JP7707625B2 - Hybrid vehicle control device - Google Patents

Description

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

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

JP 2013-189170 A

The inventors have considered performing a regeneration process for the exhaust aftertreatment device when the shaft torque of the internal combustion engine is not zero. In particular, as a regeneration process, they have considered stopping combustion control only for some cylinders, making the air-fuel ratio of the remaining cylinders richer than the theoretical air-fuel ratio, and supplying unburned fuel and oxygen into the exhaust. In that case, the torque fluctuation of the internal combustion engine becomes large, and there is a risk that the above-mentioned abnormal noise will be particularly noticeable when the torque of the electric motor is small, compared to when the regeneration process is not being performed.

Means for solving the above problems and their effects will be described below.
1. A control device for a hybrid vehicle that is applied to a hybrid vehicle that includes an internal combustion engine and an electric motor connected to a crankshaft of the internal combustion engine via a gear, the internal combustion engine having a plurality of cylinders, that executes a stop process that stops combustion control in some of the plurality of cylinders, and that sets a minimum value of the torque magnitude of the electric motor when the stop process is being executed higher than a minimum value of the torque magnitude of the electric motor when the internal combustion engine is operating and the stop process is not being executed.

When the stop process is executed in the above configuration, torque fluctuations occur in which the torque of the internal combustion engine drops significantly at the period when the compression top dead center of some cylinders occurs. Therefore, when the magnitude of the torque of the electric motor is small, noticeable 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 being executed, the minimum value of the torque magnitude of the electric motor is increased compared to when the process is not being executed. Therefore, since the gears are more strongly meshed with each other compared to when the minimum value is not increased, the generation of abnormal noise can be suppressed even when the stop process is being executed.

2. A control device for a hybrid vehicle as described in 1 above, which executes a limiting process for limiting the absolute value of the torque command value for the electric motor to a lower limit guard value or more, and the limiting process includes a process for setting the lower limit guard value to a value greater than when the stop process is executed compared to when the stop process is not executed.

In the above configuration, the lower limit guard value in the limiting process is set to be larger when the stop process is being executed than when it is not being executed. This allows the minimum value of the torque magnitude of the electric motor to be larger when the internal combustion engine is operating and the stop process is being executed compared to when it is not being executed.

3. A control device for a hybrid vehicle as described above in 1, which executes a prohibition process to prohibit the stop process when the torque of the electric motor is less than a lower limit guard value, and the lower limit guard value is a value greater than the minimum value of the torque of the electric motor when the internal combustion engine is operating.

In the above configuration, the stop process is prohibited when the torque of the electric motor is less than the lower limit guard value, and the lower limit guard value is set to a value greater than the minimum torque value of the electric motor when the internal combustion engine is operating. This makes it possible to increase the minimum torque value of the electric motor when the internal combustion engine is operating and the stop process is being executed, compared to when the process is not being executed.

4. A control device for a hybrid vehicle as described in any one of 1 to 3 above, which executes a variation process that periodically varies the torque of the internal combustion engine at a period that is an integer multiple of the period at which the compression top dead center occurs in the internal combustion engine when the stop process is executed.

Even if the stop process is not performed, the torque of the internal combustion engine fluctuates in the cycle in which the compression top dead center occurs. Furthermore, due to the stop process, the torque of the internal combustion engine fluctuates in the cycle in which the compression top dead center occurs in some cylinders. Therefore, the torque fluctuation of the internal combustion engine tends to be an integer multiple of the cycle in which the compression top dead center occurs. Therefore, in the above configuration, the torque of the electric motor is set to a torque that fluctuates in the same integer multiple cycle, so that the torque fluctuation caused by the stop process can be suitably attenuated. Therefore, in the above configuration, the vibration of the vehicle can be suitably suppressed.

