Control device for hybrid vehicle

Abstract

To provide a control device of a hybrid vehicle configured to be able to suppress abnormal noise from occurring.SOLUTION: A CPU 72 limits a command value of torque of a second motor generator 54 to a value above a lower limit guard value. The CPU 72 stops combustion control of a cylinder #1 for regeneration treatment of a GPF 34 and makes air-fuel ratios of air-fuel mixtures in cylinders #2-#4 rich. The CPU 72 sets the lower limit guard value to be larger when executing the regeneration treatment, in comparison with when not executing the regeneration treatment.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a control device for a hybrid vehicle.

Background Art

[0002] For example, Patent Document 1 below describes a hybrid vehicle in which an internal combustion engine and a traveling electric motor are mechanically connected by a gear. The control device of this hybrid vehicle controls so that the absolute value of the command value of the torque of the electric motor does not enter a predetermined region near zero. This aims to suppress abnormal noise caused by the gear mechanism when the torque of the electric motor is small.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The inventor considered performing a regeneration process of an exhaust aftertreatment device when the shaft torque of the internal combustion engine is not zero. Specifically, as the regeneration process, it was considered to stop the combustion control of only some cylinders and make the air-fuel ratio of the remaining cylinders richer than the stoichiometric air-fuel ratio to supply unburned fuel and oxygen into the exhaust. In that case, since the torque fluctuation of the internal combustion engine becomes large, there is a risk that the above abnormal noise becomes particularly prominent when the torque of the electric motor is small, compared with when the regeneration process is not being performed.

Means for Solving the Problems

[0005] Hereinafter, means for solving the above problems and their effects will be described. 1. A control device for a hybrid vehicle, which is applied to a hybrid vehicle including an internal combustion engine and an electric motor connected to a crankshaft of the internal combustion engine via a gear. The internal combustion engine includes a plurality of cylinders, and executes a stop process for stopping combustion control in some of the plurality of cylinders. When the internal combustion engine is operating and the stop process is not executed, the minimum value of the torque of the electric motor when the stop process is executed is made larger than the minimum value of the torque of the electric motor.

[0006] In the above configuration, when the stop process is executed, torque fluctuations occur in which the torque of the internal combustion engine drops significantly in the cycle in which the compression top dead center of some cylinders appears. Therefore, when the magnitude of the torque of the electric motor is small, significant abnormal noise is likely to occur in the gear portion. Therefore, in the above configuration, when the internal combustion engine is operating and the stop process is executed, the minimum value of the magnitude of the torque of the electric motor is made larger than when the stop process is not executed. Therefore, since the gears are meshed more strongly compared to the case where the minimum value is not increased, even when the stop process is executed, the occurrence of abnormal noise can be suppressed.

[0007] 2. The control device for a hybrid vehicle according to item 1 above, which executes a limiting process for limiting the absolute value of the torque command value for the electric motor to be equal to or greater than a lower guard value, and the limiting process includes a process of setting the lower guard value to a larger value when the stop process is executed than when the stop process is not executed.

[0008] In the above configuration, the lower guard value in the limiting process is made larger when the stop process is executed than when it is not executed. Thereby, when the internal combustion engine is operating and the stop process is executed, the minimum value of the magnitude of the torque of the electric motor can be made larger than when the stop process is not executed.

[0009] 3. When the torque of the electric motor is less than the lower guard value, a prohibiting process for prohibiting the stop process is executed, and the lower guard value is a value larger than the minimum value of the torque of the electric motor during the operation of the internal combustion engine. The control device for a hybrid vehicle according to the above item 1.

[0010] In the above configuration, when the torque of the electric motor is less than the lower guard value, the stop process is prohibited, and the lower guard value is set to a value larger than the minimum value of the torque of the electric motor during the operation of the internal combustion engine. Thereby, when the internal combustion engine is operating and the stop process is being executed, the minimum value of the magnitude of the torque of the electric motor can be increased as compared with when the stop process is not being executed.

[0011] 4. When the stop process is executed, a variation process for periodically varying the torque of the internal combustion engine at a period that is an integral multiple of the period in which the compression top dead center appears in the internal combustion engine is executed. The control device for a hybrid vehicle according to any one of the above items 1 to 3.

[0012] Even when the stop process is not performed, the torque of the internal combustion engine varies at the period in which the compression top dead center appears. Also, due to the stop process, the torque of the internal combustion engine varies at the period in which the compression top dead center appears in some cylinders. Therefore, the variation of the torque of the internal combustion engine tends to be an integral multiple of the period in which the compression top dead center appears. Therefore, in the above configuration, by setting the torque of the electric motor to a torque that varies at the same integral multiple of the period, the torque variation caused by the stop process can be preferably attenuated. Therefore, in the above configuration, the vibration of the vehicle can be preferably suppressed.

[0013] 5. The internal combustion engine is provided with a post-treatment device in the exhaust system. When the stop process is executed, a rich combustion process for making the air-fuel ratio of the air-fuel mixture in the remaining cylinders richer than the theoretical air-fuel ratio is executed, and the temperature of the post-treatment device is increased by the stop process and the rich combustion process to constitute a regeneration process of the post-treatment device. The control device for a hybrid vehicle according to any one of the above items 1 to 4.

