Diagnostic method for internal combustion engine and diagnostic device for internal combustion engine

Abstract

This internal combustion engine (1) has a GPF (4), and regenerates the GPF (4) by removing captured exhaust microparticles by combustion. The GPF (4) is regenerated in a temperature-increasing mode for increasing the temperature of the GPF (4), and in a motoring mode for motoring the internal combustion engine (1) and supplying air to the GPF (4). The temperature-increasing mode includes a first temperature-increasing mode for increasing the temperature of the GPF (4) by retarding the ignition timing of the internal combustion engine (1), a second temperature-increasing mode for increasing the temperature of the GPF (4) by increasing the engine speed of the internal combustion engine (1), and a third temperature-increasing mode for increasing the temperature of the GPF (4) by increasing the torque of the internal combustion engine (1). If implementation of the temperature-increasing mode is confirmed and implementation of the motoring mode is confirmed, regeneration of the GPF (4) is determined to be feasible.

Description

Diagnostic method and diagnostic device for internal combustion engine

[0001] The present invention relates to a diagnostic method and a diagnostic device for an internal combustion engine.

[0002] For example, Patent Document 1 discloses a configuration in which a particulate filter is provided in the exhaust pipe of an internal combustion engine to collect particulate matter in the exhaust by depositing it. In Patent Document 1, regeneration control is performed to burn the particulate matter deposited on the particulate filter by, for example, performing post-injection, which is fuel injection during the exhaust stroke, at an appropriate time.

[0003] Furthermore, in Patent Document 1, when the amount of oxygen flowing into the particulate filter between the start and end of regeneration control is equal to or less than a predetermined amount, it is determined that the regeneration control is not being performed normally.

[0004] However, in Patent Document 1, the regeneration control of the particulate filter merely determines an abnormality in which particulate matter cannot be sufficiently burned from the amount of oxygen flowing in, and it is not clear whether the regeneration control of the particulate filter is operating properly.

[0005] Therefore, in Patent Document 1, if the regeneration control of the particulate filter is not operating properly, there is a risk that it will not be possible to determine from the amount of oxygen flowing in whether the particulate matter trapped in the particulate filter has been sufficiently burned.

[0006] That is, in Patent Document 1, it is not certain whether the regeneration control of the particulate filter is operating properly, and there is room for further improvement in determining whether the particulate filter is in a state where it can be regenerated properly.

[0007] JP 2009-197763 A

[0008] The internal combustion engine of the present invention has an exhaust particulate filter that is arranged in an exhaust passage and captures particulate matter in the exhaust, and regenerates the exhaust particulate filter by removing the captured exhaust particulates through combustion. The regeneration of the exhaust particulate filter is carried out in a temperature rise mode in which the temperature of the exhaust particulate filter is raised, and a motoring mode in which the internal combustion engine is motored to supply air to the exhaust particulate filter. The temperature rise mode is a first temperature rise mode in which the ignition timing of the internal combustion engine is retarded to raise the temperature of the exhaust particulate filter, a second temperature rise mode in which the engine speed of the internal combustion engine is increased to raise the temperature of the exhaust particulate filter, or a third temperature rise mode in which the torque of the internal combustion engine is increased to raise the temperature of the exhaust particulate filter. When it is confirmed that the temperature rise mode is being performed and also when it is confirmed that the motoring mode is being performed, it is determined that the exhaust particulate filter is in a state where it can be regenerated.

[0009] The internal combustion engine of the present invention can ensure that the regeneration of the exhaust particulate filter is carried out correctly by determining whether a process of increasing the temperature of the exhaust particulate filter and a process of burning the exhaust particulates captured in the exhaust particulate filter are being carried out.

[0010] 1 is an explanatory diagram schematically showing the system configuration of an internal combustion engine to which the present invention is applied. FIG. 1 is a timing chart showing an example of changes in various parameters when implementation of the first heating mode can be confirmed. FIG. 2 is a timing chart showing an example of changes in various parameters when implementation of the first heating mode cannot be confirmed. FIG. 3 is a flowchart showing an example of a control flow when confirming implementation of the first heating mode. FIG. 4 is a timing chart showing an example of changes in various parameters when implementation of the second heating mode can be confirmed. FIG. 5 is a timing chart showing an example of changes in various parameters when implementation of the second heating mode cannot be confirmed. FIG. 6 is a flowchart showing an example of a control flow when confirming implementation of the second heating mode. FIG. 7 is a timing chart showing an example of changes in various parameters when implementation of the third heating mode can be confirmed. FIG. 8 is a timing chart showing an example of changes in various parameters when implementation of the third heating mode cannot be confirmed. FIG. 9 is a flowchart showing an example of a control flow when confirming implementation of the second heating mode. FIG. 10 is a timing chart showing an example of changes in various parameters when implementation of the motoring mode can be confirmed.

[0011] An embodiment of the present invention will be described in detail below with reference to the drawings.

[0012] FIG. 1 is an explanatory diagram that schematically shows the system configuration of an internal combustion engine 1 to which the present invention is applied.

[0013] A first catalyst 3, a gasoline particulate filter (GPF) 4 serving as an exhaust particulate filter, and a second catalyst 5 are arranged in series in an exhaust passage 2 of an internal combustion engine 1. In this embodiment, the GPF 4 and the second catalyst 5 are unitized in series and housed in a single casing 6. The internal combustion engine 1 is a gasoline engine that uses gasoline as fuel.

[0014] The first catalyst 3 is, for example, a three-way catalyst that purifies the three components of HC, CO, and NOx in the inflowing exhaust gas when the excess air ratio is approximately 1, i.e., when the exhaust gas air-fuel ratio is approximately the stoichiometric air-fuel ratio.

[0015] The GPF 4 collects particulate matter in the exhaust gas.

[0016] The GPF 4 is typically a wall-flow honeycomb filter (so-called plugged type) made of a filter material such as cordierite, with numerous honeycomb-shaped fine passages formed in the filter material and the ends of the passages alternately blocked. The GPF 4 is located downstream of the first catalyst 3 in the exhaust gas flow direction. The GPF 4 may also support a catalyst similar to a three-way catalyst.

[0017] The second catalyst 5 is, for example, a three-way catalyst, and is located downstream of the GPF 4 in the exhaust gas flow direction.

[0018] A muffler 7 is disposed downstream of the second catalyst 5 .