5. The control device for a hybrid vehicle described in any one of 1 to 4 above, in which the internal combustion engine is provided with an aftertreatment device in the exhaust system, and when the stop process is performed, a rich combustion process is performed to make the air-fuel ratio of the mixture in the remaining cylinders richer than the theoretical air-fuel ratio, and the stop process and the rich combustion process increase the temperature of the aftertreatment device, thereby forming a regeneration process for the aftertreatment device.

In the above configuration, the air-fuel ratio of the mixture in the remaining cylinders is richer than the theoretical air-fuel ratio, so torque fluctuations are greater than in the case of the theoretical air-fuel ratio. Furthermore, since the regeneration process continues for a relatively long time, if the torque of the electric motor is small, there is a risk of abnormal noise occurring for a long period of time. For this reason, setting a minimum value for the torque of the electric motor is particularly effective.

1 is a diagram showing a configuration of a hybrid vehicle according to a first embodiment; FIG. 2 is a block diagram illustrating a process executed by a control device according to the embodiment. 4 is a flowchart showing a procedure of a process executed by the control device according to the embodiment. 4 is a flowchart showing a procedure of a process executed by the control device according to the embodiment. 4 is a flowchart showing a procedure of a process executed by the control device according to the embodiment. 4 is a time chart showing the operation of the embodiment; 10 is a flowchart showing a procedure of a process executed by a control device according to a second embodiment.

First Embodiment
Hereinafter, the first embodiment will be described with reference to the drawings.
As shown in Fig. 1, an internal combustion engine 10 has four cylinders #1 to #4. A throttle valve 14 is provided in an intake passage 12 of the internal combustion engine 10. A port injection valve 16 that injects fuel into an intake port 12a, which is a downstream portion of the intake passage 12, is provided. Air drawn into the intake passage 12 and fuel injected from the port injection valve 16 flow into a combustion chamber 20 when an intake valve 18 opens. Fuel is injected into the combustion chamber 20 from an in-cylinder injection valve 22. A mixture of air and fuel in the combustion chamber 20 is combusted in response to a spark discharge from an ignition plug 24. The combustion energy generated at this time is converted into the rotational energy of a crankshaft 26.

The air-fuel mixture burned in the combustion chamber 20 is discharged as exhaust gas into the exhaust passage 30 when the exhaust valve 28 opens. The exhaust passage 30 is provided with a three-way catalyst 32 with oxygen storage capacity and a gasoline particulate filter (GPF 34). The GPF 34 is a filter that collects PM and is supported by a three-way catalyst.

The crankshaft 26 is mechanically connected to the carrier C of the planetary gear mechanism 50 constituting the power split device via the damper 27. The rotating shaft 52a of the first motor generator 52 is mechanically connected to the sun gear S of the planetary gear mechanism 50. The rotating shaft 54a of the second motor generator 54 and the drive wheels 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. An AC voltage is applied to the terminals of the second motor generator 54 by the second inverter 58.

The control device 70 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 spark plug 24, to control the torque and exhaust component ratio as the control quantity of the internal combustion engine 10. The control device 70 also operates the first inverter 56 to control the torque, which is the control quantity of the first motor generator 52. The control device 70 also operates the second inverter 58 to control the torque, which is the control quantity of the second motor generator 54. FIG. 1 shows the operation signals MS1 to MS6 of the throttle valve 14, the port injection valve 16, the in-cylinder injection valve 22, the spark 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 to control the control quantity of the internal combustion engine 10. The control device 70 also refers to the water temperature THW detected by the water temperature sensor 86 and the exhaust pressure Pex flowing into the GPF 34 detected by the exhaust pressure sensor 88. The control device 70 also 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. The control device 70 also 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. The control device 70 also 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 amount of depression of the accelerator pedal detected by the accelerator sensor 96.

The control device 70 includes a CPU 72, a ROM 74, and a peripheral circuit 76, which are capable of communicating with each other via a communication line 78. Here, the peripheral circuit 76 includes a circuit that generates a clock signal that regulates 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 a program stored in the ROM 74.

