Hybrid vehicle control device and hybrid vehicle control program

Abstract

A control device for a hybrid vehicle and a control program for a hybrid vehicle, wherein the control device is capable of executing a first diagnostic process and a second diagnostic process, wherein in the first diagnostic process, when a first execution condition is satisfied, a towing process is executed and the air-fuel ratio sensor is diagnosed for abnormality, and in the second diagnostic process, when a second execution condition is satisfied, a towing process is executed and the GPF is diagnosed for abnormality. In the execution determination process, the control device prohibits the execution of both the first diagnostic process and the second diagnostic process when at least one of the first execution condition and the second execution condition is not satisfied, and permits the execution of both the first diagnostic process and the second diagnostic process when both the first execution condition and the second execution condition are satisfied.

Description

Technical Field

[0001] The present invention relates to a control device for a hybrid vehicle and a control program for a hybrid vehicle. Background Art

[0002] The vehicle disclosed in Japanese Patent Application Laid-Open No. 2010-179712 includes an internal combustion engine, an electric generator, and a control device. The internal combustion engine includes a cylinder and an output shaft that rotates according to the combustion of fuel in the cylinder. The electric generator is connected to the output shaft of the internal combustion engine. The electric generator can impart torque to the output shaft of the internal combustion engine to rotate the output shaft.

[0003] The control device can execute a motoring process in which the output shaft of the internal combustion engine is rotated by the motor generator while fuel supply to the cylinder is stopped. The control device performs diagnosis on a plurality of diagnostic items related to the internal combustion engine while executing the motoring process. Summary of the invention

[0004] In the technology of diagnosing an internal combustion engine by using a drag process as in Japanese Patent Laid-Open No. 2010-179712, depending on the diagnostic item, the state of the internal combustion engine may need to satisfy certain conditions in order to obtain an appropriate diagnostic result. In the case where such a diagnostic item exists, depending on the state of the internal combustion engine when the drag process is executed, the diagnostic item requiring the above conditions may not be diagnosed. If even one undiagnosed item is assumed, the drag process must be performed again for the diagnosis of the diagnostic item.

[0005] The control device for a hybrid vehicle for solving the above-mentioned problems is applicable to a hybrid vehicle, the hybrid vehicle having an internal combustion engine and an electric motor capable of rotating an output shaft of the internal combustion engine, the internal combustion engine having an air-fuel ratio sensor for detecting an air-fuel ratio of exhaust gas, a filter for capturing particulate matter in the exhaust gas, and a state detection sensor for detecting the temperature or pressure of the exhaust gas on the upstream and downstream sides of the filter, the control device being capable of executing a dragging process, a first diagnostic process and a second diagnostic process, in which the output shaft of the internal combustion engine is rotated by the electric motor in a state where the fuel supply to the cylinders in the internal combustion engine is stopped, and in the first diagnostic process, when a first execution condition including a condition that there is no output request for the internal combustion engine is satisfied, the control device executes a dragging process. The dragging process is performed and the air-fuel ratio sensor is diagnosed to have abnormality based on the detection signal of the air-fuel ratio sensor. In the second diagnostic process, when the second execution condition including the condition that there is no output request for the internal combustion engine and including a condition different from the first execution condition is met, the dragging process is performed and the filter is diagnosed to have abnormality based on the detection signal of the state detection sensor. The control device performs an execution determination process. In the execution determination process, when at least one of the first execution condition and the second execution condition is not met, the execution of both the first diagnostic process and the second diagnostic process is prohibited, and when both the first execution condition and the second execution condition are met, the execution of both the first diagnostic process and the second diagnostic process is allowed.

[0006] According to the above structure, even if the first execution condition is satisfied, if the second execution condition is not satisfied, the execution of both diagnostic processes is prohibited. Therefore, in two diagnostic processes with different execution conditions, only one diagnostic process will not be performed. On the other hand, when both the first execution condition and the second execution condition are satisfied, the execution of both diagnostic processes is allowed. Therefore, when the execution conditions of both diagnostic processes are met, the two diagnostic processes can be executed together. With such a structure, when the drag process is used to diagnose the internal combustion engine, the number of executions of the drag process can be suppressed to a minimum.

[0007] In the control device of a hybrid vehicle, the state detection sensor may be a first temperature sensor for detecting the temperature of the exhaust gas on the upstream side of the filter, and a second temperature sensor for detecting the temperature of the exhaust gas on the downstream side of the filter, and the second execution condition may include a condition that the detection temperature of the first temperature sensor or the second temperature sensor is above a specified temperature.

[0008] When the dragging process is performed, the temperature of the gas flowing in the exhaust passage gradually decreases as air is introduced into the exhaust passage. That is, when the dragging process starts, the temperature of the gas in the exhaust passage decreases regardless of the upstream or downstream side of the filter. In the case of a filter, during the execution of the dragging process, when the gas passes through the filter, the gas obtains heat from the filter that has been heated before the start of the dragging process. That is, after the dragging process is started in a state where the temperature of the exhaust gas is high to a certain extent, the temperature and the way the temperature changes on the upstream and downstream sides of the filter will differ depending on whether the filter is correctly installed and whether there is a gas leak in the filter. According to the above-mentioned structure, when the temperature of the exhaust gas is above the specified temperature, the filter is diagnosed for abnormality based on the temperature on the upstream and downstream sides of the filter, so that accurate abnormality diagnosis can be performed.

[0009] In the control device of a hybrid vehicle, when the amount of change per unit time of the detected temperature of the first temperature sensor is set as the first temperature change amount and the amount of change per unit time of the detected temperature of the second temperature sensor is set as the second temperature change amount, in the second diagnostic processing, the presence or absence of abnormality of the filter is diagnosed based on a value obtained by accumulating a detection parameter which is a value obtained by subtracting the first temperature change amount from the second temperature change amount within a certain period after the start of the drag processing.

[0010] The detection parameter is a variable indicating the amount of heat received by the gas from the filter when the gas passes through the filter. As described above, the amount of heat received by the gas from the filter changes depending on whether the filter has an abnormality. Therefore, by using the detection parameter to diagnose the filter, it is possible to appropriately diagnose whether the filter has an abnormality.

[0011] In the control device for a hybrid vehicle, the second execution condition may include a condition that the temperature detected by the first temperature sensor is equal to or higher than the temperature detected by the second temperature sensor.

[0012] Assuming that the filter is removed from the exhaust passage, the gas is not affected by the heat from the filter, so the detection parameter is close to zero. On the other hand, when the filter is present in the exhaust passage and the gas receives heat from the filter, the value of the detection parameter is greater than zero. The above configuration is suitable for distinguishing between normal and abnormal conditions of the filter using the detection parameter indicating such characteristics.

[0013] A control program for a hybrid vehicle for solving the above-mentioned problems causes a control device of the hybrid vehicle to execute a drag process, a first diagnostic process, a second diagnostic process, and an execution determination process. The hybrid vehicle comprises an internal combustion engine and an electric motor capable of rotating an output shaft of the internal combustion engine. The internal combustion engine comprises an air-fuel ratio sensor for detecting an air-fuel ratio of exhaust gas, a filter for collecting particulate matter in the exhaust gas, and a state detection sensor for detecting the temperature or pressure of the exhaust gas on the upstream and downstream sides of the filter. In the drag process, the output shaft of the internal combustion engine is rotated by the electric motor in a state where fuel supply to cylinders in the internal combustion engine is stopped. In the first diagnostic process, in the first diagnostic process including a condition that there is no output request for the internal combustion engine, When the execution condition is met, the dragging process is performed and the air-fuel ratio sensor is diagnosed for abnormality based on the detection signal of the air-fuel ratio sensor. In the second diagnostic process, when the second execution condition including the condition that there is no output request for the internal combustion engine and including a condition different from the first execution condition is met, the dragging process is performed and the filter is diagnosed for abnormality based on the detection signal of the state detection sensor. In the execution determination process, when at least one of the first execution condition and the second execution condition is not met, the execution of both the first diagnostic process and the second diagnostic process is prohibited, and when both the first execution condition and the second execution condition are met, the execution of both the first diagnostic process and the second diagnostic process is allowed.

[0014] According to the above structure, even if the first execution condition is satisfied, if the second execution condition is not satisfied, the execution of both diagnostic processes is prohibited. Therefore, in two diagnostic processes with different execution conditions, only one diagnostic process will not be performed. On the other hand, when both the first execution condition and the second execution condition are satisfied, the execution of both diagnostic processes is allowed. Therefore, when the execution conditions of both diagnostic processes are met, the two diagnostic processes can be executed together. With such a structure, when the drag process is used to diagnose the internal combustion engine, the number of executions of the drag process can be suppressed to a minimum. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, in which like reference numerals represent like elements, and in which:

[0016] Figure 1 This is a schematic diagram of the vehicle.

[0017] Figure 2A This is a diagram showing an example of temporal changes in various parameters after the start of the drag process when the GPF is normal.

[0018] Figure 2B This is a diagram showing an example of temporal changes in various parameters after the start of the drag process when the GPF is normal.

