, and a storage medium. An upstream gas temperature indicates a temperature of exhaust gas upstream of an exhaust gas purification device in an exhaust passage. A downstream gas temperature indicates a temperature of exhaust gas downstream of the exhaust gas purification device. An upstream cumulative value is a cumulative value of a difference obtained by subtracting the upstream gas temperature at a cumulative start time point from the upstream gas temperature after the internal combustion engine is started. A downstream cumulative value is a cumulative value of a difference obtained by subtracting the downstream gas temperature at the cumulative start time point from the downstream gas temperature after the internal combustion engine is started. An abnormality diagnosis process obtains an abnormality determination result indicating that the exhaust gas purification device is detached when a level based on a deviation between the upstream cumulative value and the downstream cumulative value until the downstream gas temperature after the internal combustion engine is started reaches above a determination threshold is small. The determination threshold is higher than a dew point.

Description

Technical Field

[0001] This disclosure relates to a control device for an internal combustion engine, a control method for an internal combustion engine, and a storage medium. Background Technology

[0002] The exhaust gas purification device is installed in the exhaust gas passage. The heat of the exhaust gas introduced into the purification device is consumed through heat exchange with the device. As a result, a difference arises between the temperature changes of the exhaust gas upstream of the purification device and the temperature changes of the exhaust gas downstream of the purification device.

[0003] Japanese Patent Application Publication No. 2020-106028 discloses a control device for an internal combustion engine. A filter traps particulate matter in the exhaust gas. The control device detects whether the filter has been removed from the exhaust gas passage.

[0004] The control device disclosed in this document compares the temperature change of the exhaust gas upstream of the filter with the temperature change of the exhaust gas downstream of the filter. Furthermore, the control device determines whether the filter has been removed based on the difference between the temperature change of the upstream exhaust gas and the temperature change of the exhaust gas downstream of the filter. Summary of the Invention

[0005] The problem that the invention aims to solve

[0006] However, the control device of the internal combustion engine, which determines anomalies by detecting the state of the exhaust gas purification device, such as the state of being removed from the exhaust gas passage, is required to determine anomalies with higher precision.

[0007] Technical solutions for solving the problem

[0008] According to one aspect of this disclosure, a control device for an internal combustion engine is provided. The control device is suitable for an internal combustion engine mounted in a vehicle. The control device includes a processing circuit. The processing circuit is configured to perform cumulative value calculation processing and anomaly diagnosis processing. The cumulative value calculation processing repeatedly acquires upstream gas temperature and downstream gas temperature, the upstream gas temperature representing the temperature of exhaust gas upstream of the exhaust gas purification device in the exhaust gas passage, and the downstream gas temperature representing the temperature of exhaust gas downstream of the exhaust gas purification device. The cumulative value calculation processing also calculates upstream cumulative value and downstream cumulative value. The upstream cumulative value is the cumulative difference obtained by subtracting the upstream gas temperature at the cumulative start time from the upstream gas temperature after the internal combustion engine starts. The downstream cumulative value is the cumulative difference obtained by subtracting the downstream gas temperature at the cumulative start time from the downstream gas temperature after the internal combustion engine starts. The anomaly diagnosis processing obtains an anomaly determination result if the deviation between the upstream cumulative value and the downstream cumulative value up to the point where the downstream gas temperature after the internal combustion engine starts reaches or exceeds a determination threshold is less than a baseline level, the anomaly determination result indicating that the exhaust gas purification device has been removed. The determination threshold is higher than the dew point.

[0009] When an exhaust gas purification device is installed, the heat of the exhaust gas is consumed as the heat of vaporization of the water before the water adhering to the device evaporates. That is, the change in downstream gas temperature stagnates. Therefore, the deviation between the upstream cumulative value and the downstream cumulative value up to the point where the downstream gas temperature reaches a threshold higher than the dew point becomes larger.

[0010] On the other hand, when the exhaust gas purification device is removed, heat exchange between the exhaust gas introduced into the purification device and the purification device is not performed. Therefore, the stagnation of the downstream gas temperature rise will not occur. Consequently, the deviation between the upstream cumulative value and the downstream cumulative value up to the point where the downstream gas temperature reaches a threshold higher than the dew point becomes smaller.

[0011] Therefore, the aforementioned control device can make anomaly determinations with high accuracy based on the fact that the deviation ratio between the upstream cumulative value and the downstream cumulative value up to a determination threshold higher than the dew point is small. Attached Figure Description

[0012] Figure 1 This is a schematic diagram showing an engine control unit as one embodiment of an internal combustion engine control device, an engine controlled by the engine control unit, and a hybrid vehicle equipped with the engine.

[0013] Figure 2 It means by Figure 1A flowchart of the process involved in the routines for temperature control performed by the engine control unit.

[0014] Figure 3 It means in Figure 1 A graph showing the temperature changes of upstream and downstream gases in an exhaust gas passage equipped with an exhaust gas purification device.

[0015] Figure 4 It means from Figure 1 A graph showing the temperature changes of the upstream and downstream gases when the exhaust gas purification device is removed from the exhaust gas passage.

[0016] Figure 5 It means by Figure 1 A block diagram showing the relationships between the various processes involved in the abnormal diagnosis performed by the engine control unit.

[0017] Figure 6 It means by Figure 1 The flowchart shows the routines involved in the gas temperature update process performed by the engine control unit.

[0018] Figure 7 It means Figure 5 The flowchart shown is for the routines involved in the chiller status determination process M12.

[0019] Figure 8 It means Figure 7 A graph showing the relationship between placement time and allowable temperature during the treatment.

[0020] Figure 9 It means Figure 5 The flowchart shown is for the routine involved in obtaining the starting temperature of process M20.

[0021] Figure 10 It means Figure 5 The flowchart shown is for the routine involved in the cumulative value calculation process M30.

[0022] Figure 11 It means Figure 5 The flowchart shown is for the routine involved in the calculation completion determination process M42.

[0023] Figure 12 It means Figure 5 The flowchart shown is for the routines involved in the abnormal diagnosis and handling M50.

[0024] Figure 13 It means Figure 12 The flowchart shows the routine involved in the threshold calculation process (S630).

[0025] Figure 14 It means Figure 5The flowchart shown is a part of the routine involved in the external temperature determination process (external temperature estimation process) M60.

[0026] Figure 15 It means Figure 5 The external temperature determination process M60 shown in the example routines involves... Figure 14 The flowchart is shown for the part not shown in the diagram.

[0027] Figure 16 It means Figure 5 The flowchart shown is for determining the routines involved in the process M70. Detailed Implementation

[0028] The following is for reference Figures 1 to 16 The engine control unit 110, which is one embodiment of the control device for an internal combustion engine, will be described. That is, the engine control unit 110 executes the control method and control processing of the internal combustion engine.

[0029] <Regarding the structure of the vehicle>

[0030] like Figure 1 As shown, engine 10 is an internal combustion engine with four cylinders, #1 to #4. Engine 10 is mounted in a vehicle. A throttle valve 14 is provided on the intake passage 12 of engine 10. An intake port injection valve 16 is provided at the intake port 12a, which is a downstream part of the intake passage 12, to inject fuel into the intake port 12a. Air drawn into the intake passage 12 and fuel injected from the intake port injection valve 16 flow into the combustion chamber 20 as the intake valve 18 opens. In-cylinder injection valves 22 are also provided on engine 10 to inject fuel into cylinders #1 to #4. Sometimes fuel is injected into the combustion chamber 20 from the in-cylinder injection valves 22. In addition, the air-fuel mixture in the combustion chamber 20 is supplied for combustion with the spark discharge of the spark plug 24. The combustion energy generated at this time is converted into the rotational energy of the crankshaft 26.

[0031] The air-fuel mixture supplied to the combustion chamber 20 is discharged as exhaust gas into the exhaust passage 30 along with the opening of the exhaust valve 28. A three-way catalytic converter 32 with oxygen-absorbing capacity and a gasoline particulate filter 34 (hereinafter referred to as GPF34) are installed in the exhaust passage 30. For example, the GPF34 functions as an exhaust gas purification device. Furthermore, the GPF34 is a filter that carries the three-way catalytic converter on a filter that captures particulate matter (hereinafter referred to as PM) contained in the exhaust gas.

[0032] A crank rotor 40 with teeth 42 is mounted on the crankshaft 26. The crank rotor 40 has approximately 32 teeth 42 per 10° CA. Therefore, the crank rotor 40 has one missing tooth section 44, where the spacing between adjacent teeth 42 is widened by two missing teeth 42. This missing tooth section 44 is used to indicate a rotation angle that serves as a reference for the crankshaft 26.

[0033] The crankshaft 26 is mechanically connected to the planet carrier C of the planetary gear mechanism 50, which constitutes the power distribution device. The rotating shaft 52a of the first electric generator 52 is mechanically connected to the sun gear S of the planetary gear mechanism 50. Additionally, the rotating shaft 54a of the second electric generator 54 and the drive wheel 60 are mechanically connected to the ring gear R of the planetary gear mechanism 50. AC voltage is applied to the terminals of the first electric generator 52 via an inverter 56. AC voltage is applied to the terminals of the second electric generator 54 via an inverter 58.

[0034] <Regarding Control Device 500>

[0035] The control unit 500 controls the engine 10, the first electric generator 52, and the second electric generator 54. The control unit 500 includes an engine control unit 110 that controls the engine 10. Additionally, the control unit 500 includes an electric motor control unit 130 that controls the first electric generator 52 and the second electric generator 54. Furthermore, the control unit 500 includes a unified control unit 100 that unifies vehicle control by connecting to the engine control unit 110 and the electric motor control unit 130. These control units are composed of processing circuitry and a memory storing programs executed by the processing circuitry.

[0036] The control device 500 controls the engine 10, the first electric generator 52, and the second electric generator 54. That is, the control device 500 controls the vehicle's powertrain system. Detection signals from sensors located in various parts of the vehicle are input to the control device 500.

[0037] The engine control unit 110 operates the engine 10's operating parts, such as the throttle valve 14, intake port injection valve 16, cylinder injection valve 22, and spark plug 24, in order to control the torque, exhaust gas composition ratio, and other control quantities of the engine 10.

[0038] Furthermore, the motor control unit 130 operates the inverter 56 to control the rotational speed, which is a control quantity for the first electric generator 52. Additionally, the motor control unit 130 operates the inverter 58 to control the torque, which is a control quantity for the second electric generator 54.

[0039] Figure 1The document records the operating signals MS1 to MS6 for the throttle body 14, intake injection valve 16, cylinder injection valve 22, spark plug 24, and inverters 56 and 58. The engine control unit 110, in order to control the engine 10, refers to the intake air volume Ga and intake air temperature THA detected by the air flow meter 80. Additionally, the engine control unit 110 also refers to the output signal Scr of the crankshaft angle sensor 82, the water temperature THW detected by the coolant temperature sensor 86, and the pressure Pex of the exhaust gas flowing into the GPF 34 detected by the exhaust gas pressure sensor 88. Furthermore, the engine control unit 110 also refers to the atmospheric pressure PA detected by the atmospheric pressure sensor 85. The electric motor control unit 130, in order to control the first electric generator 52, refers to the output signal Sm1 of the first rotation angle sensor 90 that detects the rotation angle of the first electric generator 52. The electric motor control unit 130, in order to control the second electric generator 54, refers to the output signal Sm2 of the second rotation angle sensor 92 that detects the rotation angle of the second electric generator 54.

[0040] The engine control unit 110 and the electric motor control unit 130 are connected to the unified control unit 100 via communication lines. Furthermore, the unified control unit 100, the electric motor control unit 130, and the engine control unit 110 each exchange and share information and calculated information based on detection signals input from sensors via CAN communication.

