Control device for internal combustion engine and control method for internal combustion engine

Abstract

To suppress stall of an internal combustion engine due to rapid decline of speed of the internal combustion engine.SOLUTION: A control device for an internal combustion engine sets a target intake air amount and target ignition timing on the basis of target torque corresponding to request acceleration of a vehicle, predicts an increase of a load of power generation by a power generator coupled to a power transmission system for transmitting power from the internal combustion engine to a driving wheel and driven by output torque output from the internal combustion engine to generate electric power, sets an increase correction amount of an intake air amount on the basis of power generation torque used for driving the power generator when the increase of the load of the power generation by the power generator is predicted, sets a timing delay amount of the target ignition timing on the basis of a difference between the output torque of the internal combustion engine attained by the intake air amount after the increase amount correction and the target torque, and returns the target ignition timing to the timing advance side when rapid decline of the speed of the internal combustion engine occurs.SELECTED DRAWING: Figure 7

Description

[Technical field]

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

[0002] When a vehicle is running using the power output from an internal combustion engine, if the engine speed drops suddenly, the engine may stop (stall). In response to this, a technique is known that increases the intake air amount when the engine speed falls below a target engine speed to avoid the engine stalling.

[0003] For example, Patent Document 1 discloses a control device for an internal combustion engine whose operation is controlled by the opening degree of an intake air control valve and the ignition timing, which calculates a target valve opening degree for the internal combustion engine to realize a torque obtained as an engine request plus a reserve torque (excess torque), and a target ignition timing for realizing the required torque by the target valve opening degree, obtains the amount of change in the required torque, corrects the reserve torque to a larger value as the amount of change in the required torque increases, and restricts the execution of the correction means when the amount of change in the required torque reaches a predetermined large amount. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2010-216419 A Summary of the Invention [Problem to be solved by the invention]

[0005] The control device described in Patent Document 1 avoids the inability to realize the required torque when the ignition timing is advanced by adding a margin torque whose value increases according to the amount of change in the required torque. However, the control device described in Patent Document 1 may add an excessive margin torque that exceeds the increase in the required torque, which may reduce the combustion efficiency. In addition, if the margin torque is increased, the amount of retardation of the ignition timing must also be increased until the required torque increases, and if there is a limit to the amount of retardation of the ignition timing, such as during lean burn control, the required torque of the internal combustion engine may not be realized.

[0006] The present disclosure has been made in consideration of the above problems, and an object of the present disclosure is to provide an internal combustion engine control device and an internal combustion engine control method that are capable of appropriately setting the intake air volume to be increased and corrected in order to suppress stall of the internal combustion engine. [Means for solving the problem]

[0007] In order to solve the above problem, according to one aspect of the present disclosure, there is provided a control device for an internal combustion engine having a throttle valve that adjusts an intake air amount and an ignition plug that ignites an air-fuel mixture in a cylinder, the control device including: an operation target setting unit that sets a target intake air amount and a target ignition timing based on a target torque corresponding to a required acceleration of a vehicle equipped with the internal combustion engine; a power generation load prediction unit that predicts an increase in the load of power generation by a generator that is connected to a power transmission system that transmits power from the internal combustion engine to drive wheels and is driven by an output torque output from the internal combustion engine to generate power; and a correction unit that, when an increase in the load of power generation by the generator is predicted, sets an increase correction amount of the target intake air amount based on the power generation torque used to drive the generator, and sets a retard amount of the target ignition timing based on the difference between the output torque of the internal combustion engine realized by the intake air amount after the increase correction and the target torque, and returns the target ignition timing to the advance side when a sudden drop in the rotation speed of the internal combustion engine occurs.

