Control device for internal combustion engine

Abstract

To suppress a fuel injection from being not started when restarting an internal combustion engine.SOLUTION: A control apparatus executes first processing for acquiring a BTDC indicating a position of a piston in a specific cylinder that is a cylinder meeting with a compression stroke. The control apparatus executes second processing for turning on a postponing flag when the BTDC is equal to or less than a first threshold ZA. The control apparatus executes third processing for turning off the postponing flag when the BTDC is equal to or less than a second threshold ZB. The control apparatus executes fourth processing for determining the fuel injection in the specific cylinder when the postponing flag is turned off, and postponing the fuel injection in the specific cylinder when the postponing flag is turned on. The control apparatus repetitively executes the first to fourth processing at a certain control cycle from when the restart of an internal combustion engine is requested to when the fuel is combusted first in the cylinder. In the third processing, the postponing flag is turned off even when a compression stroke of a cylinder meeting with the compression stroke before one control cycle is ended.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a control device for an internal combustion engine. [Background technology]

[0002] The internal combustion engine of Patent Document 1 includes a cylinder, an intake passage, an exhaust passage, a piston, a crankshaft, and a fuel injection valve. The cylinder is a space for burning fuel. The intake passage introduces intake air into the cylinder. The exhaust passage discharges exhaust gas from the cylinder. The piston reciprocates within the cylinder. The reciprocating motion of the piston rotates the crankshaft. The fuel injection valve supplies fuel into the cylinder.

[0003] The control device of the internal combustion engine in Patent Document 1 obtains the position of the piston in the cylinder undergoing the compression stroke when restarting the internal combustion engine after the combustion of fuel in the cylinder has been stopped.The control device then injects the amount of fuel based on the position of the piston from the fuel injection valve.As a result, the amount of fuel corresponding to the amount of intake air present in the cylinder undergoing the compression stroke is supplied to the cylinder. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2013-252725 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the control device of the internal combustion engine as in Patent Document 1, when the internal combustion engine is restarted, fuel may be injected from the cylinder that will be in the compression stroke next, rather than from the cylinder that is in the compression stroke. The following process is known as a process for determining the cylinder to be injected first when the internal combustion engine is restarted. First, the cylinder that is in the compression stroke at the time when the restart of the internal combustion engine is requested is identified. Also, the position of the piston in the specific cylinder is acquired. Then, if the position of the piston is more advanced than the compression top dead center by a certain amount, fuel injection is started from the specific cylinder. On the other hand, if the position of the piston is close to the compression top dead center, fuel injection in the specific cylinder is postponed. If fuel injection in the specific cylinder is postponed, the postponement of fuel injection is canceled when the piston position reaches a position between the position of the piston where fuel injection is performed and the compression top dead center. By canceling the postponement of fuel injection in this way, fuel injection is started from the cylinder that will be in the compression stroke next to the specific cylinder.

[0006] However, the above series of controls are premised on the assumption that the rotation speed of the crankshaft is low when the internal combustion engine is restarted. If the rotation speed of the crankshaft is high when the internal combustion engine is restarted, the crankshaft rotates significantly even during one control cycle by the control device, and as a result, the position of the piston also changes significantly. Therefore, for example, after fuel injection in a specific cylinder is postponed in a certain control cycle, the position of the piston may have already passed the compression top dead center when the next control cycle begins. In this case, the condition for canceling the postponement of fuel injection, that is, "the position of the piston is between the position of the piston where fuel injection is performed and the compression top dead center," is not satisfied. Therefore, the postponement of fuel injection may remain effective, and fuel injection may not be started thereafter. [Means for solving the problem]