[0041] An accelerator position sensor 101, a brake sensor 102, and a vehicle speed sensor 103 are connected to the unified control unit 100. The accelerator position sensor 101 detects the accelerator opening. The brake sensor 102 detects the amount of brake operation. The vehicle speed sensor 103 detects the vehicle speed SPD, which is the vehicle's speed.

[0042] Additionally, an air-fuel ratio sensor 81 is installed in the exhaust gas passage 30. The air-fuel ratio sensor 81 is connected to the engine control unit 110. The air-fuel ratio sensor 81 detects the air-fuel ratio.

[0043] Additionally, an upstream temperature sensor 87 is connected to the engine control unit 110. This upstream temperature sensor 87 is used to detect the upstream gas temperature Tin, which is the temperature of the exhaust gas between the three-way catalyst 32 and the GPF 34 in the exhaust gas passage 30. Furthermore, a downstream temperature sensor 89 is also connected to the engine control unit 110. This downstream temperature sensor 89 is used to detect the downstream gas temperature Tout, which is the temperature of the exhaust gas downstream of the GPF 34.

[0044] The engine control unit 110 counts the number of times the output signal Scr from the crankshaft angle sensor 82 is input, and calculates a value corresponding to the crankshaft angle, namely the counter CNT. The value of the counter CNT corresponds to the crankshaft angle, indicating that the larger the value of the counter CNT, the larger the crankshaft angle. Moreover, when it reaches 720°CA, which is equivalent to 0°CA, the counter CNT is reset to "0". Furthermore, the crankshaft angle at which the counter CNT is "0" is the crankshaft angle at the top dead center of the compression stroke.

[0045] <Regarding fuel injection methods>

[0046] The engine control unit 110 changes the fuel injection method in the engine 10 according to the engine load rate KL and the engine rotation speed NE. For example, in the high-load region, the engine 10 supplies fuel only through in-cylinder injection, which is performed by the in-cylinder injection valve 22. In the low-load region, the engine 10 supplies fuel only through intake injection, which is performed by the intake port injection valve 16. Alternatively, the engine 10 may sometimes supply fuel through both intake port injection and in-cylinder injection. In this case, the engine control unit 110 changes the ratio of intake port injection to in-cylinder injection according to the engine load rate KL and the engine rotation speed NE. The engine 10 thus achieves the formation of a mixture suitable for combustion.

[0047] Furthermore, the internal combustion engine speed NE is calculated by the engine control unit 110 based on the output signal Scr. Additionally, the internal combustion engine load rate KL is calculated by the engine control unit 110 based on the intake air volume Ga and the internal combustion engine speed NE.

[0048] <Regarding Temperature Control>

[0049] Figure 2 The diagram shows the processing steps in the routine involved in the temperature control executed by the engine control unit 110. Figure 2 The illustrated routine is implemented by processing circuitry 111 repeatedly executing a program stored in memory (e.g., ROM) at predetermined intervals. Processing circuitry 111 appropriately stores the data in RAM.

[0050] exist Figure 2In the illustrated example, the processing circuit 111 of the engine control unit 110 first obtains the internal combustion engine speed NE, internal combustion engine load rate KL, and coolant temperature THW in step S10. In the subsequent step S12, the processing circuit 111 calculates the update amount ΔDPM of the accumulated amount DPM based on the internal combustion engine speed NE, internal combustion engine load rate KL, and coolant temperature THW. Here, the accumulated amount DPM is the amount of PM captured by the GPF 34. Specifically, the processing circuit 111 calculates the amount of PM in the exhaust gas discharged into the exhaust gas passage 30 based on the internal combustion engine speed NE, internal combustion engine load rate KL, and coolant temperature THW. Then, the processing circuit 111 calculates the update amount ΔDPM based on the amount of PM in the exhaust gas, GPF temperature, air-fuel ratio, and the execution state of the temperature rise control described later.

[0051] Next, in step S14, the processing circuit 111 updates the accumulation amount DPM. Specifically, the processing circuit 111 adds the updated amount ΔDPM to the accumulated amount DPM as the new accumulation amount DPM. Furthermore, the updated amount ΔDPM calculated in step S12 may sometimes be negative. Due to the execution of the temperature control described later, when the temperature of GPF34 increases, the accumulation amount DPM decreases because PM burns. When the updated amount ΔDPM calculated by the processing circuit 111 is negative, the accumulation amount DPM calculated in step S14 decreases. Next, in step S16, the processing circuit 111 determines whether the first flag F1 is "1". If the first flag F1 is "1", it indicates a request to execute the PM temperature control for combustion to remove GPF34. Conversely, if the first flag F1 is "0", it indicates that temperature control has not been requested.

[0052] If, during the processing in step S16, the first flag F1 is determined to be "0" (step S16: No), the processing circuit 111 proceeds to step S18. Then, during the processing in step S18, the processing circuit 111 determines whether the buildup amount DPM is above the temperature execution value DPMH. Furthermore, the temperature execution value DPMH is a threshold used to determine whether PM needs to be removed based on the buildup amount DPM being above the temperature execution value DPMH.

[0053] If, during the processing in step S18, it is determined that the accumulated amount DPM is above the temperature rise execution value DPMH (step S18: Yes), the processing circuit 111 proceeds to step S20. Then, during the processing in step S20, the processing circuit 111 substitutes "1" into the first flag F1. Then, the processing circuit 111 proceeds to step S22. During the processing in step S22, the processing circuit 111 performs temperature rise control. Furthermore, when the engine control unit 110 requests temperature rise control because the first flag F1 is "1", it performs temperature rise control appropriate to the current state. Temperature rise control is used to remove PM captured by the GPF34 by increasing the temperature of the exhaust gas purification device, thereby utilizing an oxidation reaction. Among the temperature rise controls performed by the engine control unit 110, there is a first temperature rise control with a larger (e.g., faster) temperature rise and a second temperature rise control with a smaller degree of temperature rise than the first temperature rise control.

[0054] For example, as an example of the first temperature rise control, there is a fuel cut-off fuel injection that introduces unburned fuel into the exhaust gas purification device (34) by injecting fuel during fuel cut-off. Through fuel cut-off fuel injection, oxygen and fuel are supplied to the exhaust gas purification device (34), and the temperature of the exhaust gas purification device (34) is raised by utilizing the heat of reaction from the oxidation reaction. Thus, when the exhaust gas purification device (34) reaches a high temperature and oxygen is supplied, the PM captured by the GPF34 is oxidized and removed. Another example of the first temperature rise control is a stop process that stops the fuel supply to a portion of the cylinders (e.g., #1) of the engine 10 and supplies fuel to the remaining cylinders (e.g., #2 to #4). At this time, the air-fuel ratio in the cylinders supplying fuel is made richer than the stoichiometric air-fuel ratio. As a result, exhaust gas containing unburned fuel is discharged from the cylinders supplying fuel. Furthermore, air is discharged from the cylinders where fuel supply has been stopped. As a result, oxygen and fuel are supplied to the exhaust gas purification device (34), and therefore the temperature of the exhaust gas purification device (34) rises.

[0055] Additionally, as an example of a second temperature-increasing control, there is lean control. In lean control, by operating the engine 10 with an air-fuel ratio leaner than the stoichiometric air-fuel ratio, the heat of vaporization of the fuel is reduced, thereby increasing the temperature of the exhaust gas flowing into the exhaust gas purification device (34). The high-temperature exhaust gas flows into the exhaust gas purification device (34), thereby increasing the temperature of the exhaust gas purification device (34). Furthermore, as an example of a second temperature-increasing control, there is delay control. In delay control, by delaying the ignition timing, combustion in the combustion chamber 20 is slowed down, thereby increasing the temperature of the exhaust gas flowing into the exhaust gas purification device (34).

[0056] Additionally, pulse control can also be implemented as a temperature rise control. In pulse control, a portion of the cylinders are designated as rich cylinders, and the remaining cylinders are designated as lean cylinders. In the rich cylinders, combustion occurs at an air-fuel ratio lower than the stoichiometric air-fuel ratio. In the lean cylinders, combustion occurs at an air-fuel ratio higher than the stoichiometric air-fuel ratio. As a result, exhaust gas from the lean cylinders, which contain more residual oxygen, and exhaust gas from the rich cylinders, which contain more unburned fuel, alternately flow into the exhaust gas purification device (34). As a result, the temperature of the exhaust gas purification device (34) rises. Furthermore, in pulse control, if the difference between the fuel injection amount to the rich cylinders and the fuel injection amount to the lean cylinders is increased, pulse control becomes the first temperature rise control with a large degree of temperature rise. Moreover, in pulse control, if the difference between the fuel injection amount to the rich cylinders and the fuel injection amount to the lean cylinders is decreased, pulse control becomes the second temperature rise control with a small degree of temperature rise.

[0057] Thus, in the processing of step S22, the processing circuit 111, which executes temperature control appropriate for the current state, temporarily terminates the routine.

[0058] On the other hand, in the process of step S18, if it is determined that the accumulation amount DPM is less than the temperature rise execution value DPMH (step S18: no), the processing circuit 111 does not execute the processes of step S20 and step S28 and directly terminates the routine temporarily.

[0059] Furthermore, if the first flag F1 is determined to be "1" during the processing in step S16 (step S16: Yes), the processing circuit 111 proceeds to step S26. Then, during the processing in step S26, the processing circuit 111 determines whether the accumulation amount DPM is below the stop threshold DPML. Furthermore, the stop threshold DPML is used to determine the threshold at which temperature control can be stopped based on the accumulation amount DPM being below the stop threshold DPML.

[0060] If, during the processing in step S26, it is determined that the accumulation amount DPM is below the stop threshold DPML (step S26: Yes), the processing circuit 111 proceeds to step S28. Then, during the processing in step S28, the processing circuit 111 stops the temperature rise control by substituting "0" into the first flag F1. Then, the processing circuit 111 temporarily terminates the routine.

[0061] <Principles of Abnormal Diagnosis and Handling>

[0062] However, if the exhaust gas purification device (34) is removed from the exhaust gas passage 30, the exhaust gas cannot be purified. Therefore, when the engine control unit 110 detects that the exhaust gas purification device (34) is removed from the exhaust gas passage 30, it performs an abnormality diagnosis process to obtain an abnormality determination result, which indicates that the exhaust gas purification device (34) is removed from the exhaust gas passage 30.

[0063] Figure 3 This indicates the shift in upstream gas temperature Tin and downstream gas temperature Tout since the engine 10 has finished starting. Figure 3 In this context, the upstream gas temperature Tin and downstream gas temperature Tout, obtained at time t0 after startup and when engine 10 begins operation, are denoted as the initial temperature Ts. The initial temperature Ts of the upstream gas temperature Tin is the initial upstream gas temperature Ts_in. That is, the initial upstream gas temperature Ts_in is the upstream gas temperature Tin obtained at time t0. Figure 3 In this diagram, the initial upstream gas temperature Ts_in is taken as the origin, and the movement of the upstream gas temperature Tin represents the change in temperature. The initial temperature Ts of the downstream gas temperature Tout is the initial downstream gas temperature Ts_out. That is, the initial downstream gas temperature Ts_out is the downstream gas temperature Tout obtained at time t0. Figure 3 In this context, the initial downstream gas temperature Ts_out is taken as the origin, and the movement of the downstream gas temperature Tout is represented.