[0014] In the above configuration, since the air-fuel ratio of the air-fuel mixture in the remaining cylinders is richer than the stoichiometric air-fuel ratio, torque fluctuations are larger compared to the case of the stoichiometric air-fuel ratio. Moreover, since the regeneration process continues for a relatively long time, there is a risk of abnormal noise occurring over a long period when the torque of the electric motor is small. Therefore, setting the minimum value of the torque of the electric motor is particularly effective.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Modes for Carrying Out the Invention

[0016] <The First Embodiment> Hereinafter, the first embodiment will be described with reference to the drawings. As shown in FIG. 1, the internal combustion engine 10 includes four cylinders #1 to #4. A throttle valve 14 is provided in the intake passage 12 of the internal combustion engine 10. A port injection valve 16 for injecting fuel into the intake port 12a, which is the downstream portion of the intake passage 12, is provided. Air inhaled into the intake passage 12 and fuel injected from the port injection valve 16 flow into the combustion chamber 20 as the intake valve 18 opens. Fuel is injected into the combustion chamber 20 from the in-cylinder injection valve 22. Further, the air-fuel mixture in the combustion chamber 20 is subjected to combustion by the spark discharge of the ignition plug 24. The combustion energy generated at that time is converted into the rotational energy of the crankshaft 26.

[0017] The air-fuel mixture subjected to combustion in the combustion chamber 20 is discharged as exhaust into the exhaust passage 30 as the exhaust valve 28 opens. A three-way catalyst 32 having an oxygen storage capacity and a gasoline particulate filter (GPF 34) are provided in the exhaust passage 30. Note that the GPF 34 is a filter that collects PM and has a three-way catalyst supported thereon.

[0018] The crankshaft 26 is mechanically connected via a damper 27 to the carrier C of the planetary gear mechanism 50 that constitutes a power split device. The rotating shaft 52a of the first motor generator 52 is mechanically connected to the sun gear S of the planetary gear mechanism 50. Further, the rotating shaft 54a of the second motor generator 54 and the drive wheel 60 are mechanically connected to the ring gear R of the planetary gear mechanism 50. An AC voltage is applied to the terminals of the first motor generator 52 by the first inverter 56. Also, an AC voltage is applied to the terminals of the second motor generator 54 by the second inverter 58.

[0019] The control device 70 controls the internal combustion engine 10, and operates the operation parts of the internal combustion engine 10 such as the throttle valve 14, the port injection valve 16, the in-cylinder injection valve 22, and the ignition plug 24 in order to control the torque, exhaust component ratio, etc. as its control amounts. Further, the control device 70 controls the first motor generator 52, and operates the first inverter 56 in order to control the torque which is its control amount. Further, the control device 70 controls the second motor generator 54, and operates the second inverter 58 in order to control the torque which is its control amount. FIG. 1 shows the respective operation signals MS1 to MS6 of the throttle valve 14, the port injection valve 16, the in-cylinder injection valve 22, the ignition plug 24, the first inverter 56, and the second inverter 58. The control device 70 refers to the intake air amount Ga detected by the air flow meter 80 and the output signal Scr of the crank angle sensor 82 in order to control the control amount of the internal combustion engine 10. Further, the control device 70 refers to the coolant temperature THW detected by the coolant temperature sensor 86 and the pressure Pex of the exhaust gas flowing into the GPF 34 detected by the exhaust pressure sensor 88. Further, the control device 70 refers to the output signal Sm1 of the first rotation angle sensor 90 that detects the rotation angle of the first motor generator 52 in order to control the control amount of the first motor generator 52. Further, the control device 70 refers to the output signal Sm2 of the second rotation angle sensor 92 that detects the rotation angle of the second motor generator 54 in order to control the control amount of the second motor generator 54. Further, the control device 70 refers to the output signal Sp of the output-side rotation angle sensor 94 that detects the rotation angle of the ring gear R and the accelerator operation amount ACCP which is the depression amount of the accelerator pedal detected by the accelerator sensor 96.

[0020] The control device 70 includes a CPU 72, a ROM 74, and a peripheral circuit 76, and they are communicable via a communication line 78. Here, the peripheral circuit 76 includes a circuit that generates a clock signal that defines the internal operation, a power supply circuit, a reset circuit, and the like. The control device 70 controls the control amount by the CPU 72 executing the program stored in the ROM 74.

[0021] Below, among the processes executed by the control device 70, the base process, the reproduction process of the GPF 34, the vibration suppression process accompanying the reproduction process, and the output distribution process will be described in this order of detail. (Base process) FIG. 2 shows a part of the processes executed by the control device 70. The processes shown in FIG. 2 are realized by the CPU 72 executing the programs stored in the ROM 74.

[0022] The base injection amount setting process M10 is a process of calculating the base injection amount Qb based on the filling efficiency η. The base injection amount Qb is the injection amount for setting the air-fuel ratio of the air-fuel mixture in the combustion chamber 20 to the target air-fuel ratio. The target air-fuel ratio is the stoichiometric air-fuel ratio. Incidentally, the filling efficiency η is calculated by the CPU 72 based on the engine rotational speed NE and the intake air amount Ga. Also, the engine rotational speed NE is calculated by the CPU 72 based on the output signal Scr.