[0007] A control device for an internal combustion engine for solving the above problems is applied to an internal combustion engine including a cylinder for burning fuel, an intake passage for introducing intake air into the cylinder, an exhaust passage for discharging exhaust gas from the cylinder, a piston that reciprocates within the cylinder, a crankshaft that rotates due to the reciprocating motion of the piston, and a fuel injection valve that supplies fuel into the cylinder, When the rotation speed of the crankshaft is higher than a predetermined specified rotation speed, A control device for controlling a restart of the internal combustion engine, comprising: a first process for acquiring a position of the piston in the specific cylinder when the cylinder undergoing a compression stroke is designated as a specific cylinder; a second process for turning on the skip flag when the position of the piston acquired in the first process is within a skip range defined as a range from a position on the advanced side of the position of the piston when fuel is injected in the specific cylinder to a compression top dead center when the cylinder undergoes a compression stroke and a skip flag when the skip flag is ON; It is possible to execute a third process of turning off the postpone flag when the amount of fuel injected into the specific cylinder is within a cancellation range defined as the range from the initial point to the point at which the fuel injection is to be stopped, and a fourth process of deciding to inject fuel into the specific cylinder when the postpone flag is OFF after the second process or the third process, and postponing fuel injection into the specific cylinder when the postpone flag is ON. The first process to the fourth process are repeatedly executed at a constant control period from when a request to restart the internal combustion engine is made until fuel is first combusted in the cylinder, and in the third process, the postpone flag is turned OFF even if the compression stroke of the cylinder that was in the compression stroke one control period before the third process has ended.

[0008] According to the above configuration, the postpone flag is turned OFF even when the compression stroke of the cylinder that was in the compression stroke one control cycle before in the third process has ended. In other words, the postpone flag is turned OFF even when the condition that the position of the piston is within the cancellation range is not satisfied. This makes it possible to prevent fuel injection from not being started due to the rotation speed of the crankshaft being high when a request to restart the internal combustion engine is made. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic configuration diagram of a vehicle. [Diagram 2] 1 is a schematic diagram of an internal combustion engine. [Diagram 3] 13 is a flowchart showing switching control of a pass-off flag. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] <Vehicle mechanical configuration> An embodiment of the present invention will now be described with reference to Figures 1 to 3. First, the mechanical configuration of a vehicle 100 will be described.

[0011] As shown in Fig. 1, a vehicle 100 includes an internal combustion engine 10. As shown in Fig. 2, the internal combustion engine 10 includes a plurality of cylinders 11, an intake passage 12, an exhaust passage 13, a plurality of pistons 16, a plurality of connecting rods 17, and a crankshaft 18.

[0012] As shown in FIG. 2, the cylinder 11 is a space for burning a mixture of fuel and intake air. In this embodiment, the internal combustion engine 10 includes six cylinders 11. The internal combustion engine 10 is a so-called in-line six-cylinder engine in which the six cylinders 11 are arranged in a row. In the following, when the six cylinders 11 are collectively described, they are simply referred to as cylinders 11. When the six cylinders 11 are individually described, they are referred to as the first cylinder 11A, the second cylinder 11B, the third cylinder 11C, the fourth cylinder 11D, the fifth cylinder 11E, and the sixth cylinder 11F from the end in the order in which the six cylinders 11 are arranged. In FIG. 2, only one cylinder 11 is shown as a representative.

[0013] The piston 16 is located inside the cylinder 11. The piston 16 is connected to a crankshaft 18 via a connecting rod 17. The piston 16 reciprocates inside the cylinder 11 as a mixture of fuel and intake air is burned in the cylinder 11. The reciprocating motion of the piston 16 causes the crankshaft 18 to rotate.

[0014] The intake passage 12 is connected to the cylinders 11. The intake passage 12 introduces intake air from outside the internal combustion engine 10 to each cylinder 11. The exhaust passage 13 is connected to the cylinders 11. The exhaust passage 13 discharges exhaust gas from each cylinder 11 to outside the internal combustion engine 10.

[0015] The internal combustion engine 10 includes a throttle valve 21 , a plurality of port injection valves 22 , a plurality of in-cylinder injection valves 23 , a plurality of ignition devices 24 , a plurality of intake valves 26 , and a plurality of exhaust valves 27 .

[0016] The throttle valve 21 is located in the intake passage 12. The throttle valve 21 adjusts the amount of intake air flowing through the intake passage 12. The port injection valve 22 is located in the intake passage 12 near the cylinder 11. The port injection valve 22 injects fuel into the intake passage 12 to supply fuel into the cylinder 11 via the intake passage 12. The internal combustion engine 10 includes six port injection valves 22 corresponding to the six cylinders 11. A portion including a tip of the in-cylinder injection valve 23 is located inside the cylinder 11. The in-cylinder injection valve 23 injects fuel into the cylinder 11 to supply fuel into the cylinder 11. The internal combustion engine 10 includes six in-cylinder injection valves 23 corresponding to the six cylinders 11. In this embodiment, the port injection valve 22 and the in-cylinder injection valve 23 are fuel injection valves that supply fuel into the cylinder 11.