[0064] also, Figure 3 This indicates the shift in upstream gas temperature Tin and downstream gas temperature Tout after a cold start, under normal conditions, when the exhaust gas purification device (34) is installed in the exhaust gas passage 30. A cold start refers to a start-up that begins after the engine 10 has cooled to a temperature comparable to the outside air temperature. In this case, such as... Figure 3 As shown, the upstream gas temperature Tin rises rapidly, while the downstream gas temperature Tout is difficult to rise compared to the upstream gas temperature Tin. This is because, in a cold state, the moisture contained in the exhaust gas condenses and adheres to the exhaust gas purification device (34). As the temperature of the exhaust gas rises due to the start of engine 10 operation, the upstream gas temperature Tin rises. In contrast, before the moisture evaporates, the heat of the exhaust gas passing through the exhaust gas purification device (34) is consumed as the heat of vaporization of water. Therefore, the downstream gas temperature Tout is difficult to rise. That is, the rise of the downstream gas temperature Tout stagnates before the vaporization of water in the exhaust gas purification device (34). When the water has evaporated, the temperature of the exhaust gas purification device (34) and the downstream gas temperature Tout both rise.

[0065] Figure 4 This refers to the shift in upstream gas temperature Tin and downstream gas temperature Tout after cold start-up of the exhaust gas purification device (34) in the state where it has been removed from the exhaust gas passage 30, i.e., in an abnormal state. Figure 4 In, with Figure 3 Similarly, taking the initial upstream gas temperature Ts_in as the origin, this represents the progression of the upstream gas temperature Tin. Additionally, with... Figure 3Similarly, with the initial downstream gas temperature Ts_out as the origin, the movement of the downstream gas temperature Tout is represented. Figure 4 The shift of upstream gas temperature Tin in the middle and Figure 3 The situation is the same. However, as... Figure 4 As shown, in Figure 4 In this case, since the exhaust gas purification device (34) is removed from the exhaust gas passage 30, the above-mentioned [issue] will not occur. Figure 3 The rise in downstream gas temperature Tout caused by such exhaust gas passing through the exhaust gas purification device (34) is halted. Therefore, Figure 4 The downstream gas temperature Tout is from the ratio Figure 3 The temperature rises earlier than usual. Furthermore, the stagnation in the rise of downstream gas temperature Tout when the exhaust gas purification device (34) is installed in the exhaust gas passage 30 is not only related to the heat of vaporization of water, but also to the heat capacity of the exhaust gas purification device (34), namely the heat of the three-way catalyst 32 and the heat capacity of the GPF 34.

[0066] The engine control unit 110 performs anomaly diagnosis processing by utilizing the difference in downstream gas temperature Tout caused by the presence or absence of such an exhaust gas purification device (34), which indicates that the exhaust gas purification device (34) has been removed from the exhaust gas passage 30. Specifically, the engine control unit 110 repeatedly calculates the difference between the upstream gas temperature Tin and the initial upstream gas temperature Ts_in. Then, the engine control unit 110 calculates the upstream cumulative value ΣΔTin, which is the cumulative value of this difference after the engine 10 starts. That is, time t0 is the cumulative start time point for the accumulation of the upstream cumulative value ΣΔTin. Similarly, the engine control unit 110 repeatedly calculates the difference between the downstream gas temperature Tout and the initial downstream gas temperature Ts_out. Then, the engine control unit 110 calculates the downstream cumulative value ΣΔTout, which is the cumulative value of this difference after the engine 10 starts. The engine control unit 110 calculates the upstream cumulative value ΣΔTin and the downstream cumulative value ΣΔTout until the downstream gas temperature Tout reaches the judgment threshold Tf. Then, if the deviation between the upstream cumulative value ΣΔTin and the downstream cumulative value ΣΔTout is less than a baseline level, an anomaly judgment is made. Furthermore, the judgment threshold Tf is set to a temperature higher than the dew point.

[0067] like Figure 4 As shown, when the exhaust gas purification device (34) is removed from the exhaust gas passage 30, the downstream gas temperature Tout reaches the judgment threshold Tf at time t5. In contrast, as... Figure 3As shown, when the exhaust gas purification device (34) is installed in the exhaust gas passage 30, the downstream gas temperature Tout reaches the judgment threshold Tf at time t10 after time t5.

[0068] exist Figure 3 and Figure 4 In the anomaly diagnosis process, the upstream cumulative value ΣΔTin is equivalent to the area between the upstream gas temperature Ts_in and the upstream gas temperature Tin at the beginning, up to the point when the downstream gas temperature Tout reaches the judgment threshold Tf. Furthermore, in... Figure 3 and Figure 4 In the anomaly diagnosis process, the downstream cumulative value ΣΔTout is equivalent to the area between the initial downstream gas temperature Ts_out and the downstream gas temperature Tout up to the point where the downstream gas temperature Tout reaches the judgment threshold Tf. (Comparison) Figure 3 and Figure 4 It is clear that when the exhaust gas purification device (34) is removed from the exhaust gas passage 30 ( Figure 4 In the case where the exhaust gas purification device (34) is installed in the exhaust gas passage 30, Figure 3 Compared to the previous method, the deviation between the upstream cumulative value ΣΔTin and the downstream cumulative value ΣΔTout becomes smaller.

[0069] Therefore, in the abnormal diagnosis process, the engine control unit 110 obtains the abnormality determination result when the quotient of the upstream cumulative value ΣΔTin divided by the downstream cumulative value ΣΔTout is less than the diagnostic threshold dTth (e.g., Figure 12 Step S640).

[0070] Next, a series of procedures performed to diagnose the abnormality of the exhaust gas purification device (34) being removed from the exhaust gas passage 30 will be described in more detail.

[0071] <The various treatments involved in abnormal diagnosis (M10-M70) and the relationships between these treatments>

[0072] like Figure 5 As shown, the engine control unit 110 executes the start temperature acquisition process M20 and the cumulative value calculation process M30 based on the condition that the calculation condition is determined to be met in the calculation condition determination process M10. The calculation condition is a logical AND condition of the following two conditions.

[0073] • The cold-state determination process M12 performs the cold-state determination.

[0074] • In the precondition determination process M14, it is determined that all other preconditions are true.

[0075] That is, the calculation conditions are met when the chiller state determination is performed and all other preconditions are met. Furthermore, the initial temperature acquisition process M20 obtains the initial temperature Ts of the upstream gas temperature Tin and the downstream gas temperature Tout. The cumulative value calculation process M30 calculates the upstream cumulative value ΣΔTin and the downstream cumulative value ΣΔTout.

[0076] Then, when the engine control unit 110 determines in the execution condition determination process M40 that the execution condition is met, it executes the abnormal diagnosis process M50. The execution condition is the logical AND condition of the following two conditions.

[0077] • In the calculation condition determination process M10, the calculation condition is determined to be true.

[0078] • By using the calculation termination determination process M42, a determination was made indicating that the calculation termination condition was met.

[0079] In the calculation completion determination process M42, the engine control unit 110 determines that the calculation completion condition is met when the downstream gas temperature Tout reaches or exceeds the determination threshold Tf.

[0080] As described above, the anomaly diagnosis process M50 is a process that determines anomalies when the deviation ratio between the upstream cumulative value ΣΔTin and the downstream cumulative value ΣΔTout is small, serving as a benchmark. Even if the engine control unit 110 obtains an anomaly determination result in the anomaly diagnosis process M50, it does not immediately determine the result of the anomaly diagnosis. The engine control unit 110 determines the reliability of the anomaly diagnosis result performed by the anomaly diagnosis process M50 using the external temperature determination process M60. Then, in the determination process M70, the engine control unit 110 determines whether to determine the result of the anomaly diagnosis based on the determination result of the external temperature determination process M60. If the result of the anomaly diagnosis is determined in the determination process M70, the engine control unit 110 outputs the determined result.

[0081] Furthermore, in the external temperature determination process M60, the engine control unit 110 estimates the external temperature based on the intake air temperature THA to determine whether sufficient rest time tsoak has been ensured. That is, the engine control unit 110 uses the estimated external temperature value based on the intake air temperature THA to determine whether the result of the anomaly diagnosis is based on the result of the appropriate anomaly diagnosis process M50 performed after starting from a cold start.

[0082] <Regarding Gas Temperature Update Processing>

[0083] In order to perform these various processes (M10 to M70), the engine control unit 110 repeatedly performs gas temperature update processing during operation. The gas temperature update processing is implemented by the processing circuit 111 executing the program stored in the memory of the engine control unit 110.

[0084] Figure 6 This is a flowchart illustrating the routines involved in the gas temperature update process. When starting... Figure 6 In the example shown, the processing circuit 111 first obtains the detection values ​​of the upstream temperature sensor 87 and the downstream temperature sensor 89 in step S100. Then, in the processing of step S110, the processing circuit 111 determines whether the engine 10 has completed its start-up process.

[0085] If, in step S110, it is determined that the engine 10 is about to start (step S110: No), the processing circuit 111 proceeds to step S130. Then, in step S130, the processing circuit 111 substitutes the first determination value X1 into the determination value Xth. Conversely, if, in step S110, it is determined that the engine 10 has finished starting (step S110: Yes), the processing circuit 111 proceeds to step S120. Then, in step S120, the processing circuit 111 substitutes the second determination value X2 into the determination value Xth. Furthermore, the second determination value X2 is a value greater than the first determination value X1 (X1 < X2).

[0086] When a determination value Xth is set through the processing in step S120 or step S130, the processing circuit 111 proceeds to step S140. In step S140, the processing circuit 111 determines whether the absolute value of the difference between the detected value and the gas temperature T is less than the determination value Xth. Then, if the absolute value of the difference is determined to be less than the determination value Xth (step S150: Yes), the processing circuit 111 proceeds to step S150. Then, in step S150, the gas temperature T is updated by substituting the detected value into the gas temperature T. On the other hand, if the absolute value of the difference is determined to be greater than or equal to the determination value Xth (step S150: No), the processing circuit 111 does not execute step S150 and temporarily terminates the routine.

[0087] Furthermore, the gas temperature T can be either the upstream gas temperature Tin or the downstream gas temperature Tout. That is, when the detected value from the upstream temperature sensor 87 deviates from the judgment value Xth by more than a certain amount from the upstream gas temperature Tin, the processing circuit 111 will not reflect the detected value in the upstream gas temperature Tin. Similarly, when the detected value from the downstream temperature sensor 89 deviates from the judgment value Xth by more than a certain amount from the downstream gas temperature Tout, the processing circuit 111 will not reflect the detected value in the downstream gas temperature Tout.

[0088] The gas temperature update process updates the gas temperature T to a value equal to the detected value if the deviation between the detected value from the temperature sensors (87, 89) and the previously obtained gas temperature T (Tin, Tout) is less than a judgment value Xth. In this way, the engine control unit 110 suppresses the influence of noise on the gas temperature T through this gas temperature update process.

[0089] <Regarding update processing>

[0090] In addition, the engine control unit 110 repeatedly executes update processes to update other values ​​required for performing various processes (M10 to M70). This update process is also implemented by the processing circuit 111 executing a program stored in the memory of the engine control unit 110.

[0091] In this update process, processing circuit 111 updates the first cumulative time Σt1, the second cumulative time Σt2, the high-load cumulative air volume ΣGA, and the minimum intake air temperature Tmin. The first cumulative time Σt1 is the cumulative execution time of the first temperature rise control during the stroke from when the vehicle's main switch is turned on to when it is turned off. In other words, one stroke is from when the vehicle's system starts operating until it stops. The second cumulative time Σt2 is the cumulative execution time of the second temperature rise control during this stroke. The high-load cumulative air volume ΣGA is the cumulative value of the intake air volume Ga during high-load operation in this stroke. When the intake air volume Ga is above a predetermined value, processing circuit 111 updates the high-load cumulative air volume ΣGA by accumulating the intake air volume Ga. The minimum intake air temperature Tmin is the minimum value of the intake air temperature THA during this stroke. Whenever the intake air temperature THA is lower than the minimum intake air temperature Tmin, processing circuit 111 updates the minimum intake air temperature Tmin by substituting the current intake air temperature THA into the minimum intake air temperature Tmin.