[0023] The injection valve operation process M12 is a process of operating the port injection valve 16 and the in-cylinder injection valve 22 with the base injection amount Qb as an input. The drive torque setting process M20 is a process of calculating the required drive torque Trq*, which is the required torque for the drive wheels 60, based on the accelerator operation amount ACCP and the output-side rotational speed Np, which is the rotational speed of the ring gear R. Here, the output-side rotational speed Np is calculated by the CPU 72 based on the output signal Sp.

[0024] The required output setting process M22 is a process of calculating the required output Pd* based on the required drive torque Trq*, the output-side rotational speed Np, and the required power generation amount Pg* for the first motor generator 52. The required output Pd* is the required amount for the total output of the internal combustion engine 10, the first motor generator 52, and the second motor generator 54.

[0025] The output distribution process M24 is a process of allocating the required output Pd* to the engine required output Pe*, the first required output Pmg1*, and the second required output Pmg2*. Note that the engine required output Pe* is the required output for the internal combustion engine 10. Also, the first required output Pmg1* is the required output for the first motor generator 52. Further, the second required output Pmg2* is the required output for the second motor generator 54.

[0026] The engine torque setting process M26 is a process of calculating the engine required torque Te*, which is the required torque for the internal combustion engine 10, based on the engine required output Pe*. The throttle opening command value setting process M28 is a process of setting the opening command value TA*, which is the command value of the opening degree of the throttle valve 14, based on the engine required torque Te*. The throttle operation process M30 is a process of outputting an operation signal MS1 to the throttle valve 14 to control the opening degree of the throttle valve 14 to the opening command value TA*.

[0027] The MG operation process M32 is a process of outputting an operation signal MS5 to the first inverter 56 to control the torque of the first motor generator 52 based on the first required output Pmg1*. Also, the MG operation process M32 is a process of outputting an operation signal MS6 to the second inverter 58 to control the torque of the second motor generator 54 based on the second required output Pmg2*.

[0028] (Regeneration process of GPF34) Fig. 3 shows the procedure of the regeneration process. The process shown in Fig. 3 is realized by the CPU 72 repeatedly executing the program stored in the ROM 74, for example, at a predetermined cycle. Note that hereinafter, the step numbers of each process are represented by numbers with "S" added at the beginning.

[0029] In the series of processes shown in FIG. 3, the CPU 72 first acquires the engine rotational speed NE, the charging efficiency η, and the water temperature THW (S10). Next, the CPU 72 calculates an update amount ΔDPM of the deposition amount DPM based on the engine rotational speed NE, the charging efficiency η, and the water temperature THW (S12). Here, the deposition amount DPM is the amount of PM collected by the GPF 34. Specifically, the CPU 72 calculates the amount of PM in the exhaust gas discharged into the exhaust passage 30 based on the engine rotational speed NE, the charging efficiency η, and the water temperature THW. Further, the CPU 72 calculates the temperature of the GPF 34 based on the engine rotational speed NE and the charging efficiency η. Then, the CPU 72 calculates the update amount ΔDPM based on the amount of PM in the exhaust gas and the temperature of the GPF 34. Note that when executing the process of S22 described later, the temperature of the GPF 34 and the update amount ΔDPM may be calculated based on the increment coefficient K.

[0030] Next, the CPU 72 updates the deposition amount DPM according to the update amount ΔDPM (S14). Next, the CPU 72 determines whether the flag F is "1" (S16). The flag F indicates that a temperature increase process for combusting and removing the PM of the GPF 34 is being executed when it is "1", and indicates otherwise when it is "0". When the CPU 72 determines that it is "0" (S16: NO), it determines whether the logical sum of the deposition amount DPM being greater than or equal to the regeneration execution value DPMH and the process of S22 described later being in an interrupted period is true (S18). The regeneration execution value DPMH is set to a value at which the amount of PM collected by the GPF 34 is large and it is desired to remove the PM.

[0031] When the CPU 72 determines that the logical sum is true (S18: YES), it determines whether the condition that the logical product of the following conditions (a) and (i), which are the execution conditions of the temperature increase process, is true (S20).

[0032] Condition (a): A condition that the engine required torque Te* is equal to or greater than a predetermined value Teth. The predetermined value Teth is set based on the lower limit value of the value for applying the torque on the accelerating side of the drive wheels 60 to the drive wheels 60 by the crankshaft 26. This is a condition indicating that the internal combustion engine 10 is operating under load.

