Hybrid vehicle abnormality diagnosis device

Abstract

To suppress a diagnosis of an accidental fire abnormality caused by a temporal accidental fire occurring just after an engine is started from hot soak.SOLUTION: An engine control unit 300 executes: accidental fire determination processing; accidental fire count processing for increasing an accidental fire count value every time when occurrence of an accidental fire is determined; and abnormality diagnosis processing for diagnosing whether or not an accidental fire abnormality occurs or not, on the basis of the accidental fire count values integrated until the cumulative number of rotation of a crank shaft 59 reaches a predetermined number of rotation. Further the engine control unit 300 executes hot soak determination processing for determining that an engine is started from hot soak. When it is determined that the engine is started from hot soak, the engine control unit 300 makes increments of the accidental fire count values in the accidental fire count processing every time when the occurrence of the accidental fire is determined, smaller than when it is not determined that the engine is started from hot soak.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an abnormality diagnosis device for a hybrid vehicle. [Background technology]

[0002] In vehicles equipped with engines, abnormality diagnosis is performed to diagnose a state in which misfires occur frequently enough that tailpipe emissions exceed a reference value as a misfire abnormality. An abnormality diagnosis device that performs such a misfire abnormality diagnosis checks the misfire rate during operation up to a preset number of rotations, for example, every time the output shaft of the engine rotates a preset number of times. Then, if the misfire rate is equal to or greater than a threshold value, the abnormality diagnosis device diagnoses that a misfire abnormality has occurred.

[0003] However, in the case of a hybrid vehicle, the vehicle may run only on the driving force of the motor without operating the engine. Therefore, during running, the vehicle may switch to running only on the driving force of the motor, and the engine operation may end before the output shaft of the engine rotates a predetermined number of times.

[0004] Patent Document 1 discloses an example of an abnormality diagnosis device for a hybrid vehicle. This abnormality diagnosis device retains information on the number of revolutions of the engine output shaft and the number of misfire occurrences even during a soak when the engine operation is stopped. When the engine operation is resumed, the abnormality diagnosis device accumulates the number of revolutions and the number of misfire occurrences, and calculates the cumulative number of revolutions and the cumulative number of misfires. Then, each time the cumulative number of revolutions reaches a predetermined number, the abnormality diagnosis device calculates the misfire rate from the cumulative number of revolutions and the cumulative number of misfires. This ensures an opportunity to diagnose misfire abnormalities, even in a hybrid vehicle. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2014-043805 A Summary of the Invention [Problem to be solved by the invention]

[0006] After the engine has finished running, it may be started from a hot soak state, where the fuel lines and injectors are still warm and hot. Immediately after starting from the hot soak state, the fuel in the fuel lines and injectors is vaporized. In this state, the amount of fuel injected is reduced, making misfires more likely to occur.

[0007] This type of misfire that occurs immediately after starting from a hot soak is a temporary phenomenon and does not qualify as a misfire abnormality, which is the target of abnormality diagnosis. However, as described above, misfires are more likely to occur temporarily immediately after starting from a hot soak. As a result, in the case of hybrid vehicles, the cumulative number of misfires increases and the vehicle may be diagnosed with a misfire abnormality. [Means for solving the problem]

[0008] The means for solving the above problems and their effects will be described below. The abnormality diagnosis device for a hybrid vehicle for solving the above problems is an abnormality diagnosis device applied to a hybrid vehicle having an engine and a motor. The abnormality diagnosis device executes a misfire determination process for determining the occurrence of a misfire during operation of the engine, a misfire count process for increasing a misfire count value each time the occurrence of a misfire is determined through the misfire determination process, and an abnormality diagnosis process for diagnosing whether a misfire abnormality has occurred based on the misfire count value accumulated through the misfire count process until the cumulative number of revolutions of the output shaft of the engine reaches a predetermined number. The abnormality diagnosis device executes a hot soak determination process for determining that the engine is started from a hot soak when the temperature of the engine at the time of starting is equal to or higher than a predetermined temperature, and when it is determined that the engine is started from a hot soak, the increase in the misfire count value in the misfire count process each time the occurrence of a misfire is determined is smaller than when it is not determined that the engine is started from a hot soak.

[0009] According to the above configuration, when the engine is started from a hot soak, the misfire count value is increased by a smaller amount each time a misfire is determined to have occurred, compared to when the engine is not started from a hot soak. This makes it possible to prevent a misfire diagnosis from being made due to a temporary misfire occurring immediately after starting from a hot soak. In other words, the above configuration makes it possible to secure opportunities to diagnose misfires by using the cumulative number of revolutions, while improving the accuracy of misfire diagnosis. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of a hybrid vehicle equipped with an engine control unit that is one embodiment of an abnormality diagnosis device. [Diagram 2] FIG. 2 is a flowchart showing a series of processes in an initial value setting routine executed by the engine control unit at engine start. [Diagram 3] FIG. 3 is a flowchart showing a series of processes in a storage routine executed by the engine control unit when the engine operation is terminated. [Figure 4] FIG. 4 is a flowchart showing a series of steps in a diagnostic routine executed by the engine control unit while the system is in operation. [Diagram 5] Fig. 5 is a time chart showing the transition of various states when the engine is started from a hot soak. Fig. 5(a) shows the engine operating state, Fig. 5(b) shows the hot soak judgement state, Fig. 5(c) shows the cumulative number of revolutions, Fig. 5(d) shows the cumulative number of revolutions after the hot soak, and Fig. 5(e) shows the misfire rate. [Figure 6] FIG. 6 is a flowchart showing a series of steps in an initial value setting routine executed by the engine control unit when the abnormality diagnosis process is executed in another mode. [Figure 7] FIG. 7 is a flowchart showing a series of steps in a diagnostic routine for the abnormality diagnosis process according to the other aspect described above. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, one embodiment of an abnormality diagnosis device for a hybrid vehicle will be described with reference to Figs. <About the configuration of vehicle 10> As shown in Fig. 1, the vehicle 10 includes an engine 50. The vehicle 10 also includes a battery 30 that stores electric power. The vehicle 10 further includes a first motor generator 11 and a second motor generator 12. The first motor generator 11 and the second motor generator 12 are motors that generate driving force in response to power supplied from the battery 30, and also function as generators that receive external power and generate electric power to charge the battery 30.