[0008] In addition, in order to solve the above-mentioned problems, according to another aspect of the present disclosure, there is provided a control method for an internal combustion engine having a throttle valve that adjusts an intake air amount and an ignition plug that ignites an air-fuel mixture in a cylinder, the control method executing the following steps: setting a target intake air amount and a target ignition timing based on a target torque corresponding to a required acceleration of a vehicle equipped with the internal combustion engine; predicting an increase in the load of power generation by a generator that is connected to a power transmission system that transmits power from the internal combustion engine to drive wheels and is driven by an output torque output from the internal combustion engine to generate power; when an increase in the load of power generation by the generator is predicted, setting an increase correction amount of the intake air amount based on the power generation torque used to drive the generator, and setting an amount of retardation of the target ignition timing based on the difference between the output torque of the internal combustion engine realized by the intake air amount after the increase correction and the target torque; and returning the target ignition timing to the advance side when a sudden drop in the rotation speed of the internal combustion engine occurs. Effect of the Invention

[0009] As described above, according to the present disclosure, it is possible to appropriately set the intake air amount to be increased and corrected in order to suppress stalling of the internal combustion engine. [Brief description of the drawings]

[0010] [Figure 1] 1 is a schematic diagram illustrating an example configuration of a drive system of a vehicle to which an internal combustion engine control device according to an embodiment of the present disclosure can be applied. [Diagram 2] 2 is a block diagram showing an example of the configuration of a control device for an internal combustion engine according to the embodiment; FIG. [Diagram 3] 4 is a flowchart showing an example of a control method for the internal combustion engine according to the embodiment. [Figure 4] 4 is a flowchart showing an example of a control method for the internal combustion engine according to the embodiment. [Diagram 5] 4 is a flowchart showing an example of a control method for the internal combustion engine according to the embodiment. [Figure 6]5 is a flowchart showing a process for determining whether a correction execution condition is satisfied, which is performed by the control device for the internal combustion engine according to the embodiment; [Figure 7] FIG. 13 is an explanatory diagram showing the operation of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In this specification and the drawings, components having substantially the same functional configurations are denoted by the same reference numerals, and redundant description will be omitted.

[0012] <1. Overall configuration of vehicle drive system> First, a configuration example of a drive system of a vehicle to which an internal combustion engine control device according to an embodiment of the present disclosure can be applied will be described. The following description will be given taking as an example a vehicle equipped with an internal combustion engine as a drive power source. However, the vehicle may be a hybrid vehicle equipped with an internal combustion engine and a drive motor as drive power sources.

[0013] Fig. 1 is a schematic diagram showing an example of the overall configuration of a drive system 1. The drive system 1 shown in Fig. 1 includes an internal combustion engine 11 and a transmission 20. Output torque generated by the internal combustion engine 11 is transmitted to drive wheels 25 via a crankshaft 11a and the transmission 20. The transmission 20 may be a continuously variable transmission (CVT) or a stepped transmission. In addition, the drive system 1 includes a clutch (not shown).

[0014] The internal combustion engine 11 includes a throttle valve 13, a fuel injector 15, and a spark plug 17. The throttle valve 13 is provided in an intake passage, and adjusts the amount of intake air introduced into a cylinder by changing the opening degree. The fuel injector 15 injects fuel into the cylinder. The spark plug 17 ignites the mixture formed by mixing the intake air and fuel in the cylinder. The operation of the throttle valve 13, the fuel injector 15, and the spark plug 17 are each controlled by a control device 50. In addition, the internal combustion engine 11 includes known components of a gasoline engine, such as an intake valve, an exhaust valve, a piston, and a connecting rod.

[0015] An alternator 31, which is a component of the power supply unit 2, is connected to the crankshaft 11a of the internal combustion engine 11 directly or via a pulley mechanism and a power transmission belt. The alternator 31 is a generator that is connected to a power transmission system that transmits power from the internal combustion engine 11 to the drive wheels 25, and is driven by the output torque output from the internal combustion engine 11 to generate power. The power supply unit 2 is configured to include the alternator 31, a generated current sensor 32, a power converter 33, a battery 35, a battery voltage sensor 37, a battery current sensor 39, and a power generation control device 30.

[0016] The alternator 31 is a generator that generates electricity when driven by the rotational torque output from the internal combustion engine 11. Specifically, a field current is supplied to a field coil of the alternator 31 by the rotation of the crankshaft 11a of the internal combustion engine 11, and a three-phase AC induced current is generated. The field current of the field coil is adjusted through a regulator or the like, and the generated voltage of the alternator 31 is controlled.