Below, among the processes executed by the control device 70, the details of the base process, the regeneration process of the GPF 34, the vibration suppression process associated with the regeneration process, and the output distribution process will be described in that order.
(Base processing)
2 shows a part of the process executed by the control device 70. The process shown in FIG.

The base injection amount setting process M10 is a process for calculating the base injection amount Qb based on the charging efficiency η. The base injection amount Qb is the injection amount for setting the air-fuel ratio of the mixture in the combustion chamber 20 to the target air-fuel ratio. The target air-fuel ratio is the theoretical air-fuel ratio. Incidentally, the charging efficiency η is calculated by the CPU 72 based on the engine rotation speed NE and the intake air amount Ga. In addition, the engine rotation speed NE is calculated by the CPU 72 based on the output signal Scr.

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

The required output setting process M22 is a process for calculating the required output Pd* based on the required drive torque Trq*, the output side rotation 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 amount of output from the internal combustion engine 10, the first motor generator 52, and the second motor generator 54.

The output allocation process M24 allocates the required output Pd* to the engine required output Pe*, the first required output Pmg1*, and the second required output Pmg2*. The engine required output Pe* is the required output for the internal combustion engine 10. The first required output Pmg1* is the required output for the first motor generator 52. The second required output Pmg2* is the required output for the second motor generator 54.

The engine torque setting process M26 is a process for 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 for setting the opening command value TA*, which is the command value for the opening of the throttle valve 14, based on the engine required torque Te*. The throttle operation process M30 is a process for outputting an operation signal MS1 to the throttle valve 14 to control the opening of the throttle valve 14 to the opening command value TA*.

MG operation process M32 is a process that outputs 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*. In addition, MG operation process M32 is a process that outputs 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*.

(Regeneration process of GPF34)
The procedure of the playback process is shown in Fig. 3. The process shown in Fig. 3 is realized by the CPU 72 repeatedly executing a program stored in the ROM 74, for example, at a predetermined interval. In the following description, the step number of each process is represented by a number preceded by "S."

In the series of processes shown in FIG. 3, the CPU 72 first acquires the engine speed NE, the charging efficiency η, and the water temperature THW (S10). Next, the CPU 72 calculates the update amount ΔDPM of the accumulation amount DPM based on the engine speed NE, the charging efficiency η, and the water temperature THW (S12). Here, the accumulation amount DPM is the amount of PM trapped in the GPF 34. In detail, the CPU 72 calculates the amount of PM in the exhaust discharged to the exhaust passage 30 based on the engine speed NE, the charging efficiency η, and the water temperature THW. The CPU 72 also calculates the temperature of the GPF 34 based on the engine speed NE and the charging efficiency η. The CPU 72 then calculates the update amount ΔDPM based on the amount of PM in the exhaust and the temperature of the GPF 34. Note that when the process of S22 described later is executed, the temperature of the GPF 34 and the update amount ΔDPM may be calculated based on the increase coefficient K.

Next, the CPU 72 updates the accumulation amount DPM according to the update amount ΔDPM (S14). Next, the CPU 72 determines whether or not the flag F is "1" (S16). When the flag F is "1", it indicates that the temperature increase process is being performed to burn and remove the PM in the GPF 34, and when it is "0", it indicates that this is not the case. When the CPU 72 determines that the flag F is "0" (S16: NO), it determines whether or not the logical sum of the accumulation amount DPM being equal to or greater than the regeneration execution value DPMH and the period during which the process of S22 described below is interrupted is true (S18). The regeneration execution value DPMH is set to a value at which the amount of PM collected by the GPF 34 has increased and it is desired to remove the PM.

When the CPU 72 determines that the logical sum is true (S18: YES), it determines whether the condition for executing the temperature rise process, that is, the logical product of the following condition (a) and condition (b), is true, is satisfied (S20).

Condition (A): The engine torque requirement Te* is equal to or greater than a predetermined value Teth. The predetermined value Teth is set based on the lower limit of the torque that accelerates the drive wheels 60 and is applied to the drive wheels 60 by the crankshaft 26. This is a condition that indicates that the internal combustion engine 10 is operating under load.