[0012] The vehicle 10 is further provided with a planetary gear mechanism 13 having three rotating elements, a sun gear 14, a planetary carrier 15, and a ring gear 16. A crankshaft 59, which is an output shaft of the engine 50, is connected to the planetary carrier 15 of the planetary gear mechanism 13, and a first input shaft 25, which is connected to a rotating shaft of the first motor generator 11, is connected to the sun gear 14 of the planetary gear mechanism 13. A counter drive gear 17 is integrally provided to the ring gear 16 of the planetary gear mechanism 13. A counter driven gear 18 is meshed with the counter drive gear 17. A reduction gear 19 is meshed with the counter driven gear 18. A second input shaft 26, which is connected to the rotating shaft of the second motor generator 12, is connected to the reduction gear 19.

[0013] A final drive gear 20 is connected to the counter driven gear 18 so as to be rotatable together with the counter driven gear 18. A final driven gear 21 is meshed with the final drive gear 20. A drive shaft 24 of drive wheels 23 is connected to the final driven gear 21 via a differential mechanism 22.

[0014] <About the System Control Unit 100> The system control unit 100 includes a storage device in which a program is stored, and a processing circuit that executes the program stored in the storage device to perform various controls. The system control unit 100 is connected to a power control unit 200 and an engine control unit 300.

[0015] <About the power control unit 200> The first motor generator 11 and the second motor generator 12 are connected to the battery 30 via a power control unit 200. The power control unit 200 includes a control circuit, an inverter, and a converter. The power control unit 200 operates based on a command from the system control unit 100. The power control unit 200 adjusts the amount of power supplied from the battery 30 to the first motor generator 11 and the second motor generator 12, and the amount of charge from the first motor generator 11 and the second motor generator 12 to the battery 30. The vehicle 10 is provided with a connector 31 that can be connected to an external power source 40. Therefore, the battery 30 can also be charged by the power supplied from the external power source 40. That is, the vehicle 10 is a plug-in hybrid vehicle.

[0016] <About the engine control unit 300> The engine control unit 300 controls the engine 50 based on commands from the system control unit 100. The engine control unit 300 includes a storage device in which programs are stored, and a processing circuit that executes the programs stored in the storage device to perform various types of control.

[0017] Detection signals from various sensors that detect the operating state of engine 50 are input to engine control unit 300. The sensors that input detection signals to engine control unit 300 include a crank position sensor 134 that detects the rotation angle of crankshaft 59. The crank position sensor 134 outputs a crank angle signal according to a change in the rotation phase of crankshaft 59. Engine control unit 300 calculates the engine rotation speed, which is the rotation speed of crankshaft 59, based on the detection signal of the rotation angle of crankshaft 59 input from crank position sensor 134.

[0018] Also connected to the engine control unit 300 is an intake air temperature sensor 135 that detects the temperature of the intake air taken into the combustion chamber of the engine 50. Furthermore, also connected to the engine control unit 300 is a water temperature sensor 136 that detects the temperature of the cooling water for the engine 50.

[0019] 1, a main switch 130 that allows the driver of the vehicle 10 to start and stop the system of the vehicle 10 is connected to the system control unit 100. An accelerator position sensor 131 that detects an accelerator operation amount and a brake sensor 132 that detects a brake operation amount are also connected to the system control unit 100. A vehicle speed sensor 133 that detects the vehicle speed, which is the speed of the vehicle 10, is also connected to the system control unit 100.

[0020] Further, the current, voltage, and temperature of the battery 30 are input to the power control unit 200. The power control unit 200 calculates a state of charge index value SOC, which is the ratio of the remaining charge to the charge capacity of the battery 30, based on the current, voltage, and temperature.

[0021] The engine control unit 300 and the power control unit 200 are each connected to the system control unit 100. The system control unit 100, the power control unit 200, and the engine control unit 300 mutually exchange and share information based on detection signals input from sensors and calculated information.

[0022] Based on this information, the system control unit 100 outputs commands to the engine control unit 300 and controls the engine 50 through the engine control unit 300. The system control unit 100 also outputs commands to the power control unit 200 based on this information. As a result, the system control unit 100 controls the first motor generator 11 and the second motor generator 12 and controls the charging of the battery 30 through the power control unit 200. In this way, the system control unit 100 controls the vehicle 10 by outputting commands to the power control unit 200 and the engine control unit 300.

[0023] <Regarding control of vehicle 10> Next, the control of the vehicle 10 performed by the system control unit 100 will be described in more detail.

[0024] The system control unit 100 calculates a required output, which is a required value of the output of the vehicle 10, based on the accelerator operation amount and the vehicle speed. The system control unit 100 then determines the torque distribution of the engine 50, the first motor generator 11, and the second motor generator 12 according to the required output and a state of charge index value SOC of the battery 30. The system control unit 100 then controls the output of the engine 50 and power running / regeneration by the first motor generator 11 and the second motor generator 12. The system control unit 100 switches the driving mode of the vehicle 10 depending on the magnitude of the state of charge index value SOC.

[0025] When the state of charge index value SOC exceeds a certain level, the system control unit 100 selects a motor driving mode in which the vehicle runs using the driving force from the second motor generator 12 and the driving force from the first motor generator 11 without operating the engine 50. In other words, the system control unit 100 selects the motor driving mode when the remaining charge of the battery 30 is sufficient.

[0026] On the other hand, when the state of charge index value SOC falls below a certain level, the system control unit 100 selects a hybrid driving mode in which the engine 50 is used in addition to the first motor generator 11 and the second motor generator 12.

[0027] Even if the state of charge index value SOC exceeds a certain level, the system control unit 100 selects the hybrid driving mode in the following cases. When the vehicle speed exceeds the upper limit of the motor driving mode.

[0028] When a large amount of power is needed temporarily, such as during rapid acceleration with a large amount of accelerator pedal operation. When engine 50 needs to be started. When the hybrid driving mode is selected, the system control unit 100 causes the first motor generator 11 to function as a starter motor when starting the engine 50. Specifically, the system control unit 100 causes the first motor generator 11 to rotate the sun gear 14, thereby rotating the crankshaft 59 and starting the engine 50.

