Abnormality determination device for internal combustion engine and abnormality determination program for internal combustion engine

Abstract

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

Description

[Technical field]

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

[0002] The system of Patent Document 1 includes an internal combustion engine and an abnormality determination device. The internal combustion engine includes a plurality of cylinders, an exhaust passage, and a PM trapping device. The cylinders are spaces in which fuel is burned. The exhaust passage allows exhaust gas discharged from each cylinder to flow. The PM trapping device is attached midway through the exhaust passage. The PM trapping device traps particulate matter in the exhaust gas.

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

[0004] Therefore, the abnormality determination device of Patent Document 1 obtains an upstream temperature, which is the temperature of the exhaust gas upstream of the exhaust purification device in the exhaust passage.The abnormality determination device also obtains a downstream temperature, which is the temperature of the exhaust gas downstream of the exhaust purification device in the exhaust passage.The abnormality determination device then determines that the exhaust purification device has been removed from the exhaust passage when the absolute value of the difference between the upstream temperature and the downstream temperature becomes small. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2020-106028 A Summary of the Invention [Problem to be solved by the invention]

[0006] In an internal combustion engine such as that described in Patent Document 1, hydrocarbons may accumulate in the PM trapping device. If hydrocarbons accumulate in this way, the hydrocarbons in the PM trapping device may burn during operation of the internal combustion engine. If the hydrocarbons in the PM trapping device burn, the downstream temperature, which is the temperature of the exhaust gas downstream of the PM trapping device, may increase. In this case, the absolute value of the difference between the upstream temperature and the downstream temperature becomes small. Therefore, when such a situation occurs, there is a risk that it will be erroneously determined that the PM trapping device has been removed from the exhaust passage, even though the PM trapping device is actually attached to the exhaust passage. [Means for solving the problem]

[0007] An abnormality determination device for an internal combustion engine to solve the above problem is an abnormality determination device applied to an internal combustion engine that has a cylinder that combusts fuel, an exhaust passage through which exhaust gas discharged from the cylinder flows, and an exhaust purification device located in the exhaust passage and purifying the exhaust gas, and executes a first process of acquiring an upstream temperature that is the temperature of exhaust gas upstream of the exhaust purification device in the exhaust passage, a second process of acquiring a downstream temperature that is the temperature of exhaust gas downstream of the exhaust purification device in the exhaust passage, a third process of acquiring an exhaust flow rate that is the flow rate of exhaust gas flowing through the exhaust passage, a fourth process of determining whether the exhaust flow rate during operation of the internal combustion engine in the previous trip, when the upstream temperature is equal to or higher than a predetermined specified temperature, is equal to or higher than a predetermined reference flow rate, and a fifth process of determining whether the exhaust purification device has been removed from the exhaust passage based on the absolute value of the difference between the upstream temperature and the downstream temperature, with a positive determination in the fourth process being a necessary condition.

[0008] The abnormality determination program for an internal combustion engine to solve the above-mentioned problems is targeted at an abnormality determination device applied to an internal combustion engine that has a cylinder that combusts fuel, an exhaust passage through which exhaust gas discharged from the cylinder flows, and an exhaust purification device located in the exhaust passage and purifying the exhaust gas, and causes the abnormality determination device to execute a first process of acquiring an upstream temperature that is the temperature of exhaust gas upstream of the exhaust purification device in the exhaust passage, a second process of acquiring a downstream temperature that is the temperature of exhaust gas downstream of the exhaust purification device in the exhaust passage, a third process of acquiring an exhaust flow rate that is the flow rate of exhaust gas flowing through the exhaust passage, a fourth process of determining whether the exhaust flow rate during operation of the internal combustion engine in a previous trip, when the upstream temperature is equal to or higher than a predetermined specified temperature, is equal to or higher than a predetermined reference flow rate, and a fifth process of determining whether the exhaust purification device has been removed from the exhaust passage based on the absolute value of the difference between the upstream temperature and the downstream temperature, with a positive determination in the fourth process being a necessary condition. Effect of the Invention