[0017] A part of the ignition device 24 including a tip is located inside the cylinder 11. The ignition device 24 ignites a mixture of fuel and intake air by spark discharge. The internal combustion engine 10 has six ignition devices 24 corresponding to the six cylinders 11. The six ignition devices 24 ignite the first cylinder 11A, the fifth cylinder 11E, the third cylinder 11C, the sixth cylinder 11F, the second cylinder 11B, and the fourth cylinder 11D in this order. In other words, the internal combustion engine 10 goes through a combustion stroke in the order of the first cylinder 11A, the fifth cylinder 11E, the third cylinder 11C, the sixth cylinder 11F, the second cylinder 11B, and the fourth cylinder 11D. Each cylinder 11 repeats an intake stroke, a compression stroke, a combustion stroke, and an exhaust stroke every time the crankshaft 18 rotates twice. Therefore, in the internal combustion engine 10, one of the six cylinders 11 undergoes a new combustion stroke every time the crankshaft 18 rotates through 120 degrees.

[0018] The intake valve 26 is located at the downstream end of the intake passage 12. The intake valve 26 opens and closes the downstream end of the intake passage 12 by a driving force from a valve mechanism (not shown). The internal combustion engine 10 is provided with six intake valves 26 corresponding to the six cylinders 11. The exhaust valve 27 is located at the upstream end of the exhaust passage 13. The exhaust valve 27 opens and closes the upstream end of the exhaust passage 13 by a driving force from a valve mechanism (not shown). The internal combustion engine 10 is provided with six exhaust valves 27 corresponding to the six cylinders 11.

[0019] As shown in FIG. 1, the vehicle 100 includes a clutch 31, a motor generator 40, an automatic transmission 61, a differential mechanism 62, and a plurality of drive wheels 63. The motor generator 40 includes a rotating shaft 41, a rotor 42, and a stator 43. The rotating shaft 41 is connected to the rotor 42. Therefore, the rotating shaft 41 is rotatable relative to the stator 43. The rotating shaft 41 of the motor generator 40 is connected to the crankshaft 18 of the internal combustion engine 10 via a clutch 31. The connection state of the clutch 31 is switched between an engaged state and a released state depending on the pressure of oil supplied to the inside of the clutch 31.

[0020] Furthermore, the rotating shaft 41 of the motor generator 40 is connected to drive wheels 63 via an automatic transmission 61 and a differential mechanism 62. An example of the automatic transmission 61 is a stepped automatic transmission. The automatic transmission 61 can change the gear ratio in stages. The differential mechanism 62 allows a difference in rotation speed to occur between the left and right drive wheels 63.

[0021] <Vehicle Electrical Configuration> 1, the vehicle 100 includes a battery 71 and an inverter 72. When the motor generator 40 functions as a power generator, the battery 71 stores the electric power generated by the motor generator 40. When the motor generator 40 functions as an electric motor, the battery 71 supplies electric power to the motor generator 40. The inverter 72 adjusts the amount of electric power exchanged between the motor generator 40 and the battery 71.

[0022] 1, vehicle 100 is equipped with an accelerator operation amount sensor 81, a vehicle speed sensor 82, and a crank angle sensor 83. The accelerator operation amount sensor 81 detects an accelerator operation amount ACC, which is the amount of operation of an accelerator pedal (not shown) operated by a driver. The vehicle speed sensor 82 detects a vehicle speed SP, which is the speed of vehicle 100. The crank angle sensor 83 detects a crank angle SC, which is the angular position of crankshaft 18.

[0023] As shown in Fig. 1, the vehicle 100 is equipped with a control device 90. The control device 90 obtains a signal indicating an accelerator operation amount ACC from an accelerator operation amount sensor 81. The control device 90 obtains a signal indicating a vehicle speed SP from a vehicle speed sensor 82. The control device 90 obtains a signal indicating a crank angle SC from a crank angle sensor 83. The control device 90 calculates an engine rotation speed NE, which is the rotation speed of the crankshaft 18, based on the crank angle SC.