[0029] Furthermore, when the hybrid driving mode is selected, the system control unit 100 switches the control during vehicle stop according to the magnitude of the state of charge index value SOC. Specifically, when the state of charge index value SOC is equal to or greater than a threshold value, the system control unit 100 stops the operation of the engine 50 and does not drive the first motor generator 11 and the second motor generator 12. That is, the system control unit 100 stops the operation of the engine 50 during vehicle stop to suppress idling. Note that, when the state of charge index value SOC of the battery 30 is less than a threshold value, the system control unit 100 operates the engine 50. Then, the first motor generator 11 is driven by the output of the engine 50 to function as a generator.

[0030] When the hybrid driving mode is selected, the system control unit 100 switches the control according to the state of charge index value SOC even during driving. When the state of charge index value SOC of the battery 30 is equal to or greater than the threshold value when starting or during light load driving, the system control unit 100 starts and drives the vehicle 10 only by the driving force of the second motor generator 12. In this case, the engine 50 is stopped, and the first motor generator 11 does not generate power. On the other hand, when the state of charge index value SOC of the battery 30 is less than the threshold value when starting or during light load driving, the system control unit 100 starts the engine 50, causes the first motor generator 11 to generate power, and charges the generated power to the battery 30. In this case, the vehicle 10 runs by part of the driving force of the engine 50 and the driving force of the second motor generator 12. During steady running, when the state of charge index value SOC of the battery 30 is equal to or higher than the threshold value, the system control unit 100 operates the engine 50 in a state of high operating efficiency, and runs the vehicle 10 mainly with the output of the engine 50. At this time, the power of the engine 50 is divided between the drive wheels 23 side and the first motor generator 11 side via the planetary gear mechanism 13. As a result, the vehicle 10 runs while generating power with the first motor generator 11. Then, the system control unit 100 drives the second motor generator 12 with the generated power, and the power of the second motor generator 12 assists the power of the engine 50. On the other hand, during steady running, when the state of charge index value SOC of the battery 30 is less than the threshold value, the system control unit 100 increases the engine rotation speed. Then, the power generated by the first motor generator 11 is used to drive the second motor generator 12, and the surplus power is charged to the battery 30. During acceleration, the system control unit 100 increases the engine rotation speed and uses the electric power generated by the first motor generator 11 to drive the second motor generator 12. This causes the vehicle 10 to accelerate using the power of the engine 50 and the power of the second motor generator 12. During deceleration, the system control unit 100 stops the operation of the engine 50.The system control unit 100 then causes the second motor generator 12 to function as a generator, and the generated electric power is charged to the battery 30. In the vehicle 10, the resistance caused by such power generation is used as a brake. Such power generation control during deceleration is called regenerative control.

[0031] <Diagnosis of misfire abnormalities> The engine control unit 300 performs an abnormality diagnosis to diagnose a misfire abnormality in the engine 50. The engine control unit 300 diagnoses, as a misfire abnormality, a state in which misfires occur with such frequency that tail pipe emissions in the engine 50 exceed a reference value.

[0032] 2 to 4, a routine executed by the engine control unit 300 regarding the abnormality diagnosis process for diagnosing whether or not a misfire abnormality has occurred will be described. Fig. 2 shows a process flow of an initial value setting routine executed by the engine control unit 300. When the engine 50 is started, the engine control unit 300 executes this initial value setting routine. As shown in Fig. 2, when the engine control unit 300 starts this initial value setting routine, it first initializes the accumulated number of revolutions Σrev in the process of step S100. Specifically, the engine control unit 300 assigns the stored accumulated number of revolutions Σrev_last to the accumulated number of revolutions Σrev to initialize the accumulated number of revolutions Σrev.

[0033] The cumulative number of revolutions Σrev is a value that is counted up by one each time the crankshaft 59 rotates once while the engine 50 is operating through the diagnostic routine. That is, the cumulative number of revolutions Σrev is a value obtained by accumulating the number of revolutions of the crankshaft 59. The details of the diagnostic routine will be described later with reference to FIG.

[0034] The stored cumulative revolution count Σrev_last is the value of the cumulative revolution count Σrev stored in the storage device through the storage routine at the time when the operation of the engine 50 is terminated. Details of the storage routine will be described later with reference to FIG.

[0035] After initializing the cumulative number of revolutions Σrev through the process of step S100, the engine control unit 300 advances the process to step S110. Then, in the process of step S110, the engine control unit 300 initializes the misfire count value cnt. Specifically, the engine control unit 300 assigns the stored misfire count value cnt_last to the misfire count value cnt to initialize the misfire count value cnt.

[0036] The misfire count value cnt is a value that is incremented each time a misfire is determined to have occurred through the misfire determination process in the diagnostic routine. The stored misfire count value cnt_last is the value of the misfire count value cnt that is stored in the storage device when the operation of the engine 50 is terminated through the storage routine.

[0037] After initializing the misfire count value cnt through the process of step S110, the engine control unit 300 advances the process to step S120. Then, in the process of step S120, the engine control unit 300 initializes the accumulated number of revolutions after hot soak rev_h to "0." The accumulated number of revolutions after hot soak rev_h is a value that is counted up by one each time the crankshaft 59 rotates once during the operation of the engine 50 from the hot soak through the diagnostic routine. In other words, the accumulated number of revolutions after hot soak rev_h is a value obtained by accumulating the number of revolutions of the crankshaft 59 during the operation of the engine 50 from the hot soak.

[0038] After initializing the post-hot soak cumulative revolution count rev_h through the process of step S120, engine control unit 300 advances the process to step S130. Then, in the process of step S130, engine control unit 300 executes a hot soak determination process.