[0033] Condition (a): A condition indicating that the engine rotation speed NE is equal to or higher than a predetermined speed NEth. When the CPU 72 determines that the logical product is true (S20: YES), the CPU 72 executes a temperature-raising process and assigns "1" to the flag F (S22). As the temperature-raising process according to the present embodiment, the CPU 72 stops the injection of fuel from the port injection valve 16 and the in-cylinder injection valve 22 of the cylinder #1, and makes the air-fuel ratio of the air-fuel mixture in the combustion chambers 20 of the cylinders #2, #3, and #4 richer than the stoichiometric air-fuel ratio. This process is, firstly, a process for raising the temperature of the three-way catalyst 32. That is, by discharging oxygen and unburned fuel into the exhaust passage 30, the unburned fuel is oxidized in the three-way catalyst 32 to raise the temperature of the three-way catalyst 32. Secondly, it is a process for raising the temperature of the GPF 34 and supplying oxygen to the GPF 34 at a high temperature to oxidize and remove the PM collected by the GPF 34. That is, when the temperature of the three-way catalyst 32 becomes high, the temperature of the GPF 34 rises as the high-temperature exhaust flows into the GPF 34. Then, as oxygen flows into the GPF 34 at a high temperature, the PM collected by the GPF 34 is oxidized and removed.

[0034] Specifically, the CPU 72 assigns "0" to the required injection amount Qd for the port injection valve 16 and the in-cylinder injection valve 22 of the cylinder #1. On the other hand, the CPU 72 assigns a value obtained by multiplying the base injection amount Qb by the increment coefficient K to the required injection amounts Qd of the cylinders #2, #3, and #4.

[0035] The CPU 72 sets the increment coefficient K to be equal to or less than an amount such that the unburned fuel in the exhaust discharged from the cylinders #2, #3, and #4 into the exhaust passage 30 reacts with the oxygen discharged from the cylinder #1 without excess or deficiency. Specifically, at the initial stage of the regeneration process of the GPF 34, the CPU 72 makes the air-fuel ratio of the air-fuel mixture in the cylinders #2, #3, and #4 as close as possible to the amount that reacts without excess or deficiency in order to raise the temperature of the three-way catalyst 32 at an early stage.

[0036] On the other hand, when the CPU 72 determines that the flag F is "1" (S16: YES), it determines whether the deposition amount DPM is less than or equal to the stop lower guard value DPML (S24). The stop lower guard value DPML is set to a value at which the amount of PM collected by the GPF 34 becomes sufficiently small and the regeneration process may be stopped. When the CPU 72 determines that it is greater than the stop lower guard value DPML (S24: NO), it proceeds to the process of S20.

[0037] On the other hand, when the CPU 72 is less than or equal to the stop lower guard value DPML (S24: YES) or makes a negative determination in the process of S20, it stops or interrupts the process of S22 and assigns "0" to the flag F (S26). Here, when an affirmative determination is made in the process of S24, the process of S22 is stopped assuming it has been completed, and when a negative determination is made in the process of S20, the process of S22 is interrupted at a stage where it has not yet been completed.

[0038] Note that when the CPU 72 completes the processes of S22 and S26 or makes a negative determination in the process of S18, it temporarily ends the series of processes shown in FIG. 3. (Vibration suppression process associated with the regeneration process) FIG. 4 shows the detailed procedure of the MG operation process M32. The process shown in FIG. 4 is realized by the CPU 72 repeatedly executing the program stored in the ROM 74 at a predetermined cycle, for example.

[0039] In the series of processes shown in FIG. 4, the CPU 72 first acquires the engine rotational speed NE, the first rotational speed Nmg1, the second rotational speed Nmg2, the engine required torque Te*, the first required output Pmg1*, and the second required output Pmg2* (S30). The first rotational speed Nmg1 is the rotational speed of the rotating shaft 52a of the first motor generator 52. The first rotational speed Nmg1 is calculated by the CPU 72 based on the output signal Sm1. The second rotational speed Nmg2 is the rotational speed of the rotating shaft 54a of the second motor generator 54. The second rotational speed Nmg2 is calculated by the CPU 72 based on the output signal Sm2.

[0040] Next, the CPU 72 substitutes the value obtained by dividing the first required output Pmg1* by the first rotation speed Nmg1 into the first required torque base value Tmg1b* (S32). Also, the CPU 72 substitutes the value obtained by dividing the second required output Pmg2* by the second rotation speed Nmg2 into the second required torque base value Tmg2b* (S34).

[0041] Next, the CPU 72 determines whether the flag F is "1" (S36). When the CPU 72 determines that the flag F is "1" (S36: YES), it inputs the engine rotation speed NE, the engine required torque Te*, and the first rotation speed Nmg1, and calculates the first amplitude A1 and the first phase φ1 (S38). These variables define the first superimposed torque ΔTmg1* that is superimposed on the first required torque base value Tmg1b*. The first superimposed torque ΔTmg1* is a sinusoidal torque having the first amplitude A1. Note that the phase of the sine wave is the first phase φ1. The first superimposed torque ΔTmg1* is shown below.

[0042] ΔTmg1* = A1·sin(2·θe + φ1) Here, the crank angle θe is used. The crank angle θe is calculated by the CPU 72 based on the output signal Scr. According to the above formula, the first superimposed torque ΔTmg1* has a period of 180°CA. In other words, it has a period that is "1" times the period in which the top dead center of compression appears in the internal combustion engine 10.

[0043] The CPU 72 substitutes the value obtained by adding the first superimposed torque ΔTmg1* to the first required torque base value Tmg1b* into the first required torque Tmg1* (S40). Then, the CPU 72 outputs an operation signal MS5 to the first inverter 56 to control the torque of the first motor generator 52 to the first required torque Tmg1* (S42).