Condition (A): The engine 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), it executes a temperature increase process and assigns "1" to the flag F (S22). As the temperature increase process according to this 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 mixture in the combustion chamber 20 of the cylinders #2, #3, and #4 richer than the theoretical air-fuel ratio. This process is a process for first increasing 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 increase the temperature of the three-way catalyst 32. Secondly, it is a process for increasing the temperature of the GPF 34 and supplying oxygen to the high-temperature GPF 34 to oxidize and remove the PM captured by the GPF 34. That is, when the temperature of the three-way catalyst 32 becomes high, high-temperature exhaust gas flows into the GPF 34, thereby increasing the temperature of the GPF 34. Then, oxygen flows into the high-temperature GPF 34, whereby the PM trapped by the GPF 34 is oxidized and removed.

In more detail, 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 cylinder #1. On the other hand, the CPU 72 assigns the value obtained by multiplying the base injection amount Qb by the increase coefficient K to the required injection amount Qd for cylinders #2, #3, and #4.

The CPU 72 sets the increase coefficient K so that the unburned fuel in the exhaust discharged from cylinders #2, #3, and #4 into the exhaust passage 30 is equal to or less than the amount at which the unburned fuel reacts just right with the oxygen discharged from cylinder #1. In detail, in the early stage of the regeneration process of the GPF 34, the CPU 72 sets the air-fuel ratio of the mixture in cylinders #2, #3, and #4 to a value as close as possible to the amount at which the unburned fuel reacts just right, in order to raise the temperature of the three-way catalyst 32 as soon as possible.

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

On the other hand, if the value is equal to or less than the lower limit guard value DPML for stopping (S24: YES) or if a negative judgment is made in the processing of S20, the CPU 72 stops or interrupts the processing of S22 and assigns "0" to flag F (S26). Here, if a positive judgment is made in the processing of S24, the processing of S22 is deemed completed and is stopped, whereas if a negative judgment is made in the processing of S20, the processing of S22 is interrupted at a stage where it has not yet been completed.

When the CPU 72 completes the processes of S22 and S26, or when a negative determination is made in the process of S18, the CPU 72 temporarily ends the series of processes shown in FIG.
(Vibration suppression process associated with regeneration process)
A detailed procedure of the MG operation process M32 is shown in Fig. 4. The process shown in Fig. 4 is realized by the CPU 72 repeatedly executing a program stored in the ROM 74, for example, at a predetermined interval.

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

Next, the CPU 72 assigns the value obtained by dividing the first required output Pmg1* by the first rotation speed Nmg1 to the first required torque base value Tmg1b* (S32). The CPU 72 also assigns the value obtained by dividing the second required output Pmg2* by the second rotation speed Nmg2 to the second required torque base value Tmg2b* (S34).

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), the engine rotation speed NE, the engine required torque Te*, and the first rotation speed Nmg1 are input, and the first amplitude A1 and the first phase φ1 are calculated (S38). These variables determine the first superimposed torque ΔTmg1* that is superimposed on the first required torque base value Tmg1b*. The first superimposed torque ΔTmg1* is a sine wave torque having the first amplitude A1. The phase of the sine wave is the first phase φ1. The first superimposed torque ΔTmg1* is shown below.

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 at which the compression top dead center occurs in the internal combustion engine 10.

The CPU 72 assigns the value obtained by adding the first superimposed torque ΔTmg1* to the first required torque base value Tmg1b* to the first required torque Tmg1* (S40). The CPU 72 then 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).

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

ΔTmg2*=A2・sin(2・θe+φ2)
According to the above formula, 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 occurs in the internal combustion engine 10.

The CPU 72 assigns the value obtained by adding the second superimposed torque ΔTmg2* to the second required torque base value Tmg2b* to the second required torque Tmg2* (S46). The CPU 72 then 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).

On the other hand, when the CPU 72 determines that the flag F is "0" (S36: NO), it assigns the first required torque Tmg1* to the first required torque base value Tmg1b* (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). The CPU 72 also assigns the second required torque base value Tmg2b* to 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).