[0019] The internal combustion engine 1 is a reciprocating spark ignition internal combustion engine, and is mounted, for example, in a hybrid vehicle to generate electricity to drive a motor generator 8, which is an electric motor. The motor generator 8 generates electricity when driven by the internal combustion engine 1. The motor generator 8 is also supplied with power from a battery (not shown), enabling it to drive (idle) the internal combustion engine 1 by so-called motoring.

[0020] The internal combustion engine 1 is controlled by a control unit 11. For example, the ignition timing, engine speed, and torque of the internal combustion engine 1 can be controlled by the control unit 11. The control unit 11 is a well-known digital computer equipped with a CPU, ROM, RAM, and an input / output interface.

[0021] The control unit 11 receives signals from various sensors, such as an air flow meter 13 that detects the amount of intake air into the internal combustion engine 1, a GPF temperature sensor 14 that detects the catalyst temperature of the GPF 4, an accelerator opening sensor 15 that detects the amount of depression of an accelerator pedal (not shown), a crank angle sensor 16 that detects the crank angle of a crankshaft (not shown) of the internal combustion engine 1, a differential pressure sensor 17 that detects the differential pressure before and after the GPF 4, and a vehicle speed sensor 18 that detects the speed of the vehicle.

[0022] The differential pressure sensor 17 is capable of detecting the pressure difference (differential pressure ΔP) between the exhaust pressure in the exhaust passage 2 upstream of the GPF 4 and the exhaust pressure in the exhaust passage 2 downstream of the GPF 4. In addition, the control unit 11 is capable of calculating the engine speed of the internal combustion engine 1, which is the rotation speed of the crankshaft, based on the detection signal of the crank angle sensor 16.

[0023] Here, when a predetermined GPF regeneration request occurs while the internal combustion engine 1 is running, the internal combustion engine 1 performs a regeneration process of the GPF 4, which burns and removes exhaust particulates trapped (accumulated) in the GPF 4. In other words, when a predetermined GPF regeneration request occurs while the internal combustion engine 1 is running, the control unit 11 as a control unit is capable of burning and removing the exhaust particulates trapped by the GPF 4, thereby regenerating the GPF 4.

[0024] The GPF regeneration request is made, for example, when the amount (accumulation amount) of exhaust particulate matter trapped in the GPF 4 exceeds a preset upper limit of the amount of trapped particulate matter.

[0025] When the GPF 4 attempts to remove trapped (accumulated) exhaust particulates and regenerate itself, it raises the temperature of the exhaust particulate filter and supplies air (oxygen) to the exhaust particulate filter, thereby burning the trapped exhaust particulates.

[0026] Specifically, the regeneration process of the GPF 4, which is performed in response to a GPF regeneration request, is realized by implementing a temperature rise mode in which the temperature of the GPF 4 is raised, and a motoring mode in which the internal combustion engine 1 is motored to supply air to the GPF 4. The temperature rise modes include, for example, first to third temperature rise modes.

[0027] In the first temperature rise mode, the temperature of the GPF 4 is raised by retarding the ignition timing of the internal combustion engine 1 relative to the ignition timing at which MBT (Minimum Advance for the Best Torque) is obtained. In other words, the first temperature rise mode is an ignition timing retard mode. MBT is the ignition timing at which the output and fuel consumption rate are optimized.

[0028] In the second temperature increase mode, the temperature of the GPF 4 is increased by increasing the engine speed of the internal combustion engine 1. In other words, the second temperature increase mode is a speed increase mode.

[0029] In the third temperature increase mode, the temperature of the GPF 4 is increased by increasing the torque of the internal combustion engine 1. In other words, the third temperature increase mode is a torque increase mode.

[0030] In the motoring mode, air is supplied to the GPF 4 by motoring, in which the internal combustion engine 1 is driven by the motor generator 8 .

[0031] When the implementation of the temperature increase mode and the motoring mode is confirmed, the internal combustion engine 1 is determined to be in a state where regeneration of the GPF 4 is possible. In other words, when the control unit 11 confirms the implementation of the temperature increase mode and the motoring mode, the internal combustion engine 1 is determined to be in a state where regeneration of the GPF 4 is possible.

[0032] As shown in Figures 2 and 3, the first temperature rise mode is confirmed by determining whether the ignition timing command value (target value) output from the control unit 11 to the internal combustion engine 1 is retarded from the ignition timing at which MBT occurs.

[0033] FIG. 2 is a timing chart showing an example of changes in various parameters when it is confirmed that the first temperature rise mode is being performed. FIG. 3 is a timing chart showing an example of changes in various parameters when it is not confirmed that the first temperature rise mode is being performed. The ignition timing shown by the solid line in FIGS. 2 and 3 is the MBT ignition timing at which the MBT is obtained. The ignition timing shown by the thick solid line in FIGS. 2 and 3 is the target ignition timing (ignition timing command value) output from the control unit 11 to the internal combustion engine 1. The ignition timing shown by the dashed line in FIGS. 2 and 3 is an ignition timing threshold value for determination. The ignition timing threshold value is the ignition timing that is retarded by a predetermined amount set in advance with respect to the MBT ignition timing.

[0034] The first temperature rise mode is deemed to be implemented when it is confirmed that the target ignition timing is retarded from the ignition timing threshold, which is a predetermined threshold.

[0035] A case where it is confirmed that the first temperature rise mode is being performed will be described with reference to FIG.

[0036] The timing of time t1 in Fig. 2 is the timing at which a request for regeneration of the GPF 4 is generated. Note that in the example of Fig. 2, before time t1, a request for retarding the ignition timing (another retard request) is made to the internal combustion engine 1 due to a factor other than the request for regeneration of the GPF 4, and the ignition timing at time t1 is retarded relative to the MBT ignition timing.

[0037] At time t2 in FIG. 2 , the other retard requests described above are no longer present, and the ignition timing diagnosis permission flag is set to ON. The ignition timing diagnosis permission flag is set to ON when there is a request for regeneration of the GPF 4 and no other retard requests. In FIG. 2 , when the ignition timing diagnosis permission flag is set to ON at time t2, the target ignition timing is significantly retarded relative to the ignition timing threshold from time t2 in order to regenerate the GPF 4. In other words, in FIG. 2 , the first temperature rise mode is started from time t2.