[0044] Further, the CPU 72 calculates a second amplitude A2 and a second phase φ2 by using the engine rotational speed NE, the engine required torque Te*, and the second rotational speed Nmg2 as inputs (S44). These variables define a second superimposed torque ΔTmg2* that is superimposed on the second required torque base value Tmg2b*. The second superimposed torque ΔTmg2* is a sinusoidal torque having the second amplitude A2. Note that the phase of the sine wave is the second phase φ2. The second superimposed torque ΔTmg2* is shown below.

[0045] ΔTmg2* = A2·sin(2·θe + φ2) According to the above equation, the second superimposed torque ΔTmg2* has a period of 180°CA. In other words, it has the same period as the period in which the compression top dead center appears in the internal combustion engine 10.

[0046] The CPU 72 substitutes the value obtained by adding the second superimposed torque ΔTmg2* to the second required torque base value Tmg2b* into the second required torque Tmg2* (S46). Then, the CPU 72 outputs an operation signal MS6 to the second inverter 58 to control the torque of the second motor generator 54 to the second required torque Tmg2* (S48).

[0047] On the other hand, when the CPU 72 determines that the flag F is "0" (S36: NO), it substitutes the first required torque base value Tmg1b* into the first required torque Tmg1* (S50). Then, the CPU 72 outputs an operation signal MS5 to the first inverter 56 to control the torque of the first motor generator 52 to the first required torque Tmg1* (S52). Also, the CPU 72 substitutes the second required torque base value Tmg2b* into the second required torque Tmg2* (S54). Then, the CPU 72 outputs an operation signal MS6 to the second inverter 58 to control the torque of the second motor generator 54 to the second required torque Tmg2* (S56).

[0048] Note that when the CPU 72 completes the processes of S48 and S56, it temporarily terminates the series of processes shown in FIG. 4. (Details of Output Distribution Processing) Fig. 5 shows the procedure of the output distribution process M24. The process shown in Fig. 5 is realized by the CPU 72 repeatedly executing a program stored in the ROM 74 at a predetermined cycle, for example.

[0049] In the series of processes shown in Fig. 5, the CPU 72 first acquires the required output Pd* (S60). Then, the CPU 72 calculates the engine required output base value Peb*, the first required output Pmg1*, and the second required output Pmg2* (S62). Here, the engine required output base value Peb* satisfies the following formula (c1).

[0050] Peb* + Pmg1* + Pmg2* = Pd* …(c1) Next, the CPU 72 determines whether the flag F is "0" (S64). When the CPU 72 determines that the flag F is "0" (S64: YES), the CPU 72 substitutes the engine required output base value Peb* into the engine required output Pe* (S66). Further, the CPU 72 substitutes the reference value Tmin0 for the lower limit guard value Tmin of the torque of the second motor generator 54 (S68).

[0051] Here, the reference value Tmin0 is set to an appropriate value to suppress the generation of abnormal noise in the mechanical backlash portion, which is the clearance of the meshing of gears including the planetary gear mechanism 50 during normal operation of the internal combustion engine 10. This is in view of the fact that when the torque of the second motor generator 54 is excessively small, abnormal noise may occur in the backlash portion. That is, there may be a component of the torque fluctuation of the crankshaft 26 that cannot be completely attenuated by the damper 27. And even if that component is input to the planetary gear mechanism 50, when the magnitude of the torque of the second motor generator 54 is large, abnormal noise is less likely to occur because the gears are pressed against each other and engaged. On the other hand, when the magnitude of the torque of the second motor generator 54 is small, since the force pressing the gears against each other is weak, there is a possibility that abnormal noise such as gear rattling noise may occur due to the above-mentioned fluctuation component.

[0052] On the other hand, when the CPU 72 determines that the flag F is "1" (S64: NO), it calculates the output reduction rate Rdp of the internal combustion engine 10 (S70). In the case of the present embodiment, since the combustion control is stopped only for cylinder #1 among cylinders #1 to #4, the reduction rate Rdp is "1 / 4". Then, the CPU 72 substitutes the value obtained by dividing the engine required output base value Peb* by "1 - Rdp" into the engine required output Pe* (S72). Thereby, the opening degree command value TA* calculated by the throttle opening degree command value setting process M28 becomes an appropriate value for making the output of the internal combustion engine 10 equal to the engine required output base value Peb* during the regeneration process.

[0053] Further, the CPU 72 substitutes the value obtained by adding the regeneration increase amount ΔF and the second amplitude A2 to the reference value Tmin0 into the lower guard value Tmin (S74). Thereby, the minimum value of the torque of the second motor generator 54 is set to be greater than or equal to a value that is larger than the reference value Tmin0 by the regeneration increase amount ΔF. Here, the reason for using the regeneration increase amount ΔF is that during the regeneration process, since the combustion control is stopped in cylinder #1, the torque fluctuation of the crankshaft 26 becomes larger than when the regeneration process is not being performed.