[0039] In this hot soak determination process, the engine control unit 300 determines that the engine 50 has started from a hot soak when the temperature of the engine 50 is equal to or higher than a specified temperature. In the process of step S130, the engine control unit 300 regards the temperature of the cooling water detected by the water temperature sensor 136 as the temperature of the engine 50. Then, when the temperature of the cooling water detected by the water temperature sensor 136 is equal to or higher than a preset water temperature and the temperature of the intake air detected by the intake air temperature sensor 135 is equal to or higher than a preset temperature, the engine control unit 300 determines that the engine 50 has started from a hot soak. The preset water temperature is, for example, 95°C. The preset temperature is, for example, 75°C. When the engine control unit 300 determines that the engine 50 has started from a hot soak, the engine control unit 300 sets a hot soak flag indicating that the engine 50 has started from a hot soak to ON and stores the flag in the storage device. The hot soak flag is OFF in the initial state. On the other hand, when the engine control unit 300 determines that the engine 50 has not started from a hot soak, the engine control unit 300 ends the hot soak determination process as it is. That is, in this case, the hot soak flag remains OFF.

[0040] After executing the hot soak determination process in this manner, the engine control unit 300 ends this initialization routine. Next, the storage routine will be described with reference to Fig. 3. When the engine control unit 300 ends the operation of the engine 50, it executes the storage routine shown in Fig. 3. When this storage routine is started, as shown in Fig. 3, the engine control unit 300 first stores the cumulative number of revolutions Σrev in the storage device in the process of step S400, and stores it as the stored cumulative number of revolutions Σrev_last.

[0041] Next, in the process of step S410, the engine control unit 300 stores the misfire count value cnt in the storage device as a stored misfire count value cnt_last.

[0042] After storing the cumulative number of revolutions Σrev and the misfire count value cnt during the engine operation stop in the storage device, the engine control unit 300 ends the storage routine.

[0043] Next, the diagnostic routine will be described with reference to Fig. 4. The engine control unit 300 repeatedly executes the diagnostic routine shown in Fig. 4 while the system of the vehicle 10 is operating. The execution cycle of this diagnostic routine is shorter than the execution cycle of ignition in the engine 50. For example, if the engine 50 is a four-cylinder engine, this diagnostic routine is repeatedly executed at a cycle shorter than 180° CA.

[0044] When this diagnostic routine is started, the engine control unit 300 first determines whether or not the engine 50 is operating in the process of step S210. If it is determined in the process of step S210 that the engine 50 is operating (step S210: YES), the engine control unit 300 proceeds to the process of step S220. Then, in the process of step S220, the engine control unit 300 updates the cumulative number of revolutions Σrev and the post-hot soak cumulative number of revolutions rev_h.

[0045] Specifically, in the process of step S220, the engine control unit 300 grasps the rotation phase of the crankshaft 59 based on the crank angle signal. Then, the engine control unit 300 counts up the cumulative number of rotations Σrev by one each time the crankshaft 59 rotates once. For example, when it is detected from the crank angle signal that the crank angle has crossed 0° CA, and when it is detected that the crank angle has crossed 360° CA, the engine control unit 300 counts up the cumulative number of rotations Σrev by one each time the crankshaft 59 rotates once, using the same method as above, on condition that the hot soak flag is ON.

[0046] In the process of step S210, when it is determined that the engine 50 is not operating and is stopped (step S210: NO), the engine control unit 300 advances the process to step S230. In the process of step S230, the engine control unit 300 holds the cumulative number of revolutions Σrev and the cumulative number of revolutions after hot soak rev_h. Then, the engine control unit 300 temporarily ends this diagnostic routine. That is, in this diagnostic routine, the engine control unit 300 holds the cumulative number of revolutions Σrev and the cumulative number of revolutions after hot soak rev_h without resetting them even while the engine 50 is stopped. Specifically, they are stored in a storage device. Then, when the operation of the engine 50 is resumed, the process of step S220 is executed using the values ​​of the cumulative number of revolutions Σrev and the cumulative number of revolutions after hot soak rev_h stored in the storage device. That is, when the operation of the engine 50 is resumed, the engine control unit 300 continues counting the number of revolutions from the values ​​stored in the storage device.

[0047] When the process of step S220 is executed, in the process of the next step S240, the engine control unit 300 judges whether or not it has been determined that a misfire has occurred. The engine control unit 300 repeatedly executes a misfire judgment process for judging whether or not a misfire has occurred each time an ignition occurs in each cylinder while the engine 50 is in operation. In the process of step S240, it is confirmed whether or not it has been determined that a misfire has occurred through the misfire judgment process.

[0048] In the misfire determination process, for example, the change in the angular velocity of the crank angle during the combustion stroke of the cylinder to be determined is compared with the change in the angular velocity of the crank angle during the combustion stroke of the other cylinders, and if the change in the angular velocity during the combustion stroke of the cylinder to be determined is smaller than the angular velocities during the combustion stroke of the other cylinders, it is determined that a misfire has occurred in the cylinder to be determined.

[0049] If it is determined that a misfire has occurred (step S240: YES), the engine control unit 300 advances the process to step S250. In the process of step S250, engine control unit 300 determines whether or not the vehicle is operating from a hot soak. Specifically, engine control unit 300 determines whether or not a hot soak flag is ON. If the hot soak flag is ON, that is, if it is determined that the vehicle is operating from a hot soak (step S250: YES), engine control unit 300 proceeds to step S260. On the other hand, if the hot soak flag is OFF, that is, if it is determined that the vehicle is not operating from a hot soak (step S250: NO), engine control unit 300 proceeds to step S280.

[0050] In the process of step S280, the engine control unit 300 adds "1" to the misfire count value cnt and sets the sum as the new misfire count value cnt. That is, in this case, the engine control unit 300 increases the misfire count value cnt by "1". Then, the engine control unit 300 advances the process to step S290.

[0051] When it is determined in the process of step S250 that the engine is operating from the hot soak (step S250: YES), the engine control unit 300 advances the process to step S260 as described above. In the process of step S260, the engine control unit 300 determines whether the cumulative number of revolutions after the hot soak rev_h is equal to or less than the first predetermined number X1. The first predetermined number X1 is a threshold value for determining whether the state in which misfire is likely to occur after starting from the hot soak continues. Immediately after starting from the hot soak, the fuel in the fuel pipe and the injector is vaporized. In this state, the amount of fuel injected is reduced, so that misfire is likely to occur. This state is resolved when the fuel pipe and the injector are filled with liquid fuel by fuel injection. The first predetermined number X1 is a threshold value for determining whether the state in which misfire is likely to occur has been resolved based on the cumulative number of revolutions after the hot soak rev_h. The first predetermined number X1 is set based on the results of experiments and the like conducted in advance. For example, the first preset number of times X1 is set to "1000 times."