When the CPU 72 completes the processes of S48 and S56, the CPU 72 temporarily ends the series of processes shown in FIG.
(Details of output distribution process)
The procedure of the output distribution process M24 is shown in Fig. 5. The process shown in Fig. 5 is realized by the CPU 72 repeatedly executing a program stored in the ROM 74, for example, at a predetermined interval.

In the series of processes shown in FIG. 5, the CPU 72 first obtains the required output Pd* (S60). The CPU 72 then 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).

Peb*+Pmg1*+Pmg2*=Pd*...(c1)
Next, the CPU 72 determines whether or not the flag F is "0" (S64). When the CPU 72 determines that the flag F is "0" (S64: YES), the CPU 72 assigns the engine required output base value Peb* to the engine required output Pe* (S66). The CPU 72 also assigns a reference value Tmin0 to the lower limit guard value Tmin of the torque of the second motor-generator 54 (S68).

Here, the reference value Tmin0 is set to an appropriate value for suppressing the generation of abnormal noise in the mechanical backlash portion, which is the gap between the meshing gears including the planetary gear mechanism 50 during normal operation of the internal combustion engine 10. This is in consideration of the risk of abnormal noise being generated in the backlash portion when the torque of the second motor generator 54 is excessively small. In other words, the torque fluctuation of the crankshaft 26 may contain a component that cannot be completely attenuated by the damper 27. Even if this component is input to the planetary gear mechanism 50, when the torque of the second motor generator 54 is large, the gears are engaged by pressing against each other, so abnormal noise is unlikely to occur. On the other hand, when the torque of the second motor generator 54 is small, the force pressing the gears against each other is weak, so there is a risk of abnormal noise such as gear rattle due to the above-mentioned fluctuation component.

On the other hand, when the CPU 72 determines that the flag F is "1" (S64: NO), it calculates the reduction rate Rdp of the output of the internal combustion engine 10 (S70). In 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 assigns a value obtained by dividing the engine required output base value Peb* by "1-Rdp" to the engine required output Pe* (S72). As a result, the opening degree command value TA* calculated by the throttle opening degree command value setting process M28 becomes an appropriate value for setting the output of the internal combustion engine 10 to the engine required output base value Peb* during the regeneration process.

The CPU 72 also assigns the value obtained by adding the regeneration increase amount ΔF and the second amplitude A2 to the reference value Tmin0 to the lower limit guard value Tmin (S74). As a result, the minimum value of the torque of the second motor generator 54 is set to a value that is greater than the reference value Tmin0 by the regeneration increase amount ΔF. The regeneration increase amount ΔF is used here because, during regeneration processing, combustion control is stopped in cylinder #1, and therefore the torque fluctuation of the crankshaft 26 becomes greater than when regeneration processing is not being performed.

When the CPU 72 completes the processing of S68 and S74, it determines whether the absolute value of the value obtained by dividing the second required output Pmg2* by the second rotation speed Nmg2 is smaller than the lower limit guard value Tmin (S76). If the CPU 72 determines that the second required output Pmg2* is smaller than the lower limit guard value Tmin (S76: YES), it increases the magnitude of the second required output Pmg2* to the product of the lower limit guard value Tmin and the second rotation 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* using the second required output Pmg2* reset by the processing of S78 so that the above formula (c1) is satisfied. The relationship between the engine required output base value Peb* and the engine required output Pe* is determined by the processing of S72.

When the CPU 72 completes the process of S80 or makes a negative determination in the process of S76, the CPU 72 temporarily ends the series of processes shown in FIG.
Here, the operation and effects of this embodiment will be described.