[0019] Figure 3A This is a diagram showing the situation in which an abnormality occurs in the GPF. Figure 2A Figure 1 shows an example of the corresponding time variation.

[0020] Figure 3B This is a diagram showing the situation in which an abnormality occurs in the GPF. Figure 2B Figure 1 shows an example of the corresponding time variation.

[0021] Figure 4 This is a flowchart showing the processing procedure of the first process.

[0022] Figure 5 This is a flowchart showing the processing procedure of the second process.

[0023] Figure 6 Detailed description of the process flow of executing the determination process. DETAILED DESCRIPTION

[0024] Hereinafter, an embodiment of a control device for a hybrid vehicle will be described with reference to the drawings.

[0025] <General structure of the vehicle>

[0026] like Figure 1 As shown, a hybrid vehicle (hereinafter referred to as a vehicle) 500 includes an internal combustion engine 10, a first motor generator (hereinafter referred to as a first MG) 71, a second motor generator (hereinafter referred to as a second MG) 72, a battery 73, and a battery sensor 89. In addition, the vehicle 500 includes a planetary gear mechanism 40, a reduction gear 50, a drive shaft 60, a differential 61, and drive wheels 62.

[0027] The internal combustion engine 10, the first MG71, and the second MG72 serve as the driving source of the vehicle 500. The details of the internal combustion engine 10 will be described later. The first MG71 is a generator motor having the functions of both a motor and a generator. The second MG72 is a generator motor like the first MG71. The first MG71 and the second MG72 are electrically connected to the battery 73 via a converter. The battery 73 supplies power to the first MG71 and the second MG72, or stores the power supplied from the first MG71 and the second MG72. The converter performs a DC to AC power conversion. In addition, Figure 1 The illustration of the converter is omitted. The battery sensor 89 is mounted on the battery 73. The battery sensor 89 detects battery information B such as the current, voltage, and temperature of the battery 73.

[0028] The internal combustion engine 10 and the first MG 71 are connected to the planetary gear mechanism 40. The planetary gear mechanism 40 has a sun gear 41, a ring gear 42, a plurality of pinion gears 43, and a planetary carrier 44. The sun gear 41 is an external gear. The ring gear 42 is an internal gear. The ring gear 42 can rotate coaxially with the sun gear 41. The plurality of pinion gears 43 are interposed between the sun gear 41 and the ring gear 42. The plurality of pinion gears 43 mesh with both the sun gear 41 and the ring gear 42. The planetary carrier 44 supports the plurality of pinion gears 43. The planetary carrier 44 can rotate coaxially with the sun gear 41.

[0029] The sun gear 41 is connected to the rotation shaft of the first MG 71. The planetary carrier 44 is connected to the crankshaft 20 which is the output shaft of the internal combustion engine 10. The ring gear 42 is connected to the drive shaft 60. The drive shaft 60 is connected to the second MG 72 via the reduction gear 50. The reduction gear 50 reduces the torque of the second MG 72 and transmits it to the drive shaft 60. In addition, the drive shaft 60 is connected to the left and right drive wheels 62 via the differential 61. The differential 61 allows the left and right drive wheels 62 to have a rotation speed difference.

[0030] The internal combustion engine 10 and the first MG 71 can transmit power to each other via the planetary gear mechanism 40. When the torque of the internal combustion engine 10 is input to the first MG 71, the first MG 71 functions as a generator. On the other hand, when the first MG 71 functions as a motor, the torque of the first MG 71 can rotate the crankshaft 20.

[0031] In addition, when the vehicle 500 is decelerated, the second MG 72 is made to function as a generator, thereby generating a regenerative braking force corresponding to the amount of power generated by the second MG 72 in the vehicle 500. On the other hand, when the second MG 72 is made to function as a motor, the torque of the second MG 72 can be input to the drive wheel 62 via the reduction gear 50, the drive shaft 60, and the differential 61.

[0032] The vehicle 500 includes an accelerator sensor 91 and a vehicle speed sensor 92. The accelerator sensor 91 detects an accelerator operation amount ACP, which is an operation amount of an accelerator pedal in the vehicle 500. The vehicle speed sensor 92 detects a vehicle speed SP, which is a running speed of the vehicle 500.

[0033] Although not shown in the figure, the vehicle 500 has a first warning light 98 and a second warning light 99. The first warning light 98 and the second warning light 99 are located in the cabin of the vehicle 500. The first warning light 98 and the second warning light 99 are lights for warning of abnormality related to the internal combustion engine 10.

[0034] <General structure of an internal combustion engine>

[0035] The internal combustion engine 10 includes an engine body 10A, the crankshaft 20 described above, and a crank angle sensor 88 .

[0036] The internal combustion engine body 10A has four cylinders 11. Each cylinder 11 is a space obtained by dividing the internal combustion engine body 10A. Although not shown in the figure, each cylinder 11 accommodates a piston. The piston can reciprocate in each cylinder 11. The piston in each cylinder 11 is connected to the crankshaft 20 via a connecting rod. The crankshaft 20 rotates according to the reciprocating motion of the piston in each cylinder 11. The crankshaft angle sensor 88 is located near the crankshaft 20. The crankshaft angle sensor 88 detects the rotational position of the crankshaft 20 as the detected rotational position Scr.

[0037] The internal combustion engine 10 has four spark plugs 19. Each spark plug 19 is provided for each cylinder 11. The tip of each spark plug 19 is located in each cylinder 11. Each spark plug 19 ignites a mixture of air and fuel in each cylinder 11 by spark discharge.

[0038] The internal combustion engine 10 has an intake passage 15, an air flow meter 87, a throttle valve 13, and four fuel injection valves 17. The intake passage 15 is a passage for sucking air into each cylinder 11. The intake passage 15 is connected to each cylinder 11. The air flow meter 87 is located in the middle of the intake passage 15. The air flow meter 87 detects the amount of intake air as the detected intake air amount GA. The throttle valve 13 is located on the downstream side of the air flow meter 87 in the intake passage 15. The throttle valve 13 adjusts the amount of intake air. The four fuel injection valves 17 are located on the downstream side of the throttle valve 13 in the intake passage 15. The four fuel injection valves 17 are provided for each cylinder 11. The four fuel injection valves 17 inject fuel. The fuel injected by each fuel injection valve 17 is supplied to each cylinder 11.

[0039] The internal combustion engine 10 has an exhaust passage 21, a three-way catalyst 22, and a gasoline particulate filter (hereinafter referred to as GPF) 23. The exhaust passage 21 is a passage for discharging exhaust gas from each cylinder 11. The exhaust passage 21 is connected to each cylinder 11. The three-way catalyst 22 is located in the middle of the exhaust passage 21. The three-way catalyst 22 purifies the exhaust gas. The three-way catalyst 22 has an oxygen storage capacity. The GPF 23 is located on the downstream side of the three-way catalyst 22 in the exhaust passage 21. The GPF 23 captures particulate matter contained in the exhaust gas.

[0040] The internal combustion engine 10 has an air-fuel ratio sensor 81, a first temperature sensor 83, and a second temperature sensor 84. The air-fuel ratio sensor 81 is located on the upstream side of the three-way catalyst 22 in the exhaust passage 21. The air-fuel ratio sensor 81 detects the air-fuel ratio of the gas on the upstream side of the three-way catalyst 22 in the exhaust passage 21 as a detected air-fuel ratio AS. The first temperature sensor 83 is located between the three-way catalyst 22 and the GPF 23 in the exhaust passage 21. The first temperature sensor 83 detects the temperature of the gas between the three-way catalyst 22 and the GPF 23 in the exhaust passage 21 as a first detected temperature T1. The second temperature sensor 84 is located on the downstream side of the GPF 23 in the exhaust passage 21. The second temperature sensor 84 detects the temperature of the gas on the downstream side of the GPF 23 in the exhaust passage 21 as a second detected temperature T2. The first temperature sensor 83 and the second temperature sensor 84 constitute a state detection sensor.

[0041] <General structure of control device>

[0042] The vehicle 500 has a control device 100. The control device 100 can be configured as one or more processors that perform various processes according to a computer program (software). In addition, the control device 100 can also be configured as a circuit (circuitry) that includes one or more dedicated hardware circuits such as an integrated circuit (ASIC) for a specific purpose that performs at least a part of the various processes, or a combination of the above-mentioned one or more dedicated hardware circuits and the above-mentioned one or more processors. The processor includes a CPU, and a memory such as RAM and ROM. The memory stores program codes or instructions that enable the CPU to perform processing. The memory, i.e., a computer-readable medium, includes all available media that can be accessed by a general or special-purpose computer. The control device 100 has a storage device that is a non-volatile memory that can be electrically rewritten.

[0043] The control device 100 receives detection signals from various sensors mounted on the vehicle 500. Specifically, the control device 100 receives detection signals regarding the following parameters.