[0052] In the process of step S260, when it is determined that the post-hot soak cumulative number of revolutions rev_h is greater than the first predetermined number of times X1 (step S260: NO), the engine control unit 300 advances the process to step S280. That is, in this case as well, the engine control unit 300 increases the misfire count value cnt by "1". Then, the engine control unit 300 advances the process to step S290.

[0053] On the other hand, when it is determined in the process of step S260 that the post-hot soak cumulative revolution count rev_h is equal to or less than the first preset number X1 (step S260: YES), the engine control unit 300 advances the process to step S270. In the process of step S270, the engine control unit 300 adds the product of "1" multiplied by the coefficient k1 to the misfire count value cnt, and sets the sum as a new misfire count value cnt. Note that the coefficient k1 is a value smaller than "1" and larger than "0". For example, the coefficient k1 is "0.2" here. That is, in this case, the engine control unit 300 increases the misfire count value cnt by "0.2". Then, the engine control unit 300 advances the process to step S290.

[0054] In this way, when it is determined that the engine is starting from a hot soak and a misfire is likely to occur, the engine control unit 300 increases the misfire count value cnt by a smaller amount than when it is not determined that the engine is starting from a hot soak.

[0055] If it is not determined in the process of step S240 that a misfire has occurred (step S240: NO), the engine control unit 300 advances the process to step S290. That is, in this case, the misfire count value cnt is not increased and the process advances to step S290.

[0056] In the diagnosis routine of FIG. 4, the processes from step S220 to step S280 are misfire count processes that increase the misfire count value cnt every time the occurrence of a misfire is determined through the misfire determination process.

[0057] In the process of step S290, the engine control unit 300 determines whether the cumulative number of revolutions Σrev is equal to or greater than the second preset number of revolutions X2. For example, the second preset number of revolutions X2 is set to "1000 times." In the process of step S290, when it is determined that the cumulative number of revolutions Σrev is equal to or greater than the second preset number of revolutions X2 (step S290: YES), the engine control unit 300 advances the process to step S300.

[0058] Then, in the process of step S300, the engine control unit 300 judges whether the misfire rate is equal to or greater than the threshold value X3. Specifically, in the process of step S300, the engine control unit 300 divides the value of the misfire count value cnt by the cumulative number of revolutions Σrev, and sets the quotient as the misfire rate. In the process of step S300, if it is judged that the misfire rate is equal to or greater than the threshold value X3 (step S300: YES), the engine control unit 300 advances the process to step S310. In the process of step S310, the engine control unit 300 makes an abnormality diagnosis that a misfire abnormality has occurred. Note that, here, a state in which misfires occur at such a frequency that the tail pipe emission exceeds a reference value is regarded as a misfire abnormality. The threshold value X3 is set as a misfire rate threshold value for judging such a misfire abnormality. For example, the threshold value X3 is set to "0.02".

[0059] When the abnormality diagnosis is made in this way, the engine control unit 300 records information indicating the occurrence of a misfire abnormality in a storage device. The engine control unit 300 also turns on a warning light and displays on the display at the driver's seat that a misfire abnormality has occurred.

[0060] If an abnormality is diagnosed through the process of step S310, the engine control unit 300 advances the process to step S320. In the process of step S320, the engine control unit 300 resets the cumulative number of revolutions Σrev and the misfire count value cnt to "0". Then, the engine control unit 300 temporarily ends this diagnostic routine. Note that if an abnormality is diagnosed, the diagnostic routine will not be executed until repairs are performed and the information indicating the occurrence of a misfire abnormality is cleared.

[0061] If it is determined in the process of step S300 that the misfire rate is less than the threshold value X3 (step S300: NO), the engine control unit 300 proceeds to step S320 without executing the process of S310. In this manner, the engine control unit 300 executes the abnormality diagnosis process through a series of processes from step S300 to step S320 in the diagnosis routine.

[0062] In addition, in step S290, when it is determined that the cumulative number of revolutions Σrev is less than the second predetermined number of revolutions X2 (step S290: NO), the engine control unit 300 ends this diagnostic routine once as it is. That is, in this case, the engine control unit 300 ends this diagnostic routine once without executing the abnormality diagnosis process.

[0063] As described above, by repeatedly executing this diagnostic routine, the engine control unit 300 executes the abnormality diagnosis process every time the cumulative number of revolutions Σrev reaches the second preset number of times X2.

[0064] <Action of this embodiment> Next, the operation of this embodiment will be described with reference to Fig. 5. When the engine 50 of the vehicle 10 is operating as shown in Fig. 5(a), the cumulative number of revolutions Σrev is incremented by "1" each time the crankshaft 59 rotates once as shown in Fig. 5(c). In the example shown in Fig. 5, the hot soak flag is OFF at this time as shown in Fig. 5(b). Therefore, the cumulative number of revolutions after hot soak rev_h does not increase as shown in Fig. 5(d). Also, the misfire rate does not increase and remains at "0" as shown in Fig. 5(e).

[0065] At time t1, when the cumulative number of revolutions Σrev reaches the second predetermined number of revolutions X2 (step S290: YES), the abnormality diagnosis process is executed. At this time, the value of the misfire count value cnt is "0", so the misfire rate is "0" (step S300: NO). Therefore, the abnormality diagnosis that a misfire abnormality has occurred is not made.

[0066] When the abnormality diagnosis process is executed at time t1, the cumulative number of revolutions Σrev and the misfire count value cnt are reset to 0. Then, after time t1, as the engine 50 operates, the cumulative number of revolutions Σrev increases again.

[0067] 5(a), when the engine 50 is stopped at time t2, the engine control unit 300 executes a storage routine. Then, the engine control unit 300 stores the cumulative number of revolutions Σrev and the misfire count value cnt at that time in the storage device (steps S400 and S410).