FIG. 6 illustrates an example of setting the lower limit guard value Tmin according to this embodiment.
As shown in Fig. 6, before time t1, the regeneration process is not executed, and therefore the lower limit guard value Tmin is set to the reference value Tmin0. On the other hand, after time t1, the regeneration process is executed, and therefore the lower limit guard value Tmin is set to a value that is greater than the reference value Tmin0 by "A2+ΔF". Therefore, even when the second superimposed torque ΔTmg2* is at its minimum value when fluctuating with the second amplitude A2, the torque of the second motor generator 54 shown by the two-dot chain line in Fig. 6 is limited to a value that is greater than the reference value Tmin0 by the regeneration increase amount ΔF or more. Therefore, even if the torque fluctuation of the crankshaft 26 becomes large due to the regeneration process, the abnormal noise of the backlash portion can be sufficiently suppressed.

According to the present embodiment described above, the following actions and effects 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 if the regeneration process is not performed, the torque of the internal combustion engine 10 varies in the period in which the compression top dead center appears. In addition, the regeneration process causes the torque of the internal combustion engine 10 to vary in the period in which the compression top dead center of the cylinder #1 appears. Therefore, the torque fluctuation of the internal combustion engine 10 tends to be an integer multiple of the period in which 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 regeneration process can be suitably attenuated. Therefore, the vibration of the vehicle VC can be suitably suppressed.

(2) In the regeneration process, a stop process is performed to stop the combustion control of cylinder #1, and a rich combustion process is performed to make the air-fuel ratio of the mixture in the remaining cylinders richer than the stoichiometric air-fuel ratio. Because the air-fuel ratio of the mixture in the remaining cylinders is richer than the stoichiometric air-fuel ratio, the torque fluctuation is larger than in the case of the stoichiometric air-fuel ratio. Furthermore, since the regeneration process continues for a relatively long time, if the torque of the second motor-generator 54 is small, there is a risk of abnormal noise occurring for a long period of time. Therefore, it is particularly effective to set the minimum value 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.

Second Embodiment
The second embodiment will be described below with reference to the drawings, focusing on the differences from the first embodiment.

In the first embodiment described above, the magnitude of the second required torque Tmg2* is limited to be equal to or greater than the lower limit guard value Tmin. In contrast, in this embodiment, if the second required torque Tmg2* becomes small, the regeneration process is prohibited.

Figure 7 shows the procedure for the playback process according to this embodiment. The process shown in Figure 7 is realized by the CPU 72 repeatedly executing a program stored in the ROM 74, for example at a predetermined interval. For convenience, the processes in Figure 7 that correspond to those shown in Figure 3 are given the same step numbers and their explanations are omitted.

In the series of processes shown in FIG. 7, if the CPU 72 makes a positive judgment in the process of S18, it judges whether the logical product of the above conditions (a) and (b) and the following condition (c) is true (S20a).

Condition (c): The absolute value of the second required output Pmg2* divided by the second rotation speed Nmg2 is equal to or greater than the reference value Tmin0 plus the regeneration increase amount ΔF. Here, the regeneration increase amount ΔF is the regeneration increase amount ΔF in the first embodiment plus the maximum value of the second amplitude A2.

In other words, in this embodiment, the conditions for executing the regeneration process include condition (c). As a result, the minimum value of the torque of the second motor generator 54 during the regeneration process is limited to equal to or greater than "Tmin0 + ΔF - A2". This is a value that is greater than the minimum value when the regeneration process is not being executed.

If the CPU 72 makes a positive determination in the process of S20a, the process proceeds to S22, whereas if the CPU 72 makes a negative determination, the process proceeds to S26.
<Correspondence>
The correspondence between the matters in the above embodiment and the matters described in the "Means for solving the problem" column is as follows. Below, the correspondence is shown for each number of the means for solving the problem described in the "Means for solving the problem" column. [1] The electric motor corresponds to the second motor generator 54. The stop processing corresponds to the processing of S22. [2] The restriction processing corresponds to the processing of S64 to S78. [3] The prohibition processing corresponds to the processing of S20a. [4] The variation processing corresponds to the processing of S38 to S48. [5] The aftertreatment device corresponds to the three-way catalyst 32 and the GPF 34.