[0038] Time t3 in Fig. 2 is the timing when a predetermined time has elapsed since time t2 in Fig. 2. In order to determine whether the first temperature rise mode is being performed from the timing of time t3 in Fig. 2, the first OK / NG count determination timer starts counting up its count value from the timing of time t3.

[0039] The timing at which the count value of the first OK / NG count determination timer is incremented is the timing at which the count value of a retard request OK counter (not shown) serving as an OK counter or a retard request NG counter (not shown) serving as an NG counter is incremented. The retard request OK counter serving as an OK / NG counter counts up (increments) the OK count value when the target ignition timing is retarded more than the ignition timing threshold. The retard request NG counter serving as an OK / NG counter counts up (increments) the NG count value when the target ignition timing is not retarded more than the ignition timing threshold.

[0040] In other words, from the timing of time t3 in Figure 2 to the timing of time t4 in Figure 2 described later, either the OK count value of the retard request OK counter or the NG count value of the retard request NG counter is counted up at predetermined time intervals.

[0041] Time t4 in Figure 2 is the time when the OK count value of the retard request OK counter reaches the ignition timing OK count threshold, which is a count threshold. In Figure 2, the OK count value of the retard request OK counter reaches the ignition timing OK count threshold at time t4, so the OK determination flag is turned ON at time t4, and it is determined at time t4 that the first temperature rise mode has been performed. Also in Figure 2, the determination of the first temperature rise mode is completed at time t4, so the first diagnosis end flag is turned ON at time t4. The first diagnosis is a diagnosis of whether the first temperature rise mode has been performed.

[0042] A case where the implementation of the first temperature rise mode cannot be confirmed will be described with reference to FIG.

[0043] The timing of time t1 in Fig. 3 is the timing at which a request for regeneration of the GPF 4 is generated. Note that in the example of Fig. 3, before time t1, a request for retarding the ignition timing (another retard request) is made to the internal combustion engine 1 due to a factor other than the request for regeneration of the GPF 4, and the ignition timing at time t1 is retarded relative to the MBT ignition timing.

[0044] At time t2 in Figure 3, the other retard requests described above are no longer present and the ignition timing diagnosis permission flag is set to ON. In Figure 3, the first warm-up mode is attempted to be started at time t2, but the target ignition timing is advanced relative to the ignition timing threshold. In other words, in Figure 3, although the first warm-up mode is started at time t2, the target ignition timing is not set to an ignition timing that ensures regeneration of the GPF 4.

[0045] Time t3 in Fig. 3 is the timing when a predetermined time has elapsed since time t2 in Fig. 3. In order to determine whether the first temperature rise mode is being performed from the timing of time t3 in Fig. 3, the first OK / NG count determination timer starts counting up its count value from the timing of time t3.

[0046] Time t4 in Figure 3 is the time when the NG count value of the retard request NG counter reaches the ignition timing NG count threshold, which is a count threshold. In Figure 3, the NG count value of the retard request NG counter reaches the ignition timing NG count threshold at time t4, so the NG determination flag is turned ON at time t4, and it is determined at time t4 that the first warm-up mode has not been confirmed. Also in Figure 3, the determination of whether the first warm-up mode has been confirmed is completed at time t4, so the first diagnosis end flag is turned ON at time t4.

[0047] The target ignition timing used when checking whether the first temperature rise mode is being performed is an averaged target ignition timing. In Figures 2 and 3, the target ignition timing is shown in a state where the averaged target ignition timing has been performed.

[0048] FIG. 4 is a flowchart showing an example of a control flow when confirming whether the first temperature increase mode is performed.

[0049] In step S11, it is determined whether or not there is a request to regenerate the GPF 4. If there is a request to regenerate the GPF 4 in step S11, the process proceeds to step S12. If there is no request to regenerate the GPF 4 in step S11, the current routine is terminated.

[0050] In step S12, it is determined whether or not the ignition timing is being retarded in response to a request for regeneration of the GPF 4. If it is determined in step S12 that the ignition timing is being retarded in response to a request for regeneration of the GPF 4, the process proceeds to step S13. If it is determined in step S12 that the ignition timing is not being retarded in response to a request for regeneration of the GPF 4, the current routine is terminated.

[0051] In step S13, it is determined whether the target ignition timing is retarded from the ignition timing threshold. If the target ignition timing is retarded from the ignition timing threshold in step S13, the process proceeds to step S14. If the target ignition timing is not retarded from the ignition timing threshold in step S13, the process proceeds to step S15.

[0052] In step S14, the count value of the retard request OK counter is incremented (counted up).

[0053] In step S15, the count value of the retard request NG counter is incremented (counted up).

[0054] In step S16, it is determined whether the count value of the retard request OK counter is equal to or greater than a predetermined ignition timing OK count threshold, and whether the count value of the retard request NG counter is equal to or greater than a predetermined ignition timing NG count threshold. If in step S16 either the count value of the retard request OK counter or the count value of the retard request NG counter is equal to or greater than the count threshold, the routine proceeds to step S17. If in step S16 both the count values ​​of the ignition timing OK counter and the ignition timing NG counter are less than the count threshold, the current routine is terminated.

[0055] In step S17, if the count value of the retard request OK counter is equal to or greater than the ignition timing OK count threshold, it is determined that the first temperature rise mode is being performed, and the OK determination is confirmed. Also, in step S17, if the count value of the retard request NG counter is equal to or greater than the ignition timing NG count threshold, it is determined that the first temperature rise mode is not being performed, and the NG determination is confirmed.

[0056] The second temperature rise mode is confirmed by determining whether the detected engine speed of the internal combustion engine 1 is controlled to be the target speed when the regeneration of the GPF 4 is requested, as shown in FIGS.

[0057] Fig. 5 is a timing chart showing an example of changes in various parameters when it is confirmed that the second temperature rise mode is being performed. Fig. 6 is a timing chart showing an example of changes in various parameters when it is not confirmed that the second temperature rise mode is being performed. The engine speed shown by the solid line in Figs. 5 and 6 is the target engine speed when a regeneration request is made for the GPF 4. The engine speed shown by the thick solid line in Figs. 5 and 6 is the detected actual engine speed (actual engine speed) of the internal combustion engine 1. In Figs. 5 and 6, the speed threshold is a value that is a predetermined amount smaller than the target engine speed when a regeneration request is made for the GPF 4.