[0068] In this way, the engine control unit 300 holds the values ​​of the cumulative number of revolutions Σrev and the misfire count value cnt in the storage device even while the system of the vehicle 10 is stopped. Then, at time t3, when the system of the vehicle 10 is restarted and the engine 50 is started, the initial value setting routine is executed. As a result, the engine control unit 300 initializes the cumulative number of revolutions Σrev, the misfire count value cnt, and the post-hot soak cumulative number of revolutions rev_h (steps S100, S110, and S120). Through the initialization, the cumulative number of revolutions Σrev is substituted with the stored cumulative number of revolutions Σrev_last. And the misfire count value cnt is substituted with the stored misfire count value cnt_last. Therefore, after time t3, the counts of the cumulative number of revolutions Σrev and the misfire count value cnt stored at time t2 are continued.

[0069] As described with reference to Fig. 4, in the diagnostic routine, an abnormality diagnosis process is performed each time the cumulative number of rotations Σrev becomes equal to or greater than the second preset number of rotations X2. In the case of a hybrid vehicle, the vehicle may run using only the driving force of the second motor generator 12 without operating the engine 50. Therefore, the operation of the engine 50 may end before the crankshaft 59 rotates the second preset number of rotations X2.

[0070] Therefore, as described above, the engine control unit 300, which is an abnormality diagnosis device, holds information on the cumulative number of revolutions Σrev and information on the misfire count value cnt even during a soak when the operation of the engine 50 is stopped. Then, when the operation of the engine 50 is resumed, the cumulative number of revolutions Σrev and the misfire count value cnt are continuously accumulated. This ensures an opportunity to diagnose misfire abnormalities even in a hybrid vehicle.

[0071] In the example shown in FIG. 5, the hot soak determination process executed at time t3 determines that engine 50 is starting from a hot soak, and the hot soak flag is ON.

[0072] In this way, after the engine 50 has finished operating, it may be started from a hot soak state in which the fuel pipes and injectors are still warm and hot. Immediately after starting from the hot soak state, the fuel in the fuel pipes and injectors is vaporized. In this state, the amount of fuel injected is reduced, making misfires more likely to occur.

[0073] Such misfires occurring immediately after starting from a hot soak are a temporary phenomenon and do not fall under the category of misfire abnormality that is the target of the abnormality diagnosis process. However, as described above, misfires are more likely to occur temporarily immediately after starting from a hot soak. As a result, in the case of a hybrid vehicle, the misfire count value cnt accumulated across the hot soak increases and a misfire abnormality may be diagnosed. In particular, if the misfire count value cnt is already relatively high when the engine 50 is stopped, an abnormality is likely to be diagnosed immediately after starting the engine 50 from a hot soak.

[0074] Therefore, in the diagnostic routine executed by the engine control unit 300, when it is determined that the engine is starting from a hot soak, the increase in the misfire count value cnt is reduced by multiplying it by a coefficient k1, as shown by the solid line in Figure 5(e).

[0075] In addition, in Fig. 5(e), the dashed line shows the progress of the misfire rate in the case where the process of decreasing the increase amount is not executed and the value of the misfire count value cnt is increased by "1" every time a misfire is judged to occur. In this case, the misfire count value cnt is increased by "1" every time a misfire, which occurs frequently because the engine is started from a hot soak, is judged to occur. Therefore, when the cumulative number of revolutions Σrev reaches the second predetermined number of revolutions X2 at time t4, it is judged that the misfire rate is equal to or higher than the threshold value X3, and an abnormality diagnosis is made.

[0076] In the example shown in Fig. 5, the state in which misfire is likely to occur due to the effects of the hot soak continues until time t5. The first predetermined number X1 is a threshold value for determining that the state in which misfire is likely to occur due to the effects of the hot soak has been resolved. Therefore, the magnitude of the first predetermined number X1 is set so that the post-hot soak cumulative number of rotations rev_h reaches the first predetermined number X1 after time t5.

[0077] When the post-hot soak cumulative number of revolutions rev_h becomes equal to or greater than the first predetermined number of revolutions X1 at time t6 (step S260: NO), the process of decreasing the increment is cancelled thereafter. That is, the misfire count value cnt is increased by "1" each time a misfire is detected (step S280).

[0078] <Effects of this embodiment> According to the engine control unit 300, when the engine is started from a hot soak, the misfire count value cnt is increased by a smaller amount each time a misfire is detected, compared to when the engine is not started from a hot soak. This makes it possible to prevent a misfire abnormality from being diagnosed due to a temporary misfire occurring immediately after starting from a hot soak. In other words, it is possible to ensure opportunities to diagnose a misfire abnormality by using the cumulative number of revolutions Σrev, while improving the accuracy of misfire abnormality diagnosis.

[0079] <Example of change> This embodiment can be modified as follows: This embodiment and the following modifications can be combined with each other to the extent that there is no technical contradiction.

[0080] Although an example has been given in which the increase in the misfire count value cnt is reduced by multiplying the coefficient k1 which is smaller than "1" and larger than "0," the present invention is not limited to this. For example, a positive value smaller than "1" may be set as an option for the increase in the misfire count value cnt in addition to "1," and when starting from a hot soak, a value smaller than "1" may be selected as the increase in the misfire count value cnt.

[0081] The vehicle 10 is not limited to a plug-in hybrid vehicle. It may be a hybrid vehicle that does not have a configuration for performing external charging. Similar problems may occur in hybrid vehicles that may run only on the driving force of the motor. Therefore, the configuration of the hybrid vehicle is not limited to the configuration of the vehicle 10 illustrated. For example, the hybrid vehicle may be a one-motor hybrid vehicle equipped with only one motor.

[0082] In the above example, the occurrence of a misfire abnormality is diagnosed based on the misfire rate being equal to or greater than the threshold value X3. However, instead of calculating the misfire rate, the occurrence of a misfire abnormality may be diagnosed based on the misfire count value cnt being equal to or greater than the threshold value when the cumulative number of revolutions Σrev becomes equal to or greater than the second predetermined number of revolutions X2.

[0083] The routines of Figures 2 to 4 may be executed by the system control unit 100 to diagnose a misfire abnormality. In this case, the system control unit 100 serves as an abnormality diagnosis device. Also, any of the routines of Figures 2 to 4 may be executed by the system control unit 100, and the remaining routines may be executed by the engine control unit 300. In this case, the engine control unit 300 and the system control unit 100 work together to realize an abnormality diagnosis device.