<Other embodiments>
This embodiment can be modified as follows: This embodiment and the following modifications can be combined with each other to the extent that no technical contradiction occurs.

"About Restriction Processing"
The limiting process is not limited to the process of setting the lower limit guard value Tmin to a value obtained by adding the regeneration increase amount ΔF and the second amplitude A2 to the reference value Tmin0 when the regeneration process is executed. In other words, it is not limited to the process of limiting the minimum value of the periodically varying torque of the second motor generator 54 to a value equal to or greater than the reference value Tmin0 plus the regeneration increase amount ΔF. For example, the limiting process may be a process of limiting the average value of the periodically varying torque of the second motor generator 54 to a value equal to or greater than the reference value Tmin0 plus the regeneration increase amount ΔF. This can be realized, for example, by substituting the value obtained by adding the regeneration increase amount ΔF to the reference value Tmin0 in the process of S74 for the lower limit guard value Tmin. In this case, the regeneration increase amount ΔF may be set to a value greater than the maximum value that the second amplitude A2 can take.

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

"About Prohibited Processing"
7, the regeneration process is prohibited when "Pmg2*/Nmg2" is less than the lower limit guard value Tmin, but the comparison target with the lower limit guard value Tmin is not limited to this. For example, if there is a command value for the second rotation speed Nmg2, the value obtained by dividing the second required output Pmg2* by that command value may be used as the comparison target. In short, it is sufficient to prohibit the regeneration process when the variable indicating the torque of the second motor generator 54 is less than the lower limit guard value.

The regeneration increase amount ΔF, which determines the lower limit guard value Tmin used to determine whether or not to prohibit the regeneration process, is not limited to a value greater than the maximum value that the second amplitude A2 can take. Even in this case, the minimum value of the average torque of the second motor generator 54 during the regeneration process can be made greater than when the regeneration process is not being performed.

"Compensation for power loss due to combustion control shutdown"
In the above embodiment, the output reduction caused by the stop of the combustion control of cylinder #1 is compensated for by increasing the amount of combustion energy in the remaining cylinders #2 to #4, but this is not limited to the above. For example, the output of at least one of the first motor-generator 52 and the second motor-generator 54 may be increased to compensate. Also, for example, while the process of S72 is the basis, the output reduction may be compensated for by increasing the output of the second motor-generator 54 only when a positive determination is made in the process of S76. This makes it possible to make a negative determination in the process of S76.

"About non-recurring processing"
In Fig. 4, the first amplitude A1 and the first phase φ1 are variably set in response to the engine speed NE, the engine required torque Te*, and the first rotation speed Nmg1, but this is not limiting. For example, if the engine speed NE at which the regeneration process is executed is limited to a narrow range, the first amplitude A1 and the first phase φ1 may be variably set in response to only the engine required torque Te* and the first rotation speed Nmg1. Furthermore, if the first rotation speed Nmg1 at that time is also limited to a narrow range, the first amplitude A1 and the first phase φ1 may be variably set in response to only the engine required torque Te*.

Furthermore, the first amplitude A1 and the first phase φ1 are not limited to being variably set in response to only some of the engine speed NE, the engine required torque Te*, and the first speed Nmg1. For example, they may be variably set in response to the engine required output Pe*, the engine speed NE, and the first speed Nmg1. Here, the engine required torque Te* can be expressed by a set of two variables, the engine required output Pe* and the engine speed NE. Therefore, when determining the first amplitude A1 using the engine required output Pe* and the engine 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.

- In FIG. 4, the second amplitude A2 and the second phase φ2 are variably set in response to the engine speed NE, the engine required torque Te*, and the second rotation speed Nmg2, but this is not limited to the above. For example, if the engine speed NE at which the regeneration process is executed is limited to a narrow range, the second amplitude A2 and the second phase φ2 may be variably set in response to only the engine required torque Te* and the second rotation speed Nmg2. Furthermore, if the second rotation speed Nmg2 at that time is also limited to a narrow range, the second amplitude A2 and the second phase φ2 may be variably set in response to only the engine required torque Te*.