[0058] The second temperature rise mode is considered to be implemented when, when there is a request for regeneration of GPF4, it is confirmed that the actual engine speed is greater than a predetermined speed threshold and follows the target speed at the time of the request for regeneration of GPF4.

[0059] A case where the implementation of the second temperature increase mode can be confirmed will be described with reference to FIG.

[0060] At time t1 in FIG. 5, an operation request with higher priority than the regeneration request of the GPF 4 occurs.

[0061] 5 is the timing at which a regeneration request is made for the GPF 4. At the timing of time t2 in Fig. 5, an operation request with a higher priority than the regeneration request for the GPF 4 is made, and therefore the target rotation speed of the internal combustion engine 1 is not switched to the target rotation speed at the time of the regeneration request for the GPF 4.

[0062] The timing of time t3 in Fig. 5 is the timing when, while a regeneration request for GPF 4 has been issued, there is no longer any operation request with a higher priority than the regeneration request for GPF 4. Therefore, at the timing of time t3 in Fig. 5, a regeneration request permission flag that permits the regeneration request for GPF 4 is turned ON. Also, the timing of time t3 in Fig. 5 is the timing when, as a result of the regeneration request for GPF 4 being permitted, the target value of the engine speed of the internal combustion engine 1 is switched to the target speed at the time of the regeneration request for GPF 4, and the rotation speed diagnosis permission flag is turned ON. The rotation speed diagnosis permission flag is turned ON when there is a regeneration request for GPF 4 and there is no operation request with a higher priority than the regeneration request for GPF 4.

[0063] In Fig. 5, when the rotation speed diagnosis permission flag is turned ON at time t3, the target engine rotation speed is switched to a value for regenerating the GPF 4 from time t3 in Fig. 5. That is, in Fig. 5, the second temperature rise mode is started from time t3.

[0064] Time t4 in Fig. 5 is the timing when a predetermined time has elapsed since time t3 in Fig. 5. In order to determine whether the second temperature rise mode is being performed from the timing of time t4 in Fig. 5, the second OK / NG count determination timer starts counting up its count value from the timing of time t4.

[0065] The timing at which the count value of the second OK / NG count determination timer is counted up is the timing at which the count value of a rotation speed OK counter (not shown) serving as an OK counter or a rotation speed NG counter (not shown) serving as an NG counter is counted up (incremented). The rotation speed OK counter serving as an OK / NG counter counts up (increments) the OK count value when the actual engine rotation speed (actual engine rotation speed) of the internal combustion engine 1 is equal to or greater than the rotation speed threshold. The rotation speed NG counter serving as an OK / NG counter counts up (increments) the NG count value when the actual engine rotation speed (actual engine rotation speed) of the internal combustion engine 1 is less than the rotation speed threshold.

[0066] In other words, from the timing of time t4 in Figure 5 to the timing of time t5 in Figure 5 described later, either the OK count value of the rotation number OK counter or the NG count value of the rotation number NG counter is counted up at predetermined time intervals.

[0067] Time t5 in Figure 5 is the time when the OK count value of the rotation speed OK counter counts up to the OK count threshold, which is a count threshold. In Figure 5, the OK count value of the rotation speed OK counter reaches the OK count threshold at time t5, so the OK determination flag is turned ON at time t5, and it is determined at time t5 that the second temperature rise mode has been performed. Also in Figure 5, the determination of whether the second temperature rise mode has been performed is completed at time t5, so the second diagnosis end flag is turned ON at time t5. The second diagnosis is a diagnosis of whether the second temperature rise mode has been performed.

[0068] At time t6 in FIG. 5, the regeneration request from GPF4 is no longer issued.

[0069] A case where the implementation of the second temperature increase mode cannot be confirmed will be described with reference to FIG.

[0070] At time t1 in FIG. 6, an operation request with higher priority than the regeneration request of the GPF 4 occurs.

[0071] 6 is the timing at which a regeneration request is made for the GPF 4. At the timing of time t2 in Fig. 6, an operation request with a higher priority than the regeneration request for the GPF 4 is made, so the target rotation speed of the internal combustion engine 1 is not switched to the target rotation speed at the time of the regeneration request for the GPF 4.

[0072] The timing of time t3 in Fig. 6 is the timing when, while a regeneration request for the GPF 4 has been issued, there is no longer an operation request with a higher priority than the regeneration request for the GPF 4. Therefore, at the timing of time t3 in Fig. 6, a regeneration request permission flag that permits the regeneration request for the GPF 4 is turned ON. Also, the timing of time t3 in Fig. 6 is the timing when, as a result of the regeneration request for the GPF 4 being permitted, the engine speed of the internal combustion engine 1 is switched to the target speed at the time of the regeneration request for the GPF 4, and the rotation speed diagnosis permission flag is turned ON.

[0073] In Fig. 6, when the rotation speed diagnosis permission flag is turned ON at time t3, the target engine rotation speed is switched from time t3 to a value for regenerating the GPF 4. That is, in Fig. 6, the second temperature rise mode is started from time t3.

[0074] Time t4 in Fig. 6 is the timing when a predetermined time has elapsed since time t3 in Fig. 6. In order to determine whether the second temperature rise mode is being performed from time t4 in Fig. 6, the second OK / NG count determination timer starts counting up its count value from time t4. In other words, from time t4 in Fig. 6 to time t5 in Fig. 6 (described later), either the OK count value of the rotation speed OK counter or the NG count value of the rotation speed NG counter is counted up at predetermined time intervals.

[0075] Time t5 in Figure 6 is the time when the NG count value of the rotation speed NG counter reaches the NG count threshold, which is a count threshold. In Figure 6, the NG count value of the rotation speed NG counter reaches the NG count threshold at time t5, so the NG determination flag is turned ON at time t5, and it is determined at time t5 that the second warm-up mode is not being performed. Also in Figure 6, the determination of whether the second warm-up mode is being performed ends at time t5, so the second diagnosis end flag is turned ON at time t5.

[0076] The timing of time t6 in FIG. 6 is the timing when the regeneration request from GPF4 is no longer made.

[0077] FIG. 7 is a flowchart showing an example of a control flow when confirming whether the second temperature increase mode is performed.

[0078] In step S21, it is determined whether or not there is a request to regenerate the GPF 4. If there is a request to regenerate the GPF 4 in step S21, the process proceeds to step S22. If there is no request to regenerate the GPF 4 in step S21, the current routine is terminated.

