Hybrid vehicle control device

Abstract

To suppress compensation torque from deviating from required torque while processing a fuel-cut.SOLUTION: A vehicle includes an internal combustion engine, a first motor-generator, and a control apparatus. The internal combustion engine has multiple cylinders. The first motor-generator is connected to a crank shaft of the internal combustion engine. The control apparatus executes: torque calculation processing to calculate required torque; upper limit calculation processing to calculate an upper limit value of torque; fuel-cut processing; and calculating, during the fuel-cut processing, compensation torque for compensating at least a part of variation of the torque on the basis of the required torque to execute torque compensation processing for causing the first motor-generator to output the compensation torque to the crank shaft. The control apparatus is capable of executing stop processing to stop the fuel-cut processing in a case where the required torque exceeds the upper limit value while executing the fuel-cut processing.SELECTED DRAWING: Figure 3

Description

[Technical field]

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

[0002] The hybrid vehicle disclosed in Patent Document 1 includes an internal combustion engine, a motor generator, and a control device. The internal combustion engine has a plurality of cylinders and a crankshaft. The motor generator is connected to the crankshaft. The motor generator applies torque to the crankshaft and is driven by the crankshaft to operate as a generator. When the hybrid vehicle satisfies a specific condition, the control device stops combustion in one cylinder while continuing combustion in the other cylinders. In this way, the torque of the crankshaft periodically decreases as combustion in a specific cylinder is stopped. To compensate for this periodic torque decrease, the control device causes the motor generator to output a compensation torque to the crankshaft. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-060027 Summary of the Invention [Problem to be solved by the invention]

[0004] In a hybrid vehicle such as that of Patent Document 1, when combustion in a specific cylinder is stopped, the upper limit of the torque that the internal combustion engine can output is smaller than that during normal driving. Therefore, when the torque required for the internal combustion engine exceeds the upper limit when combustion in a specific cylinder is stopped, the torque output by the internal combustion engine is limited to the upper limit. On the other hand, the compensation torque is generally calculated based on the torque required for the internal combustion engine. In other words, when the torque of the internal combustion engine is limited, the compensation torque is calculated based on a value different from the torque actually output by the internal combustion engine. In this case, the calculated compensation torque becomes a value larger than the ideal compensation torque. Note that, although an example in which the upper limit of the torque that the internal combustion engine can output is reduced by stopping combustion in a specific cylinder has been described, if the upper limit of the torque that the internal combustion engine can output is determined in some way, a similar problem may occur. [Means for solving the problem]

[0005] In order to solve the above problems, the present invention is a control device applied to a hybrid vehicle equipped with an internal combustion engine having a plurality of cylinders and a motor generator connected to a crankshaft of the internal combustion engine, the control device being capable of executing the following: a torque calculation process that calculates a required torque required of the internal combustion engine based on the vehicle speed and accelerator operation amount of the hybrid vehicle; an upper limit calculation process that calculates an upper limit value of the torque that can be output by the internal combustion engine based on the state of the hybrid vehicle; a fuel cut process that repeats a pattern of burning fuel in the cylinders M consecutive times and a pattern of stopping fuel combustion in the cylinders N consecutive times, where M and N are natural numbers, while continuing to operate the internal combustion engine; a torque compensation process that calculates a compensation torque for compensating for at least a portion of the torque fluctuations associated with stopping fuel combustion in the cylinders during the fuel cut process based on the required torque and outputs the compensation torque from the motor generator to the crankshaft; and a stop process that stops the fuel cut process if the required torque exceeds the upper limit value during the fuel cut process.

[0006] According to the above configuration, when a difference occurs between the torque actually output by the internal combustion engine and the required torque on which the compensation torque is calculated, the fuel cut process is stopped. When the fuel cut process is stopped, the torque compensation process is also stopped accordingly, so that problems associated with the compensation torque deviating from an ideal value do not occur. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic diagram of a vehicle. [Diagram 2] 4 is a flowchart of combustion mode switching control executed by the control device. [Diagram 3] 4 is a flowchart of fuel cut stop control executed by the control device. [Figure 4] 4 is a timing chart showing fluctuations in required torque accompanying control executed by the control device. [Diagram 5] 10 is a flowchart of fuel cut stop control executed by a control device of a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] <Vehicle Overview> An embodiment of the present invention will now be described with reference to the drawings. First, a schematic configuration of a vehicle 500 will be described.