[0054] When the CPU 72 completes the processes of S68 and S74, it determines whether the absolute value of the value obtained by dividing the second required output Pmg2* by the second rotational speed Nmg2 is smaller than the lower guard value Tmin (S76). And when the CPU 72 determines that it is smaller than the lower guard value Tmin (S76: YES), it raises the magnitude of the second required output Pmg2* to the product of the lower guard value Tmin and the second rotational speed Nmg2 (S78). Then, the CPU 72 recalculates the engine required output Pe* and the first required output Pmg1* (S80). That is, the CPU 72 calculates the engine required output base value Peb* and the first required output Pmg1* so that the above formula (c1) holds, using the second required output Pmg2* re-set by the process of S78. Note that the relationship between the engine required output base value Peb* and the engine required output Pe* is the relationship determined by the process of S72.

[0055] Incidentally, when the CPU 72 completes the process of S80 or makes a negative determination in the process of S76, the series of processes shown in FIG. 5 are temporarily terminated. Here, the operations and effects of the present embodiment will be described.

[0056] FIG. 6 illustrates the setting of the lower guard value Tmin according to the present embodiment. As shown in FIG. 6, before time t1, since the reproduction process has not been executed, the lower guard value Tmin is set to the reference value Tmin0. On the other hand, after time t1, since the reproduction process is executed, the lower guard value Tmin is set to a value larger than the reference value Tmin0 by "A2 + ΔF". Therefore, even when the second superimposed torque ΔTmg2* becomes the minimum value when fluctuating at the second amplitude A2, the torque of the second motor generator 54 indicated by the two-dot chain line in FIG. 6 is limited to a value larger than the reference value Tmin0 by at least the reproduction increase amount ΔF. Therefore, even when the torque fluctuation of the crankshaft 26 increases due to the reproduction process, abnormal noise in the rattling portion can be sufficiently suppressed.

[0057] According to the present embodiment described above, the operations and effects described below can be obtained. (1) The first superimposed torque ΔTmg1* and the second superimposed torque ΔTmg2* are varied by "1" times the appearance period of the compression top dead center. Even when the reproduction process is not performed, the torque of the internal combustion engine 10 fluctuates at the period when the compression top dead center appears. Further, due to the reproduction process, the torque of the internal combustion engine 10 fluctuates at the period when the compression top dead center of cylinder #1 appears. Therefore, the torque fluctuation of the internal combustion engine 10 tends to be an integer multiple of the period when the compression top dead center appears. Therefore, by varying the first superimposed torque ΔTmg1* and the second superimposed torque ΔTmg2* by "1" times the appearance period of the compression top dead center, the torque fluctuation caused by the reproduction process can be preferably attenuated. Therefore, the vibration of the vehicle VC can be preferably suppressed.

[0058] (2) During the regeneration process, a stop process for stopping the combustion control of cylinder #1 was executed, and a rich combustion process for making the air-fuel ratio of the air-fuel mixture in the remaining cylinders richer than the stoichiometric air-fuel ratio was executed. Since the air-fuel ratio of the air-fuel mixture in the remaining cylinders is richer than the stoichiometric air-fuel ratio, torque fluctuations become larger compared to the case of the stoichiometric air-fuel ratio. Moreover, since the regeneration process continues for a relatively long time, if the magnitude of the torque of the second motor generator 54 is small, abnormal noises may occur over a long period. Therefore, it is particularly effective to set the minimum value of the magnitude of the torque of the second motor generator 54 to be equal to or greater than the lower limit guard value Tmin determined by the process of S74.

[0059] <Second Embodiment> Hereinafter, the second embodiment will be described with reference to the drawings, focusing on the differences from the first embodiment.

[0060] In the above first embodiment, the magnitude of the second required torque Tmg2* was restricted to be equal to or greater than the lower limit guard value Tmin. In contrast, in this embodiment, when the second required torque Tmg2* becomes small, the regeneration process is prohibited.

[0061] FIG. 7 shows the procedure of the regeneration process according to this embodiment. The process shown in FIG. 7 is realized by the CPU 72 repeatedly executing a program stored in the ROM 74, for example, at a predetermined period. In FIG. 7, for the process corresponding to the process shown in FIG. 3, the same step numbers are given for convenience and the description thereof is omitted.

[0062] In the series of processes shown in FIG. 7, when the CPU 72 makes an affirmative determination in the process of S18, it determines whether the logical product of the above conditions (a) and (i) and the following condition (u) is true (S20a).

[0063] Condition (c): A condition that the absolute value of the value obtained by dividing the second required output Pmg2* by the second rotational speed Nmg2 is equal to or greater than the reference value Tmin0 plus the amount of increase ΔF during reproduction. Here, the amount of increase ΔF during reproduction is a value obtained by adding the maximum value of the second amplitude A2 to the amount of increase ΔF during reproduction in the first embodiment.

[0064] That is, in this embodiment, condition (c) is included in the execution conditions of the reproduction process. As a result, the minimum value of the torque of the second motor generator 54 during the reproduction process is restricted to be equal to or greater than "Tmin0 + ΔF - A2". This is a value larger than the minimum value when the reproduction process is not executed.