[0024] The control device 90 calculates the vehicle required driving force, which is a required value of driving force necessary for the vehicle 100 to travel, based on the accelerator operation amount ACC and the vehicle speed SP. The control device 90 determines the torque distribution between the internal combustion engine 10 and the motor generator 40 based on the vehicle required driving force. The control device 90 controls the output of the internal combustion engine 10 and the power running and regeneration of the motor generator 40 based on the torque distribution between the internal combustion engine 10 and the motor generator 40.

[0025] The control device 90 performs various types of control such as adjusting the opening of the throttle valve 21, adjusting the amount of fuel injected from the port injection valve 22, adjusting the amount of fuel injected from the in-cylinder injection valve 23, and adjusting the ignition timing of the ignition device 24 by outputting control signals to the internal combustion engine 10. The control device 90 also outputs a control signal to the inverter 72 in order to control the motor generator 40. The control device 90 then controls the motor generator 40 by adjusting the amount of power exchanged between the motor generator 40 and the battery 71 via the inverter 72.

[0026] The control device 90 outputs a control signal to the clutch 31 to control the connection state of the clutch 31. The control device 90 outputs a control signal to the automatic transmission 61 to control the gear ratio of the automatic transmission 61.

[0027] When a stop condition, which is a predetermined condition, is satisfied, the control device 90 executes an automatic stop process that stops the combustion of fuel in the cylinder 11 and controls the throttle valve 21 to a closed state. Here, one example of the stop condition is that the accelerator operation amount ACC becomes zero, thereby reducing the vehicle required driving force.

[0028] When a request to restart the internal combustion engine 10 is made while the internal combustion engine 10 is stopped by the automatic stop process, the control device 90 executes one of the low speed restart process and the high speed restart process to restart the internal combustion engine 10. Note that an example of a request to restart the internal combustion engine 10 is when the accelerator operation amount ACC becomes greater than zero, causing the vehicle required driving force to increase.

[0029] When the rotation speed is equal to or lower than a predetermined specified rotation speed A, the control device 90 executes a low speed restart process to restart the internal combustion engine 10. Here, an example of the specified rotation speed A is several hundred rpm. In the low speed restart process, the control device 90 first controls the connection state of the clutch 31 to an engaged state by outputting a control signal to the clutch 31. Then, the control device 90 applies torque from the rotating shaft 41 of the motor generator 40 to the crankshaft 18 of the internal combustion engine 10 via the clutch 31 by outputting a control signal to the inverter 72. As a result, the engine rotation speed NE increases. Furthermore, the control device 90 controls the port injection valve 22 and the in-cylinder injection valve 23 to supply fuel into the cylinder 11. Moreover, the control device 90 controls the ignition device 24 to ignite the mixture of fuel and intake air in the cylinder 11 by spark discharge. As a result, the internal combustion engine 10 restarts.

[0030] Furthermore, when the engine speed NE is higher than the specified speed A, the control device 90 executes a high-speed restart process to restart the internal combustion engine 10. In the high-speed restart process, the control device 90 first outputs a control signal to the clutch 31 to control the connection state of the clutch 31 to a released state. Then, the control device 90 controls the port injection valve 22 and the in-cylinder injection valve 23 to supply fuel to the cylinder 11. Furthermore, the control device 90 controls the ignition device 24 to ignite the mixture of fuel and intake air in the cylinder 11 by spark discharge. As a result, the internal combustion engine 10 restarts. After that, the control device 90 outputs a control signal to the clutch 31 to control the connection state of the clutch 31 to an engaged state.

[0031] When restarting the internal combustion engine 10, the control device 90 executes a skip process for skipping fuel injection in a specific cylinder according to a skip flag. Here, the specific cylinder is the cylinder 11 that is undergoing a compression stroke at the time of executing the skip process. When the skip flag is OFF in the skip process, the control device 90 decides to execute fuel injection in the specific injection. On the other hand, when the skip flag is ON in the skip process, the control device 90 postpones execution of fuel injection in the specific injection. In this embodiment, when the control device 90 executes switching control of the skip flag described later, it executes the skip process thereafter. That is, the control device 90 executes the skip process based on the skip flag after the switching control. Note that the switching control is a control for switching the skip flag from one of ON and OFF to the other. In this embodiment, the skip process is a fourth process.

[0032] In this embodiment, the control device 90 repeatedly executes various processes at a constant control period. That is, the control device 90 also repeatedly executes the above-mentioned sending off process at a constant control period. An example of one control period is several msec to several tens of msec.