[0079] In step S22, it is determined whether or not the engine speed of the internal combustion engine 1 is being increased in response to a regeneration request for the GPF 4. That is, in step S22, it is determined whether or not the target speed of the internal combustion engine 1 is the target speed at the time of the regeneration request for the GPF 4.

[0080] If it is determined in step S22 that the engine speed of the internal combustion engine 1 is being increased in response to a request for regeneration of the GPF 4, the process proceeds to step S23. If it is determined in step S22 that the engine speed of the internal combustion engine 1 is not being increased in response to a request for regeneration of the GPF 4, the current routine is terminated.

[0081] In step S23, it is determined whether the actual engine speed of the internal combustion engine 1 is equal to or greater than the rotation speed threshold. If the actual engine speed of the internal combustion engine 1 is equal to or greater than the rotation speed threshold in step S23, the process proceeds to step S24. If the actual engine speed of the internal combustion engine 1 is not equal to or greater than the rotation speed threshold in step S23, the process proceeds to step S25.

[0082] In step S24, the count value of the rotation number OK counter is incremented (counted up).

[0083] In step S25, the count value of the rotation number NG counter is incremented (counted up).

[0084] In step S26, it is determined whether the count value of the rotation number OK counter is equal to or greater than a predetermined rotation number OK count threshold, and whether the count value of the rotation number NG counter is equal to or greater than a predetermined rotation number NG count threshold. If in step S26 either the count value of the rotation number OK counter or the count value of the rotation number NG counter is equal to or greater than the count threshold, the routine proceeds to step S27. If in step S26 both the count values ​​of the rotation number OK counter and the rotation number NG counter are less than the count threshold, the current routine is terminated.

[0085] In step S27, if the count value of the rotation speed OK counter is equal to or greater than the rotation speed OK count threshold, it is determined that the second temperature rise mode is being performed, and an OK determination is confirmed. Also, in step S27, if the count value of the rotation speed NG counter is equal to or greater than the rotation speed NG count threshold, it is determined that the second temperature rise mode is not being performed, and an NG determination is confirmed.

[0086] 8 and 9, the third temperature rise mode is confirmed by determining whether the torque command value (target value) output from the control unit 11 to the internal combustion engine 1 is controlled to be the target torque value when a regeneration request is made for the GPF 4. In other words, the third temperature rise mode is confirmed by determining whether the torque command value set in the control unit 11 to control the torque of the internal combustion engine 1 is the target torque value when a regeneration request is made for the GPF 4.

[0087] FIG. 8 is a timing chart showing an example of changes in various parameters when it is confirmed that the third temperature rise mode is being performed. FIG. 9 is a timing chart showing an example of changes in various parameters when it is not confirmed that the third temperature rise mode is being performed. The torque shown by the solid line in FIGS. 8 and 9 is the target torque when a regeneration request is made for the GPF 4. The torque shown by the thick solid line in FIGS. 8 and 9 is the torque command value set in the control unit 11 for controlling the torque of the internal combustion engine 1. Note that the torque threshold in FIGS. 8 and 9 is a value that is a predetermined amount smaller than the target torque when a regeneration request is made for the GPF 4. In other words, the torque threshold is set to a value that is a predetermined amount smaller than the target torque when a regeneration request is made for the GPF 4.

[0088] The third heating mode is considered to be implemented when, when there is a request to regenerate GPF4, it is confirmed that the torque command value is greater than a predetermined torque threshold value and follows the target torque at the time of the request to regenerate GPF4.

[0089] A case where it is confirmed that the third temperature increase mode is being performed will be described with reference to FIG.

[0090] At time t1 in FIG. 8, an operation request with a higher priority than the regeneration request for the GPF 4 occurs.

[0091] The timing of time t2 in Fig. 8 is the timing at which a regeneration request is made for the GPF 4. At the timing of time t2 in Fig. 8, an operation request with a higher priority than the regeneration request for the GPF 4 is made, so the torque command value for the internal combustion engine 1 is not switched to the target torque at the time of the regeneration request for the GPF 4.

[0092] The timing of time t3 in Fig. 8 is the timing when, while a regeneration request for GPF 4 has been issued, there is no longer any operation request with a higher priority than the regeneration request for GPF 4. Therefore, at the timing of time t3 in Fig. 8, a regeneration request permission flag that permits the regeneration request for GPF 4 is turned ON. Also, the timing of time t3 in Fig. 8 is the timing when, as a result of the regeneration request for GPF 4 being permitted, the torque command value for the internal combustion engine 1 is switched to the target torque at the time of the regeneration request for GPF 4, and the torque diagnosis permission flag is turned ON. The torque diagnosis permission flag is turned ON when there is a regeneration request for GPF 4 and there is no operation request with a higher priority than the regeneration request for GPF 4.

[0093] In Fig. 8, when the torque diagnosis permission flag is turned ON at time t3, the torque command value is switched to a value for regenerating the GPF 4 from time t3 in Fig. 8. That is, in Fig. 8, the third temperature rise mode is started from time t3.

[0094] In order to determine whether the third temperature rise mode is being performed from time t3 in FIG. 8, the third OK / NG count determination timer starts counting up its count value from time t3.

[0095] The timing at which the count value of the third OK / NG count determination timer is counted up is the timing at which the count value of a torque OK counter (not shown) serving as an OK counter or a torque NG counter (not shown) serving as an NG counter is counted up (incremented). The torque OK counter serving as an OK / NG counter counts up (increments) the OK count value when the torque command value of the internal combustion engine 1 is equal to or greater than a torque threshold value. The torque NG counter serving as an OK / NG counter counts up (increments) the NG count value when the torque command value of the internal combustion engine 1 is less than the torque threshold value.

[0096] In other words, from the timing of time t3 in Figure 8 to the timing of time t4 in Figure 8 described later, either the OK count value of the torque OK counter or the NG count value of the torque NG counter is counted up at predetermined time intervals.

[0097] Time t4 in Figure 8 is the time when the OK count value of the torque OK counter is counted up to the torque OK count threshold, which is a count threshold. In Figure 8, the OK count value of the torque OK counter reaches the torque OK count threshold at time t4, so the OK determination flag is turned ON at time t4, and it is determined at time t4 that the third temperature rise mode has been implemented. Also in Figure 8, the determination of whether the third temperature rise mode has been implemented is completed at time t4, so the third diagnosis end flag is turned ON at time t4. The third diagnosis is a diagnosis of whether the third temperature rise mode has been implemented.