[0044] The accelerator operation amount ACP detected by the accelerator sensor 91

[0045] The vehicle speed SP detected by the vehicle speed sensor 92

[0046] Battery information B detected by battery sensor 89

[0047] Air flow meter 87 detects the intake air volume GA

[0048] · Detection rotation position Scr detected by the crank angle sensor 88

[0049] · Detected air-fuel ratio AS detected by the air-fuel ratio sensor 81

[0050] The first detected temperature T1 detected by the first temperature sensor 83

[0051] The second detected temperature T2 detected by the second temperature sensor 84

[0052] The control device 100 calculates the rotation speed of the crankshaft 20 per unit time, that is, the internal combustion engine speed NE, based on the detected rotation position Scr. In addition, the control device 100 calculates the storage amount SOC of the battery 73 based on the battery information B.

[0053] The control device 100 has a general control unit 102. The general control unit 102 controls the internal combustion engine 10, the first MG 71, and the second MG 72. The general control unit 102 calculates the required value of the driving force of the vehicle 500, that is, the vehicle required output, based on the accelerator operation amount ACP and the vehicle speed SP. In addition, the general control unit 102 calculates the required value of the output torque of the internal combustion engine 10, that is, the internal combustion engine required torque TE, based on the vehicle required output and the storage capacity SOC. In addition, the general control unit 102 calculates the required value of the power running torque or regeneration torque of the first MG 71, that is, the first MG required torque TG1, based on the vehicle required output and the storage capacity SOC. In addition, the general control unit 102 calculates the required value of the power running torque or regeneration torque of the second MG 72, that is, the second MG required torque TG2, based on the vehicle required output and the storage capacity SOC. In addition, the general control unit 102 controls the internal combustion engine 10 according to the internal combustion engine required torque TE. Furthermore, the overall control unit 102 controls the first MG 71 based on the first MG required torque TG1 , and controls the second MG 72 based on the second MG required torque TG2 .

[0054] <Drag processing>

[0055] The general control unit 102 can execute a drag process as a process for controlling the internal combustion engine 10 and the first MG 71. The drag process is a process for rotating the crankshaft 20 by the first MG 71 in a state where the fuel supply to each cylinder 11 in the internal combustion engine 10 is stopped. In the drag process, the general control unit 102 controls the internal combustion engine 10 in a manner that stops the fuel injection from each fuel injection valve 17 and the ignition based on each spark plug 19. In addition, in the drag process, the general control unit 102 controls the first MG 71 in a manner that the internal combustion engine speed NE becomes an idle speed. The idle speed is the minimum internal combustion engine speed NE at which the internal combustion engine 10 can continue to operate autonomously. The general control unit 102 can execute the drag process based on the execution request signal of the drag process output by other functional units of the control device 100. In addition, the general control unit 102 executes the drag process when there is no output request for the internal combustion engine 10, that is, when the internal combustion engine required torque TE is less than zero.

[0056] <First treatment>

[0057] Control device 100 performs processing related to diagnosis of vehicle 500. Hereinafter, the processing of the diagnosis will be described.

[0058] The control device 100 has a first processing unit 104. The first processing unit 104 can execute a first process as a process for diagnosing the internal combustion engine 10. The first processing unit 104 can execute a first diagnostic process as a part of the first process. The first diagnostic process is a process for diagnosing whether the air-fuel ratio sensor 81 has an abnormality based on the detection of the air-fuel ratio AS while executing the drag process when the first execution condition is satisfied. The above-mentioned first execution condition includes the following items.

[0059] (A1) The first diagnostic process is not completed during one trip.

[0060] (A2) The crankshaft 20 is rotating.

[0061] (A3) There is no output request to the internal combustion engine 10.

[0062] Regarding item (A1), one trip refers to a period from when the ignition switch of vehicle 500 is turned on to when it is turned off. Item (A1) is set so that the first diagnosis process is completed once during one trip.

[0063] Item (A2) is determined by taking into account the power consumption caused by performing the dragging process. As described above, the first diagnostic process is accompanied by the execution of the dragging process. When the dragging process is performed in a state where the rotation of the crankshaft 20 is stopped, the power required to start the rotation of the crankshaft 20 through the first MG 71 and increase the internal combustion engine speed NE to the idle speed will consume corresponding power. Therefore, item (A2) is set to avoid performing the dragging process when the crankshaft 20 is stopped, and to perform the first diagnostic process only when the crankshaft 20 is already rotating.

[0064] Item (A3) is set as a necessary condition for performing the drag process.

[0065] In the first diagnostic process, the following diagnostic method is used to diagnose whether the air-fuel ratio sensor 81 is abnormal. That is, the first processing unit 104 diagnoses the air-fuel ratio sensor 81 using the detected air-fuel ratio AS after the first judgment period H1 set in advance has passed since the start of the engine-turning process. The first processing unit 104 determines that the air-fuel ratio sensor 81 is normal when the detected air-fuel ratio AS after the first judgment period H1 is a value within the predetermined judgment range, and otherwise determines that the air-fuel ratio sensor 81 is abnormal. When the crankshaft 20 rotates in a state where the engine-turning process is started and the fuel supply to the cylinder 11 is stopped, air is discharged from the cylinder 11 to the exhaust passage 21. The first judgment period H1 is determined by experiments, for example, as the time required for the gas flowing in the exhaust passage 21 to be replaced from exhaust gas to air after the engine-turning process is started. The first judgment period H1 is, for example, several seconds. The above-mentioned judgment range is determined by experiments, for example, as the range of values ​​that the air-fuel ratio sensor 81 should detect when the gas flowing in the exhaust passage 21 becomes air.

[0066] <Process 2>

[0067] The control device 100 has a second processing unit 106. The second processing unit 106 can execute a second processing as a processing for diagnosing the internal combustion engine 10. The second processing unit 106 can execute a second diagnostic processing as a part of the second processing. The second diagnostic processing is a processing for diagnosing whether the GPF23 has an abnormality based on the detected temperatures detected by the first temperature sensor 83 and the second temperature sensor 84 while executing the drag processing when the second execution condition is satisfied. In the second diagnostic processing, the second processing unit 106 mainly diagnoses whether the GPF23 is defective as an abnormality of the GPF23. The defect of the GPF23 refers to a situation where the GPF23 is removed from the exhaust passage 21. As a situation where the GPF23 is removed from the exhaust passage 21, there is a situation where the entire GPF23 is removed from the exhaust passage 21, and there is also a situation where a part of the GPF23, such as a part of the GPF23 on the downstream side than the center, is removed from the exhaust passage 21.

[0068] The second execution condition mentioned above includes the following items.

[0069] (B1) The second diagnostic process is not completed during one trip.

[0070] (B2) The crankshaft 20 is rotating.

[0071] (B3) There is no output request to the internal combustion engine 10.

[0072] (B4) The first detected temperature T1 is equal to or higher than the predetermined temperature TK.

[0073] (B5) The first detected temperature T1 is equal to or higher than the second detected temperature T2.

[0074] Items (B1) to (B3) are set from the same perspective as items (A1) to (A3) of the first execution condition. Items (B4) and (B5) are set from the perspective of the necessity of ensuring the diagnostic accuracy of the second diagnostic process. The reason why items (B4) and (B5) are required as the second execution condition will be described later.

[0075] <Diagnostic principle of the second diagnostic process>

[0076] In the second diagnosis process, the temperature of the gas around the GPF 23 is used to perform a diagnosis related to the GPF 23. First, the principle of the diagnosis and the parameters used as indicators of the diagnosis are described.

[0077] As described above, when the dragging process starts, air is discharged from the cylinder 11 to the exhaust passage 21. Along with this, the temperature of the gas flowing in the exhaust passage 21 gradually decreases. Figure 2A As shown in FIG. 1 , when the dragging process is started at time tm1, the first detected temperature T1 on the upstream side of the GPF 23 and the second detected temperature T2 on the downstream side of the GPF 23 both decrease with the passage of time. Figure 1 As shown by the thin arrow in FIG. 1 , when there is a GPF 23 in the exhaust passage 21, when the gas passes through the GPF 23, the gas obtains heat from the GPF 23 which has become high temperature due to the heat of the exhaust gas before the start of the drag process. Figure 2A As shown in FIG. 1 , the decrease in the second detected temperature T2 from the start of the dragging process is smaller than the decrease in the first detected temperature T1. On the other hand, when the GPF 23 is removed from the exhaust passage 21, the gas does not receive heat from the GPF 23. Figure 3A As shown, when GPF23 is removed from exhaust passage 21, after time tm1 when the dragging process is started, the decrease in the second detected temperature T2 is the same as the decrease in the first detected temperature T1. In the second diagnostic process, the characteristics of the temperature change related to the heat exchange between GPF23 and the gas as described above are used to diagnose whether GPF23 is abnormal. In addition, as described in the above-mentioned item (B4), the diagnosis of GPF23 is performed when the first detected temperature T1 on the upstream side of GPF23 is higher than the second detected temperature T2 on the downstream side. In this regard, Figure 2A and Figure 3A In the example shown, the first detected temperature T1 is higher than the second detected temperature T2. The reason why the item (B4) is required as the second execution condition will be described later.