[0009] 1, the vehicle 500 includes an internal combustion engine 10, a first motor generator 71, and a second motor generator 72. Therefore, the vehicle 500 is a so-called hybrid vehicle.

[0010] The internal combustion engine 10 includes four cylinders 11, a crankshaft 12, an intake passage 21, a throttle valve 22, four fuel injection valves 23, four ignition devices 24, an exhaust passage 26, a three-way catalyst 27, and a filter 28.

[0011] The cylinder 11 is a space for burning a mixture of fuel and intake air. The cylinder 11 is a substantially cylindrical space. A piston is housed inside the space. The piston reciprocates inside the cylinder 11. Note that the piston is not shown in FIG. 1.

[0012] The intake passage 21 is connected to the cylinders 11. The intake passage 21 is a passage for introducing intake air into the cylinders 11. A portion of the intake passage 21, including the downstream end, is branched into four. Each of the branched passages is connected to each of the cylinders 11.

[0013] The throttle valve 22 is located upstream of the branched portion of the intake passage 21. The throttle valve 22 is a valve for adjusting the amount of intake air flowing through the intake passage 21.

[0014] The four fuel injection valves 23 are located in the middle of the intake passage 21. Specifically, the four fuel injection valves 23 are located in respective branched intake passages 21. The fuel injection valves 23 inject fuel toward the cylinder 11 side.

[0015] The four ignition devices 24 are each located inside the cylinder 11. The ignition devices 24 ignite an air-fuel mixture of fuel and intake air by spark discharge. The exhaust passage 26 is connected to the cylinders 11. The exhaust passage 26 is a passage for discharging exhaust gas from the cylinders 11. A portion of the exhaust passage 26, including the upstream end, is branched into four. Each of the branched passages is connected to each of the cylinders 11.

[0016] The three-way catalyst 27 is located downstream of the branched portion of the exhaust passage 26. The three-way catalyst 27 purifies hydrocarbons, carbon monoxide, and nitrogen oxides contained in the exhaust gas. The three-way catalyst 27 also has an oxygen storage capacity. The filter 28 is located downstream of the three-way catalyst 27 in the exhaust passage 26. The filter 28 collects particulate matter in the exhaust gas.

[0017] The crankshaft 12 is connected to pistons located in each cylinder 11. The crankshaft 12 is rotated by combustion of a mixture of fuel and intake air in the cylinder 11. The crankshaft 12 is also connected to a first motor-generator 71.

[0018] The vehicle 500 includes a first planetary gear mechanism 40, a ring gear shaft 45, a second planetary gear mechanism 50, a reduction mechanism 62, a differential mechanism 63, and driving wheels 64. The first planetary gear mechanism 40 includes a sun gear 41, a ring gear 42, a plurality of pinion gears 43, and a carrier 44. The sun gear 41 is an external gear. The sun gear 41 is connected to a first motor generator 71. The ring gear 42 is an internal gear and is positioned coaxially with the sun gear 41. Each pinion gear 43 is positioned between the sun gear 41 and the ring gear 42. Each pinion gear 43 meshes with both the sun gear 41 and the ring gear 42. The carrier 44 supports the pinion gear 43. The pinion gear 43 is rotatable on its own axis and is revolvable by rotating together with the carrier 44. The carrier 44 is connected to the crankshaft 12.

[0019] When the internal combustion engine 10 is driven and torque is input from the crankshaft 12 to the carrier 44 of the first planetary gear mechanism 40, the torque is transmitted to the sun gear 41 side and the ring gear 42 side. On the other hand, when the first motor generator 71 operates as a motor, torque is input to the sun gear 41 side of the first planetary gear mechanism 40. The torque input to the sun gear 41 is transmitted to the carrier 44 side and the ring gear 42 side. In other words, the first motor generator 71 can apply torque to the crankshaft 12.

[0020] The ring gear shaft 45 is connected to the ring gear 42. The ring gear shaft 45 is also connected to drive wheels 64 via a reduction mechanism 62 and a differential mechanism 63. The reduction mechanism 62 reduces the rotation speed of the ring gear shaft 45 and outputs it. The differential mechanism 63 allows a difference in rotation speed to occur between the left and right drive wheels 64.