[0092] <Regarding the chiller status determination and processing M12>

[0093] Figure 7 This is a flowchart representing the routines involved in the cold machine status determination process M12. Figure 7 The illustrated routine is implemented by processing circuit 111 executing a program stored in memory. Processing circuit 111 executes the routine only once during one stroke of the vehicle's main switch from being turned on to being turned off. Processing circuit 111 executes the routine when the engine 10 is initially started by the operation of engine control unit 110.

[0094] like Figure 7As shown, when this routine begins, the processing circuit 111 first obtains the upstream gas temperature Tin in step S200. Furthermore, in the accompanying drawings, the upstream gas temperature is described with the word "side" as upstream side gas temperature, for example; however, in this specification, for the sake of brevity and clarity, the word "side" is omitted. Next, in step S210, the processing circuit 111 obtains the downstream gas temperature Tout. Then, in step S220, the processing circuit 111 obtains the settling time tsoak. The settling time tsoak is the time during which the engine control unit 110 stops operating. For example, the settling time tsoak is the time from when the vehicle's main switch is turned off until it is turned on again.

[0095] In step S230, processing circuit 111 determines whether the placement time tsoak is less than a first predetermined time tth1. The first predetermined time tth1 is a threshold used to determine that the placement time tsoak is insufficient to determine that the machine is in a cold state. The value of the first predetermined time tth1 is set such that if the placement time tsoak is less than the first predetermined time tth1, it can be determined that the placement time tsoak is insufficient.

[0096] If, during the processing in step S230, it is determined that the placement time tsoak is less than the first predetermined time tth1 (step S230: Yes), the processing circuit 111 proceeds to step S250. Then, during the processing in step S250, the processing circuit 111 substitutes the prohibition value Toff into the allowable temperature Tth1. For example, the prohibition value Toff is a value smaller than the lower limit of the acceptable range of the upstream gas temperature Tin.

[0097] If, during the processing in step S230, it is determined that the placement time tsoak is greater than or equal to a first predetermined time tth1 (step S230: No), the processing circuit 111 proceeds to step S240. Then, during the processing in step S240, the processing circuit 111 determines whether the placement time tsoak is longer (greater) than a second predetermined time tth2. The second predetermined time tth2 is a threshold used to determine that the placement time tsoak is long enough to be considered a cold state. The value of the second predetermined time tth2 is set such that if the placement time tsoak is longer than the second predetermined time tth2, it can be determined that the placement time tsoak is long enough.

[0098] If, during the processing in step S240, it is determined that the placement time tsoak is longer than the second predetermined time tth2 (step S240: Yes), the processing circuit 111 proceeds to step S260. Then, during the processing in step S260, the processing circuit 111 substitutes the allowable value Ton into the allowable temperature Tth1. The allowable value Ton is a value greater than the upper limit of the range that the upstream gas temperature Tin can take.

[0099] If, in step S240, it is determined that the placement time tsoak is less than or equal to the second predetermined time tth2 (step S240: No), the processing circuit 111 proceeds to step S270. Then, in step S270, the processing circuit 111 calculates and sets the allowable temperature Tth1 based on the placement time tsoak. The calculation method for the allowable temperature Tth1 in step S270 will be referred to... Figure 8 This will be described later. After setting the allowable temperature Tth1 by performing the processing of step S250, step S260 or step S270, the processing circuit 111 causes the processing to proceed to step S280.

[0100] In step S280, the processing circuit 111 determines whether the refrigeration condition is met. The refrigeration condition is a logical AND of the following three conditions.

[0101] • The deviation between the upstream gas temperature Tin and the downstream gas temperature Tout is less than the predetermined level.

[0102] • The upstream gas temperature Tin is less than the allowable temperature Tth1.

[0103] • The downstream gas temperature Tout is less than the predetermined chiller judgment value.

[0104] In addition, the cold start judgment value is set to, for example, a value below 50°C.

[0105] Figure 8 This indicates the relationship between the allowable temperature Tth1 set through steps S230 to S270 and the placement time tsoak.

[0106] like Figure 8 As shown, when the placement time tsoak is less than the first predetermined time tth1, the allowable temperature Tth1 is set to the prohibited value Toff. As mentioned above, the prohibited value Toff is a value smaller than the lower limit of the acceptable range for the upstream gas temperature Tin. Therefore, when the placement time tsoak is less than the first predetermined time tth1, the upstream gas temperature Tin will not be less than the allowable temperature Tth1. Therefore, when the placement time tsoak is less than the first predetermined time tth1, the second condition is not met, and thus the chiller determination condition is not met.

[0107] On the other hand, if the placement time tsoak is longer than the second predetermined time tth2, the allowable temperature Tth1 is set to the allowable value Ton. As mentioned above, the allowable value Ton is a value greater than the upper limit of the range that the upstream gas temperature Tin can take. Therefore, if the placement time tsoak is longer than the second predetermined time tth2, the upstream gas temperature Tin must be less than the allowable temperature Tth1. Therefore, if the other two conditions are met when the placement time tsoak is longer than the second predetermined time tth2, the chiller determination condition is met.

[0108] When the placement time tsoak is greater than or equal to a first predetermined time tth1 and less than a second predetermined time tth2, as described above, the processing circuit 111 calculates the allowable temperature Tth1 based on the placement time tsoak during the processing in step S270. Figure 8 As shown, the longer the placement time tsoak, the higher the allowable temperature Tth1 will be set by the processing circuit 111. Figure 8 In the example shown, when the placement time tsoak is a first predetermined time tth1, the allowable temperature Tth1 is "TL". When the placement time tsoak is a second predetermined time tth2, the allowable temperature Tth1 is "TH", which is greater than "TL". Thus, the longer the placement time tsoak, the larger the allowable temperature Tth1 is set to. Therefore, the longer the placement time tsoak, the easier it is for the cold start condition to be met.

[0109] In the process of step S280, if the cold machine determination condition is met (step S280: yes), the processing circuit 111 causes the process to proceed to step S290.

[0110] In step S290, the processing circuit 111 sets the second flag F2 to "1" to indicate that the engine 10 is in a cold state during startup. When the second flag F2 is "1", it indicates that a determination has been made that the engine 10 is in a cold state during startup. On the other hand, when the second flag F2 is "0", it indicates that a determination has not been made that the engine 10 is in a cold state during startup.

[0111] In the process of step S280, if the cold start determination condition is not met (step S280: No), the processing circuit 111 causes the process to proceed to step S295. In the process of step S295, in order to indicate that the engine 10 is not in a cold start state when it is started, the processing circuit 111 sets the second flag F2 to "0".

[0112] Thus, after the second flag F2 is set through step S290 or step S295, the processing circuit 111 terminates the process. Figure 7The example shown is the cold machine status determination process M12.

[0113] <Regarding the Prerequisite Determination and Processing M14>

[0114] return Figure 5 During the operation of the engine control unit 110 when the vehicle's main switch is turned on, the processing circuit 111 repeatedly executes the precondition determination process M14. In the precondition determination process M14, the processing circuit 111 determines whether the preconditions are met. The preconditions are the logical AND conditions of the following nine conditions.

[0115] • Upstream temperature sensor 87 and downstream temperature sensor 89 are normal.

[0116] • Intake air temperature THA is determined by extremely low temperature (e.g., -15°C) or above.

[0117] • The engine 10's starting water temperature THW is above the extremely low temperature determination water temperature (e.g., -15°C).

[0118] • If the atmospheric pressure (PA) is above the high-altitude threshold, then it is determined not to be high ground.

[0119] • The battery was not diagnosed as being in a low voltage state.

[0120] • The water temperature (THW) is within the specified range (e.g., above -25°C and below 65°C).

[0121] • The cumulative value of the intake air volume Ga is less than the specified value.

[0122] • The cumulative time of fuel cut-off is less than the specified value.

[0123] The rise in upstream gas temperature Tin and downstream gas temperature Tout is not unstable.

[0124] When all nine conditions are met, i.e., when the preconditions are deemed met, the processing circuit 111 sets the third flag F3 to "1". A "1" value for the third flag F3 indicates that the preconditions are met. Conversely, a "0" value for the third flag F3 indicates that the preconditions are not met. When the processing circuit 111 determines that the preconditions are not met, it sets the third flag F3 to "0".

[0125] Furthermore, if the temporarily established precondition becomes invalid, the processing circuit 111 will not execute the precondition determination process M14 in the subsequent stroke. That is, if the temporarily established precondition becomes invalid, the third flag F3 will not become "1" in the subsequent stroke. In other words, if the temporarily established calculation condition becomes invalid, the engine control unit 110 will not perform the subsequent calculation condition determination process M10 and the cumulative value calculation process M30 in the subsequent stroke, and will not execute the abnormal diagnosis process M50.

[0126] <Regarding the calculation condition judgment and processing M10>

[0127] like Figure 5 As shown, during the operation of the engine control unit 110 when the vehicle's main switch is turned on, the processing circuit 111 repeatedly executes the calculation condition determination process M10. In the calculation condition determination process M10, the processing circuit 111 determines whether the calculation condition is met. Specifically, in the calculation condition determination process M10, the processing circuit 111 obtains the second flag F2 and the third flag F3, and determines that the calculation condition is met if both the second flag F2 and the third flag F3 are "1". On the other hand, the processing circuit 111 determines that the calculation condition is not met if either the second flag F2 or the third flag F3 is "0".

[0128] Then, if the processing circuit 111 determines that the calculation condition is met, it sets the fourth flag F4 to "1". On the other hand, if the processing circuit 111 determines that the calculation condition is not met, it sets the fourth flag F4 to "0". When the fourth flag F4 is "1", it indicates that the calculation condition is met. On the other hand, when the fourth flag F4 is "0", it indicates that the calculation condition is not met.

[0129] <Regarding the initial temperature acquisition process M20>

[0130] Figure 9 This is a flowchart representing the routines involved in the initial temperature acquisition process M20. Figure 9 The routine shown is implemented by the processing circuit 111 executing a program stored in memory. The processing circuit 111 repeatedly executes the routine from the moment the vehicle's main switch is turned on until the initial upstream gas temperature Ts_in and the initial downstream gas temperature Ts_out are set.

[0131] like Figure 9 As shown, when the routine begins, the processing circuit 111 first determines whether the fourth flag F4 is "1" in the processing of step S300. If the processing of step S300 determines that the fourth flag F4 is "1" (step S300: Yes), the processing circuit 111 causes the processing to proceed to step S310.

[0132] In step S310, the processing circuit 111 obtains the upstream gas temperature Tin. Then, in the next step S320, the processing circuit 111 obtains the downstream gas temperature Tout.

[0133] Next, in step S330, the processing circuit 111 substitutes the upstream gas temperature Tin into the initial upstream gas temperature Ts_in. Thus, the processing circuit 111 sets the initial upstream gas temperature Ts_in through the processing in step S330.

[0134] Next, in step S340, the processing circuit 111 substitutes the downstream gas temperature Tout into the initial downstream gas temperature Ts_out. Thus, the processing circuit 111 sets the initial downstream gas temperature Ts_out through the processing in step S340.

[0135] After setting the initial upstream gas temperature Ts_in and the initial downstream gas temperature Ts_out, the processing circuit 111 terminates the routine. On the other hand, if it is determined in step S300 that the fourth flag F4 is not "1" (step S300: No), the processing circuit 111 does not execute the processes of steps S310 to S340 and temporarily terminates the routine. That is, the processing circuit 111 repeatedly performs the initial temperature acquisition process M20 until the fourth flag F4 becomes "1" due to the calculation condition being met. Then, when the fourth flag F4 becomes "1" due to the calculation condition being met, the processing circuit 111 sets the current gas temperature T (i.e., Tin, Tout) to the initial temperature Ts (i.e., Ts_in, Ts_out).