[0084] Although an example has been shown in which the water temperature is regarded as the temperature of engine 50 and the condition for determining whether or not a hot soak has occurred is that the water temperature is equal to or higher than a predetermined water temperature, this is not essential. The specific method of determination can be changed as appropriate. In other words, the hot soak determination process only needs to determine that the temperature of engine 50 is equal to or higher than a predetermined temperature and determine that a hot soak has occurred. For example, a sensor for detecting the temperature of engine 50 may be provided. Also, a configuration for estimating the temperature of engine 50 may be adopted.

[0085] In the above embodiment, the engine control unit 300, which is the abnormality diagnosis device, executes software processing. However, this is merely an example. For example, the abnormality diagnosis device may include a dedicated hardware circuit (e.g., ASIC, etc.) that processes at least a part of the software processing executed in the above embodiment. That is, the abnormality diagnosis device may have any of the following configurations (a) to (c). (a) The abnormality diagnosis device includes a processing circuit that executes all processing according to a program, and a storage device that stores the program. That is, the abnormality diagnosis device includes a software execution device. (b) The abnormality diagnosis device includes a processing circuit that executes a part of the processing according to a program, and a storage device. Furthermore, the abnormality diagnosis device includes a dedicated hardware circuit that executes the remaining processing. (c) The abnormality diagnosis device includes a dedicated hardware circuit that executes all processing. Here, the software execution device and / or the dedicated hardware circuit may be multiple. That is, the above processing may be executed by a processing circuitry that includes at least one of one or more software execution devices and one or more dedicated hardware circuits. The storage device that stores the program, i.e., the computer-readable medium, includes any available medium that can be accessed by a general-purpose or dedicated computer.

[0086] <Additional Notes> In the above embodiment, when it is determined that the engine is being started from a hot soak, the increase in the misfire count value cnt is reduced to prevent a misfire diagnosis due to a temporary misfire occurring immediately after the engine is started from a hot soak. It is also possible to prevent a misfire diagnosis due to a temporary misfire occurring immediately after the engine is started from a hot soak in other ways.

[0087] The following describes an example of an abnormality diagnosis device that suppresses the diagnosis of a misfire abnormality caused by the occurrence of a temporary misfire immediately after starting from a hot soak in another embodiment. For example, even if the engine control unit executes the initial setting routine shown in Fig. 6 and the diagnosis routine shown in Fig. 7, it is possible to suppress the diagnosis of a misfire abnormality caused by a temporary misfire occurring immediately after starting from a hot soak. In this example, the storage routine is the same as that in Fig. 3.

[0088] In this case, the initial value setting routine shown in Fig. 6 is executed by the engine control unit when the engine 50 is started, similar to the initial setting routine shown in Fig. 2. As shown in Fig. 6, when the initial value setting routine is started, the engine control unit determines whether or not the engine is being started from a hot soak in the process of step S500. In the process of step S500, for example, it may be determined whether or not the engine is being started from a hot soak in the same manner as the hot soak determination process of the above embodiment.

[0089] If it is determined in the process of step S500 that the start is not from a hot soak (step S500: NO), the engine control unit proceeds to the process of step S530. Then, in the process of step S530, the engine control unit assigns the stored cumulative number of rotations Σrev_last to the cumulative number of rotations Σrev, to initialize the cumulative number of rotations Σrev, in the same manner as in the above-mentioned step S100.

[0090] Then, in the process of the next step S540, the engine control unit initializes the misfire count value cnt by substituting the stored misfire count value cnt_last into the misfire count value cnt, as in the above step S110, and then the engine control unit ends this initialization routine.

[0091] On the other hand, if it is determined in the process of step S500 that the engine is starting from a hot soak (step S500: YES), the engine control unit proceeds to step S510. In the process of step S510, the engine control unit resets the cumulative number of revolutions Σrev to "0" to initialize the cumulative number of revolutions Σrev.

[0092] Then, in the process of the next step S520, the engine control unit resets the misfire count value cnt to "0" to initialize the misfire count value cnt, and then the engine control unit ends this initialization routine.

[0093] The diagnostic routine shown in FIG. 7 is repeatedly executed by the engine control unit when the system of the vehicle 10 is operating, similarly to the diagnostic routine shown in FIG. 4. As shown in FIG. 7, when this diagnostic routine is started, in the process of step S600, the engine control unit determines whether the engine 50 is operating, similarly to the process of step S210 described above. If it is determined in the process of step S600 that the engine 50 is operating (step S600: YES), the engine control unit advances the process to step S610. Then, in the process of step S610, the engine control unit updates the cumulative number of revolutions Σrev. In the process of step S610, the engine control unit grasps the rotation phase of the crankshaft 59 based on the crank angle signal, similarly to the process of step S220 described above. Then, the engine control unit counts up the cumulative number of revolutions Σrev by one every time the crankshaft 59 rotates once.

[0094] On the other hand, if it is determined in the process of step S600 that the engine 50 is not operating and is stopped (step S600: NO), the engine control unit advances the process to step S620. Then, in the process of step S620, the engine control unit 300 holds the cumulative number of revolutions Σrev. After executing the process of step S610 or step S620 in this manner, the engine control unit advances the process to step S630.

[0095] In the process of step S630, the engine control unit determines whether or not a determination that a misfire has occurred has been made, similarly to the above-mentioned step S240. That is, in the process of step S630, it is confirmed whether or not a determination that a misfire has occurred has been made through the misfire determination process.

[0096] If it is determined in the process of step S630 that a misfire has occurred (step S630: YES), the engine control unit advances the process to step S640. Then, in the process of step S640, the engine control unit adds "1" to the misfire count value cnt, and sets the sum as the new misfire count value cnt. That is, in this case, the engine control unit increases the misfire count value cnt by "1". Then, the engine control unit advances the process to step S650.

[0097] On the other hand, if it is determined in the process of step S630 that a misfire has not occurred (step S630: NO), the engine control unit advances the process to step S650. That is, in this case, the misfire count value cnt is not increased and the process advances to step S650.