[0021] The second planetary gear mechanism 50 includes a sun gear 51, a ring gear 52, a plurality of pinion gears 53, a carrier 54, and a case 55. The sun gear 51 is an external gear. The sun gear 51 is connected to the second motor generator 72. The ring gear 52 is an internal gear and is located coaxially with the sun gear 51. The ring gear 52 is connected to the ring gear shaft 45. Each pinion gear 53 is located between the sun gear 51 and the ring gear 52. Each pinion gear 53 meshes with both the sun gear 51 and the ring gear 52. The carrier 54 supports the pinion gear 53. The pinion gear 53 is rotatable. The carrier 54 is fixed to the case 55. Therefore, the pinion gear 53 is not capable of revolving.

[0022] When the second motor generator 72 operates as a motor and torque is input to the ring gear shaft 45 , the torque is transmitted to the differential mechanism 63 . Furthermore, when torque from the drive wheels 64 side is input to the second motor generator 72 via the ring gear shaft 45, the second motor generator 72 functions as a generator. That is, the second motor generator 72 can generate a regenerative braking force for the vehicle 500.

[0023] The vehicle 500 includes a battery 75, a first inverter 76, and a second inverter 77. The battery 75 is a secondary battery. The first inverter 76 performs AC-DC power conversion between the first motor generator 71 and the battery 75. The first inverter 76 also adjusts the amount of power exchanged between the first motor generator 71 and the battery 75. The second inverter 77 performs AC-DC power conversion between the second motor generator 72 and the battery 75. The second inverter 77 adjusts the amount of power exchanged between the second motor generator 72 and the battery 75.

[0024] The vehicle 500 is equipped with a water temperature sensor 83 , a crank angle sensor 84 , an accelerator operation amount sensor 85 , and a vehicle speed sensor 86 . The water temperature sensor 83 detects a coolant temperature THW which is the temperature of the coolant flowing through each part of the internal combustion engine 10. The crank angle sensor 84 detects a crank angle SC which is the rotational position of the crankshaft 12. The accelerator operation amount sensor 85 detects an accelerator operation amount ACC which is the operation amount of the accelerator pedal operated by the driver. The vehicle speed sensor 86 detects a vehicle speed SP which is the speed of the vehicle 500.

[0025] The vehicle 500 is equipped with a control device 100. The control device 100 obtains a signal indicating a cooling water temperature THW from a water temperature sensor 83. The control device 100 obtains a signal indicating a crank angle SC from a crank angle sensor 84. The control device 100 obtains a signal indicating an accelerator operation amount ACC from an accelerator operation amount sensor 85. The control device 100 obtains a signal indicating a vehicle speed SP from a vehicle speed sensor 86.

[0026] The control device 100 calculates the engine speed NE, which is the number of revolutions per unit time of the crankshaft 12, based on the crank angle SC. The control device 100 also calculates the temperature of the filter 28 based on the intake air charging efficiency and the operating conditions of the internal combustion engine 10, such as the engine speed NE. The control device 100 calculates the PM accumulation amount, which is the amount of particulate matter accumulated on the filter 28, based on the engine speed NE and the temperature of the filter 28. The intake air charging efficiency is expressed as the ratio of the cylinder inflow air amount, which is the mass of intake air flowing into each cylinder 11, to the mass of intake air in standard atmospheric conditions that occupies the stroke volume of the cylinder.

[0027] The control device 100 is capable of executing a torque calculation process. In the torque calculation process, the control device 100 calculates a required torque TR required of the internal combustion engine 10. The required torque TR is calculated based on the vehicle speed SP and accelerator operation amount ACC of the vehicle 500. That is, in the required torque calculation process, the control device 100 first acquires the current accelerator operation amount ACC from the accelerator operation amount sensor 85. The control device 100 acquires the current vehicle speed SP from the vehicle speed sensor 86. The control device 100 then calculates the required torque TR based on the values ​​acquired from these sensors. The larger the accelerator operation amount ACC and the vehicle speed SP are, the larger the required torque TR is calculated to be.

[0028] The control device 100 can execute a fuel cut process. In the fuel cut process, the control device 100 repeats a pattern of burning fuel in three consecutive cylinders 11 and a pattern of stopping fuel combustion in one cylinder 11 while continuing the operation of the internal combustion engine 10. Specifically, the control device 100 stops the supply of fuel to one cylinder 11 and allows intake air to flow from that cylinder 11 to the exhaust passage 26. In addition, the control device 100 allows exhaust air to flow from that cylinder 11 to the exhaust passage 26 while supplying fuel to three cylinders 11 in succession in the order of the cylinders 11 that will undergo the combustion stroke. In this way, when the fuel cut process is executed, combustion is stopped in one cylinder 11, and oxygen is supplied to the filter 28. Particulate matter deposited on the filter 28 reacts with the oxygen supplied to the filter 28 and is burned.