[0136] <Regarding the calculation and processing of cumulative values ​​M30>

[0137] Figure 10 This is a flowchart representing the routines involved in the cumulative value calculation process M30. Figure 10 The routine shown is implemented by the processing circuit 111 executing a program stored in memory. The processing circuit 111 repeatedly executes the routine while the engine control unit 110 is operating due to the vehicle's main switch being turned on.

[0138] like Figure 10 As shown, when the routine begins, the processing circuit 111 first determines whether the fourth flag F4 is "1" in the processing of step S400. If the processing of step S400 determines that the fourth flag F4 is "1" (step S400: Yes), the processing circuit 111 causes the processing to proceed to step S410.

[0139] In step S410, the processing circuit 111 obtains the upstream gas temperature Tin. Then, in the next step S420, the processing circuit 111 obtains the downstream gas temperature Tout.

[0140] Next, in step S430, processing circuit 111 calculates the change ΔTin. Specifically, processing circuit 111 calculates the difference between the current upstream gas temperature Tin and the initial upstream gas temperature Ts_in. This calculated difference is the change ΔTin.

[0141] In the next step S440, processing circuit 111 updates the upstream cumulative value ΣΔTin. The upstream cumulative value ΣΔTin is the cumulative value of the change ΔTin after the engine 10 starts. Specifically, processing circuit 111 calculates the sum obtained by adding the change ΔTin calculated in the current step S430 to the upstream cumulative value ΣΔTin updated in the previous step S440. This calculated sum is the new upstream cumulative value ΣΔTin.

[0142] Next, in step S450, processing circuit 111 calculates the change ΔTout. Specifically, processing circuit 111 calculates the difference between the current downstream gas temperature Tout and the initial downstream gas temperature Ts_out. This calculated difference is the change ΔTout.

[0143] In the next step S460, processing circuit 111 updates the downstream cumulative value ΣΔTout. The downstream cumulative value ΣΔTout is the cumulative value of the change ΔTout after the engine 10 starts. Specifically, processing circuit 111 calculates the sum obtained by adding the change ΔTout calculated in the current step S450 to the downstream cumulative value ΣΔTout updated in the previous step S460. This calculated sum is the new downstream cumulative value ΣΔTout.

[0144] After updating the upstream cumulative value ΣΔTin and the downstream cumulative value ΣΔTout in this way, the processing circuit 111 temporarily terminates the routine. On the other hand, if it is determined in step S400 that the fourth flag F4 is not "1" (step S400: No), the processing circuit 111 does not execute the processing of steps S410 to S460 and temporarily terminates the routine. That is, when the fourth flag F4 becomes "1" due to the calculation condition being met, the upstream cumulative value ΣΔTin and the downstream cumulative value ΣΔTout are updated.

[0145] <Regarding the calculation completion determination process M42>

[0146] Figure 11This is a flowchart representing the routines involved in the calculation completion determination process M42. Figure 11 The routine shown is implemented by the processing circuit 111 executing a program stored in memory. The processing circuit 111 repeatedly executes the routine from setting the downstream gas temperature Ts_out at the start until setting the fifth flag F5 to "1".

[0147] like Figure 11 As shown, when the routine begins, processing circuit 111 first obtains the downstream gas temperature Tout in step S500. Then, in the next step S510, processing circuit 111 obtains the placement time tsoak. Next, in step S520, processing circuit 111 obtains the initial downstream gas temperature Ts_out.

[0148] Then, in the processing of step S530, processing circuit 111 calculates the decision threshold Tf. In step S530, processing circuit 111 calculates, for example, a product larger than the initial downstream gas temperature Ts_out by multiplying it by a correction coefficient Kcor greater than "1.0". This product is the decision threshold Tf. Furthermore, processing circuit 111 calculates the correction coefficient Kcor, for example, by using a mapping operation with the placement time tsoak as an input variable. The mapping used in this operation is designed based on results from prior experiments, etc., such that the shorter the placement time tsoak, the larger the correction coefficient Kcor. After calculating the decision threshold Tf based on the placement time tsoak through the processing of step S530, processing circuit 111 proceeds to step S540.

[0149] In step S540, the processing circuit 111 determines whether the downstream gas temperature Tout is above the determination threshold Tf. If it is determined in step S540 that the downstream gas temperature Tout is above the determination threshold Tf (step S540: Yes), the processing circuit 111 proceeds to step S550. Then, in step S550, the processing circuit 111 sets the fifth flag F5 to "1". When the fifth flag F5 is "1", it indicates that the calculation termination conditions for the upstream cumulative value ΣΔTin and the downstream cumulative value ΣΔTout are met. On the other hand, when the fifth flag F5 is not "1", it indicates that the calculation termination conditions for the upstream cumulative value ΣΔTin and the downstream cumulative value ΣΔTout are not met.

[0150] When the fifth flag F5 is set to "1" in step S550, the processing circuit 111 terminates the routine. On the other hand, if it is determined in step S540 that the downstream gas temperature Tout is less than the determination threshold Tf (step S540: No), the processing circuit 111 does not execute the processing in step S550 and temporarily terminates the routine.

[0151] <Regarding the execution condition determination and processing M40>

[0152] return Figure 5 When the engine control unit 110 is operated by the main switch of the vehicle being turned on, the processing circuit 111 repeatedly executes the execution condition determination process M40. In the execution condition determination process M40, the processing circuit 111 determines whether the execution condition of the abnormal diagnosis process M50 is met. Specifically, in the execution condition determination process M40, the processing circuit 111 obtains the fourth flag F4 and the fifth flag F5, and if either the fourth flag F4 or the fifth flag F5 is "1", it determines that the execution condition of the abnormal diagnosis process M50 is met. On the other hand, if either the fourth flag F4 or the fifth flag F5 is "0", the processing circuit 111 determines that the execution condition of the abnormal diagnosis process M50 is not met.

[0153] Then, if the processing circuit 111 determines that the execution condition for the abnormal diagnosis process M50 is met, it sets the sixth flag F6 to "1". Conversely, if the processing circuit 111 determines that the execution condition for the abnormal diagnosis process M50 is not met, it sets the sixth flag F6 to "0". When the sixth flag F6 is "1", it indicates that the execution condition for the abnormal diagnosis process M50 is met. Conversely, when the sixth flag F6 is "0", it indicates that the execution condition for the abnormal diagnosis process M50 is not met.

[0154] <Regarding Abnormal Diagnosis and Handling M50>

[0155] Figure 12 This is a flowchart representing the routines involved in the abnormal diagnosis and handling M50. Figure 12 The routine shown is implemented by the processing circuit 111 executing a program stored in memory. The processing circuit 111 repeatedly executes the routine while the engine control unit 110 is operating due to the vehicle's main switch being turned on, until the seventh flag F7 is set.

[0156] like Figure 12 As shown, when the routine begins, the processing circuit 111 first determines whether the sixth flag F6 is "1" in the processing of step S600. If the processing of step S600 determines that the sixth flag F6 is "1" (step S600: yes), the processing circuit 111 causes the processing to proceed to step S610.

[0157] In step S610, the processing circuit 111 obtains the upstream cumulative value ΣΔTin. Then, in the following step S620, the processing circuit 111 obtains the downstream cumulative value ΣΔTout.

[0158] Next, as part of step S630, the processing circuit 111 performs threshold calculation processing. Figure 13 This is a flowchart representing the routines involved in the threshold calculation process. For example... Figure 13 As shown, during the initial threshold calculation process, in step S700, processing circuit 111 obtains the first accumulated time Σt1, which has been updated in the aforementioned update process. In the next step S710, processing circuit 111 obtains the second accumulated time Σt2. In step S720, processing circuit 111 obtains the high-load accumulated air volume ΣGA. In step S730, processing circuit 111 obtains the minimum intake air temperature Tmin.

[0159] Next, in step S740, the processing circuit 111 determines whether the first cumulative time Σt1 is greater than or equal to the first threshold Σth1. The first threshold Σth1 is a threshold used to determine whether the proportion of first temperature control executed in this stroke is high. If in step S740 it is determined that the first cumulative time Σt1 is greater than or equal to the first threshold Σth1 (step S740: Yes), the processing circuit 111 proceeds to step S750. In step S750, the processing circuit 111 calculates the diagnostic threshold dTth using a first mapping. The first mapping is an operational mapping that calculates the diagnostic threshold dTth by using the high-load cumulative air volume ΣGA and the minimum intake temperature Tmin as input variables. The first mapping is designed based on the results of prior experiments, etc., such that the higher the high-load cumulative air volume ΣGA, the smaller the output diagnostic threshold dTth, and the lower the minimum intake temperature Tmin, the smaller the output diagnostic threshold dTth.

[0160] If, in step S740, it is determined that the first cumulative time Σt1 is less than the first threshold Σth1 (step S740: No), the processing circuit 111 proceeds to step S760. In step S760, the processing circuit 111 determines whether the second cumulative time Σt2 is greater than or equal to the second threshold Σth2. The second threshold Σth2 is a threshold used to determine whether the proportion of second temperature control executed during this process is excessive.

[0161] If, during the processing in step S760, it is determined that the second cumulative time Σt2 is greater than or equal to the second threshold Σth2 (step S760: Yes), the processing circuit 111 proceeds to step S770. In the processing of step S770, the processing circuit 111 calculates the diagnostic threshold dTth using a second mapping. The second mapping is also an operational mapping that calculates the diagnostic threshold dTth by using the high-load cumulative air volume ΣGA and the minimum intake temperature Tmin as input variables. The second mapping is also designed based on the results of prior experiments, etc., such that the higher the high-load cumulative air volume ΣGA, the smaller the output diagnostic threshold dTth, and the lower the minimum intake temperature Tmin, the smaller the output diagnostic threshold dTth. Furthermore, the second mapping is designed to output a diagnostic threshold dTth larger than that of the first mapping, given the same input variables.

[0162] If, in step S760, it is determined that the second cumulative time Σt2 is less than the second threshold Σth2 (step S760: No), the processing circuit 111 proceeds to step S780. In step S780, the processing circuit 111 calculates the diagnostic threshold dTth using a third mapping. The third mapping is also an operational mapping that calculates the diagnostic threshold dTth by using the high-load cumulative air volume ΣGA and the minimum intake temperature Tmin as input variables. The third mapping is also designed based on the results of prior experiments, etc., such that the higher the high-load cumulative air volume ΣGA, the smaller the output diagnostic threshold dTth, and the lower the minimum intake temperature Tmin, the smaller the output diagnostic threshold dTth. Furthermore, the third mapping is designed to output a diagnostic threshold dTth larger than that of the second mapping, given the same input variables.

[0163] When the diagnostic threshold dTth is calculated through the processing in step S750, step S770, or step S780, the processing circuit 111 terminates. Figure 12 The threshold calculation process in step S630. Then, as... Figure 12 As shown, processing circuit 111 causes the processing to proceed to step S640. In step S640, processing circuit 111 determines whether the quotient obtained by dividing the upstream cumulative value ΣΔTin by the downstream cumulative value ΣΔTout is greater than or equal to the diagnostic threshold dTth. If it is determined that the quotient obtained by dividing the upstream cumulative value ΣΔTin by the downstream cumulative value ΣΔTout is greater than or equal to the diagnostic threshold dTth (step S640: Yes), processing circuit 111 causes the processing to proceed to step S650. Then, in the processing of step S650, processing circuit 111 sets the seventh flag F7 to "0".

[0164] On the other hand, if it is determined that the quotient obtained by dividing the upstream cumulative value ΣΔTin by the downstream cumulative value ΣΔTout is less than the diagnostic threshold dTth (step S640: No), the processing circuit 111 causes the processing to proceed to step S660. Then, the processing circuit 111 obtains the abnormality determination result, and in the processing of step S660, sets the seventh flag F7 to "1", which indicates that the exhaust gas purification device (34) is in a state where it has been removed from the exhaust gas passage 30.