[0078] As an index representing the characteristics of the above-mentioned temperature change, the detection parameter Z is used in the second diagnostic process. The detection parameter Z is a variable representing the amount of heat received by the gas from the GPF23 when passing through the GPF23, and is defined by the amount of change in the heat of the gas around the GPF23 (hereinafter referred to as the heat change amount). Here, for the heat change amount ΔQ1 of the gas at the upstream side of the GPF23, the heat ΔQg obtained by the gas from the GPF23, and the heat change amount ΔQ2 of the gas at the downstream side of the GPF23, the relationship of formula (1) holds. That is, the value obtained by adding the heat change amount ΔQ1 of the gas at the upstream side of the GPF23 to the heat ΔQg obtained by the gas from the GPF23 becomes the heat change amount ΔQ2 of the gas at the downstream side of the GPF23.

[0079] ΔQ1+ΔQg=ΔQ2···(1)

[0080] By modifying the above formula (1), the following formula (2) can be obtained as a relationship formula representing the amount of heat ΔQg taken by the gas from the GPF 23. That is, the amount of heat ΔQg taken by the gas from the GPF 23 can be calculated as a value obtained by subtracting the amount of heat change ΔQ1 on the upstream side of the GPF 23 from the amount of heat change ΔQ2 on the downstream side of the GPF 23.

[0081] ΔQg=ΔQ2-ΔQ1···(2)

[0082] The heat change of the gas is the product of the specific heat, the amount of gas, and the temperature change of the gas. On the upstream and downstream sides of GPF23, the specific heats are the same, and the amount of gas is also the same. Therefore, if the product of the above-mentioned specific heat and the amount of gas is set to the gas constant V, the right side of formula (2) can be summarized by the gas constant V, and the right side can be divided into the gas constant V and the term related to the temperature change of the gas. That is, as shown in formula (3), the heat ΔQg obtained by the gas from GPF23 can be expressed as the product of the gas constant V and the term related to the temperature change of the gas. The term related to the temperature change of the gas is a value obtained by subtracting the temperature change at the upstream side of GPF23, that is, the change in the second detected temperature T2 (hereinafter, referred to as the second temperature change) ΔT2, from the change in the temperature at the downstream side of GPF23, that is, the change in the first detected temperature T1 (hereinafter, referred to as the first temperature change) ΔT1. Furthermore, the temperature change amount is, for example, a value obtained by subtracting the temperature of the gas at the first timing of a certain period from the temperature of the gas at the last timing of the certain period when it is assumed that the temperature of the gas changes during the certain period.

[0083] ΔQg=V·(ΔT2-ΔT1)···(3)

[0084] As shown in formula (4), the above-mentioned detection parameter Z is determined as a term related to the temperature change of the gas in formula (3). Based on the relationship of formula (3), the detection parameter Z is proportional to the amount of heat received by the gas from GPF23 when passing through GPF23. That is, the detection parameter Z is a variable representing the amount of heat received by the gas from GPF23 when passing through GPF23.

[0085] Z=(ΔT2-ΔT1)···(4)

[0086] The detection parameter Z can be a positive value or a negative value according to the first temperature change amount ΔT1 and the second temperature change amount ΔT2. In addition, as described above, when the drag process starts, the temperature of the gas flowing in the exhaust passage 21 decreases. Therefore, based on the definition of the temperature change amount, as Figure 2B As shown in FIG. 1 , both the first temperature change amount ΔT1 and the second temperature change amount ΔT2 become negative values.

[0087] <Specific diagnostic method of the second diagnostic treatment>

[0088] In the second diagnosis process, the above-mentioned detection parameter Z is used to perform the diagnosis related to the GPF 23 as follows. Figure 2B As shown, the second processing unit 106 calculates the detection parameter Z per unit time, for example, after the moment tm1 at which the dragging process is started. Then, the second processing unit 106 accumulates the calculated detection parameter Z from the moment tm1 until the moment tm2 after the second judgment period H2. In addition, the above-mentioned unit time is the same as the time interval at which the control device 100 receives the first detection temperature T1 and the second detection temperature T2. The second processing unit 106 calculates the first temperature change ΔT1 per unit time by subtracting the first detection temperature T1 received at the previous time from the latest first detection temperature T1 received by the control device 100. In addition, the second processing unit 106 calculates the second temperature change ΔT2 in the same manner. Then, the second processing unit 106 applies the above-mentioned calculated first temperature change ΔT1 and second temperature change ΔT2 to formula (4) to calculate the detection parameter Z per unit time.

[0089] When the cumulative value of the detection parameter Z calculated in this way is positive and large, the gas has taken a lot of heat from GPF23. In this case, it can be inferred that GPF23 exists in the exhaust passage 21, that is, GPF23 is normal, and there is heat exchange between GPF23 and the gas. By the way, as described above, when GPF23 is normal, the second detection temperature T2 on the downstream side of GPF23 includes the heat effect from GPF23. Therefore, if Figure 2BAs shown in FIG. 1 , when the GPF 23 is normal, the second temperature change amount ΔT2, which is a negative value, is larger than the first temperature change amount ΔT1, which is a negative value. Reflecting this, the cumulative value of the detection parameter Z is larger than zero. Figure 2B In FIG. 1 , the accumulated value of the detection parameter Z is represented by a dotted area.

[0090] On the other hand, Figure 3B As shown in FIG. 1 , when the cumulative value of the detection parameter Z calculated by the second processing unit 106 is small, the amount of heat taken by the gas from the GPF 23 is small. In this case, it can be inferred that the entire or a part of the GPF 23 is removed from the exhaust passage 21, that is, an abnormality occurs in the GPF 23, and there is no heat exchange between the GPF 23 and the gas, or the heat exchange is small. Figure 3B As shown, when an abnormality occurs in the GPF 23, the difference between the second temperature change amount ΔT2 and the first temperature change amount ΔT1 is small. Reflecting this, the integrated value of the detection parameter Z approaches zero.

[0091] Based on the above, in the second diagnostic processing, the second processing unit 106 determines that GPF23 is normal when the cumulative value of the detection parameter Z is greater than the predetermined judgment value ZK. On the other hand, when the cumulative value of the detection parameter Z is less than the judgment value ZK, it is determined that GPF23 is abnormal. In addition, the above-mentioned second judgment period H2 is determined, for example, by experiments, to be a length that can clearly distinguish the difference in the cumulative value of the detection parameter Z when GPF23 is normal and when it is abnormal. The second judgment period H2 is the same as the first judgment period H1, for example, several seconds. In addition, the above-mentioned judgment value ZK is determined, for example, by experiments, to be the minimum value that the cumulative value of the detection parameter Z can take when the second judgment period H2 has passed since the start of the dragging process when GPF23 is normal.

[0092] <Items concerning the second execution condition (B4)>

[0093] In order to improve the diagnostic accuracy when the above method is used, the second execution condition includes the item (B4) that the first detected temperature T1 is equal to or higher than the predetermined temperature TK. The reason for this will be described below.

[0094] The higher the temperature of the exhaust gas at the start of the drag process, the greater the amount of temperature reduction of the gas from the start of the drag process to the temperature of the gas being stabilized to a certain level. In the second process, the characteristic of the temperature reduction of the gas after the start of the drag process is utilized, so it is required to ensure the temperature reduction of the gas accordingly. First, from such a point of view, item (B4) is necessary. In addition, due to the thermodynamic properties of the gas, the higher the temperature of the exhaust gas at the time point of the start of the drag process, the higher the rate of temperature reduction of the gas after the start of the drag process. Here, it is assumed that the temperature of the exhaust gas at the time point of the start of the drag process is low. In this case, when calculating the detection parameter Z per unit time, the first temperature change ΔT1 per unit time after the start of the drag process and the second temperature change ΔT2 per unit time become smaller due to the thermodynamic properties of the gas described above. Under such a condition, even if there is a GPF23 in the exhaust passage 21 and the gas obtains heat from the GPF23, it is difficult to produce a difference between the first temperature change ΔT1 per unit time and the second temperature change ΔT2 per unit time. Therefore, the detection parameter Z per unit time is close to zero. In this case, when the integrated value of the detection parameter Z is calculated, it is difficult to distinguish between a normal state and an abnormal state of the GPF 23 , and therefore it is difficult to diagnose the GPF 23 with high accuracy.

[0095] In contrast, when the temperature of the exhaust gas at the time of starting the dragging process is high, the first temperature change amount ΔT1 per unit time and the second temperature change amount ΔT2 per unit time are basically large. Therefore, when the GPF 23 is present in the exhaust passage 21 and the gas obtains heat from the GPF 23, a difference easily occurs between the first temperature change amount ΔT1 per unit time and the second temperature change amount ΔT2 per unit time, and the detection parameter Z per unit time and the cumulative value of the detection parameter Z become large. Therefore, it is possible to appropriately distinguish between the normal state and the abnormal state of the GPF 23, and to diagnose the GPF 23 with high accuracy.