[0098] The timing of time t5 in FIG. 8 is the timing when the regeneration request from GPF4 is no longer made.

[0099] A case where the implementation of the third temperature increase mode cannot be confirmed will be described with reference to FIG.

[0100] At time t1 in FIG. 9, an operation request with higher priority than the regeneration request for the GPF 4 occurs.

[0101] 9 is the timing at which a regeneration request is made for the GPF 4. At the timing of time t2 in Fig. 9, an operation request with a higher priority than the regeneration request for the GPF 4 is made, so the torque command value for the internal combustion engine 1 is not switched to the target torque at the time of the regeneration request for the GPF 4.

[0102] The timing of time t3 in Fig. 9 is the timing when, while a regeneration request for GPF 4 has been issued, there is no longer an operation request with a higher priority than the regeneration request for GPF 4. Therefore, at the timing of time t3 in Fig. 9, a regeneration request permission flag that permits the regeneration request for GPF 4 is turned ON. Also, the timing of time t3 in Fig. 9 is the timing when, as a result of the regeneration request for GPF 4 being permitted, the torque command value for the internal combustion engine 1 is switched to the target torque at the time of the regeneration request for GPF 4, and the torque diagnosis permission flag is turned ON.

[0103] In Fig. 9, when the torque diagnosis permission flag is turned ON at time t3, from time t3 the torque command value is switched to a value for regenerating the GPF 4. That is, in Fig. 9, the third temperature rise mode is started from time t3.

[0104] Time t4 in Figure 9 is the time when the NG count value of the torque NG counter reaches the torque NG count threshold, which is a count threshold. In Figure 9, the NG count value of the torque NG counter reaches the NG count threshold at time t4, so the NG determination flag is turned ON at time t4, and it is determined at time t4 that the third temperature rise mode has not been confirmed. Also in Figure 9, the determination as to whether the third temperature rise mode has been confirmed is completed at time t4, so the third diagnosis end flag is turned ON at time t4.

[0105] At time t5 in FIG. 9, the playback request from GPF4 is no longer issued.

[0106] FIG. 10 is a flowchart showing an example of a control flow when confirming whether the third temperature increase mode is performed.

[0107] In step S31, it is determined whether or not there is a request to regenerate the GPF 4. If there is a request to regenerate the GPF 4 in step S31, the process proceeds to step S32. If there is no request to regenerate the GPF 4 in step S31, the current routine is terminated.

[0108] In step S32, it is determined whether or not the torque of the internal combustion engine 1 is being increased in response to a regeneration request from the GPF 4. That is, in step S32, it is determined whether or not the torque command value of the internal combustion engine 1 is the target torque at the time of the regeneration request from the GPF 4.

[0109] If it is determined in step S32 that the torque of the internal combustion engine 1 is being increased in response to a regeneration request for the GPF 4, the process proceeds to step S33. If it is determined in step S32 that the torque of the internal combustion engine 1 is not being increased in response to a regeneration request for the GPF 4, the current routine is terminated.

[0110] In step S33, it is determined whether the torque command value of the internal combustion engine 1 is equal to or greater than the torque threshold value. If the torque command value of the internal combustion engine 1 is equal to or greater than the torque threshold value in step S33, the process proceeds to step S34. If the torque command value of the internal combustion engine 1 is not equal to or greater than the torque threshold value in step S33, the process proceeds to step S35.

[0111] In step S34, the count value of the torque OK counter is incremented (counted up).

[0112] In step S35, the count value of the torque NG counter is incremented (counted up).

[0113] In step S36, it is determined whether the count value of the torque OK counter is equal to or greater than a predetermined torque OK count threshold, and whether the count value of the torque NG counter is equal to or greater than a predetermined torque NG count threshold. If in step S36 either the count value of the torque OK counter or the count value of the torque NG counter is equal to or greater than the count threshold, the process proceeds to step S37. If in step S36 both the count values ​​of the torque OK counter and the torque NG counter are less than the count threshold, the current routine is terminated.

[0114] In step S37, if the count value of the torque OK counter is equal to or greater than the torque OK count threshold, it is determined that the third temperature rise mode is being performed, and an OK determination is confirmed. Also, in step S37, if the count value of the torque NG counter is equal to or greater than the torque NG count threshold, it is determined that the third temperature rise mode is not being performed, and an NG determination is confirmed.

[0115] As shown in Figures 11 and 12, the motoring mode is confirmed by determining whether the engine speed of the internal combustion engine 1 in the motoring state is controlled to be the target speed during motoring when regeneration of the GPF 4 is requested.

[0116] FIG. 11 is a timing chart showing an example of changes in various parameters when it is confirmed that the motoring mode is being performed. FIG. 12 is a timing chart showing an example of changes in various parameters when it is not confirmed that the motoring mode is being performed. The engine speeds shown by solid lines in FIGS. 11 and 12 are target speeds during motoring when a regeneration request is made for the GPF 4. The engine speeds shown by thick solid lines in FIGS. 11 and 12 are actual engine speeds (actual speeds) of the internal combustion engine 1 that are detected. Note that in FIGS. 11 and 12, the speed thresholds are set to values ​​that are a predetermined amount smaller than the target speed when a regeneration request is made for the GPF 4. In other words, the speed thresholds in FIGS. 11 and 12 are set to values ​​that are a predetermined amount smaller than the target speed when a regeneration request is made for the GPF 4.

[0117] The motoring mode is considered to be implemented when, in response to a request for regeneration of GPF4, fuel injection is stopped or the amount of fuel injection is reduced, and the engine speed when motoring the internal combustion engine 1 is greater than a predetermined speed threshold, and it is confirmed that the engine speed is following the target speed at the time of the request for regeneration of GPF4.

[0118] A case where it is confirmed that the motoring mode is in operation will be described with reference to FIG.

[0119] At time t1 in FIG. 11, an operation request with a higher priority than the regeneration request for the GPF 4 occurs.