[0165] When the seventh flag F7 is "1", it indicates that an abnormality determination result was obtained through the abnormality diagnosis process M50, indicating that the exhaust gas purification device (34) has been removed from the exhaust gas passage 30. On the other hand, when the seventh flag F7 is "0", it indicates that a normal determination result was obtained through the abnormality diagnosis process M50, that is, no abnormality determination result was obtained. By performing the process of step S650 or step S660 in this way, the processing circuit 111 ends the routine after the seventh flag F7 is set.

[0166] Furthermore, if the sixth flag F6 is determined to be "0" in step S600 (step S600: No), the processing circuit 111 does not execute the processing steps S600 to S660, and directly terminates the process temporarily. Figure 12 The routine.

[0167] <Regarding the determination and processing of external temperature M60>

[0168] Figure 14 and Figure 15 This is a flowchart representing the routines involved in the external temperature determination process M60. Figure 14 and Figure 15 The routine shown is implemented by the processing circuit 111 executing a program stored in memory. The processing circuit 111 executes the routine when the engine control unit 110 is activated due to the vehicle's main switch being turned on.

[0169] like Figure 14 As shown, when the routine begins, processing circuit 111 first obtains the downstream gas temperature Tout in step S800. In the subsequent step S810, processing circuit 111 obtains the placement time tsoak.

[0170] Next, in step S820, the processing circuit 111 determines whether the placement time tsoak is less than a first predetermined time tA. The first predetermined time tA is a threshold used to determine that the length of the placement time tsoak is insufficient to determine the diagnostic result of the abnormality diagnosis process M50.

[0171] If, during the processing in step S820, it is determined that the placement time tsoak is less than the first predetermined time tA (step S820: Yes), the processing circuit 111 proceeds to step S840. Then, during the processing in step S840, the processing circuit 111 sets the eighth flag F8 to "0". When the eighth flag F8 is "1", it indicates that the condition for determining the diagnostic result of the abnormality diagnostic process M50 is met. Conversely, when the eighth flag F8 is "0", it indicates that the condition for determining the diagnostic result of the abnormality diagnostic process M50 is not met.

[0172] If, during the processing in step S820, it is determined that the placement time tsoak is greater than or equal to a first predetermined time tA (step S820: No), the processing circuit 111 proceeds to step S830. Then, during the processing in step S830, the processing circuit 111 determines whether the placement time tsoak is longer than a second predetermined time tB. The second predetermined time tB is a threshold used to determine whether the length of the placement time tsoak is sufficient for determining the diagnostic result of the abnormality diagnostic processing M50.

[0173] In the process of step S830, if it is determined that the placement time tsoak is longer than the second predetermined time tB (step S830: Yes), the processing circuit 111 causes the process to proceed to step S850. Then, in the process of step S850, the processing circuit 111 sets the eighth flag F8 to "1".

[0174] If, in step S830, the placement time tsoak is determined to be less than the second predetermined time tB (step S830: No), then... Figure 15 As shown, processing circuit 111 causes the process to proceed to step S860. In the processing of step S860, processing circuit 111 calculates the allowable temperature Tprm based on the placement time tsoak. Specifically, the longer the placement time tsoak, the larger the value of the allowable temperature Tprm calculated by processing circuit 111.

[0175] Next, in step S870, the processing circuit 111 determines whether the condition for obtaining the minimum intake air temperature Tmin is met. The condition is a logical OR condition of the following three conditions (A), (B), and (C).

[0176] (A) The vehicle speed SPD is the cumulative value of the intake air volume Ga at a given vehicle speed or above the given amount.

[0177] (B) Based on the change in atmospheric pressure PA, it is estimated that from the start of engine 10, the altitude change is above the predetermined level.

[0178] (C) The distance traveled during the trip exceeds the predetermined distance.

[0179] That is, if any one of (A) to (C) above is true, the processing circuit 111 determines that the condition is met in the processing of step S870.

[0180] Furthermore, condition (A) is used to determine whether ventilation has been carried out in the engine compartment through the driving air. Additionally, conditions (B) and (C) are used to determine whether a diagnostic result should be determined before environmental changes from the point when engine 10 is started reach an unacceptable level.

[0181] If the processing condition is determined to be met in step S870 (step S870: Yes), the processing circuit 111 proceeds to step S880. Conversely, if the processing condition is determined to be unmet in step S870 (step S870: No), the processing circuit 111 repeatedly executes step S870. That is, the processing circuit 111 waits for the condition to be met before proceeding to step S880. In step S880, the processing circuit 111 obtains the minimum intake air temperature Tmin. Here, this obtained minimum intake air temperature Tmin is used as an estimated external air temperature value. Then, in the next step S890, the processing circuit 111 determines whether the minimum intake air temperature Tmin is less than the allowable temperature Tprm.

[0182] In step S890, if it is determined that the minimum intake air temperature Tmin is less than the allowable temperature Tprm (step S890: Yes), the processing circuit 111 proceeds to step S850. Then, in step S850, the processing circuit 111 sets the eighth flag F8 to "1". Conversely, in step S890, if it is determined that the minimum intake air temperature Tmin is greater than or equal to the allowable temperature Tprm (step S890: No), the processing circuit 111 proceeds to step S840. Then, in step S840, the processing circuit 111 sets the eighth flag F8 to "0".

[0183] When the eighth flag F8 is set through the processing of step S840 and / or step S850, the processing circuit 111 terminates the routine.

[0184] <Regarding the determination of processing M70>

[0185] Figure 16 This is a flowchart representing the routines involved in determining the processing of M70. Figure 16 The routine shown is implemented by the processing circuit 111 executing a program stored in memory. The processing circuit 111 executes the routine when the seventh flag F7 is set by the exception diagnosis process M50.

[0186] like Figure 16 As shown, when the routine begins, the processing circuit 111 first determines whether the eighth flag F8 is "1" in step S900. If the eighth flag F8 is determined to be "1" in step S900 (step S900: Yes), the processing circuit 111 proceeds to step S910. In step S910, the processing circuit 111 determines the result of the judgment based on the anomaly diagnosis process M50 as the formal diagnosis result. Specifically, when the seventh flag F7 is "1", the processing circuit 111 determines the anomaly judgment result of the anomaly diagnosis process M50 as the formal diagnosis result. When the seventh flag F7 is "0", the processing circuit 111 determines the normal judgment result, indicating that no anomaly judgment result was obtained, as the formal diagnosis result. After the judgment result is determined in this way, in the following step S920, the processing circuit 111 terminates the routine by outputting the determined judgment result.

[0187] On the other hand, if the eighth flag F8 is determined to be "0" in step S900 (step S900: Yes), the processing circuit 111 does not execute the processing in steps S910 and S920, and directly terminates the routine. That is, in this case, even if an anomaly diagnosis is performed through the anomaly diagnosis process M50, the processing circuit 111 is unsure of the determination result of the anomaly diagnosis process M50. Then, the processing circuit 111 does not output the determination result and terminates the routine.

[0188] Thus, if the eighth flag F8 in the external temperature determination process M60 is not set to "1", the engine control unit 110 will not determine the determination result of the abnormal diagnosis process M50 as the formal diagnosis result, and therefore will not output the diagnosis result.

[0189] <The function of this implementation method>

[0190] The calculation conditions, including the cold engine status determination (M12, F2=1), are met (M10, F4=1). In the cumulative value calculation process M30, the upstream cumulative value ΣΔTin and the downstream cumulative value ΣΔTout are calculated. Then, the anomaly diagnosis process M50 is executed if the condition is met that the downstream gas temperature Tout reaches a determination threshold Tf higher than the dew point (S540: Yes). In the anomaly diagnosis process M50, if the determination is that the quotient obtained by dividing the upstream cumulative value ΣΔTin by the downstream cumulative value ΣΔTout is less than the diagnosis threshold dTth (S640: No), an anomaly determination result is obtained, and the seventh flag F7 becomes "1" (S660). If the placement time tsoak is longer than the second predetermined time tB (S830: Yes), or if the minimum inlet temperature Tmin is less than the allowable temperature Tprm (S890: Yes), the anomaly determination result is determined as a formal diagnosis result (F8=1).

[0191] <Effects of this implementation method>

[0192] (1) When the exhaust gas purification device (34) is installed in the exhaust gas passage 30, the heat of the exhaust gas is consumed as the heat of vaporization of the water before the water adhering to the exhaust gas purification device (34) evaporates. Therefore, the deviation between the upstream cumulative value ΣΔTin and the downstream cumulative value ΣΔTout until the downstream gas temperature Tout becomes above the threshold value Tf that is higher than the dew point becomes larger. Figure 3 On the other hand, when the exhaust gas purification device (34) is removed from the exhaust gas passage 30, no heat exchange occurs between the exhaust gas introduced into the exhaust gas purification device (34) and the exhaust gas purification device (34). Therefore, the rise of the downstream gas temperature Tout will not stagnate. Therefore, the deviation between the upstream cumulative value ΣΔTin and the downstream cumulative value ΣΔTout until the downstream gas temperature Tout becomes above the determination threshold Tf becomes smaller. Figure 4 ).

[0193] In contrast, when the deviation between the upstream cumulative value ΣΔTin and the downstream cumulative value ΣΔTout is small, the processing circuit 111 of the engine control unit 110 executes an anomaly diagnosis process M50 to obtain an anomaly determination result, which indicates that the exhaust gas purification device (34) has been removed from the exhaust gas passage 30. Therefore, the engine control unit 110 can perform anomaly determination with high accuracy when the deviation ratio between the upstream cumulative value ΣΔTin and the downstream cumulative value ΣΔTout is small as a reference level.

[0194] (2) When the exhaust gas passage 30 from the engine 10 to the exhaust gas purification device (34) is long and the system is operating under low load, the changes in the upstream gas temperature Tin and the downstream gas temperature Tout are unlikely to differ. Therefore, for example, when making an anomaly determination by comparing the slope of the upstream gas temperature Tin and the slope of the downstream gas temperature Tout, misjudgment is likely to occur. In contrast, the anomaly diagnosis processing M50 of the engine control unit 110 uses the upstream cumulative value ΣΔTin and the downstream cumulative value ΣΔTout accumulated over a certain period (M30). Therefore, although this embodiment takes time, it can make anomaly determination with high accuracy compared to, for example, comparing the slope of the upstream gas temperature Tin and the slope of the downstream gas temperature Tout.

[0195] (3) Because the intake air volume Ga is large during high-load operation, the flow rate of exhaust gas through the exhaust gas purification device (34) also increases. Therefore, even when the exhaust gas purification device (34) is installed in the exhaust gas passage 30, the downstream cumulative value ΣΔTout tends to increase during high-load operation compared to non-high-load operation. Consequently, when the high-load cumulative air volume ΣGA is large, the quotient obtained by dividing the upstream cumulative value ΣΔTin by the downstream cumulative value ΣΔTout in the anomaly diagnosis process M50 becomes smaller. As a result, incorrect anomaly determinations may be made.

[0196] In contrast, during the threshold calculation process (S630), the higher the cumulative air volume ΣGA under high load, the smaller the diagnostic threshold dTth is set by the engine control unit 110. Therefore, the engine control unit 110 is able to suppress erroneous anomaly determinations.

[0197] (4) When temperature control is implemented, the temperature of the exhaust gas increases. Furthermore, the temperature Tout of the exhaust gas purification device (34) and the downstream gas tends to rise. Therefore, even when the exhaust gas purification device (34) is installed in the exhaust gas passage 30, the downstream cumulative value ΣΔTout tends to increase when temperature control is implemented compared to when it is not implemented. Therefore, when temperature control is implemented, the quotient obtained by dividing the upstream cumulative value ΣΔTin by the downstream cumulative value ΣΔTout in the anomaly diagnosis process M50 becomes smaller. As a result, incorrect anomaly determinations may be made. In contrast, in the threshold calculation process (S630) of the anomaly diagnosis process M50, the engine control unit 110 reduces the diagnostic threshold dTth (S750, S770) when the cumulative time of temperature control implementation is above a threshold (S740: Yes, S760: Yes). Therefore, the engine control unit 110 is able to suppress incorrect anomaly determinations.