[0029] When the fuel cut process is being executed, the control device 100 can execute a torque compensation process. During the fuel cut process, the torque of the internal combustion engine 10 fluctuates as fuel combustion stops in one cylinder 11. Specifically, during a period in which fuel is burned in three consecutive cylinders 11, torque is applied to the crankshaft 12 due to the fuel combustion. On the other hand, during a period in which fuel combustion stops in one cylinder, no torque is applied to the crankshaft 12 due to the fuel combustion. Therefore, if the period in which each of the four cylinders 11 undergoes a combustion stroke is defined as one cycle, the torque drops significantly once per cycle. In order to compensate for at least a part of such torque fluctuation, the control device 100 operates the first motor generator 71 to apply a compensation torque TC to the crankshaft 12 at the timing when the cylinder 11 that stops fuel combustion undergoes a combustion stroke. This prevents the torque of the crankshaft 12 from dropping significantly, and suppresses the amount of torque fluctuation in one cycle. In this torque compensation process, the control device 100 calculates the compensation torque TC in accordance with the magnitude of the required torque TR. The control device 100 calculates the compensation torque TC to be a larger value as the required torque TR increases.

[0030] The control device 100 can execute a limiting process to limit the output torque of the internal combustion engine 10 to a value equal to or less than an upper limit value TM. Specifically, when the required torque TR calculated in the torque calculation process is equal to or less than the upper limit value TM, the control device 100 controls the output torque of the internal combustion engine 10 to the required torque TR. On the other hand, when the required torque TR exceeds the upper limit value TM, the control device 100 controls the output torque of the internal combustion engine 10 to a torque equal to the upper limit value TM.

[0031] The control device 100 can execute an upper limit calculation process. The upper limit value TM of the torque is calculated according to the state of the vehicle 500. For example, when the fuel cut flag is on, the control device 100 sets the upper limit value TM to a smaller value than when the fuel cut flag is off. The control device 100 also calculates the upper limit value TM of the torque based on the cooling water temperature THW. In this case, when the temperature of the cooling water temperature THW is equal to or higher than a predetermined specified temperature, the control device 100 sets the upper limit value TM of the torque to a smaller value than when the temperature is not equal to or higher than a predetermined specified temperature. Also, for example, when an abnormality is detected in each part of the vehicle 500, the control device 100 sets the upper limit value TM of the torque to a smaller value than when the abnormality is not detected. Examples of abnormalities in the vehicle 500 include a state in which the oil lubricating the internal combustion engine 10 is insufficient, a state in which the three-way catalyst 27 or the filter 28 is clogged, and the like.

[0032] The control device 100 may be configured as a circuit including one or more processors that execute various processes according to a computer program (software). The control device 100 may be configured as a circuit including one or more dedicated hardware circuits, such as an application specific integrated circuit (ASIC), that execute at least a part of the various processes, or a combination thereof. The processor includes a CPU and memory such as a RAM and a ROM. The memory stores program code or instructions configured to cause the CPU to execute processes. The memory, i.e., computer-readable medium, includes any available medium that can be accessed by a general-purpose or dedicated computer.

[0033] <Combustion switching control> The following describes the combustion switching control executed by the control device 100. The control device 100 starts the combustion switching control on the condition that the internal combustion engine 10 is driven. The control device 100 repeatedly executes the combustion switching control until the drive of the internal combustion engine 10 stops.

[0034] As shown in Fig. 2, when the control device 100 starts the combustion switching control, it first executes the process of step S11. In step S11, the control device 100 judges whether or not the condition for executing the fuel cut process is satisfied. The condition for executing the fuel cut process is determined in advance. One example of the condition for executing the fuel cut process is that the amount of PM accumulation in the filter 28 is equal to or greater than a specified value, the vehicle speed SP is greater than zero, and the engine rotation speed NE is equal to or less than a predetermined value. If the judgment in step S11 is positive (S11: YES), the process of the control device 100 proceeds to step S12.