[0065] Note that when the CPU 72 makes an affirmative determination in the process of S20a, it proceeds to the process of S22, while when it makes a negative determination, it proceeds to the process of S26. <Corresponding relationship> The correspondence between the matters in the above embodiment and the matters described in the column of "Means for Solving the Problems" is as follows. Below, the correspondence is shown for each number of the solution means described in the column of "Means for Solving the Problems". [1] The electric motor corresponds to the second motor generator 54. The stop process corresponds to the process of S22. [2] The restriction process corresponds to the processes of S64 to S78. [3] The prohibition process corresponds to the process of S20a. [4] The variation process corresponds to the processes of S38 to S48. [5] The post-treatment device corresponds to the three-way catalyst 32 and the GPF 34.

[0066] <Other embodiments> Note that this embodiment can be implemented with the following modifications. This embodiment and the following modification examples can be implemented in combination with each other as long as they do not technically conflict with each other.

[0067] "Regarding the restriction process" ·The limiting process is not limited to the process of setting the lower limit guard value Tmin to the value obtained by adding the reproduction increase amount ΔF and the second amplitude A2 to the reference value Tmin0 when the reproduction process is executed. In other words, it is not limited to the process of limiting the minimum value of the torque of the second motor generator 54 that varies periodically to be equal to or greater than the value obtained by adding the reproduction increase amount ΔF to the reference value Tmin0. For example, it may be a process of limiting the average value of the torque of the second motor generator 54 that varies periodically to be equal to or greater than the value obtained by adding the reproduction increase amount ΔF to the reference value Tmin0. This can be achieved, for example, by substituting the value obtained by adding the reproduction increase amount ΔF to the reference value Tmin0 into the lower limit guard value Tmin in the process of S74. At this time, the reproduction increase amount ΔF may be set to a value larger than the maximum value that the second amplitude A2 can take.

[0068] ·In the process of FIG. 5, the second required output Pmg2* was changed when "Pmg2* / Nmg2" was smaller than the lower limit guard value Tmin, but the comparison target for the magnitude with the lower limit guard value Tmin is not limited to this. For example, if there is a command value for the second rotational speed Nmg2, the value obtained by dividing the second required output Pmg2* by the command value may be used as the comparison target.

[0069] "Regarding the inhibition process" ·In the process of FIG. 7, the reproduction process was prohibited when "Pmg2* / Nmg2" was less than the lower limit guard value Tmin, but the comparison target for the magnitude with the lower limit guard value Tmin is not limited to this. For example, if there is a command value for the second rotational speed Nmg2, the value obtained by dividing the second required output Pmg2* by the command value may be used as the comparison target. In short, the reproduction process may be prohibited when the variable indicating the torque of the second motor generator 54 is less than the lower limit guard value.

[0070] ·The reproduction increase amount ΔF for determining the lower limit guard value Tmin used for determining whether to prohibit the reproduction process is not limited to a value larger than the maximum value that the second amplitude A2 can take. Even in that case, the minimum value of the average value of the torque of the second motor generator 54 during the reproduction process can be made larger than when the reproduction process is not performed.

[0071] "Compensation for Output Reduction due to Combustion Control Stop" · In the above embodiment, the output reduction associated with the stop of the combustion control of cylinder #1 was compensated by increasing the combustion energy amounts of the remaining cylinders #2 to #4, but it is not limited to this. For example, it may be compensated by increasing the output of at least one of the first motor generator 52 and the second motor generator 54. Also, for example, while the process of S72 is used as a basis, the above-described output reduction may be compensated by increasing the output of the second motor generator 54 only when an affirmative determination is made in the process of S76. Thereby, it becomes possible to make a negative determination in the process of S76.

[0072] "Regarding Fluctuation Processing" · In FIG. 4, the first amplitude A1 and the first phase φ1 were variably set according to the engine rotational speed NE, the engine required torque Te*, and the first rotational speed Nmg1, but it is not limited to this. For example, if the engine rotational speed NE at which the regeneration process is executed is restricted to a narrow range, it may be variably set according to only the engine required torque Te* and the first rotational speed Nmg1. Also, when the first rotational speed Nmg1 at that time is also restricted to a narrow range, it may be variably set according to only the engine required torque Te*.

[0073] Also, the first amplitude A1 and the first phase φ1 are not limited to being variably set according to only some of the engine rotational speed NE, the engine required torque Te*, and the first rotational speed Nmg1. For example, it may be variably set according to the engine required output Pe*, the engine rotational speed NE, and the first rotational speed Nmg1. Here, the engine required torque Te* can be expressed by a combination of two variables, the engine required output Pe* and the engine rotational speed NE. Therefore, when determining the first amplitude A1 with the engine required output Pe* and the engine rotational speed NE as inputs, the first amplitude A1 can be set to a larger value when the engine required torque Te* is large than when it is small.

[0074] · In FIG. 4, the second amplitude A2 and the second phase φ2 are variably set according to the engine rotational speed NE, the engine required torque Te*, and the second rotational speed Nmg2, but are not limited thereto. For example, if the engine rotational speed NE at which the reproduction process is executed is restricted to a narrow range, it may be variably set according to only the engine required torque Te* and the second rotational speed Nmg2. Also, when the second rotational speed Nmg2 at that time is also restricted to a narrow range, it may be variably set according to only the engine required torque Te*.