[0009] In the above configuration, a positive determination in the fourth process indicates that relatively high-temperature exhaust gas flowed into the exhaust purification device during the previous trip. Therefore, if a positive determination is made in the fourth process, there is a high possibility that hydrocarbons in the exhaust purification device were combusted during the previous trip. Then, according to the above configuration, the fifth process is executed in a state where an excessive amount of hydrocarbons has not accumulated in the exhaust purification device. This makes it possible to execute the fifth process in a state where the influence of hydrocarbons that may cause erroneous determination of whether or not the exhaust purification device has been removed is low. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram of a vehicle. [Diagram 2] FIG. 2 is a flowchart showing the flag update control. [Diagram 3] FIG. 3 is a flowchart showing the first determination control. [Figure 4] FIG. 4 is a flowchart showing the second determination control. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] <Vehicle Overview> Hereinafter, one embodiment of the present invention will be described with reference to Figures 1 to 4. First, a schematic configuration of a vehicle 100 will be described.

[0012] 1, the vehicle 100 includes a spark ignition internal combustion engine 10. The vehicle 100 also includes a first motor generator 71 and a second motor generator 72 that function as both an electric motor and a generator. Therefore, the vehicle 100 is a so-called hybrid vehicle.

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

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

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

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

[0017] The exhaust passage 26 is connected to the cylinders 11. A portion of the exhaust passage 26, including the upstream end, branches into four. Each branched passage is connected to each cylinder 11. The exhaust passage 26 discharges exhaust gas from each cylinder 11 to the outside of the internal combustion engine 10. Note that exhaust valves (not shown) are located at the connections between the exhaust passage 26 and each cylinder 11. The exhaust valves open and close the connections between the exhaust passage 26 and the cylinders 11.

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

[0019] The GPF 28 is located downstream of the three-way catalyst 27 in the exhaust passage 26. In this embodiment, the GPF 28 is a filter carrying a three-way catalyst. Therefore, the GPF 28 is capable of collecting particulate matter contained in the exhaust flowing through the exhaust passage 26. Note that "GPF" is an abbreviation for Gasoline Particulate Filter. In this embodiment, the GPF 28 is an example of an exhaust purification device that is located in the exhaust passage 26 and purifies the exhaust.

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

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

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

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

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

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

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

[0027] The vehicle 100 is equipped with a control device 90. The control device 90 acquires signals indicating various values ​​from various sensors. That is, the control device 90 can execute a first process for acquiring an upstream temperature Tin. The control device 90 can also execute a second process for acquiring a downstream temperature Tout.

[0028] The control device 90 includes an execution unit 91 and a storage unit 92. An example of the execution unit 91 is a CPU. The storage unit 92 includes a ROM that can only be read, a volatile RAM that can be read and written, and a non-volatile storage that can be read and written. The storage unit 92 prestores a control program 92A as one of various programs. The execution unit 91 executes the control program 92A to realize various processes described below. In other words, the execution unit 91 executes the control program 92A to realize various processes related to abnormality determination of the internal combustion engine 10. In this embodiment, the control device 90 is an example of an abnormality determination device for the internal combustion engine 10. Also, the control program 92A is an example of an abnormality determination program for the internal combustion engine 10.

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

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

[0031] The control device 90 selects the EV mode, for example, when the charging rate of the battery 75 has a sufficient margin and the above-mentioned vehicle required driving force is small. Examples of when the vehicle required driving force is small include when the vehicle 100 starts moving and when the vehicle 100 is running under a light load with low acceleration. On the other hand, the control device 90 selects the HV mode, for example, when the charging rate of the battery 75 does not have a sufficient margin.

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

[0033] As shown in FIG. 2, when the execution unit 91 of the control device 90 starts flag update control, it executes the process of step S11. In step S11, the execution unit 91 judges whether the upstream temperature Tin is equal to or higher than a predetermined specified temperature A. Here, the specified temperature A is a temperature that is predetermined as the temperature of the exhaust gas at which hydrocarbons start to burn in the GPF 28. The specified temperature A is determined in advance through experiments, simulations, etc. An example of the specified temperature A is several hundred degrees Celsius. In step S11, when the execution unit 91 judges that the upstream temperature Tin is equal to or higher than the specified temperature A (S11: YES), the execution unit 91 advances the process to step S21.