[0017] The alternator 31 not only generates electricity using the power generation torque generated by the internal combustion engine 11, but also has a function of generating electricity (regenerative power generation) using the braking torque input from the drive wheels 25. The alternator 31 includes a rectifier, and converts the generated AC current into a DC current and outputs it. The power generated by the alternator 31 is charged into the battery 35, and is consumed by the power loads 29, such as the electric control elements and auxiliary machines of the internal combustion engine 11.

[0018] The battery 35 is connected to the alternator 31 and is charged with electric power generated by the alternator 31. When the internal combustion engine 11 or the electric power load 29 requires electric power, for example when electric power is supplied to a starter motor at the start of the internal combustion engine 11, the battery 35 supplies the stored electric power to the internal combustion engine 11 or the electric power load 29.

[0019] The battery current sensor 39 measures the current charged to and discharged from the battery 35, and transmits a sensor signal corresponding to the current value to the power generation control device 30. The battery voltage sensor 37 measures the terminal voltage of the battery 35, and transmits a sensor signal corresponding to the voltage value to the power generation control device 30.

[0020] The power generation control device 30 includes a processor such as a CPU (Central Processing Unit) and storage elements such as a RAM (Random Access Memory) and a ROM (Read Only Memory), and the processor executes a computer program to control the power supply unit 2. For example, the power generation control device 30 executes a process to control the power generation of the alternator 31 so that the state of charge (SOC) of the battery 35 is maintained at a predetermined target state of charge by supplying power from the battery 35 to the internal combustion engine 11 and the power load 29.

[0021] The power generation control device 30 determines the SOC of the battery 35 based on the battery voltage. The power generation control device 30 adjusts the excitation current supplied to the regulator according to the battery voltage, and controls the power generated by the alternator 31. When current is consumed by the internal combustion engine 11 or the power load 29, the battery voltage drops, and the power generation control device 30 accordingly makes the alternator 31 generate power, so that the power generation current value of the alternator 31 increases. The power generation control device 30 transmits information indicating at least the battery voltage, and the excitation current and field current of the alternator 31 to the control device 50 of the internal combustion engine 11.

[0022] <2. Internal combustion engine control device> Next, the control device 50 that controls the internal combustion engine 11 will be described.

[0023] (2-1. Overall composition) The control device 50 sets control targets for the internal combustion engine 11 based on information transmitted from various sensors, and controls the operation of the internal combustion engine 11 based on the set control targets. The control device 50 outputs control signals to the throttle valve 13, the fuel injector 15, the spark plug 17, etc., to control the output torque and engine speed.

[0024] The control device 50 functions as a device that controls the operation of the internal combustion engine 11 by one or more processors such as CPUs executing a computer program. The computer program is a computer program for causing the processor to execute the operations to be performed by the control device 50, which will be described later. The computer program executed by the processor may be recorded on a recording medium that functions as a storage unit (memory) provided in the control device 50, or may be recorded on a recording medium built into the control device 50 or any recording medium that can be externally attached to the control device 50.

[0025] Examples of recording media for recording computer programs include magnetic media such as HDD (Hard Disk Drive), floppy disks, and magnetic tapes, optical recording media such as CD-ROM (Compact Disk Read Only Memory), DVD (Digital Versatile Disk), and Blu-ray (registered trademark), magneto-optical media such as floptical disks, memory elements such as RAM and ROM, and flash memories such as USB (Universal Serial Bus) memory and SSD, as well as other media capable of storing programs.

[0026] Incidentally, a part or the whole of the control device 50 may be configured with updatable firmware or the like, or may be a program module or the like that is executed by instructions from a CPU or the like.

[0027] The control device 50 is configured to be able to acquire sensor signals from the accelerator sensor 41, the vehicle speed sensor 43, and the engine speed sensor 45. The accelerator sensor 41 detects the amount of operation of the accelerator pedal. The vehicle speed sensor 43 detects the vehicle speed. The engine speed sensor 45 detects the engine speed, which is the rotation speed of the crankshaft 11a. The control device 50 is also connected to the power generation control device 30 so as to be able to communicate with it. The control device 50 is configured to be able to acquire information indicating the battery voltage and the excitation current and field current of the alternator 31 from the power generation control device 30.