[0075] Also, the second amplitude A2 and the second phase φ2 are not limited to being variably set according to only some of the engine rotational speed NE, the engine required torque Te*, and the second rotational speed Nmg2. For example, it may be variably set according to the engine required output Pe*, the engine rotational speed NE, and the second rotational speed Nmg2. Here, the engine required torque Te* can be expressed by a combination of two variables, the engine required output Pe* and the engine rotational speed NE. Therefore, when determining the second amplitude A2 with the engine required output Pe* and the engine rotational speed NE as inputs, the second amplitude A2 can be set to a larger value when the engine required torque Te* is large than when it is small.

[0076] "Regarding the stop process" · The stop process is not limited to the reproduction process. For example, it may be a process of stopping the fuel supply in some cylinders to adjust the output of the internal combustion engine 10. Also, for example, when an abnormality occurs in some cylinders, it may be a process of stopping the combustion control in those cylinders. Also, for example, when the oxygen storage amount of the three-way catalyst 32 becomes equal to or less than a specified value, it may be a process of stopping the combustion control of only some cylinders to supply oxygen to the three-way catalyst 32 and executing control to make the air-fuel ratio of the air-fuel mixture in the remaining cylinders the stoichiometric air-fuel ratio.

[0077] "Regarding the estimation of the deposition amount" ·The estimation process of the deposition amount DPM is not limited to that illustrated in FIG. 3. For example, the deposition amount DPM may be estimated based on the pressure difference between the upstream side and the downstream side of the GPF 34 and the intake air amount Ga. Specifically, when the pressure difference is large, the deposition amount DPM may be estimated to be a larger value than when it is small. Even when the pressure difference is the same, when the intake air amount Ga is small, the deposition amount DPM may be estimated to be a larger value than when it is large. Here, when the pressure on the downstream side of the GPF 34 is regarded as a constant value, the above pressure Pex can be used instead of the differential pressure.

[0078] "Regarding the after-treatment device" ·The GPF 34 is not limited to being provided downstream of the three-way catalyst 32 in the exhaust passage 30. Also, it is not essential for the after-treatment device to include the GPF 34. The GPF 34 is not limited to a filter carrying a three-way catalyst. For example, when a three-way catalyst is provided upstream, it may be only a filter.

[0079] "Regarding the control device" ·The control device is not limited to including a CPU 72 and a ROM 74 and executing software processing. For example, at least a part of what was software-processed in the above embodiment may be provided with a dedicated hardware circuit such as an ASIC that performs hardware processing. That is, the control device may have any of the following configurations (a) to (c). (a) It includes a processing device that executes all of the above processing according to a program, and a program storage device such as a ROM that stores the program. (b) It includes a processing device and a program storage device that execute a part of the above processing according to a program, and a dedicated hardware circuit that executes the remaining processing. (c) It includes a dedicated hardware circuit that executes all of the above processing. Here, there may be a plurality of software execution devices including a processing device and a program storage device, and dedicated hardware circuits.

[0080] "Regarding the gear" ·The gear is not limited to the gears of the planetary gear mechanism 50. "Regarding the electric motor" ·The electric motors included in the hybrid vehicle are not limited to the first motor generator 52 and the second motor generator 54. In other words, the hybrid vehicle is not limited to a series-parallel hybrid vehicle. For example, it may be a parallel hybrid vehicle.

Explanation of Signs

[0081] 10…Internal combustion engine 12…Intake passage 16…Port injection valve 18…Intake valve 20…Combustion chamber 22…In-cylinder injection valve 24…Spark plug 26…Crankshaft 27…Damper 28…Exhaust valve 30…Exhaust passage 32…Three-way catalyst 34…GPF 50…Planetary gear mechanism 52…First motor generator 54…Second motor generator 56…First inverter 58…Second inverter 70…Control device

Claims

1. Applied to a hybrid vehicle including an internal combustion engine and an electric motor connected to a crankshaft of the internal combustion engine via a gear, the internal combustion engine includes a plurality of cylinders, executes a stop process for stopping combustion control in some of the plurality of cylinders, when the internal combustion engine is operating and the stop process is not being executed, increases the minimum value of the torque of the electric motor when the stop process is being executed compared to the minimum value of the torque of the electric motor, and when the torque of the electric motor is less than a lower guard value, executes a prohibition process for prohibiting the stop process, the lower guard value is a value greater than the minimum value of the torque of the electric motor when the internal combustion engine is operating, a control device for a hybrid vehicle.

2. When the stop process is executed, executes a variation process for periodically varying the torque of the electric motor in a cycle that is an integer multiple of the cycle in which top dead center of compression appears in the internal combustion engine, the control device for a hybrid vehicle according to Claim 1.

3. The internal combustion engine includes a post-treatment device in an exhaust system, when executing the stop process, executes a rich combustion process for making the air-fuel ratio of the air-fuel mixture in the remaining cylinders richer than the stoichiometric air-fuel ratio, by increasing the temperature of the post-treatment device by the stop process and the rich combustion process, constitutes a regeneration process for the post-treatment device, the control device for a hybrid vehicle according to Claim 1 or 2.

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