[0034] In step S21, the execution unit 91 calculates a high-temperature exhaust flow rate FH, which is the flow rate of exhaust gas flowing through the exhaust passage 26 during operation of the internal combustion engine 10 in the current trip, and is the flow rate of exhaust gas when the upstream temperature Tin is equal to or higher than the specified temperature A. Specifically, the high-temperature exhaust flow rate FH is the accumulated amount of exhaust gas whose upstream temperature Tin is equal to or higher than the specified temperature A from the start of the current trip to the processing time of step S21. For example, the execution unit 91 calculates the high-temperature exhaust flow rate FH based on the intake air amount GA and the fuel injection amount from the fuel injection valve 23. Note that a trip is a period from when the system of the vehicle 100 is started to when the system of the vehicle 100 is shut down. In this embodiment, the processing of step S21 is an example of a third processing. After step S21, the execution unit 91 advances the processing to step S22.

[0035] In step S22, the execution unit 91 judges whether the high-temperature exhaust flow rate FH is equal to or greater than a predetermined reference flow rate ZA. Here, the reference flow rate ZA is a threshold value that is predetermined as a flow rate of exhaust gas at which the hydrocarbons in the GPF 28 are expected to be completely burned when exhaust gas whose upstream temperature Tin is equal to or greater than a specified temperature A flows into the GPF 28, even if the hydrocarbons in the GPF 28 are at a maximum value. The reference flow rate ZA is predetermined by experiments, simulations, and the like. In this embodiment, the process of step S22 is an example of a fourth process. In step S22, if the execution unit 91 judges that the high-temperature exhaust flow rate FH is less than the reference flow rate ZA (S22: NO), the execution unit 91 ends the current flag update control. Then, the execution unit 91 advances the process to step S11 again.

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

[0037] On the other hand, in the above-mentioned step S11, when the execution unit 91 determines that the upstream temperature Tin is lower than the specified temperature A (S11: NO), the execution unit 91 advances the process to step S31.

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

[0039] In step S32, the execution unit 91 determines whether the low-temperature exhaust flow rate FL is equal to or greater than a predetermined flow rate ZB. Here, the predetermined flow rate ZB is a threshold value that is predetermined as a flow rate of exhaust gas at which hydrocarbons are expected to accumulate in the GPF 28 when exhaust gas whose upstream temperature Tin is less than the specified temperature A flows into the GPF 28, even if the amount of hydrocarbons in the GPF 28 is at a minimum value. The predetermined flow rate ZB is predetermined by experiments, simulations, and the like. Note that the rate at which the amount of hydrocarbons in the GPF 28 increases when exhaust gas whose upstream temperature Tin is less than the specified temperature A flows into the GPF 28 is smaller than the rate at which the amount of hydrocarbons in the GPF 28 decreases when exhaust gas whose upstream temperature Tin is more than the specified temperature A flows into the GPF 28. Therefore, the predetermined flow rate ZB is predetermined as a value greater than the reference flow rate ZA. In this embodiment, the process of step S32 is an example of a sixth process. In step S32, when the execution unit 91 determines that the low-temperature exhaust flow rate FL is less than the predetermined flow rate ZB (S32: NO), the execution unit 91 ends the current flag update control. Then, the execution unit 91 advances the process to step S11 again.

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

[0041] <First judgment control> Next, the first determination control executed by the control device 90 will be described with reference to Fig. 3. This first determination control is the first control for determining whether or not the GPF 28 has been removed from the exhaust passage 26. In this embodiment, the control device 90 starts the first determination control every time the internal combustion engine 10 operates.

[0042] 3, when the execution unit 91 of the control device 90 starts the first determination control, it executes the process of step S41. In step S41, the execution unit 91 determines whether or not a predetermined precondition is satisfied. For example, the execution unit 91 determines that the precondition is satisfied when all of the following requirements (1) to (3) are satisfied.

[0043] Requirement (1): All sensors must be functioning normally. Requirement (2): The coolant temperature THW is equal to or higher than a predetermined first low temperature threshold. Requirement (3): The intake air temperature THA is equal to or higher than a predetermined second low temperature threshold.

[0044] Here, an example of the first low temperature threshold is "-15° C." Moreover, an example of the second low temperature threshold is "-15° C." In step S41, if the execution unit 91 determines that the precondition is satisfied (S41: YES), the execution unit 91 advances the process to step S42.