[0096] Due to the above reasons, item (B4) is determined as one of the second execution conditions. The above-mentioned prescribed temperature TK is determined, for example, through experiments as a temperature at which the diagnosis of GPF23 can be performed with high accuracy using the detection parameter Z. The prescribed temperature TK is, for example, 550°C. In addition, in item (B4), the first detected temperature T1 on the upstream side of GPF23 is compared with the prescribed temperature TK, rather than the second detected temperature T2 on the downstream side. This is based on the following reasons. As described above, the value of the second detected temperature T2 is affected by the presence or absence of GPF23, while the value of the first detected temperature T1 is not affected by the presence or absence of GPF23. In terms of always grasping the temperature environment around GPF23 based on the same benchmark regardless of the presence or absence of GPF23, it is preferred to use the first detected temperature T1 whose value is not affected by the presence or absence of GPF23.

[0097] <Items concerning the second execution condition (B5)>

[0098] Similar to item (B4), in order to improve the diagnostic accuracy, the second execution condition includes item (B5) that the first detected temperature T1 is equal to or higher than the second detected temperature T2.

[0099] As described in connection with the content of item (B4), in terms of diagnosing the GPF 23 with high accuracy using the detection parameter Z, it is preferable to set the detection parameter Z when the GPF 23 is normal to a value extremely large compared to zero. Therefore, it is preferable to perform the second diagnostic processing in the internal combustion engine operating state in which the value of the detection parameter Z tends to increase. In addition, after the start of the drag processing, the first temperature change amount ΔT1 and the second temperature change amount ΔT2 that define the detection parameter Z both take negative values. Therefore, if the absolute value of the first temperature change amount ΔT1 per unit time is large and the absolute value of the second temperature change amount ΔT2 per unit time is small after the start of the drag processing, the detection parameter Z per unit time increases. That is, if the decreasing speed of the first detected temperature T1 is high and the decreasing speed of the second detected temperature T2 is low, the value of the detection parameter Z increases. Therefore, as the internal combustion engine operating state for performing the second diagnostic processing, if the decreasing speed of the first detected temperature T1 tends to increase and the decreasing speed of the second detected temperature T2 tends to decrease, it is advantageous in terms of improving the diagnostic accuracy.

[0100] As described above, due to the nature of the rate of decrease in gas temperature, the higher the first detected temperature T1 at the time of starting the dragging process, the higher the rate of decrease in the first detected temperature T1. In addition, the lower the second detected temperature T2 at the time of starting the dragging process, the lower the rate of decrease in the second detected temperature T2. Therefore, if the first detected temperature T1 becomes higher than the second detected temperature T2 at the time of starting the dragging process, the rate of decrease in the first detected temperature T1 is likely to be higher than the rate of decrease in the second detected temperature T2 as the initial internal combustion engine operating state. In addition, in the case where the first detected temperature T1 becomes higher than the second detected temperature T2 at the time of starting the dragging process, although the value of the detection parameter Z when the GPF23 is removed from the exhaust passage 21 may be greater than zero, from the viewpoint of increasing the difference in the detection parameter Z when the GPF23 is normal and abnormal, the necessary condition that the first detected temperature T1 is higher than the second detected temperature T2 has a higher effect.

[0101] In addition to the above, item (B5) is determined based on the correlation between the running state of the vehicle 500 and the temperature environment around the GPF 23. That is, the condition in which the first detected temperature T1 is higher than the second detected temperature T2 is one of the conditions that the internal combustion engine 10 is likely to produce during the running of the vehicle 500 due to the configuration of the exhaust passage 21. Specifically, the condition in which the first detected temperature T1 is higher than the second detected temperature T2 is a condition that is bound to occur as long as the vehicle 500 is accelerating. Here, during the acceleration of the vehicle 500, the three-way catalyst 22 located on the upstream side of the GPF 23 becomes a heat source that generates heat due to the combustion of unburned fuel. The first detected temperature T1 detected by the first temperature sensor 83 located between the three-way catalyst 22 and the GPF 23 basically reflects the temperature of the three-way catalyst 22. On the other hand, the GPF 23 does not generate heat by itself, but receives heat transmitted from the three-way catalyst 22 and the temperature rises. Therefore, the temperature of the GPF 23 is delayed relative to the three-way catalyst 22 and follows the temperature of the three-way catalyst 22. The second detected temperature T2 detected by the second temperature sensor 84 located downstream of the GPF 23 basically reflects the temperature of the GPF 23. Therefore, during the acceleration period of the vehicle 500, the second detected temperature T2 rises following the first detected temperature T1. Therefore, during the acceleration period of the vehicle 500, the first detected temperature T1 tends to be higher than the second detected temperature T2. Since there is such a correlation between the driving state of the vehicle 500 and the temperature environment around the GPF 23, if the necessary condition that the first detected temperature T1 is higher than the second detected temperature T2 is met, the opportunity to meet the necessary condition can be ensured accordingly. Taking this view into consideration, item (B5) is set.

[0102] In addition, during the deceleration period of the vehicle 500, the correlation between the first detected temperature T1 and the second detected temperature T2 is opposite to that during the acceleration period. As a premise, even during the deceleration period of the vehicle 500, the temperature of the GPF23 changes due to the heat transfer of the three-way catalyst 22. And, during the deceleration period of the vehicle 500, while the temperature of the GPF23 is kept high, the temperature of the three-way catalyst 22 decreases first, and the temperature of the GPF23 decreases accordingly. Therefore, during the deceleration period of the vehicle 500, especially during the extreme deceleration period, the first detected temperature T1 tends to become less than the second detected temperature T2. Since item (B5) is set as the second execution condition, the second diagnostic processing is basically not performed during the deceleration period of the vehicle 500.

[0103] <Execution judgment processing>

[0104] The control device 100 has an execution determination unit 108. The execution determination unit 108 is capable of executing an execution determination process as a process for allowing or prohibiting the execution of the first diagnostic process and the second diagnostic process. In the execution determination process, the execution determination unit 108 prohibits the execution of both the first diagnostic process and the second diagnostic process when at least one of the first execution condition and the second execution condition is not satisfied. On the other hand, in the execution determination process, the execution determination unit 108 allows the execution of both the first diagnostic process and the second diagnostic process when both the first execution condition and the second execution condition are satisfied. As described above, the control device 100 has the first processing unit 104, the second processing unit 106, and the execution determination unit 108 as functional units for diagnosing the internal combustion engine 10.

[0105] <Specific processing steps of the first processing>

[0106] The specific processing steps of the first processing, the second processing, and the execution determination processing are described. In addition, the first processing unit 104, the second processing unit 106, and the execution determination unit 108 perform the first processing, the second processing, and the execution determination processing in parallel. At this time, the first processing unit 104, the second processing unit 106, and the execution determination unit 108 perform their respective processing while referring to the activation / inactivation (ON / OFF) of the flag set by other functional units.

[0107] The processing steps of the first process are explained. When the ignition switch of the vehicle 500 is turned on, the first processing unit 104 starts the first process. In addition, in the first process, the activation / inactivation of the first completion flag FC1, which is a flag indicating the completion of the first diagnostic process, is switched. The activation of the first completion flag FC1 indicates that the first diagnostic process has been completed, and the inactivation of the first completion flag FC1 indicates that the first diagnostic process has not been completed. At the time point when the ignition switch of the vehicle 500 is turned on, the first completion flag FC1 is inactivated. In addition, in the first process, the activation / inactivation of the first condition flag FJ1 indicating the establishment of the first execution condition is switched. The inactivation of the first condition flag FJ1 indicates that the first execution condition is not established, and the activation of the first condition flag FJ1 indicates that the first execution condition is established. At the time point when the ignition switch of the vehicle 500 is turned on, the first condition flag FJ1 is inactivated.

[0108] like Figure 4 As shown, when the first processing unit 104 starts the first processing, the processing of step S110 is executed. In step S110, the first processing unit 104 sets the first condition flag FJ1 to inactive. In addition, when the processing of step S110 is executed for the first time after the first processing is started, the first processing unit 104 maintains the first condition flag FJ1 as inactive. After the first processing unit 104 completes the processing of step S110, the processing proceeds to step S120.

[0109] In step S120, the first processing unit 104 determines whether the first execution condition is satisfied. That is, the first processing unit 104 determines whether all three items (A1) to (A3) of the first execution condition are satisfied. Regarding the incomplete diagnosis specified by item (A1), the first processing unit 104 refers to the first completion flag FC1 to determine whether the item can be satisfied. When the first completion flag FC1 is inactive, the first processing unit 104 determines that the first diagnostic processing is incomplete. In addition, due to the setting of the processing content of the first processing, when executing step S120, the first completion flag FC1 is always inactive. As described later, the first completion flag FC1 is activated when the first processing is about to end, and its information is used in the execution determination processing.

[0110] Regarding the rotation of the crankshaft 20 specified in item (A2), the first processing unit 104 refers to the latest engine speed NE to determine whether the item is satisfied. The first processing unit 104 determines that the crankshaft 20 is rotating when the engine speed NE is greater than zero, and otherwise determines that the crankshaft 20 is stopped.