Furthermore, the second amplitude A2 and the second phase φ2 are not limited to being variably set in response to only some of the engine speed NE, the engine required torque Te*, and the second speed Nmg2. For example, they may be variably set in response to the engine required output Pe*, the engine speed NE, and the second speed Nmg2. Here, the engine required torque Te* can be expressed by a set of two variables, the engine required output Pe* and the engine speed NE. Therefore, when determining the second amplitude A2 using the engine required output Pe* and the engine 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.

"About the stop process"
The stop process is not limited to the regeneration process. For example, the stop process may be a process of stopping the supply of fuel to some cylinders in order to adjust the output of the internal combustion engine 10. Also, for example, the stop process may be a process of stopping the combustion control in some cylinders when an abnormality occurs in the cylinder. Also, for example, the stop process may be a process of stopping the combustion control in only some cylinders to supply oxygen to the three-way catalyst 32 when the oxygen storage amount of the three-way catalyst 32 becomes equal to or less than a specified value, and executing control to set the air-fuel ratio of the mixture in the remaining cylinders to the theoretical air-fuel ratio.

"Estimation of deposition volume"
The estimation process of the deposition amount DPM is not limited to the example shown in Fig. 3. For example, the deposition amount DPM may be estimated based on the pressure difference between the upstream and downstream sides of the GPF 34 and the intake air amount Ga. Specifically, the deposition amount DPM may be estimated to be a larger value when the pressure difference is large than when it is small, and even if the pressure difference is the same, the deposition amount DPM may be estimated to be a larger value when the intake air amount Ga is small than when it is large. Here, when the pressure downstream of the GPF 34 is regarded as a constant value, the pressure Pex may be used instead of the differential pressure.

"About post-processing device"
The GPF 34 is not limited to being provided downstream of the three-way catalyst 32 in the exhaust passage 30. In addition, it is not essential that the aftertreatment device includes the GPF 34. The GPF 34 is not limited to being a filter carrying a three-way catalyst. For example, if a three-way catalyst is provided upstream, the GPF 34 may be a filter alone.

"About the control device"
The control device is not limited to a device having a CPU 72 and a ROM 74 and executing software processing. For example, a dedicated hardware circuit such as an ASIC may be provided to perform hardware processing of at least a part of what has been processed by software in the above embodiment. That is, the control device may have any of the following configurations (a) to (c). (a) 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) 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) A dedicated hardware circuit that executes all of the above processing. Here, there may be a plurality of software execution devices having a processing device and a program storage device, and a plurality of dedicated hardware circuits.

"About Gear"
The gears are not limited to the gears of the planetary gear mechanism 50.
"About electric motors"
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, the hybrid vehicle may be a parallel hybrid vehicle.

Reference Signs List 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 (3)

The present invention 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.
executing a stop process for stopping combustion control in some of the plurality of cylinders;
The minimum value of the torque of the electric motor when the stop process is being executed is larger than the minimum value of the torque of the electric motor when the internal combustion engine is operating and the stop process is not being executed, and
When the torque of the electric motor is less than a lower limit guard value, a prohibition process is executed to prohibit the stop process.
A control device for a hybrid vehicle , wherein the lower limit guard value is a value greater than a minimum value of the torque of the electric motor when the internal combustion engine is operating . 2. The control device for a hybrid vehicle according to claim 1 , wherein when the stop process is executed, a variation process is executed to periodically vary the torque of the electric motor at a period that is an integer multiple of a period at which a compression top dead center occurs in the internal combustion engine. the internal combustion engine is provided with an aftertreatment device in an exhaust system;
When the stop process is executed, a rich combustion process is executed to make the air-fuel ratio of the mixture in the remaining cylinder richer than the stoichiometric air-fuel ratio.
3. The control device for a hybrid vehicle according to claim 1 , wherein a regeneration process for the aftertreatment device is performed by increasing the temperature of the aftertreatment device through the stop process and the rich combustion process.