[0198] (5) The higher the temperature of the exhaust gas purification device (34) when the exhaust gas passes through the exhaust gas purification device (34) after the engine 10 has started, the shorter the time from the completion of the engine 10's start-up until the downstream gas temperature Tout reaches the specified level. The engine control unit 110 uses the placement time tsoak and the initial downstream gas temperature Ts_out as index values ​​related to the temperature of the exhaust gas purification device (34) when the engine 10 has started (S510, S520). Then, the engine control unit 110 changes the magnitude of the judgment threshold Tf based on these index values ​​(S530). Therefore, by extending the time from the completion of the engine 10's start-up until the downstream gas temperature Tout reaches or exceeds the judgment threshold Tf, the time for cumulative value calculation processing M30 is ensured, thus enabling accurate abnormal diagnosis processing M50.

[0199] (6) If the placement time tsoak is short, the exhaust gas purification device (34) will not be sufficiently cooled, resulting in a high temperature. That is, the length of the placement time tsoak is an index value that is correlated with the temperature of the exhaust gas purification device (34) when the engine 10 is started. Therefore, the shorter the placement time tsoak, the larger the determination threshold Tf is set by the engine control unit 110 (S510, S530). As a result, the engine control unit 110 extends the time until the downstream gas temperature Tout reaches or exceeds the determination threshold Tf, thus ensuring the time for cumulative value calculation processing M30.

[0200] (7) The initial downstream gas temperature Ts_out is an index value that is correlated with the temperature of the upstream exhaust gas purification device (34). Therefore, the higher the initial downstream gas temperature Ts_out, the larger the determination threshold Tf is set by the engine control unit 110 (S520, S530). As a result, the engine control unit 110 extends the time until the downstream gas temperature Tout reaches or exceeds the determination threshold Tf, thus ensuring the time for cumulative value calculation processing M30.

[0201] (8) If the engine 10 is in a cold state when started, the deviation between the upstream cumulative value ΣΔTin and the downstream cumulative value ΣΔTout may differ depending on whether the exhaust gas purification device (34) is removed from the exhaust gas passage 30 or installed in the exhaust gas passage 30. That is, if the engine 10 is in a cold state when started, the engine control unit 110 can more accurately determine the abnormality in the abnormality diagnosis process M50. The engine control unit 110 performs the abnormality diagnosis process M50 based on the condition that a determination indicating a cold state has been made (M12, F2 = 1). Therefore, the engine control unit 110 can more accurately determine the abnormality in the abnormality diagnosis process M50.

[0202] (9) The lower the outside temperature, the more the engine 10 will reach a cold state even with a short placement time tsoak. Initially, the upstream gas temperature Ts_in represents a temperature close to the outside temperature. When the placement time tsoak is greater than a first predetermined time tth1 and less than a second predetermined time tth2 (S230: No, S240: No), the longer the placement time tsoak, the higher the allowable temperature Tth1 (S270, ...). Figure 8 Therefore, in the cold engine condition determination process M12, the engine control unit 110 can make a determination on whether the engine is in a cold engine condition in a way that is more in line with the actual situation (S280). Furthermore, the engine control unit 110 can ensure the opportunity for the abnormal diagnosis process M50.

[0203] (10) The anomaly diagnosis processing M50 focuses on the difference in heat capacity on the exhaust gas passage 30 caused by whether the exhaust gas purification device (34) is installed on the exhaust gas passage 30, and performs anomaly judgment based on the upstream cumulative value ΣΔTin and the downstream cumulative value ΣΔTout. After the downstream gas temperature Tout rises due to the operation of the engine 10, even if the cumulative value calculation processing M30 is re-performed, the anomaly judgment cannot be properly performed by the anomaly diagnosis processing M50.

[0204] Therefore, if the calculated conditions that should be met are not met, the engine control unit 110 will not perform subsequent calculation condition determination processing M10 and cumulative value calculation processing M30 during this stroke, and will not execute abnormal diagnosis processing M50. Thus, the engine control unit 110 can not only avoid the execution of inappropriate abnormal diagnosis processing M50, but also suppress the execution of useless processing.

[0205] (12) The temperature sensor readings may sometimes deviate significantly from the actual temperature due to noise. The engine control unit 110 does not update the gas temperature T if the reading deviates significantly from the judgment value Xth from the previously obtained value (S140: No). Therefore, it is possible to suppress the situation where the upstream gas temperature Tin and the downstream gas temperature Tout deviate significantly from the actual temperature due to the influence of noise.

[0206] (13) When the engine 10 stops, since no gas flow occurs in the exhaust gas passage 30, the fluctuation of the temperature sensor's detection value is small if the influence of noise is removed. On the other hand, when the engine 10 has finished starting, since exhaust gas flow occurs in the exhaust gas passage 30, the fluctuation of the temperature sensor's detection value increases even if the influence of noise is removed. In the gas temperature update process, the engine control unit 110 uses a first determination value X1 as the determination value Xth (S130) until the engine 10 has finished starting (S110: No). On the other hand, after the engine 10 has finished starting (S110: Yes), a second determination value X2, which is larger than the first determination value X1, is used as the determination value Xth (S120). That is, the engine control unit 110 changes the value of the determination value Xth according to the change in the magnitude of the fluctuation of the detection value before and after the start-up is completed. Therefore, the engine control unit 110 can suppress the situation where the gas temperature T is not updated due to the fluctuation of the original detection value.

[0207] (14) The processing circuit 111 executes a determination process M70 that outputs the determined diagnostic result by determining whether the result of the determination based on the anomaly diagnosis process M50 is determined as a formal diagnostic result. If the placement time tsoak is less than the first predetermined time tA (S820: Yes), the processing circuit 111 not only does not determine the result of the determination based on the anomaly diagnosis process M50 as a formal diagnostic result in the determination process M70, but also does not output the diagnostic result (F8 = 0).

[0208] If the dwell time (tsoak) is short, the exhaust gas system may not be sufficiently cooled, potentially preventing the proper anomaly diagnosis process (M50) from being performed based on the upstream gas temperature (Tin) and downstream gas temperature (Tout). Even if the engine control unit (ECU) determines that an anomaly diagnosis process (M50) is needed (S820: Yes), it will not recognize the result of the anomaly diagnosis process (M50) as a formal diagnosis result (F8 = 0). Furthermore, the engine control unit (ECU) will not output a diagnosis result. Therefore, the engine control unit (ECU) can suppress the output of inappropriate diagnosis results.

[0209] (15) If the placement time tsoak is sufficiently long (S830: Yes), the result of the appropriate abnormality diagnosis process M50 performed after starting from a cold state is determined solely based on the placement time tsoak (S850), thereby enabling the determination of the diagnosis result (S910). However, if the diagnosis result is determined only if the placement time tsoak is long enough to enable the determination of the diagnosis result solely based on the placement time tsoak, the chance of outputting the diagnosis result decreases.

[0210] When the placement time tsoak is greater than or equal to a first predetermined time tA and less than or equal to a second predetermined time tB (S830: No), the engine control unit 110 sets the allowable temperature Tprm in the external temperature determination process M60 to be larger the longer the placement time tsoak is (S860). Then, the engine control unit 110 uses the minimum intake air temperature Tmin as the estimated external temperature value based on the intake air temperature THA (S880). Then, the engine control unit 110 determines the diagnostic result in the determination process M70 and outputs it, assuming that the minimum intake air temperature Tmin is less than the allowable temperature Tprm (S890: Yes) (S910, S920).

[0211] When the vehicle is stationary, the temperature of the engine 10 is difficult to drop due to the accumulated heat in the engine compartment. Conversely, when the vehicle is moving and airflow enters the engine compartment, the accumulated heat is dissipated. Furthermore, the intake air temperature THA represents a temperature close to the outside air temperature compared to when the vehicle is stationary. The engine control unit 110 determines and outputs a diagnostic result in determination process M70 (S910, S920) based on the condition that the lowest intake air temperature Tmin obtained when the condition is met due to vehicle movement (S870: Yes) is less than the allowable temperature Tprm. Thus, through determination process M70, the engine control unit 110 can determine that the abnormal diagnostic process M50 was performed after starting from a cold engine state comparable to the outside air temperature. Furthermore, based on this determination, the engine control unit 110 can determine the result of the abnormal diagnostic process M50 as a formal diagnostic result and output it (S910, S920). That is, the engine control unit 110 can ensure the opportunity to output diagnostic results through the determination process M70 based on the estimated external temperature information estimated using the intake air temperature THA.

[0212] <Example of Change>

[0213] This embodiment can be implemented with the following modifications. This embodiment and the following modifications can be combined with each other to implement the same purpose as long as they are not technically contradictory.

[0214] · Figure 12The abnormal diagnosis processing M50 indicates an example where the deviation between the upstream cumulative value ΣΔTin and the downstream cumulative value ΣΔTout is less than a baseline level, based on the case where the quotient obtained by dividing the upstream cumulative value ΣΔTin by the downstream cumulative value ΣΔTout is less than the diagnostic threshold dTth (S640: No). However, the method for determining that the deviation between the upstream cumulative value ΣΔTin and the downstream cumulative value ΣΔTout is less than the baseline level is not limited to this. It can be appropriately modified. For example, it is also possible to determine that the deviation is less than the baseline level based on the case where the difference between the upstream cumulative value ΣΔTin and the downstream cumulative value ΣΔTout is less than the diagnostic threshold.

[0215] ·exist Figure 13 In the threshold calculation process (S630), the structure that the more high-load cumulative air volume ΣGA there is, the smaller the diagnostic threshold dTth will be.

[0216] ·exist Figure 13 In the threshold calculation process (S630), an example of switching the mapping is represented by the following: when the first cumulative time Σt1 is greater than or equal to the first threshold Σth1 (S740: Yes), the diagnostic threshold dTth is smaller than when the second cumulative time Σt2 is greater than or equal to the second threshold Σth2 (S760: Yes). Thus, it is not necessary to adopt a structure that changes the size of the diagnostic threshold dTth by dividing the heating control into a first heating control and a second heating control.

[0217] ·exist Figure 13 In the threshold calculation process (S630), the diagnostic threshold dTth can also be calculated without depending on whether temperature control is performed.

[0218] ·exist Figure 11 When calculating the determination threshold Tf in the end-of-calculation determination process M42, examples are shown using the placement time tsoak and the downstream gas temperature Ts_out at the start, as index values ​​related to the temperature of the exhaust gas purification device (34). Either can be used as the index value. Alternatively, the index value can be the water temperature THW. Alternatively, the index value can be the upstream gas temperature Tin.

[0219] ·exist Figure 7 In the cold engine state determination process M12, if the placement time tsoak is more than the first predetermined time tth1, it can be determined that the engine 10 is in a cold engine state when it is started.

[0220] ·exist Figure 14 In the external temperature determination process M60, the eighth flag F8 can also be set to "1" if the placement time tsoak is more than or equal to the first predetermined time tA.

[0221] • As an estimate of the DPM (Distribution Per Mille), it is not limited to Figure 2 The process is illustrated in the example. For instance, the buildup amount DPM can also be estimated based on the pressure difference between the upstream and downstream of the GPF34 and the intake air volume Ga. Specifically, when the pressure difference is large, the buildup amount DPM is estimated to be a larger value compared to the case where it is small. Furthermore, even if the pressure difference is the same, when the intake air volume Ga is small, the buildup amount DPM can be estimated to be a larger value compared to the case where it is large. Here, if the downstream pressure of the GPF34 is considered a constant value, the aforementioned pressure Pex can be used instead of the differential pressure.