[0111] Regarding the output request of the internal combustion engine 10 specified by item (A3), the first processing unit 104 refers to the latest internal combustion engine required torque TE to determine whether the item is established. The first processing unit 104 determines that there is no output request for the internal combustion engine 10 when the internal combustion engine required torque TE is zero or less, and determines that there is an output request for the internal combustion engine 10 in other cases.

[0112] The first processing unit 104 determines that the first execution condition is not satisfied even if there is one unsatisfied item among the three items (A1) to (A3) (step S120: NO). In this case, the first processing unit 104 executes the process of step S120 again. The first processing unit 104 repeatedly performs the process of step S120 until all three items (A1) to (A3) are satisfied. And, when all three items (A1) to (A3) are satisfied, the first processing unit 104 determines that the first execution condition is satisfied (step S120: YES). In this case, the first processing unit 104 advances the process to step S130.

[0113] In step S130 , the first processing unit 104 turns on the first condition flag FJ1 . Then, the first processing unit 104 advances the process to step S140 .

[0114] In step S140, the first processing unit 104 determines whether the permission flag FA is activated. The permission flag FA is a flag that switches between activation and inactivation by executing the determination process, and the activation / inactivation switching will be described later. The permission flag FA is a flag indicating whether the execution of the first diagnostic process is permitted or prohibited. When it is activated, the execution of the first diagnostic process is permitted, and when it is inactivated, the first diagnostic process is prohibited. When the permission flag FA is inactive (step S140: No), the first processing unit 104 returns to the process of step S110. In this case, the first processing unit 104 performs the process after step S110 again.

[0115] On the other hand, if the permission flag FA is on (step S140: Yes), the first processing unit 104 advances the process to step S150. The time interval from the end of the process of step S130 to the start of the process of step S140 is longer than the time interval required to execute a series of processes of the determination process.

[0116] In step S150, the first processing unit 104 performs the first diagnostic processing. That is, the first processing unit 104 starts to output the execution request signal of the drag processing to the general control unit 102. Accordingly, the general control unit 102 starts the drag processing. Thereafter, the first processing unit 104 waits for the first judgment period H1. Then, when the first judgment period H1 has passed since the start of outputting the execution request signal of the drag processing, the first processing unit 104 stops outputting the execution request signal. Accordingly, the general control unit 102 ends the drag processing. When stopping the output of the execution request signal of the drag processing, the first processing unit 104 refers to the latest detected air-fuel ratio AS. Then, the first processing unit 104 determines whether the air-fuel ratio sensor 81 is abnormal by determining whether the detected air-fuel ratio AS is within the determination range. In the case of an abnormality in the air-fuel ratio sensor 81, the first processing unit 104 stores the content and lights up the first warning light 98. After completing the process of step S150 , the first processing unit 104 proceeds to step S160 .

[0117] In step S160, the first processing unit 104 sets the first completion flag FC1 to be active. Thereafter, the first processing unit 104 ends a series of processing of the first processing. In addition, during the execution of the above-mentioned step S150, an output request to the internal combustion engine 10 may be generated, that is, the internal combustion engine required torque TE may be greater than zero. In this case, the first processing unit 104 interrupts the processing of step S150 and restarts the first processing from step S110.

[0118] <Specific processing steps of the second processing>

[0119] The processing steps of the second process are described. The second process is a process in which the content of the first process is replaced with a second diagnostic process, and the basic content is the same as the first process. Therefore, the description of the second process that overlaps with the description of the first process is appropriately omitted or abandoned.

[0120] The second processing unit 106 starts the second processing when the ignition switch of the vehicle 500 is turned on. In the second processing, the activation / inactivation of the second completion flag FC2, which indicates the completion of the second diagnostic processing, is switched. The second completion flag FC2 is the same as the first completion flag FC1. In addition, in the second processing, the activation / inactivation of the second condition flag FJ2, which indicates the establishment of the second execution condition, is switched. The second condition flag FJ2 is the same as the first condition flag FJ1. At the time point when the ignition switch of the vehicle 500 is turned on, the second completion flag FC2 and the second condition flag FJ2 are both inactive.

[0121] like Figure 5 As shown, when the second processing unit 106 starts the second processing, the processing of step S210 is executed. In step S210, the second processing unit 106 sets the second condition flag FJ2 to inactive. When the second processing unit 106 completes the processing of step S210, the processing proceeds to step S220.

[0122] In step S220, the second processing unit 106 determines whether the second execution condition is satisfied. That is, the second processing unit 106 determines whether all five items (B1) to (B5) of the second execution condition are satisfied. The second processing unit 106 determines whether items (B1) to (B3) are satisfied in the same manner as the first processing. For the necessary condition of the first detection temperature T1 specified by item (B3), the second processing unit 106 refers to the latest first detection temperature T1 to determine whether the item is satisfied. For the magnitude relationship between the first detection temperature T1 and the second detection temperature T2 specified by item (B5), the second processing unit 106 refers to their respective latest values ​​to determine whether the item is satisfied.

[0123] The second processing unit 106 determines that the second execution condition is not satisfied even if there is one unsatisfied item among the five items (B1) to (B5) (step S220: No). In this case, the second processing unit 106 executes the processing of step S220 again. The second processing unit 106 repeatedly performs the processing of step S220 until all five items (B1) to (B5) are satisfied. And, when all five items (B1) to (B5) are satisfied, the second processing unit 106 determines that the second execution condition is satisfied (step S220: Yes). In this case, the second processing unit 106 advances the processing to step S230.

[0124] In step S230, the second processing unit 106 turns on the second condition flag FJ2. Then, the second processing unit 106 advances the process to step S240.

[0125] In step S240, the second processing unit 106 determines whether the permission flag FA is activated. The permission flag FA is not only a flag indicating whether the execution of the first diagnostic process is permitted or prohibited, but also a flag indicating whether the execution of the second diagnostic process is permitted or prohibited. When the permission flag FA is inactive (step S240: No), the second processing unit 106 returns to the process of step S210. In this case, the second processing unit 106 performs the process after step S210 again.

[0126] On the other hand, if the permission flag FA is active (step S240: Yes), the second processing unit 106 advances the process to step S250. Also, as in the first process, the time interval from the end of the process of step S230 to the start of the process of step S240 is longer than the time interval required to execute a series of processes of the determination process.

[0127] In step S250, the second processing unit 106 performs the second diagnostic processing. That is, the second processing unit 106 starts to output the execution request signal of the drag processing. Then, the second processing unit 106 calculates the detection parameter Z per unit time and accumulates the calculated detection parameter Z. The second processing unit 106 continues the processing until the second determination period H2 has passed since the start of outputting the execution request signal of the drag processing. When the second determination period H2 has passed, the second processing unit 106 stops outputting the execution request signal of the drag processing. Thereafter, the second processing unit 106 determines whether there is an abnormality in GPF23 by determining whether the accumulated value of the detection parameter Z is greater than the determination value ZK. In the event that an abnormality occurs in GPF23, the second processing unit 106 stores the content in the storage device and lights up the second warning light 99. When the second processing unit 106 completes the processing of step S250, it proceeds to step S260.

[0128] In step S260, the second processing unit 106 turns on the second completion flag FC2. Thereafter, the second processing unit 106 ends a series of processing of the second processing. In addition, when an output request to the internal combustion engine 10 is generated during the execution of step S250, the second processing unit 106 interrupts the processing of step S250 and performs the second processing again from step S210.

[0129] <Specific processing steps for executing the determination process>

[0130] The following describes the processing procedure of the execution determination process. The execution determination unit 108 starts the execution determination process when the ignition switch of the vehicle 500 is turned on.

[0131] like Figure 6 As shown, when the execution determination unit 108 starts the execution determination process, the process of step S310 is executed. In step S310, the execution determination unit 108 determines whether the first diagnostic process and the second diagnostic process are not completed. The execution determination unit 108 makes the determination of step S310 with reference to the first completion flag FC1 set in the first diagnostic process and the second completion flag FC2 set in the second diagnostic process. When the first completion flag FC1 and the second completion flag FC2 are activated (step S310: No), that is, when the first diagnostic process and the second diagnostic process are completed, the execution determination unit 108 ends the series of processes of the execution determination process.

[0132] On the other hand, when the first completion flag FC1 and the second completion flag FC2 are inactive (step S310 : Yes), that is, when the first diagnosis process and the second diagnosis process are not completed, the execution determination unit 108 advances the process to step S320 .

[0133] In step S320, the execution determination unit 108 refers to the first condition flag FJ1 set in the first diagnostic process to determine whether the first condition flag FJ1 is activated. When the first condition flag FJ1 is inactive, that is, when the first execution condition is not satisfied (step S320: No), the execution determination unit 108 advances the process to step S350.

[0134] In step S350, execution determination unit 108 turns off permission flags FA for the first and second diagnostic processes. Thereafter, execution determination unit 108 temporarily terminates a series of execution determination processes and executes step S310 again.