[0033] The control device 90 may be configured as a circuit including one or more processors that execute various processes according to a computer program (software). The control device 90 may also 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 memories such as RAM and ROM. The memory stores program codes or instructions that are configured to cause the CPU to execute processes. The memory, i.e., computer-readable medium, includes any medium that can be accessed by a general-purpose or dedicated computer.

[0034] <Switching control of the send-off flag> Next, the switching control executed by the control device 90 will be described. The control device 90 repeatedly executes the switching control of the postponement flag at a fixed control period from when a request to restart the internal combustion engine 10 is made to the time when fuel is burned in the cylinder 11 for the first time. Here, the control period of the switching control is the same as the control period of the postponement processing described above. The time when fuel is burned in the cylinder 11 for the first time is, for example, when the control device 90 controls the ignition device 24 to spark discharge the mixture in the cylinder 11 to which fuel is first supplied. Note that, at the time when a request to restart the internal combustion engine 10 is made, the postponement flag is OFF.

[0035] As shown in FIG. 3, when the control device 90 starts switching control of the skip flag, it proceeds to the process of step S11. In step S11, the control device 90 identifies a specific cylinder at the time of processing step S11 based on the crank angle SC. That is, the control device 90 identifies the cylinder 11 that is in the compression stroke at the time of processing step S11. Then, the control device 90 identifies the position of the piston 16 in the specific cylinder. Specifically, the control device 90 calculates the change amount of the crank angle SC required for the piston 16 at the time of processing step S11 to move to the top dead center of the compression stroke, that is, the so-called BTDC, as the position of the piston 16. Therefore, the closer the piston 16 in the specific cylinder is to the top dead center, the smaller the value calculated as the BTDC. As a specific example, it is assumed that the crank angle SC from the reference angle is 90 degrees at the time of processing step S11. It is also assumed that the first cylinder 11A reaches the top dead center of the compression stroke when the crank angle SC from the reference angle is 120 degrees. In this case, the control device 90 first identifies the first cylinder 11A as the specific cylinder. Then, the control device 90 calculates 30 degrees as BTDC, which is obtained by subtracting 90 degrees, which is the crank angle SC at the time of processing in step S11, from 120 degrees, which is the crank angle SC at which the first cylinder 11A reaches the top dead center of the compression stroke. The control device 90 also stores the calculated BTDC. In this embodiment, since the internal combustion engine 10 has six cylinders 11, one cylinder 11 or two cylinders 11 may reach the compression stroke at the same time. When two cylinders 11 are in the compression stroke, the control device 90 identifies the cylinder 11 whose piston 16 is located closest to the top dead center of the compression stroke as the specific cylinder. The processing in step S11 is an example of a first processing for acquiring the position of the piston 16 in the specific cylinder when the internal combustion engine 10 is restarted. After that, the control device 90 advances the processing to step S12.

[0036] In step S12, the control device 90 determines whether or not the pass-by flag is OFF. If the control device 90 determines in step S12 that the pass-by flag is OFF (S12: YES), the control device 90 advances the process to step S21.

[0037] In step S21, the control device 90 judges whether or not the BTDC is equal to or less than a first threshold value ZA that is determined in advance. Here, the first threshold value ZA is determined as a crank angle SC that is advanced by a predetermined angle from the crank angle SC at the time when the direct injection valve 23 starts injecting fuel into a specific cylinder. In this embodiment, an example of the first threshold value ZA is several tens of degrees. Note that the range of the crank angle SC from the first threshold value ZA to the compression top dead center corresponds to a "postponement range" that is determined as a range for judging whether or not to postponing fuel injection into a specific cylinder. In step S21, when the control device 90 judges that the BTDC is greater than the first threshold value ZA (S21: NO), the control device 90 ends the current switching control. In this case, the postponing flag remains OFF.

[0038] On the other hand, in step S21, when the control device 90 determines that the BTDC is equal to or less than the first threshold value ZA (S21: YES), the control device 90 advances the process to step S26. In other words, when the position of the piston 16 in the specific cylinder acquired in the first process is within the look-forward range, the control device 90 advances the process to step S26.