[0045] In step S42, the execution unit 91 determines whether or not a predetermined cooling condition is satisfied. For example, the execution unit 91 determines that the cooling condition is satisfied when all of the following requirements (4) to (6) are satisfied.

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

[0047] Here, the soak time Tsoak is a period from when the operation of the internal combustion engine 10 ends until the operation of the internal combustion engine 10 starts again. The specified period is set as a threshold for determining whether or not the soak time Tsoak has elapsed long enough for the GPF 28 to be sufficiently cooled. An example of the specified period is about several hours to a dozen hours. The first permission temperature is a threshold for determining whether or not the upstream temperature Tin is sufficiently low. An example of the first permission temperature is several tens of degrees Celsius. The second permission temperature is a threshold for determining whether or not the downstream temperature Tout is sufficiently low. An example of the second permission temperature is several tens of degrees Celsius. In step S42, when the execution unit 91 determines that the cooling condition is satisfied (S42: YES), the execution unit 91 advances the process to step S43.

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

[0049] In step S51, the execution unit 91 sets the upstream temperature Tin at the time of the process of step S51 as the start upstream temperature TSin After step S51, the execution unit 91 advances the process to step S52.

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

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

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

[0053] 4, when the execution unit 91 of the control device 90 starts the second determination control, it executes the process of step S61. In step S61, the execution unit 91 calculates the upstream change amount ΔTin, which is a value obtained by subtracting the start upstream temperature TSin from the upstream temperature Tin at the time of the process of step S61. After step S61, the execution unit 91 advances the process to step S62.

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

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

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

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

[0058] In step S66, the execution unit 91 determines whether the downstream temperature Tout is equal to or higher than the judgment temperature TF. If the execution unit 91 determines in step S66 that the downstream temperature Tout is lower than the judgment temperature TF (S66: NO), the execution unit 91 ends this second judgment control. Then, the execution unit 91 advances the process to step S61 again. On the other hand, if the execution unit 91 determines in step S66 that the downstream temperature Tout is equal to or higher than the judgment temperature TF (S66: YES), the execution unit 91 advances the process to step S71.

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

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

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

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

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

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

[0065] On the other hand, for example, when the internal combustion engine 10 operates for a relatively long period in the previous trip, the upstream temperature Tin is often equal to or higher than the specified temperature A. Then, the exhaust gas whose upstream temperature Tin is equal to or higher than the specified temperature A flows into the GPF 28, and the hydrocarbons in the GPF 28 are burned. Therefore, the possibility that the hydrocarbons are deposited in the GPF 28 at the end of the previous trip is low. In this case, the control device 90 repeatedly executes the flag update control in the previous trip, and thereby makes a positive determination in step S22, that is, determines that the high-temperature exhaust gas flow rate FH is equal to or higher than the reference flow rate ZA. As a result, the prohibition flag FA is turned OFF at the end of the previous trip. Then, in the first determination control of the current trip, the control device 90 makes a positive determination in step S43. Then, the control device 90 executes the second determination control in the current trip. That is, in the second determination control, the control device 90 executes a determination as to whether the GPF 28 is removed from the exhaust passage 26.

[0066] <Effects of this embodiment> (1) In this embodiment, the control device 90 executes the second determination control in the current trip on the prerequisite that the prohibition flag FA was OFF at the end of the previous trip, that is, that the high-temperature exhaust gas flow rate FH was determined to be equal to or greater than the reference flow rate ZA in the previous trip. As described above, in a situation in which the high-temperature exhaust gas flow rate FH is equal to or greater than the reference flow rate ZA in the previous trip, it is unlikely that the hydrocarbons in the GPF 28 have been burned and thus accumulated in the GPF 28. In other words, the control device 90 executes the second determination control in a state in which an excessive amount of hydrocarbons has not accumulated in the GPF 28. This makes it possible to execute a determination as to whether the GPF 28 has been removed from the exhaust passage 26 in a state in which the influence of hydrocarbons that may cause an erroneous determination as to whether the GPF 28 has been removed from the exhaust passage 26 is low.