[0120] Time t2 in Figure 11 is the timing when a regeneration request for the GPF 4 is issued. Also, at time t2 in Figure 11, the catalyst temperature of the GPF 4 is equal to or higher than a predetermined GPF temperature threshold. The GPF temperature threshold is an index of the catalyst temperature at which regeneration of the GPF 4 by motoring is permitted. When the catalyst temperature of the GPF 4 is equal to or higher than the GPF temperature threshold, motoring of the stopped internal combustion engine 1 is permitted in order to regenerate the GPF 4. When the catalyst temperature is equal to or higher than the GPF temperature threshold, the internal combustion engine 1 supplies oxygen to the GPF 4 by motoring, thereby burning and removing exhaust particulates trapped in the GPF 4 and regenerating the GPF 4.

[0121] At the timing of time t2 in Figure 11, an operation request with a higher priority than the regeneration request of GPF4 has occurred, so motoring of the internal combustion engine 1 is not started and the internal combustion engine 1 remains stopped.

[0122] The timing of time t3 in Fig. 11 is the timing when a regeneration request for GPF 4 has been issued and there is no longer any operation request with a higher priority than the regeneration request for GPF 4. Therefore, at the timing of time t3 in Fig. 11, a regeneration request permission flag that permits the regeneration request for GPF 4 is turned ON. Also, the timing of time t3 in Fig. 11 is the timing when motoring of the internal combustion engine 1 is started as a result of the regeneration request for GPF 4 being permitted, and the motoring diagnosis permission flag is turned ON. The motoring diagnosis permission flag is turned ON when there is a regeneration request for GPF 4 and there is no operation request with a higher priority than the regeneration request for GPF 4.

[0123] In Figure 11, when the motoring diagnosis permission flag is turned ON at time t3, fuel injection is stopped or the fuel injection amount is reduced from time t3, and the motor generator 8 is driven to start motoring of the internal combustion engine 1. In other words, in Figure 11, the motoring mode is started from time t3.

[0124] Time t4 in Fig. 11 is the timing when a predetermined time has elapsed since time t3 in Fig. 11. In order to determine whether the motoring mode is being executed from the timing of time t4 in Fig. 11, the fourth OK / NG count determination timer starts counting up its count value from the timing of time t3.

[0125] The timing at which the count value of the fourth OK / NG count determination timer is counted up is the timing at which the count value of a motoring OK counter (not shown) serving as an OK counter or a motoring NG counter (not shown) serving as an NG counter is counted up (incremented). The motoring OK counter serving as an OK / NG counter counts up (increments) the OK count value when the actual engine speed (actual engine speed) of the internal combustion engine 1 is equal to or greater than the speed threshold. The motoring NG counter serving as an OK / NG counter counts up (increments) the NG count value when the actual engine speed (actual engine speed) of the internal combustion engine 1 is less than the speed threshold.

[0126] In other words, from the timing of time t4 in Figure 11 to the timing of time t5 in Figure 11 described later, either the OK count value of the motoring OK counter or the NG count value of the motoring NG counter is counted up at predetermined time intervals.

[0127] At time t5 in Fig. 11, the OK count value of the motoring OK counter is counted up to the motoring OK count threshold, which is a count threshold value. In Fig. 11, the OK count value of the motoring OK counter reaches the motoring OK count threshold at time t5, so the OK determination flag is turned ON at time t5, and it is determined that the motoring mode has been executed at time t4.

[0128] 11, the determination as to whether the motoring mode is being implemented is completed at time t5, and therefore the fourth diagnosis end flag is set to ON at time t5. The fourth diagnosis is a diagnosis as to whether the motoring mode is being implemented.

[0129] The timing of time t6 in FIG. 11 is the timing when the regeneration request from GPF4 is no longer made.

[0130] A case where the implementation of the motoring mode cannot be confirmed will be described with reference to FIG.

[0131] At time t1 in FIG. 12, an operation request with a higher priority than the regeneration request for the GPF 4 occurs.

[0132] The timing of time t2 in Fig. 12 is the timing at which a regeneration request is generated for the GPF 4. At the timing of time t2 in Fig. 12, a state has occurred in which an operation request with a higher priority than the regeneration request for the GPF 4 has been generated, so motoring of the internal combustion engine 1 is not started and the internal combustion engine 1 remains stopped.

[0133] The timing of time t3 in Fig. 12 is the timing when, while a regeneration request for the GPF 4 has been issued, there is no longer an operation request with a higher priority than the regeneration request for the GPF 4. Therefore, at the timing of time t3 in Fig. 12, a regeneration request permission flag that permits the regeneration request for the GPF 4 is turned ON. Also, the timing of time t3 in Fig. 12 is the timing when motoring of the internal combustion engine 1 is started due to the permission of the regeneration request for the GPF 4, and the motoring diagnosis permission flag is turned ON.

[0134] In Fig. 12, when the motoring diagnosis permission flag is turned ON at time t3, the motor generator 8 is driven from time t3 to start motoring of the internal combustion engine 1. In other words, in Fig. 12, the motoring mode is started from time t3.

[0135] Time t4 in Fig. 12 is the timing when a predetermined time has elapsed since time t3 in Fig. 12. In order to determine whether the motoring mode is being implemented from time t4 in Fig. 12, the fourth OK / NG count determination timer starts counting up its count value from time t4. In other words, from time t4 in Fig. 12 to time t5 in Fig. 12 (described later), either the OK count value of the rotation speed OK counter or the NG count value of the rotation speed NG counter is counted up at predetermined time intervals.

[0136] Time t5 in Figure 12 is the time when the NG count value of the motoring NG counter has counted up to the motoring NG count threshold, which is a count threshold. In Figure 12, the NG count value of the motoring NG counter reaches the NG count threshold at time t5, so the NG determination flag is turned ON at time t5, and it is determined that the implementation of motoring mode has not been confirmed at time t5. Also in Figure 12, the determination of whether the motoring mode is being implemented is completed at time t5, so the fourth diagnosis end flag is turned ON at time t5.

[0137] The timing of time t6 in FIG. 12 is the timing when the regeneration request from GPF4 is no longer made.

[0138] FIG. 13 is a flowchart showing an example of a control flow when confirming whether the motoring mode is being executed.

[0139] In step S41, it is determined whether or not there is a request to regenerate the GPF 4. If there is a request to regenerate the GPF 4 in step S41, the process proceeds to step S42. If there is no request to regenerate the GPF 4 in step S41, the current routine is terminated.