[0039] In step S26, the control device 90 turns on the pass-by flag. In this embodiment, the processes in steps S21 and S26 are the second process. Thereafter, the control device 90 ends the current switching control.

[0040] Furthermore, in the above-mentioned step S12, when the control device 90 determines that the pass-by flag is ON (S12: NO), the control device 90 advances the process to step S31. In step S31, the control device 90 judges whether or not the BTDC is equal to or less than a second threshold value ZB that is determined in advance. Here, the second threshold value ZB is determined as the crank angle SC at the time when the direct injection valve 23 starts injecting fuel into the specific cylinder. Therefore, the second threshold value ZB is a value smaller than the first threshold value ZA. In this embodiment, an example of the second threshold value ZB is about ten degrees to several tens of degrees. Note that the range of the crank angle SC from the second threshold value ZB to the compression top dead center corresponds to a "cancellation range" that is determined as a range for judging whether or not to turn off the postponement flag that is in the ON state. In step S31, when the control device 90 judges that the BTDC is equal to or less than the second threshold value ZB (S31: YES), the control device 90 advances the process to step S36. In other words, when the position of the piston 16 in the specific cylinder acquired in the first process is within the cancellation range, the control device 90 advances the process to step S36. On the other hand, in step S31, when the control device 90 determines that the BTDC is greater than the second threshold value ZB (S31: NO), the control device 90 advances the process to step S32.

[0041] In step S32, the control device 90 judges whether or not the cylinder 11 that was in the compression stroke one control cycle ago has finished the compression stroke. Specifically, when the BTDC in the current control cycle is greater than the BTDC in the previous control cycle, the control device 90 judges that the cylinder 11 that was in the compression stroke one control cycle ago has finished the compression stroke. On the other hand, when the BTDC in the current control cycle is equal to or less than the BTDC in the previous control cycle, the control device 90 judges that the cylinder 11 that was in the compression stroke one control cycle ago has not finished the compression stroke. In step S32, when the control device 90 judges that the cylinder 11 that was in the compression stroke one control cycle ago has not finished the compression stroke (S32: NO), the control device 90 ends the current switching control. In this case, the postpone flag remains ON.

[0042] On the other hand, in step S32, if the control device 90 determines that the cylinder 11 that was in the compression stroke one control cycle ago has completed the compression stroke (S32: YES), the control device 90 proceeds to step S36.

[0043] In step S36, the control device 90 turns off the pass-through flag. In this embodiment, the processes in steps S31, S32, and S36 are a third process. Thereafter, the control device 90 ends the current switching control.

[0044] <Action of this embodiment> For example, in the vehicle 100, it is assumed that the engine speed NE is relatively low when a request to restart the internal combustion engine 10 is made. It is also assumed that the first cylinder 11A is in the compression stroke when a request to restart the internal combustion engine 10 is made. It is also assumed that the BTDC when a request to restart the internal combustion engine 10 is made is equal to or lower than the first threshold value ZA and is greater than the second threshold value ZB. In this case, since the BTDC is equal to or lower than the first threshold value ZA at the time of execution of the first switching control, a positive determination is made in step S21. Then, in step S26, the postponement flag is turned ON. As a result, the fuel injection in the first cylinder 11A is postponed. Also, since the crankshaft 18 is rotating, the BTDC gradually becomes smaller as time passes. Then, for example, it is assumed that the second switching control is executed in a situation in which the BTDC becomes equal to or lower than the second threshold value ZB. In this case, a positive determination is made in step S31. Then, in step S36, the postponement flag is turned OFF. As a result, fuel injection is enabled in the fifth cylinder 11E, which is in the compression stroke next to the first cylinder 11A.

[0045] On the other hand, it is assumed that the engine speed NE is relatively high when a request to restart the internal combustion engine 10 is made. In this case, the amount of change in the crank angle SC is large during one control cycle of the control device 90. Therefore, even if a situation occurs in which the BTDC actually becomes equal to or smaller than the second threshold ZB, the second switching control may not be executed at that timing. In this case, the second switching control is executed after the compression stroke of the first cylinder 11A ends. At this time, the specific cylinder is the fifth cylinder 11E, which enters the compression stroke next to the first cylinder 11A. Therefore, the BTDC is calculated for the fifth cylinder 11E, which is now the new specific cylinder. As a result, the BTDC becomes larger than the second threshold ZB, and the affirmative determination is not made in step S31.