[0067] (2) In the vehicle 100, for example, in the previous trip, a state in which the internal combustion engine 10 operates and a state in which the internal combustion engine 10 does not operate may be repeated. In such a situation, not only a state in which the upstream temperature Tin is equal to or higher than the specified temperature A, but also a state in which the upstream temperature Tin is lower than the specified temperature A may occur. In this case, even if the hydrocarbons in the GPF 28 are combusted by exhaust gas whose upstream temperature Tin is equal to or higher than the specified temperature A flowing into the GPF 28, the hydrocarbons may be deposited again in the GPF 28 by exhaust gas whose upstream temperature Tin is lower than the specified temperature A flowing into the GPF 28. In this regard, when the control device 90 determines in step S32 that the low-temperature exhaust gas flow rate FL is equal to or higher than the predetermined flow rate ZB, it sets the prohibition flag FA to ON. Therefore, when there is a possibility that the hydrocarbons are deposited again in the GPF 28 by exhaust gas whose upstream temperature Tin is lower than the specified temperature A flowing into the GPF 28, the control device 90 does not execute the second determination control in the current trip. In other words, the control device 90 executes the second determination control under the prerequisite that, in the previous trip, the processing of step S22 was positive and the processing of step S32 was not positive. This makes it possible to more accurately determine that no hydrocarbons have accumulated in the GPF 28. Then, the second determination control can be executed after accurately determining that no hydrocarbons have accumulated in the GPF 28.

[0068] (3) For example, the absolute value of the difference between the upstream temperature Tin and the downstream temperature Tout may temporarily increase depending on the operating conditions of the internal combustion engine 10. Therefore, if the GPF 28 is determined to be removed from the exhaust passage 26 when the absolute value of the difference between the upstream temperature Tin and the downstream temperature Tout increases, erroneous determination is likely to occur depending on the operating conditions of the internal combustion engine 10.

[0069] In this regard, in the second determination control, the control device 90 calculates an upstream integral value ΣΔTin, which is a value obtained by integrating the upstream change amount ΔTin based on the upstream temperature Tin. The control device 90 also calculates a downstream integral value ΣΔTout, which is a value obtained by integrating the downstream change amount ΔTout based on the downstream temperature Tout. Then, when a quotient Q calculated from the upstream integral value ΣΔTin and the downstream integral value ΣΔTout is less than the diagnostic threshold value QA, the control device 90 determines that the GPF 28 is removed from the exhaust passage 26. That is, according to the present embodiment, since the integral value of the upstream temperature Tin and the integral value of the downstream temperature Tout are used, it is possible to reduce the possibility that the determination result will change simply because the absolute value of the difference between the upstream temperature Tin and the downstream temperature Tout increases temporarily.

[0070] (4) In the present embodiment, the vehicle 100 is a so-called hybrid vehicle that includes a first motor generator 71 and a second motor generator 72 as driving sources in addition to the internal combustion engine 10 as a driving source. In such a vehicle 100, the period during which the internal combustion engine 10 operates tends to be shorter than in a configuration that includes only the internal combustion engine 10 as a driving source. Therefore, it is particularly preferable to apply the present technology to such a vehicle 100.

[0071] <Example of change> This embodiment can be modified as follows: This embodiment and the following modifications can be combined with each other to the extent that there is no technical contradiction.

[0072] In the above embodiment, the flag update control may be changed. For example, the configuration for taking into account the influence of exhaust when the upstream temperature Tin is less than the specified temperature A may be changed. As a specific example, in order to take into account the influence of exhaust when the upstream temperature Tin is less than the specified temperature A, the execution unit 91 may increase the reference flow rate ZA in step S22 the more times the negative determination is made in step S11. In this case, the processing of steps S31 to S33 may be omitted. Note that, depending on the configuration of the internal combustion engine 10, there may be a low possibility that hydrocarbons will accumulate in the GPF 28 due to exhaust gas whose upstream temperature Tin is less than the specified temperature A flowing into the GPF 28. In such a case, even if the processing of steps S31 to S33 is omitted in a configuration in which the reference flow rate ZA is a fixed value, the impact is small.