[0140] In step S42, it is determined whether or not motoring of the internal combustion engine 1 is being performed in response to a regeneration request for the GPF 4. That is, in step S42, it is determined whether or not the internal combustion engine 1 is being motored by the motor generator 8, and the engine speed of the internal combustion engine 1 is the target speed for motoring at the time of the regeneration request for the GPF 4. If motoring of the internal combustion engine 1 in response to a regeneration request for the GPF 4 is being performed in step S42, the routine proceeds to step S43. If motoring of the internal combustion engine 1 in response to a regeneration request for the GPF 4 is not being performed in step S42, the current routine is terminated.

[0141] In step S43, it is determined whether the engine speed of the motoring internal combustion engine 1 is equal to or greater than the rotation speed threshold. If the engine speed of the motoring internal combustion engine 1 is equal to or greater than the rotation speed threshold in step S43, the process proceeds to step S44. If the engine speed of the motoring internal combustion engine 1 is not equal to or greater than the rotation speed threshold in step S43, the process proceeds to step S45.

[0142] In step S44, the count value of the motoring OK counter is incremented (counted up).

[0143] In step S45, the count value of the motoring NG counter is incremented (counted up).

[0144] In step S46, it is determined whether the count value of the motoring OK counter is equal to or greater than a predetermined motoring OK count threshold, and whether the count value of the motoring NG counter is equal to or greater than a predetermined motoring NG count threshold. If in step S46 either the count value of the motoring OK counter or the count value of the motoring NG counter is equal to or greater than the count threshold, the process proceeds to step S47. If in step S46 both the count values ​​of the motoring OK counter and the motoring NG counter are less than the count threshold, the current routine is terminated.

[0145] In step S47, if the count value of the motoring OK counter is equal to or greater than the motoring OK count threshold, it is determined that the motoring mode is in operation and the OK determination is confirmed.Also, in step S47, if the count value of the motoring NG counter is equal to or greater than the motoring NG count threshold, it is determined that the motoring mode is not in operation and the NG determination is confirmed.

[0146] The internal combustion engine 1 of the above-described embodiment determines that the GPF 4 is in a state where it can be regenerated when it is confirmed that the temperature rise mode and the motoring mode are being implemented, thereby ensuring that the GPF 4 is in a state where it can be properly regenerated while driving.

[0147] In other words, the internal combustion engine 1 can ensure that the regeneration of the GPF 4 is carried out correctly by determining that the temperature rise mode, which is a process of increasing the temperature of the GPF 4, and the motoring mode, which is a process of supplying air to the GPF 4 and burning the exhaust particulates captured in the GPF 4, are being carried out properly.

[0148] Although specific embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the invention.

[0149] For example, if the internal combustion engine 1 is mounted on a vehicle capable of directly transmitting driving force to the vehicle's drive wheels, a GPF regeneration request may be made when a predetermined fuel cut condition is met and fuel supply to the internal combustion engine 1 is stopped.

[0150] For example, the temperature rise mode may be at least one of the first to third temperature rise modes. That is, for example, when it is confirmed that at least one of the first to third temperature rise modes and the motoring mode are being performed, it may be determined that the GPF 4 is in a state where it can be regenerated.

[0151] For example, the internal combustion engine is not limited to that mounted on a hybrid vehicle, but may be that mounted on a vehicle in which the drive source for the drive wheels is only an internal combustion engine. In this case, it may be determined that the internal combustion engine is in a state in which GPF regeneration is possible when it is confirmed that at least one of the first to third temperature rise modes is being performed, or it may be determined that the internal combustion engine is in a state in which GPF regeneration is possible when it is confirmed that all of the first to third temperature rise modes are being performed.

[0152] The above-described embodiments relate to a diagnostic method for an internal combustion engine and a diagnostic device for an internal combustion engine.

Claims

1. A diagnostic method for an internal combustion engine having an exhaust particulate filter arranged in an exhaust passage for capturing particulate matter in the exhaust, and for regenerating the exhaust particulate filter by removing the captured exhaust particulates through combustion, wherein the regeneration of the exhaust particulate filter is carried out in a temperature rise mode in which the temperature of the exhaust particulate filter is raised, and in a motoring mode in which the internal combustion engine is motored and air is supplied to the exhaust particulate filter, and wherein the temperature rise mode is a first temperature rise mode in which the ignition timing of the internal combustion engine is retarded to raise the temperature of the exhaust particulate filter, a second temperature rise mode in which the engine speed of the internal combustion engine is increased to raise the temperature of the exhaust particulate filter, or a third temperature rise mode in which the torque of the internal combustion engine is increased to raise the temperature of the exhaust particulate filter, and wherein the diagnostic method for an internal combustion engine determines that the exhaust particulate filter is in a state where it can be regenerated when it is confirmed that the temperature rise mode is being performed and that the motoring mode is being performed.

2. A diagnostic method for an internal combustion engine as described in claim 1, wherein the implementation of the temperature rise mode is confirmed when the implementation of all of the first temperature rise mode, the second temperature rise mode, and the third temperature rise mode is confirmed.

3. A diagnostic method for an internal combustion engine as described in claim 2, wherein the implementation of the first heating mode is confirmed by the ignition timing command value being on the retard side of a predetermined threshold, the implementation of the second heating mode is confirmed by the detected value of the engine speed being greater than a predetermined threshold, the implementation of the third heating mode is confirmed by the torque command value being greater than a predetermined threshold, and the implementation of the motoring mode is confirmed by the detected value of the engine speed being greater than a predetermined threshold.

4. A diagnostic device for an internal combustion engine comprising: an exhaust particulate filter arranged in an exhaust passage for capturing particulate matter in the exhaust; and a control unit for regenerating the exhaust particulate filter by removing the captured exhaust particulates through combustion, wherein the control unit regenerates the exhaust particulate filter in a temperature rise mode for raising the temperature of the exhaust particulate filter, and a motoring mode for motoring an internal combustion engine to supply air to the exhaust particulate filter, wherein the temperature rise mode is a first temperature rise mode for retarding the ignition timing of the internal combustion engine to raise the temperature of the exhaust particulate filter, a second temperature rise mode for increasing the engine speed of the internal combustion engine to raise the temperature of the exhaust particulate filter, or a third temperature rise mode for increasing the torque of the internal combustion engine to raise the temperature of the exhaust particulate filter, and wherein the control unit determines that the exhaust particulate filter is in a state where it can be regenerated when it is confirmed that the temperature rise mode is being performed and that the motoring mode is being performed.

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