[0046] <Effects of this embodiment> (1) In this embodiment, when the control device 90 makes a negative determination in step S31, it further performs the process of step S32. Then, when the control device 90 makes a positive determination in step S32, that is, when it determines that the cylinder 11 that was in the compression stroke one control cycle ago has finished the compression stroke, it turns off the postponement flag. As a result, even if the determination in step S31 is not positive in the second switching control, for example, the postponement flag is turned off by the determination in step S32 being positive. In other words, even if the engine speed NE when the internal combustion engine 10 is requested to be restarted is relatively high, the postponement flag is turned off. As a result, it is possible to suppress a situation in which fuel injection is not started due to the engine speed NE being high when the internal combustion engine 10 is requested to be restarted.

[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 process of step S32 may be changed. Specifically, in step S32, the process of determining whether or not the cylinder 11 that was in the compression stroke one control cycle ago has completed the compression stroke may be changed. For example, in the internal combustion engine 10, one of the six cylinders 11 newly undergoes a combustion stroke every time the crankshaft 18 rotates by 120 degrees. Therefore, in the internal combustion engine 10, it is possible to determine whether or not, for example, the first cylinder 11A has completed the compression stroke based on the crank angle SC from the reference angle. Therefore, the control device 90 may determine whether or not the target cylinder 11 has completed the compression stroke based on the crank angle SC from the reference angle.

[0049] In the above embodiment, the configuration of the vehicle 100 may be changed. For example, the vehicle 100 does not need to include the motor generator 40. Even in this configuration, if the engine speed NE is relatively high when a request to restart the internal combustion engine 10 is made, it is possible to restart the internal combustion engine 10 without applying torque from the motor generator 40. Also, if the engine speed NE is zero when a request to restart the internal combustion engine 10 is made, it is possible to restart the internal combustion engine 10 by cranking using a starter motor, for example.

[0050] For example, the internal combustion engine 10 may have five or fewer cylinders 11, or may have seven or more cylinders 11. In addition, for example, the internal combustion engine 10 does not have to be equipped with a port injection valve 22. [Explanation of symbols]

[0051] 10. Internal combustion engine 11…Cylinder 12…Intake passage 13...Exhaust passage 16…Piston 17…Connecting rod 18…Crankshaft 21...Throttle valve 22...Port injection valve 23...In-cylinder injection valve 24…Ignition device 26…Intake valve 27…Exhaust valve 31…Clutch 40...Motor generator 41...Rotation axis 61…Automatic transmission 62…Differential mechanism 63...Drive wheel 71…Battery 72…Inverter 81...Accelerator operation amount sensor 82...Vehicle speed sensor 83...Crank angle sensor 90...Control device 100…Vehicle

Claims

[Claim 1] A control device is applied to an internal combustion engine including a cylinder for burning fuel, an intake passage for introducing intake air into the cylinder, an exhaust passage for discharging exhaust gas from the cylinder, a piston for reciprocating within the cylinder, a crankshaft that rotates by the reciprocating motion of the piston, and a fuel injection valve for supplying fuel into the cylinder, and controls a restart of the internal combustion engine when a rotation speed of the crankshaft is higher than a predetermined specified rotation speed, a first process of acquiring a position of the piston in the specific cylinder when the cylinder undergoing a compression stroke is designated as a specific cylinder and the internal combustion engine is restarted; a second process for turning on the skip flag when the piston position acquired in the first process is within a skip range defined as a range from a position on the advanced side of the piston position when fuel is injected in the specific cylinder to a compression top dead center, when the skip flag is OFF; a third process for turning off the postponement flag when the position of the piston acquired in the first process is within a cancellation range defined as a range from the position of the piston when fuel is injected in the specific cylinder to the compression top dead center, when the postponement flag is ON; a fourth process for determining fuel injection into the specific cylinder when the postponement flag is OFF after the second process or the third process, and postponing fuel injection into the specific cylinder when the postponement flag is ON; It is possible to execute The first process to the fourth process are repeatedly executed at a constant control period from when a request to restart the internal combustion engine is made until fuel is first combusted in the cylinder; In the third process, even if the compression stroke of the cylinder that was in the compression stroke one control cycle before the third process has ended, the postponement flag is turned OFF. A control device for an internal combustion engine.

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