[0222] • The arrangement of the three-way catalyst 32 and GPF34 in the exhaust gas passage 30 can also be such that GPF34 is located upstream of the three-way catalyst 32.

[0223] • The GPF34 is not limited to a filter carrying a three-way catalyst; it can be simply a filter. Furthermore, the GPF34 is not limited to being located downstream of the three-way catalyst 32 in the exhaust gas passage 30. Moreover, having a GPF34 is not mandatory. For example, the three-way catalyst 32 can also function as an exhaust gas purification device. The engine control unit 110 only needs to determine whether the exhaust gas purification device is disconnected from the exhaust gas passage 30. In this case, the upstream temperature sensor 87 detects the temperature upstream of the three-way catalyst 32. Additionally, both the three-way catalyst 32 and the GPF34 can function as an exhaust gas purification device.

[0224] • The engine control unit 110 is not limited to a control unit that performs software processing by having a processing circuit 111 and a memory. For example, it may also include a dedicated hardware circuit, such as an ASIC, that performs hardware processing on at least a portion of the software-processed portion in the above embodiment. That is, the engine control unit 110 may have any of the following structures (a) to (c): (a) It has a processing device that performs all of the above processing according to a program, a program storage device such as a ROM that stores the program (including a non-transitory computer-readable storage medium). (b) It has a processing device that performs a portion of the above processing according to a program, a program storage device, and a dedicated hardware circuit that performs the remaining processing. (c) It has a dedicated hardware circuit that performs all of the above processing. Here, there may be multiple software execution devices and dedicated hardware circuits that have processing devices and program storage devices.

[0225] • As a vehicle, it is not limited to a series-parallel hybrid vehicle; for example, it could also be a parallel hybrid vehicle or a series hybrid vehicle. However, it is not limited to hybrid vehicles; for example, it could also be a vehicle whose power generation device is solely the engine 10.

[0226] • An example of an inline four-cylinder engine with four cylinders is shown, but the engine 10 controlled by the engine control unit 110 is not limited to this. That is, the engine 10 is not limited to a four-cylinder engine. In addition, the engine 10 may also be a V-type engine, a horizontally opposed engine, or a W-type engine with an exhaust gas purification device (34) for each cylinder bank.

Claims

1. A control device for an internal combustion engine, wherein, The control device is suitable for the internal combustion engine mounted in a vehicle, and the control device has a processing circuit configured to perform cumulative value calculation and anomaly diagnosis. The cumulative value calculation process repeatedly obtains the upstream gas temperature and the downstream gas temperature. The upstream gas temperature represents the temperature of the exhaust gas upstream of the exhaust gas purification device in the exhaust gas path, and the downstream gas temperature represents the temperature of the exhaust gas downstream of the exhaust gas purification device. Furthermore, the cumulative value calculation process calculates the upstream cumulative value and the downstream cumulative value. The upstream cumulative value is the cumulative difference between the upstream gas temperature after the internal combustion engine starts and the upstream gas temperature at the start of the cumulative calculation. The downstream cumulative value is the cumulative difference between the downstream gas temperature after the internal combustion engine starts and the downstream gas temperature at the start of the cumulative calculation. The anomaly diagnosis process, using the deviation ratio between the upstream cumulative value and the downstream cumulative value up to the point where the downstream gas temperature reaches a threshold after the internal combustion engine starts as a benchmark, yields an anomaly determination result. This anomaly determination result indicates that the exhaust gas purification device has been removed. The threshold value is higher than the dew point. The processing circuit is configured such that, in the abnormal diagnosis process, when the quotient obtained by dividing the upstream cumulative value (up to the downstream cumulative value after the internal combustion engine starts and up to the determination threshold) by the downstream cumulative value is less than the diagnosis threshold, the abnormal determination result is obtained.

2. The control device for an internal combustion engine according to claim 1, wherein, The processing circuit is configured such that the greater the accumulated air volume under high load, the smaller the diagnostic threshold becomes. The high-load cumulative air volume is the cumulative value of the intake air volume during high-load operation from the time the downstream gas temperature reaches or exceeds the determination threshold after the internal combustion engine starts.

3. The control device for an internal combustion engine according to claim 2, wherein, When the accumulated time is above a threshold, the processing circuit reduces the diagnostic threshold compared to when the accumulated time is below the threshold. The cumulative time is the cumulative value of the time during which temperature rise control is performed from the time the downstream gas temperature reaches or exceeds the determination threshold after the internal combustion engine starts, and the temperature rise control causes the temperature of the exhaust gas flowing into the exhaust gas purification device to rise.

4. The control device for an internal combustion engine according to any one of claims 1 to 3, wherein, The processing circuit changes the value of the determination threshold based on an index value related to the temperature of the exhaust gas purification device when the internal combustion engine has finished starting.

5. The control device for an internal combustion engine according to claim 4, wherein, The index value includes the placement time of the internal combustion engine. The shorter the placement time, the higher the determination threshold is made by the processing circuit.

6. The control device for an internal combustion engine according to claim 4, wherein, The index value includes the downstream gas temperature when the internal combustion engine has finished starting. The higher the downstream gas temperature when the internal combustion engine completes startup, the higher the determination threshold is set by the processing circuit.

7. The control device for an internal combustion engine according to any one of claims 1 to 3, wherein, The processing circuit performs a cold engine status determination process, which determines whether the internal combustion engine is in a cold engine state at the time of startup based on the engine's idle time. The processing circuit is configured to perform the abnormal diagnosis process in the cold engine state determination process, based on the condition that a determination has been made indicating that the internal combustion engine is in a cold engine state at startup.

8. The control device for an internal combustion engine according to claim 7, wherein, The processing circuit is configured such that, if the placement time is less than a first predetermined time, it determines in the cold engine state determination process that the internal combustion engine is not in a cold engine state when it is started.

9. The control device for an internal combustion engine according to claim 8, wherein, If the placement time is longer than the second predetermined time, the processing circuit determines in the cold engine state determination process that the internal combustion engine is in a cold engine state at startup, where the second predetermined time is longer than the first predetermined time. The processing circuit is configured such that, when the placement time is longer than the first predetermined time and less than the second predetermined time, in the chiller state determination process, the longer the placement time, the higher the allowable temperature setting. The processing circuit is configured to determine that the internal combustion engine is in a cold state during startup, based on the condition that the upstream gas temperature is lower than the allowable temperature.

10. The control device for an internal combustion engine according to claim 7, wherein, The processing circuit performs a calculation condition determination process, which determines whether a calculation condition is met. The calculation condition includes a determination made in the cold engine state determination process that the internal combustion engine is in a cold engine state at startup. The processing circuit performs the cumulative value calculation based on the condition that the calculation conditions are met. The processing circuit is configured such that, during one trip of the vehicle system from operation to stop, if the temporarily established calculation conditions become invalid, subsequent calculation condition determination processing and cumulative value calculation processing are not performed during that trip, and the abnormality diagnosis processing is not executed.

11. The control device for an internal combustion engine according to any one of claims 1 to 3, wherein, The processing circuit is configured to update the upstream gas temperature and the downstream gas temperature through gas temperature update processing. The gas temperature update process updates the gas temperature to a value equal to the detected value if the deviation between the detected value and the previously obtained gas temperature is less than a judgment value.

12. The control device for an internal combustion engine according to claim 11, wherein, In the gas temperature update process, The processing circuit uses a first determination value as the determination value until the internal combustion engine has finished starting. After the internal combustion engine has started, the processing circuit uses a second determination value that is larger than the first determination value as the determination value.

13. The control device for an internal combustion engine according to any one of claims 1 to 3, wherein, The processing circuit is configured to perform a determination process. The determination process decides whether to accept the result of the abnormality diagnosis process as a formal diagnosis result, and outputs the determined diagnosis result. The processing circuit is configured such that, if the placement time of the internal combustion engine is less than a first predetermined time, the result of the determination based on the abnormality diagnosis process is not determined as a formal diagnosis result in the determination process, and thus the diagnosis result is not output.

14. The control device for an internal combustion engine according to claim 13, wherein, If the placement time is longer than the second predetermined time, the processing circuit, in the determination process, determines the result based on the anomaly diagnosis process as the formal diagnosis result and outputs the diagnosis result, wherein the second predetermined time is longer than the first predetermined time. The processing circuit is configured such that, when the placement time is longer than the first predetermined time and less than the second predetermined time, in the determination process, the longer the placement time, the higher the allowable temperature is set, and with the condition that the estimated external temperature value is less than the allowable temperature, the determination process determines the result based on the judgment of the abnormal diagnosis process as the formal diagnosis result, and outputs the diagnosis result, wherein the estimated external temperature value is based on the intake air temperature obtained when the condition is met due to the driving of the vehicle.

15. A control method for an internal combustion engine, wherein, The control method is applicable to the internal combustion engine mounted in a vehicle, the control method is executed by a processing circuit, and the control method includes: The upstream gas temperature is repeatedly obtained, whereby the upstream gas temperature represents the temperature of the exhaust gas in the exhaust gas passage of the internal combustion engine that is upstream of the exhaust gas purification device. The downstream gas temperature is repeatedly obtained, whereby the downstream gas temperature represents the temperature of the waste gas in the waste gas passage that is downstream of the waste gas purification device. Calculate the upstream cumulative value, which is the cumulative difference between the upstream gas temperature after the internal combustion engine starts and the upstream gas temperature at the cumulative start time. Calculate the downstream cumulative value, which is the cumulative difference between the downstream gas temperature after the internal combustion engine starts and the downstream gas temperature at the start time of the cumulative calculation; and An anomaly determination result is obtained when the deviation ratio between the upstream cumulative value and the downstream cumulative value up to the point where the downstream gas temperature reaches a threshold after the internal combustion engine starts is smaller than a baseline level. This anomaly determination result indicates that the exhaust gas purification device has been removed. The threshold value is higher than the dew point. The abnormality determination result is obtained when the quotient obtained by dividing the upstream cumulative value (up to the downstream cumulative value) by the downstream cumulative value after the internal combustion engine starts and the downstream gas temperature reaches or exceeds the determination threshold is less than the diagnostic threshold.

16. A non-transitory computer-readable storage medium storing a program that causes a processing circuit to perform control processing of an internal combustion engine, wherein, The control processing is applicable to the internal combustion engine mounted on the vehicle, and the control processing includes: The upstream gas temperature is repeatedly obtained, whereby the upstream gas temperature represents the temperature of the exhaust gas in the exhaust gas passage of the internal combustion engine that is upstream of the exhaust gas purification device. The downstream gas temperature is repeatedly obtained, whereby the downstream gas temperature represents the temperature of the waste gas in the waste gas passage that is downstream of the waste gas purification device. Calculate the upstream cumulative value, which is the cumulative difference between the upstream gas temperature after the internal combustion engine starts and the upstream gas temperature at the cumulative start time. Calculate the downstream cumulative value, which is the cumulative difference between the downstream gas temperature after the internal combustion engine starts and the downstream gas temperature at the start time of the cumulative calculation; and An anomaly determination result is obtained when the deviation ratio between the upstream cumulative value and the downstream cumulative value up to the point where the downstream gas temperature reaches a threshold after the internal combustion engine starts is smaller than a baseline level. This anomaly determination result indicates that the exhaust gas purification device has been removed. The threshold value is higher than the dew point. The abnormality determination result is obtained when the quotient obtained by dividing the upstream cumulative value (up to the downstream cumulative value) by the downstream cumulative value after the internal combustion engine starts and the downstream gas temperature reaches or exceeds the determination threshold is less than the diagnostic threshold.

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