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

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

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

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

[0077] For example, the exhaust purification device may be changed. As a specific example, the GPF 28 may include one of a filter and a three-way catalyst. In this case, one of the filter and the three-way catalyst in the GPF 28 is the exhaust purification device. As a specific example, the exhaust purification device may be the three-way catalyst 27 instead of the GPF 28. In this case, it is sufficient that the upstream temperature sensor 87 is located upstream of the three-way catalyst 27 in the exhaust passage 26. It is sufficient that the downstream temperature sensor 88 is located downstream of the three-way catalyst 27 in the exhaust passage 26. [Explanation of symbols]

[0078] 10... internal combustion engine 11... cylinder 12... crankshaft 21... intake passage 22... throttle valve 23... fuel injection valve 24... ignition device 26... exhaust passage 27... three-way catalyst 28... GPF 40... first planetary gear mechanism 50... second planetary gear mechanism 62... reduction mechanism 63... differential mechanism 64... drive wheels 71... first motor generator 72... second motor generator 75... battery 87... upstream temperature sensor 88... downstream temperature sensor 90... control device 91... execution unit 92... memory unit 92A... control program 100... vehicle

Claims

1. An abnormality determination device that is applied to an internal combustion engine that includes a cylinder that combusts fuel, an exhaust passage through which exhaust gas discharged from the cylinder flows, and an exhaust purification device that is located in the exhaust passage and purifies the exhaust gas, a first process of acquiring an upstream temperature, which is a temperature of exhaust gas upstream of the exhaust purification device in the exhaust passage; a second process of acquiring a downstream temperature, which is a temperature of exhaust gas downstream of the exhaust purification device in the exhaust passage; a third process of acquiring an exhaust flow rate, which is a flow rate of exhaust gas flowing through the exhaust passage; a fourth process for determining whether or not the exhaust flow rate during operation of the internal combustion engine in a previous trip, in a state in which the upstream temperature is equal to or higher than a predetermined specified temperature, is equal to or higher than a predetermined reference flow rate; a fifth process for determining whether or not the exhaust purification device has been removed from the exhaust passage based on an absolute value of the difference between the upstream temperature and the downstream temperature, with the affirmative determination being a necessary condition of the fourth process; Run An abnormality determination device for an internal combustion engine.

2. In the fifth process, calculating an index value indicating a difference between an integral value of the upstream temperature during a period from when the internal combustion engine starts operating until when the downstream temperature becomes equal to or higher than a predetermined judgment temperature, and an integral value of the downstream temperature during the same period; determining that the exhaust purification device is removed from the exhaust passage when the index value is smaller than a predetermined reference value; Run The abnormality determination device for an internal combustion engine according to claim 1.

3. In the fifth process, calculating an index value indicating an integral value of a rate of change per unit time of the upstream temperature during a period from when the internal combustion engine starts to operate until when the downstream temperature becomes equal to or higher than a predetermined judgment temperature, and a difference between the rate of change per unit time of the downstream temperature during the same period; determining that the exhaust purification device is removed from the exhaust passage when the index value is smaller than a predetermined reference value; Run The abnormality determination device for an internal combustion engine according to claim 1.

4. a sixth process of determining whether the exhaust flow rate during operation of the internal combustion engine in a previous trip, when the upstream temperature is lower than the specified temperature, is equal to or greater than a predetermined flow rate that is greater than the reference flow rate, The fifth process is executed under the prerequisite that the fourth process is determined to be positive and the sixth process is not determined to be positive. The abnormality determination device for an internal combustion engine according to any one of claims 1 to 3.

5. The present invention is directed to an abnormality determination device that is applied to an internal combustion engine that includes a cylinder that burns fuel, an exhaust passage through which exhaust gas discharged from the cylinder flows, and an exhaust purification device that is located in the exhaust passage and purifies the exhaust gas, The abnormality determination device includes: a first process of acquiring an upstream temperature, which is a temperature of exhaust gas upstream of the exhaust purification device in the exhaust passage; a second process of acquiring a downstream temperature, which is a temperature of exhaust gas downstream of the exhaust purification device in the exhaust passage; a third process of acquiring an exhaust flow rate, which is a flow rate of exhaust gas flowing through the exhaust passage; a fourth process for determining whether or not the exhaust flow rate during operation of the internal combustion engine in a previous trip, in a state in which the upstream temperature is equal to or higher than a predetermined specified temperature, is equal to or higher than a predetermined reference flow rate; a fifth process for determining whether or not the exhaust purification device has been removed from the exhaust passage based on an absolute value of the difference between the upstream temperature and the downstream temperature, with the affirmative determination being a necessary condition of the fourth process; Run A program for determining abnormalities in internal combustion engines.

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