[0135] On the other hand, in step S320 , when the first condition flag FJ1 is on, that is, when the first execution condition is satisfied (step S320 : Yes), the execution determination unit 108 advances the process to step S330 .

[0136] In step S330, the execution determination unit 108 refers to the second condition flag FJ2 set in the second diagnostic process to determine whether the second condition flag FJ2 is activated. When the second condition flag FJ2 is inactive, that is, when the second execution condition is not satisfied (step S330: No), the execution determination unit 108 advances the process to step S350.

[0137] On the other hand, in step S330, if the second condition flag FJ2 is on, that is, if the second execution condition is satisfied (step S330: Yes), the execution determination unit 108 advances the process to step S340. In this case, both the first execution condition and the second execution condition are satisfied.

[0138] In step S340, the execution determination unit 108 turns on the permission flag FA. Then, the execution determination unit 108 temporarily terminates a series of execution determination processing and executes the processing of step S310 again.

[0139] <Effects of implementation methods>

[0140] The second execution condition includes not only the necessary conditions for the drag process similar to the first execution condition, but also the necessary condition of the temperature around the GPF 23. Therefore, even if the first execution condition is satisfied in step S120 of the first process (step S120: Yes), depending on the operating state of the internal combustion engine 10, the second execution condition may not be satisfied in step S220 of the second process (step S220: No). In this case, the first condition flag FJ1 is activated in the first process, and on the other hand, the second condition flag FJ2 is inactivated in the second process. Accepting the setting of the above-mentioned condition flag, the permission flag FA is set to inactive in step S350 of the execution determination process. And, accepting the setting of the permission flag FA, the execution of the first process is postponed in step S140 of the first process (step S140: No).

[0141] On the other hand, when the first execution condition is satisfied in step S120 of the first process (step S120: Yes), and when the second execution condition is satisfied in step S220 of the second process (step S220: Yes), both the first condition flag FJ1 and the second condition flag FJ2 are set to be activated. Accepting the setting of the above condition flags, the permission flag FA is set to be activated in step S340 of the execution determination process. Accepting the setting of the permission flag FA, the first diagnostic process is executed in step S150 of the first process, and the second diagnostic process is executed in step S250 of the second process.

[0142] <Effects of implementation>

[0143] (1) As described in the above-mentioned function, according to the present embodiment, even if the first execution condition is satisfied, if the second execution condition is not satisfied, the execution of both diagnostic processes is prohibited. Therefore, only the first diagnostic process with fewer necessary conditions is not performed first. On the other hand, when both the first execution condition and the second execution condition are satisfied, both diagnostic processes are allowed and both diagnostic processes are executed together. In such a present embodiment, when the internal combustion engine 10 is diagnosed by the drag process, the number of executions of the drag process can be suppressed to a minimum. This helps, for example, to suppress the power consumption associated with the drag process to a minimum.

[0144] (2) When diagnosing whether GPF23 is abnormal, it is considered to use the pressure of the gas around GPF23 instead of the temperature around GPF23. When GPF23 is present in the exhaust passage 21, since GPF23 becomes a resistance to the airflow, the pressure of the gas on the downstream side of GPF23 is lower than that on the upstream side. On the other hand, when GPF23 is removed, the pressure of the gas on the upstream side and the downstream side of GPF23 is roughly the same. Such characteristics can be used to diagnose whether GPF23 is abnormal. And, when diagnosing using such characteristics, for example, a differential pressure sensor is provided in the exhaust passage 21, and the size of the difference between the pressure of the gas on the upstream side of GPF23 and the pressure of the gas on the downstream side of GPF23 can be determined. However, when a differential pressure sensor is provided in the exhaust passage 21, the cost tends to be high. That is, the differential pressure sensor has a complicated structure, such as dividing the gas chamber inside and providing a diaphragm that divides the gas chamber into two. Furthermore, when using a differential pressure sensor, a connecting passage connecting a portion of the exhaust passage 21 upstream of the GPF 23 to the differential pressure sensor and a connecting passage connecting a portion of the exhaust passage 21 downstream of the GPF 23 to the differential pressure sensor are also required.

[0145] In this regard, in the present embodiment, the gas temperature decreases after the start of the drag process, and the detection value of the temperature sensor is used to diagnose whether the GPF 23 is abnormal. If it is a temperature sensor, the structure is not so complicated, and it can be directly installed in the exhaust passage 21. Therefore, in the configuration of the present embodiment using the temperature sensor, the cost can be suppressed.

[0146] (3) In the present embodiment, when diagnosing whether or not the GPF 23 is abnormal by utilizing the characteristic of the gas temperature drop after the start of the motoring process, the detection parameter Z is utilized. The detection parameter Z is obtained by simply subtracting the first temperature change amount ΔT1 from the second temperature change amount ΔT2. Therefore, no complicated processing is required when calculating the detection parameter Z, so that the processing load of the control device 100 related to the diagnosis of the abnormality of the GPF 23 can be suppressed to a minimum.

[0147] (4) The three-way catalyst 22 is a heat source that generates heat by the combustion of unburned fuel, and has a larger heat capacity than the GPF 23. Therefore, the three-way catalyst 22 is basically difficult to lower in temperature. The first detection temperature T1 affected by the temperature of the three-way catalyst 22 is basically difficult to lower, and even if it is lowered, its lowering speed tends to decrease. From the perspective of calculating the detection parameter Z, this helps to reduce the detection parameter Z by reducing the absolute value of the first temperature change ΔT1. On the other hand, the GPF 23 does not generate heat by itself, but only receives heat transmitted from the three-way catalyst 22 to increase its temperature. Therefore, the GPF 23 is basically easy to lower in temperature. The second detection temperature T2 affected by the temperature of the GPF 23 is basically easy to lower, and when it is lowered, its lowering speed tends to increase. From the perspective of calculating the detection parameter Z, this helps to reduce the detection parameter Z by increasing the absolute value of the second temperature change ΔT2. As described above, the environment around the GPF 23 makes it basically difficult to obtain high diagnostic accuracy when using the detection parameter Z for diagnosis.

[0148] In this embodiment, although the conditions are unfavorable for obtaining high diagnostic accuracy, by making the second execution condition include item (B4) and item (B5), it is possible to diagnose the presence or absence of abnormality of GPF 23 with high diagnostic accuracy using detection parameter Z. Thus, the effects of (2) and (3) can be obtained.

[0149] <Change Example>

[0150] This embodiment can be implemented by being modified as follows. This embodiment and the following modified examples can be implemented by being combined with each other within the range that there is no technical contradiction.

[0151] ·In the above-mentioned embodiment, the first judgment period H1 and the second judgment period H2 are of the same length. However, the first judgment period H1 and the second judgment period H2 may be of different lengths. The first judgment period H1 may be set to a length suitable for diagnosing whether the air-fuel ratio sensor 81 has an abnormality. The second judgment period H2 may be set to a length suitable for diagnosing whether the GPF23 has an abnormality. For example, the first judgment period H1 may be longer than the second judgment period H2. In this case, after the second diagnostic process is completed, the first diagnostic process is still continued. Here, when the first diagnostic process is continued after the second diagnostic process is completed, the required torque TE of the internal combustion engine may also become greater than zero. In this case, the first diagnostic process is interrupted on the way. That is, a situation may occur in which the second diagnostic process is completed but the first diagnostic process is not completed. In the case of the above-mentioned embodiment, the second process is ended with the second condition flag FJ2 set to an activated state. Therefore, if the first execution condition is satisfied and the first condition flag FJ1 becomes activated when the first process is restarted after the first diagnostic process is interrupted, the flag FA is allowed to become activated in the execution determination process. Therefore, it is possible to execute only the first diagnostic process without executing the second diagnostic process. Therefore, in this case, the first diagnostic process can also be completed. In addition, even if a scheme is adopted in which the second condition flag FJ2 is set to inactive at the end of the second process, it is possible to execute only the first diagnostic process after the second diagnostic process is completed by appropriately changing the content of the execution determination process. That is, in the case where the second diagnostic process is completed, when only the first execution condition is satisfied, that is, when the second condition flag is inactive and the first condition flag is active, the content of the execution determination process can be changed in a manner that allows the execution of the first diagnostic process. In the case where the second determination period H2 is made longer than the first determination period H1, the content of the execution determination process can be changed by the same consideration as above.

[0152] The method of determining the unit time when calculating the detection parameter Z can be changed as appropriate. The unit time may be any time interval that is appropriate for calculating the integrated value of the detection parameter Z.

[0153] · The item (B5) of the second execution condition may be changed to a necessary condition that the vehicle 500 is accelerating. In this case, the same necessary condition as in the above embodiment is set. When determining whether the vehicle 500 is accelerating, for example, the differential value of the vehicle speed SP may be used, or an acceleration sensor may be provided in the vehicle 500.

[0154] The item (B5) of the second execution condition may be eliminated. In this case as well, as long as the item (B4) is set, a high-precision diagnosis can be performed accordingly.