[0035] In step S12, the control device 100 executes a fuel cut process. When the control device 100 executes the fuel cut process, it turns on a fuel cut flag. If the fuel cut process is already being executed, the control device 100 continues the fuel cut process. In addition, the control device 100 executes the above-mentioned torque compensation process in conjunction with the execution of the fuel cut process. In this case, the control device 100 keeps the fuel cut flag on. In addition, the control device 100 executes the above-mentioned torque compensation process in conjunction with the execution of the fuel cut process. Then, the control device 100 ends the combustion switching control.

[0036] On the other hand, if the determination in step S11 is negative (S11: NO), the process of the control device 100 proceeds to step S13. In step S13, the control device 100 executes normal combustion processing. That is, the control device 100 supplies fuel to all cylinders 11. When the control device 100 executes normal combustion processing, it turns off the fuel cut flag. Note that, if normal combustion processing is already being executed, the control device 100 continues normal combustion processing. In this case, the control device 100 leaves the fuel cut flag turned off. In addition, the control device 100 stops the above-mentioned torque compensation processing when the fuel cut processing is stopped. Then, the control device 100 ends the combustion switching control.

[0037] <About Fuel Cut-Off Stop Control> The following describes the fuel cut stop control executed by the control device 100. The control device 100 starts the fuel cut stop control on the condition that the fuel cut flag is turned on. That is, the fuel cut stop control is executed in conjunction with the execution of the fuel cut process.

[0038] 3, when the control device 100 starts the fuel cut stop control, the control device 100 first executes the process of step S21. In step S21, the control device 100 executes the required torque calculation process described above. After calculating the required torque TR, the process of the control device 100 proceeds to step S22.

[0039] In step S22, the control device 100 executes a process for calculating the upper limit value TM of the torque that the internal combustion engine 10 can output, that is, an upper limit calculation process. The method for calculating the upper limit value TM is as described above. When step S22 is executed, the fuel cut flag is on. Therefore, the upper limit value TM is calculated to be a value lower than that in the case of normal combustion processing. After that, the process of the control device 100 proceeds to step S23.

[0040] In step S23, the control device 100 determines whether the calculated torque upper limit value TM is smaller than the calculated required torque TR. If the determination is negative (S23: NO), the process of the control device 100 returns to step S21. That is, the fuel cut process being executed continues without being stopped. Then, the output torque of the internal combustion engine 10 is controlled to the required torque TR that is equal to or smaller than the upper limit value TM. On the other hand, if the determination is positive (S23: YES), the process of the control device 100 proceeds to step S24.

[0041] In step S24, the control device 100 stops the execution of the fuel cut process. That is, the control device 100 starts combustion in all cylinders 11. In addition, the control device 100 stops the torque compensation process accordingly. Then, the control device 100 ends the series of fuel cut stop control. The processes in steps S23 and S24 are stop processes.

[0042] In addition, when a positive judgment is made in step S23, i.e., when the upper limit value TM is less than the required torque TR, the control device 100 controls the output torque of the internal combustion engine 10 to a torque equal to the upper limit value TM by the above-mentioned limiting process.

[0043] <Action of this embodiment> As shown in FIG. 4, it is assumed that the preconditions for executing the fuel cut process are not satisfied before time T1. It is assumed that the preconditions for executing the fuel cut process are satisfied at time T1. At this time, the control device 100 executes the fuel cut process. Then, the control device 100 turns on the fuel cut flag in association with the execution of the fuel cut process. Therefore, the upper limit value TM is calculated as a small value after time T1, compared to the case where the fuel cut flag is off, that is, the normal combustion process is executed. In addition, the control device 100 executes the torque compensation process in association with the execution of the fuel cut process. Therefore, the compensation torque TC increases and decreases periodically after time T1. In addition, the compensation torque TC changes according to the magnitude of the required torque TR.

[0044] Assume that an abnormality occurs in the vehicle 500 at time T2, which is later than time T1, and this abnormality is detected by the control device 100. At this time, the control device 100 changes the upper limit value TM of the torque to a value smaller than the value from time T1 to time T2.

[0045] Assume that the accelerator operation amount ACC starts to increase at time T3 after time T2. Accordingly, the required torque TR calculated by the control device 100 also increases. As the required torque TR increases, the compensation torque TC applied to the crankshaft 12 also increases. The required torque TR continues to increase after time T3, and the required torque TR coincides with the upper limit value TM of the torque at time T4. Accordingly, the control device 100 stops the fuel cut process. By stopping the fuel cut process, the control device 100 also stops the torque compensation process. That is, the control device 100 stops the application of the compensation torque TC to the crankshaft 12 by the first motor generator 71. Note that even at time T4, if the condition for executing the above-mentioned fuel cut process is satisfied, the fuel cut flag remains on. Since the fuel cut flag is on, the upper limit value TM of the torque is applied to the upper limit value TM at the time of execution of the fuel cut process. Therefore, after time T4, the control device 100 limits the torque output by the internal combustion engine 10 to a torque equal to the upper limit value TM when the fuel cut process is executed.