[0028] (2-2. Functional configuration of the control device) Next, the functional configuration of the control device 50 for the internal combustion engine according to this embodiment will be specifically described.

[0029] Fig. 2 is an explanatory diagram showing the functional configuration of the control device 50 shown in Fig. 1. The control device 50 includes a processing unit 60 and a memory unit 71. The processing unit 60 is configured with one or more processors such as CPUs. The memory unit 71 is configured to be able to communicate with the processing unit 60. The memory unit 71 stores programs executed by the processing unit 60, parameters used in various calculations, detection data, information on calculation results, etc. A part of the memory unit 71 is used as a work area for the processing unit 60.

[0030] The control device 50 is configured to be able to acquire sensor signals output from the accelerator sensor 41, the vehicle speed sensor 43, and the engine speed sensor 45. In the illustrated example, the various sensors are directly connected to the control device 50, but information indicated by the sensor signals of the various sensors may be acquired from another controller via an in-vehicle network (not shown). The control device 50 is also connected to the power generation control device 30 directly or via an in-vehicle network such as a Controller Area Network (CAN) (not shown).

[0031] The processing unit 60 includes a target torque setting unit 61, an operation target setting unit 63, a power generation load prediction unit 65, a correction unit 67, and a drive control unit 69. The functions of these units are realized by the execution of a computer program by a processor. Note that some of the target torque setting unit 61, the operation target setting unit 63, the power generation load prediction unit 65, the correction unit 67, and the drive control unit 69 may be configured by hardware such as an analog circuit.

[0032] (Target torque setting section) The target torque setting unit 61 sets a target torque, which is a target value of the output torque output from the internal combustion engine 11. The target torque setting unit 61 sets the sum of a driving torque that is transmitted to the drive wheels 25 to run the vehicle and a power generation torque that is used for power generation by the alternator 31, as the target torque. For example, the target torque setting unit 61 calculates the driving torque based on the accelerator opening and the engine speed, with reference to a torque map previously stored in the storage unit 71. The target torque setting unit 61 also calculates the power generation torque based on the excitation current and the engine speed that determine the power generation of the alternator 31.

[0033] If there are other driving elements that utilize the output torque of the internal combustion engine 11, the target torque setting unit 61 sets the target torque by further adding the torque used by the other driving elements.

[0034] (Motion Goal Setting Section) The operation target setting unit 63 sets a target intake air amount, a target fuel injection amount, and a target ignition timing based on the target torque set by the target torque setting unit 61. For example, the operation target setting unit 63 sets the target intake air amount, the target fuel injection amount, and the target ignition timing by referring to an intake air amount map, an injection amount map, and an ignition timing map stored in advance in the storage unit 71.

[0035] The target intake air amount is a target value of the amount of intake air introduced into the cylinders of the internal combustion engine 11. The target intake air amount is set in proportion to the magnitude of the target torque. The target fuel injection amount is a target value of the amount of fuel injected into the cylinders by the fuel injector 15. Basically, the target fuel injection amount is set according to the target intake air amount so that the ratio of fuel to air in the air-fuel mixture is a constant ratio.

[0036] The target ignition timing is a target value for the timing of igniting the mixture formed in the cylinder. For example, with the top dead center of the piston of the internal combustion engine 11 as a reference, the more the ignition timing is retarded, the lower the combustion efficiency of the mixture becomes. "Retarding the ignition timing" means to retard the ignition timing relative to a certain reference ignition timing. Conversely, "advancing the ignition timing" means to advance the ignition timing relative to a certain reference ignition timing.