[0155] Regarding the item (B4) of the second execution condition, the second detected temperature T2 may be used instead of the first detected temperature T1. That is, the item (B4) may be set to the content that the second detected temperature T2 is equal to or higher than the predetermined temperature TK. If it is the approximate temperature around the GPF 23, it can also be grasped by the second detected temperature T2.

[0156] Regarding the item (B4) of the second execution condition, for example, the estimated temperature of the exhaust gas based on the engine load factor may be used instead of the first detected temperature T1. In addition, the item (B4) may be set to the content that the estimated temperature of the exhaust gas is above the predetermined temperature TK. The engine load factor indicates the ratio of the current cylinder inflow air amount to the cylinder inflow air amount when the internal combustion engine 10 is stably operated with the throttle valve 13 fully opened at the current engine speed NE. In addition, the cylinder inflow air amount is the amount of air that flows into each cylinder 11 during the intake stroke.

[0157] Regarding the item (B4) of the second execution condition, instead of the exhaust temperature, a variable indicating the exhaust temperature may be used as the object of determination. As such a variable, for example, the engine load factor may be used. Furthermore, the item (B4) may be set as a necessary condition that the engine load factor is greater than a predetermined load factor. In this case, the predetermined load factor may be set to a value equivalent to the predetermined temperature TK.

[0158] The diagnostic method used in the second diagnostic process is not limited to the method using the detection parameter Z. As described in the above embodiment, the speed of decrease of the second detected temperature T2 after the start of the drag process is different depending on whether the GPF 23 is present. Therefore, the speed of decrease of the second detected temperature T2 can be used as an indicator to determine whether the GPF 23 is abnormal.

[0159] The diagnostic method used in the second diagnostic process is not limited to the method using temperature. For example, the differential pressure between the upstream side and the downstream side of GPF23 may be used. Here, when the pressure of the exhaust gas is high, the difference in differential pressure becomes obvious depending on whether or not GPF23 is present. On the other hand, when the pressure of the exhaust gas is low, it is difficult to produce the above-mentioned difference in differential pressure. Therefore, when using differential pressure to diagnose GPF23, it is sufficient to set the exhaust gas pressure to be above a specified pressure as the second execution condition. In addition, the specified pressure may be set to the exhaust gas pressure required for accurately diagnosing whether or not GPF23 is abnormal. In the case where the second execution condition includes the necessary condition of the exhaust gas pressure, for example, the exhaust gas pressure may be estimated based on the detection of the intake air volume GA, or a pressure sensor may be provided in the exhaust passage 21.

[0160] When the GPF 23 is diagnosed by using differential pressure as in the above-mentioned modification, the necessary condition that the exhaust gas flow rate is equal to or greater than a prescribed flow rate may be set as the second execution condition. The prescribed flow rate in this case may be set to a value determined from the same viewpoint as the prescribed pressure. In addition, the necessary condition that a variable representing the exhaust gas pressure or the exhaust gas flow rate is equal to or greater than a prescribed value may be set. As such a variable, for example, the engine load factor may be used.

[0161] As the diagnostic method used in the second diagnostic process, a method for diagnosing other abnormalities related to the GPF 23 may be used instead of a method for diagnosing the presence or absence of the GPF 23 in the exhaust passage 21. The other abnormality is, for example, clogging of the GPF 23.

[0162] The second execution condition is not limited to the example of the above-mentioned embodiment. Regarding the second execution condition, the required second execution condition can be set according to the diagnostic method used in the second diagnostic process. The second execution condition is a condition that includes the necessary condition that there is no output request for the internal combustion engine 10 and is different from the first execution condition. For example, item (B2) can also be abolished.

[0163] The diagnostic method used in the first diagnostic process is not limited to the example of the above-mentioned embodiment. In the first diagnostic process, a method suitable for diagnosing whether the air-fuel ratio sensor 81 has an abnormality may be used.

[0164] The first execution condition is not limited to the example of the above embodiment. The first execution condition may be set as required according to the diagnosis method used in the first diagnosis process. The first execution condition may include that there is no output request to the internal combustion engine 10 .

[0165] The configuration of the internal combustion engine 10 can be modified as appropriate. For example, an air-fuel ratio sensor may be provided separately between the three-way catalyst 22 and the GPF 23 in the exhaust passage 21 .

[0166] When an air-fuel ratio sensor is provided between the three-way catalyst 22 and the GPF 23 in the exhaust passage 21 as in the above-mentioned modification example, in addition to or instead of the diagnosis of the air-fuel ratio sensor 81 on the upstream side of the three-way catalyst 22, it is also possible to diagnose whether the air-fuel ratio sensor between the three-way catalyst 22 and the GPF 23 has an abnormality.

[0167] The overall configuration of the vehicle 500 is not limited to the example of the above-described embodiment. The vehicle 500 may include the internal combustion engine 10 and an electric motor capable of rotating the crankshaft 20 of the internal combustion engine 10 .

Claims

1. A control device for a hybrid vehicle, The control device is suitable for a hybrid vehicle having an internal combustion engine and an electric motor capable of rotating an output shaft of the internal combustion engine, wherein the internal combustion engine is provided with an air-fuel ratio sensor for detecting an air-fuel ratio of exhaust gas, a filter for collecting particulate matter in the exhaust gas, and a state detection sensor for detecting a temperature or pressure of the exhaust gas on an upstream side and a downstream side of the filter. The control device is capable of executing a drag process, a first diagnosis process, and a second diagnosis process. In the engine running process, the output shaft of the internal combustion engine is rotated by the electric motor in a state where the supply of fuel to the cylinders of the internal combustion engine is stopped. In the first diagnosis process, when a first execution condition including a condition that there is no output request to the internal combustion engine is satisfied, the engine running process is executed and the presence or absence of an abnormality in the air-fuel ratio sensor is diagnosed based on a detection signal of the air-fuel ratio sensor. In the second diagnosis process, when a second execution condition including a condition that there is no output request to the internal combustion engine and a condition different from the first execution condition is satisfied, the drag process is executed and the presence or absence of an abnormality in the filter is diagnosed based on the detection signal of the state detection sensor, The control device performs an execution determination process, in which the execution of both the first diagnostic process and the second diagnostic process is prohibited when at least one of the first execution condition and the second execution condition is not satisfied, and the execution of both the first diagnostic process and the second diagnostic process is permitted when both the first execution condition and the second execution condition are satisfied. The state detection sensor is a first temperature sensor that detects the temperature of the exhaust gas on the upstream side of the filter, and a second temperature sensor that detects the temperature of the exhaust gas on the downstream side of the filter. The second execution condition includes a condition that the temperature detected by the first temperature sensor or the second temperature sensor is equal to or higher than a predetermined temperature.

2. The control device for a hybrid vehicle according to claim 1, When the amount of change per unit time of the temperature detected by the first temperature sensor is set as the first temperature change amount, and the amount of change per unit time of the temperature detected by the second temperature sensor is set as the second temperature change amount, In the second diagnosis process, the presence or absence of abnormality of the filter is diagnosed based on a value obtained by integrating a detection parameter that is a value obtained by subtracting the first temperature change amount from the second temperature change amount within a certain period after the start of the drag process.

3. The control device for a hybrid vehicle according to claim 2, The second execution condition includes a condition that the temperature detected by the first temperature sensor is equal to or higher than the temperature detected by the second temperature sensor.

4. A control method for a hybrid vehicle, The hybrid vehicle includes an internal combustion engine and an electric motor capable of rotating an output shaft of the internal combustion engine. The internal combustion engine includes an air-fuel ratio sensor for detecting an air-fuel ratio of exhaust gas, a filter for collecting particulate matter in the exhaust gas, and a state detection sensor for detecting a temperature or a pressure of the exhaust gas on the upstream side and the downstream side of the filter. The control method causes the control device of the hybrid vehicle to execute a drag process, a first diagnosis process, a second diagnosis process, and an execution determination process. In the engine running process, the output shaft of the internal combustion engine is rotated by the electric motor in a state where the supply of fuel to the cylinders of the internal combustion engine is stopped. In the first diagnosis process, when a first execution condition including a condition that there is no output request to the internal combustion engine is satisfied, the engine running process is executed and the presence or absence of an abnormality in the air-fuel ratio sensor is diagnosed based on a detection signal of the air-fuel ratio sensor. In the second diagnosis process, when a second execution condition including a condition that there is no output request to the internal combustion engine and a condition different from the first execution condition is satisfied, the drag process is executed and the presence or absence of an abnormality in the filter is diagnosed based on the detection signal of the state detection sensor, In the execution determination process, when at least one of the first execution condition and the second execution condition is not satisfied, the execution of both the first diagnostic process and the second diagnostic process is prohibited, and when both the first execution condition and the second execution condition are satisfied, the execution of both the first diagnostic process and the second diagnostic process is permitted. The state detection sensor is a first temperature sensor that detects the temperature of the exhaust gas on the upstream side of the filter, and a second temperature sensor that detects the temperature of the exhaust gas on the downstream side of the filter. The second execution condition includes a condition that the temperature detected by the first temperature sensor or the second temperature sensor is equal to or higher than a predetermined temperature.

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