[0046] <Effects of this embodiment> (1) The compensation torque TC is calculated based on the required torque TR for the internal combustion engine 10. On the other hand, in a state where the torque of the internal combustion engine 10 is limited to be equal to or less than the upper limit value TM, the compensation torque TC may be calculated based on a value different from the torque actually output by the internal combustion engine 10. In the above embodiment, when the required torque TR becomes larger than the upper limit value TM, the fuel cut process is stopped. When the fuel cut process is stopped, the torque compensation process is also stopped accordingly. Therefore, no problem occurs due to the compensation torque TC deviating from the ideal value.

[0047] <Example of change> This embodiment can be modified as follows: This embodiment and the following modifications can be combined with each other to the extent that there is no technical contradiction.

[0048] In the above embodiment, the number of cylinders 11 is not limited to the example of the above embodiment. For example, the number of cylinders 11 may be three or less, or may be five or more. It is sufficient that the internal combustion engine 10 is provided with a plurality of cylinders 11.

[0049] In the fuel cut process of the above embodiment, the number of cylinders 11 in which combustion is stopped and the number of cylinders 11 in which combustion is performed may be changed as long as they are each one or more. For example, "M" and "N" are natural numbers. In this case, in the fuel cut process, a pattern in which fuel is burned in M ​​consecutive cylinders 11 and a pattern in which fuel combustion is stopped in N consecutive cylinders 11 may be repeated while the internal combustion engine 10 continues to operate.

[0050] In the above embodiment, the required torque TR may be calculated taking into consideration parameters other than the vehicle speed SP and the accelerator operation amount ACC shown in the above embodiment. For example, in the vehicle 500, there are cases where it is desired to charge the battery 75 using the torque of the crankshaft 12. Therefore, the required torque TR may be calculated to be a larger value as the required amount of charging the battery 75 increases.

[0051] In the above embodiment, the conditions for executing the fuel cut process may include conditions other than those in the above embodiment. Also, the conditions for executing the fuel cut process may be any of the conditions in the above embodiment, not all of the conditions in the above embodiment.

[0052] In step S23 of the above embodiment, instead of simply comparing the upper limit value TM with the required torque TR, a certain margin may be added to the upper limit value TM or the required torque TR. For example, the upper limit value TM plus a positive constant may be compared with the required torque TR. According to this modification, even if the required torque TR momentarily increases to or exceeds the upper limit value, the fuel cut process is not stopped unless the required torque TR exceeds the upper limit value TM plus a positive constant. This prevents a situation in which the fuel cut process cannot be continued due to a sudden increase in the required torque TR.

[0053] The fuel cut process may be stopped based on the upper limit value TM instead of based on a comparison between the upper limit value TM and the required torque TR as in steps S23 and S24 in the above embodiment.

[0054] For example, in the example shown in Fig. 5, the control device 100 starts the fuel cut stop control on the condition that the fuel cut flag is turned on. That is, the fuel cut stop control is executed in conjunction with the execution of the fuel cut process.

[0055] Then, when the control device 100 starts the fuel cut stop control, first, it executes the process of step S31. In step S31, as described above, the control device 100 calculates the upper limit value TM of the torque that can be output by the internal combustion engine 10. The upper limit value TM of the torque is calculated according to the state of the vehicle 500. After that, the process of the control device 100 proceeds to step S32.

[0056] In step S32, the control device 100 judges whether the torque upper limit value TM is equal to or less than a predetermined specified value. This specified value is set to a value smaller than the required torque TR that may occur under normal driving conditions, for example. In other words, the specified value is set as a value that can determine whether there is a possibility that the output torque of the internal combustion engine 10 will be limited to the upper limit value TM.

[0057] If the determination in step S32 is negative (S32: NO), the process of the control device 100 returns to step S31. That is, the fuel cut process being executed continues without being stopped. Then, the output torque of the internal combustion engine 10 is controlled to a required torque TR that is equal to or less than the upper limit value TM. On the other hand, if the determination in step S32 is positive (S32: YES), the process of the control device 100 proceeds to step S33.