[0098] In the process of step S650, the engine control unit determines whether the cumulative number of revolutions Σrev is equal to or greater than the second preset number of revolutions X2, as in the process of step S290 described above. For example, the second preset number of revolutions X2 is set to "1000 times." In the process of step S650, if it is determined that the cumulative number of revolutions Σrev is equal to or greater than the second preset number of revolutions X2 (step S650: YES), the engine control unit 300 advances the process to step S660.

[0099] In the process of step S660, the engine control unit determines whether or not the vehicle is operating from a hot soak. Specifically, the engine control unit determines whether or not the hot soak flag is ON. If the hot soak flag is ON, i.e., if it is determined that the vehicle is operating from a hot soak (step S660: YES), the engine control unit proceeds to step S670. On the other hand, if the hot soak flag is OFF, i.e., if it is determined that the vehicle is not operating from a hot soak (step S660: NO), the engine control unit proceeds to step S680.

[0100] In the process of step S680, the engine control unit determines whether the misfire rate is equal to or greater than the threshold value X3, similarly to the process of step S300 described above. If it is determined in the process of step S680 that the misfire rate is equal to or greater than the threshold value X3 (step S680: YES), the engine control unit proceeds to the process of step S690.

[0101] Then, in the process of step S690, the engine control unit diagnoses an abnormality that a misfire abnormality has occurred, similar to the process of step S310 described above. Note that here too, a misfire abnormality is determined to be a state in which misfires occur with such frequency that tailpipe emissions exceed a reference value. The threshold value X3 is set as a misfire rate threshold value for determining such a misfire abnormality. For example, the threshold value X3 is set to "0.02".

[0102] If an abnormality is diagnosed through the process of step S690, the engine control unit advances the process to step S700. In the process of step S700, the engine control unit resets the cumulative number of revolutions Σrev and the misfire count value cnt to "0" as in the process of step S320 described above. Then, the engine control unit temporarily ends this diagnostic routine. Note that if an abnormality is diagnosed, the diagnostic routine will not be executed until repairs are performed and the information indicating the occurrence of a misfire abnormality is cleared.

[0103] If it is determined in the process of step S680 that the misfire rate is less than the threshold value X3 (step S680: NO), the engine control unit proceeds to the process of step S700 without executing the process of S690.

[0104] As described above, if it is determined in the process of step S660 that the engine is currently operating from a hot soak (step S660: YES), the engine control unit advances the process to step S670.

[0105] In the process of step S670, the engine control unit determines whether the misfire rate is equal to or greater than a threshold value X4. The threshold value X4 is set to a value greater than the threshold value X3. For example, the threshold value X4 is set to "0.1." If the engine control unit determines in the process of step S670 that the misfire rate is equal to or greater than the threshold value X4 (step S670: YES), the engine control unit proceeds to step S690.

[0106] Then, in the process of step S690, the engine control unit makes an abnormality diagnosis that a misfire abnormality has occurred. If an abnormality diagnosis is made through the process of step S690, the engine control unit advances the process to step S700. In the process of step S700, the engine control unit resets the cumulative number of revolutions Σrev and the misfire count value cnt to "0". Then, the engine control unit temporarily ends this diagnostic routine.

[0107] If it is determined in the process of step S670 that the misfire rate is less than the threshold value X4 (step S670: NO), the engine control unit proceeds to the process of step S700 without executing the process of S690.

[0108] In this manner, the engine control unit executes the abnormality diagnosis process through a series of processes from step S660 to step S700 in the diagnostic routine. In addition, in step S650, when it is determined that the cumulative number of revolutions Σrev is less than the second predetermined number of revolutions X2 (step S650: NO), the engine control unit ends this diagnostic routine once. That is, in this case, the engine control unit ends this diagnostic routine once without executing the abnormality diagnosis process.

[0109] By repeatedly executing the diagnostic routine shown in Fig. 7, the engine control unit executes the abnormality diagnosis process each time the cumulative number of revolutions Σrev reaches the second predetermined number of revolutions X2. In this diagnostic routine, the misfire rate threshold in the abnormality diagnosis process is set to a larger value when it is determined that the engine is operating from a hot soak than when it is not determined that the engine is operating from a hot soak. This configuration also makes it difficult for the misfire rate to exceed the threshold. Therefore, it is possible to prevent a misfire abnormality from being diagnosed due to a temporary misfire occurring immediately after starting from a hot soak.

[0110] Furthermore, when starting from a hot soak, the cumulative number of revolutions Σrev and the misfire count value cnt are reset to 0. This configuration also makes it difficult for the misfire rate to exceed the threshold value. [Explanation of symbols]

[0111] 10. Vehicle 11…First motor generator 12...Second motor generator 13...Planetary gear mechanism 30…Battery 31…Connector 40…External power supply 50…Engine 59…Crankshaft 100...System control unit 130…Main switch 131...Accelerator position sensor 132...Brake sensor 133...Vehicle speed sensor 134...Crank position sensor 135…Intake air temperature sensor 136...Water temperature sensor 200…Power control unit 300…Engine control unit

Claims

[Claim 1] This is applied to a hybrid vehicle equipped with an engine and a motor, a misfire determination process for determining whether a misfire has occurred during operation of the engine; a misfire count process for increasing a misfire count value every time a misfire is determined to have occurred through the misfire determination process; an abnormality diagnosis process for diagnosing whether or not a misfire abnormality has occurred based on the misfire count value accumulated through the misfire count process until the cumulative number of revolutions of the output shaft of the engine reaches a predetermined number; An abnormality diagnosis device for a hybrid vehicle, execute a hot soak determination process for determining that the engine is being started from a hot soak when the temperature of the engine at the time of starting the engine is equal to or higher than a predetermined temperature; When it is determined that a post-hot soak cumulative number of revolutions, which is an integrated value of the number of revolutions of the output shaft during operation of the engine from the hot soak, is equal to or less than a threshold value, an increase in the misfire count value in the misfire count process each time it is determined that a misfire has occurred is made smaller than an increase in the misfire count value in a case where it is not determined that the engine is starting from the hot soak. An abnormality diagnosis device for hybrid vehicles.

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