[0058] In step S33, the control device 100 stops the execution of the fuel cut process. That is, the control device 100 starts combustion in all cylinders 11. In addition, the control device 100 stops the torque compensation process accordingly. The processes in steps S32 and S33 are stop processes. Thereafter, the control device 100 ends the fuel cut stop control.

[0059] According to this modification, when the upper limit value TM is smaller than a specified value, the fuel cut process is stopped. That is, in a situation where a difference occurs between the torque actually output by the internal combustion engine 10 and the required torque TR on which the compensation torque TC is calculated, the fuel cut process is stopped. When the fuel cut process is stopped, the torque compensation process is also stopped accordingly, so that a problem does not occur when the compensation torque TC deviates from an ideal value.

[0060] In the example shown in Fig. 5, when an abnormality is detected in the vehicle 500, the upper limit value TM may be considered to be equal to or less than a specified value. For example, when the difference between the pressure between the three-way catalyst 27 and the filter 28 in the exhaust passage 26 and the pressure downstream of the filter 28 in the exhaust passage 26 becomes equal to or greater than a predetermined value, the upper limit value TM may be considered to be equal to or less than a specified value. When an abnormality is detected in the vehicle 500, for example, the upper limit value TM is set to a small value that allows the vehicle 500 to travel slowly. In this way, when it is known that the upper limit value TM will be a small value without the need to compare it with the specified value, there is no need to compare the upper limit value TM with the specified value.

[0061] In addition to the above-mentioned examples, various other abnormalities of the vehicle 500 can be envisioned, such as when the temperature of the filter 28 is above a specified temperature, when abnormalities occur in various sensors, when a misfire occurs in the internal combustion engine 10, or when excessive knocking occurs in the internal combustion engine 10.

[0062] The technical ideas that can be derived from the above-described embodiments and modifications will be described below. a control device for a hybrid vehicle that is applied to an internal combustion engine having a plurality of cylinders and a motor generator connected to a crankshaft of the internal combustion engine, the control device being capable of executing a torque calculation process that calculates a required torque required of the internal combustion engine based on a vehicle speed and an accelerator operation amount of the vehicle; an upper limit calculation process that calculates an upper limit value of the torque that can be output by the internal combustion engine based on a state of the hybrid vehicle; a fuel cut process that repeats a pattern of burning fuel in the cylinders M consecutive times and a pattern of stopping fuel combustion in the cylinders N consecutive times, where M and N are natural numbers, while continuing operation of the internal combustion engine; a torque compensation process that calculates a compensation torque for compensating for at least a part of the torque fluctuation caused by stopping fuel combustion in the cylinders based on the required torque during the fuel cut process, and outputs the compensation torque from the motor generator to the crankshaft; and a stop process that stops the fuel cut process if the upper limit value becomes equal to or less than a predetermined specified value during the fuel cut process. [Explanation of symbols]

[0063] TC: Compensation torque TM: Upper limit TR: Required torque 10. Internal combustion engine 11…Cylinder 12…Crankshaft 21…Intake passage 22...Throttle valve 23...Fuel injection valve 24...Ignition device 26…Exhaust passage 27...Three-way catalyst 28…Filter 71…First motor generator 72…Second motor generator 100...Control device 500…Vehicle

Claims

[Claim 1] An internal combustion engine having a plurality of cylinders; a motor generator connected to a crankshaft of the internal combustion engine; A control device applied to a hybrid vehicle comprising: The control device includes: a torque calculation process for calculating a required torque required for the internal combustion engine based on a vehicle speed and an accelerator operation amount of the hybrid vehicle; an upper limit calculation process for calculating an upper limit value of the torque that can be output by the internal combustion engine based on a state of the hybrid vehicle; a fuel cut process in which, while continuing the operation of the internal combustion engine, a pattern of burning fuel in the cylinder M times in succession and a pattern of stopping fuel combustion in the cylinder N times in succession, where M and N are natural numbers, are repeated; a torque compensation process for calculating a compensation torque for compensating for at least a part of a torque fluctuation caused by stopping the combustion of fuel in the cylinder during the fuel cut process based on the required torque, and outputting the compensation torque from the motor generator to the crankshaft; a stop process for stopping the fuel cut process when the required torque exceeds the upper limit value during the fuel cut process; is feasible A control device for a hybrid vehicle.

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