[0037] (Power generation load forecasting section) The power generation load prediction unit 65 predicts an increase in the load of power generation by the alternator 31. In this embodiment, the power generation load prediction unit 65 predicts in advance that the load of power generation will increase when the rate of decrease in the battery voltage is equal to or greater than a predetermined first threshold. As described above, the power generation control device 30 controls the power generation of the alternator 31 so that the SOC of the battery 35 is maintained at a predetermined target charge amount. While the amount of discharge from the battery 35 is small and the rate of decrease in the battery voltage is small, the load of power generation by the alternator 31 is relatively small and the possibility of the internal combustion engine 11 stalling is low.

[0038] On the other hand, if the amount of discharge from the battery 35 becomes excessive and the rate at which the battery voltage drops increases, the load of power generation by the alternator 31 increases, increasing the possibility of stalling the internal combustion engine 11. The power generation load prediction unit 65 predicts an increase in the load of power generation by the alternator 31 before the load actually increases.

[0039] (Correction section) When an increase in the load of power generation by the alternator 31 is predicted, the correction unit 67 sets an increase correction amount for the target intake air amount based on the power generation torque used for power generation by the alternator 31, and sets an amount of retardation of the target ignition timing based on the difference between the output torque of the internal combustion engine 11 realized by the intake air amount after the increase correction and the target torque. In addition, the correction unit 67 executes a process of returning the target ignition timing to the advance side when a sudden drop in the rotation speed of the internal combustion engine 11 occurs.

[0040] After an increase in the power generation load of the alternator 31 is predicted, the correction unit 67 increases the amount of intake air while retarding the ignition timing until the engine speed suddenly drops, thereby maintaining the target torque of the internal combustion engine 11 at the output torque. Furthermore, the correction unit 67 returns the ignition timing to the advance side when the engine speed suddenly drops. At this time, since the amount of intake air has already been increased, the responsiveness of the increase in the output torque of the internal combustion engine 11 can be improved by returning the ignition timing to the advance side.

[0041] Since the ratio of air to fuel in the air-fuel mixture is constant, the target fuel injection amount is also increased as the target intake air amount is increased.

[0042] (Drive control unit) The drive control unit 69 controls the drive of the throttle valve 13, the fuel injector 15 and the spark plug 17 based on the target intake air amount, the target fuel injection amount and the target ignition timing set by the operation target setting unit 63 and the correction unit 67, thereby controlling the internal combustion engine 11. In this way, the output torque and engine speed output from the internal combustion engine 11 are controlled.

[0043] Specifically, the drive control unit 69 sets a target opening of the throttle valve 13 based on the target intake air amount and engine speed, and rotationally drives the throttle valve 13. The drive control unit 69 also sets a drive duty ratio of the fuel injector 15 based on the target fuel injection amount, and controls the current supplied to the fuel injector 15. The drive control unit 69 also supplies a current to the spark plug 17 in accordance with the target ignition timing.

[0044] <3. Example of operation of the control device for an internal combustion engine> So far, we have described an example of the configuration of the internal combustion engine control device 50. Next, an example of the operation of the internal combustion engine control device 50 will be described.

[0045] 3 to 5 are flow charts showing an example of the processing operation by the control device 50. Note that the flow charts shown in Fig. 3 to 5 are constantly executed when the drive system 1 is in an activated state.

[0046] First, the target torque setting unit 61 sets a target torque for the internal combustion engine 11 (step S11). For example, the target torque setting unit 61 acquires a sensor signal from the accelerator sensor 41 and a sensor signal from the engine speed sensor 45, and calculates a driving torque based on the accelerator opening and the engine speed by referring to a torque map. When the vehicle is in an automatic driving state in which the acceleration is automatically controlled by a computer, information on the required acceleration set by the computer may be used instead of information on the accelerator opening. In addition, the target torque setting unit 61 calculates a power generation torque based on the excitation current of the alternator 31 and the engine speed transmitted from the power generation control device 30. The target torque setting unit 61 sets the sum of the driving torque and the power generation torque as the target torque.

[0047] Next, the operation target setting unit 63 sets the target intake air amount, the target fuel injection amount, and the target ignition timing based on the target torque set by the target torque setting unit 61 (step S13). For example, the operation target setting unit 63 acquires information on the target torque and the engine speed, and sets the target intake air amount, the target fuel injection amount, and the target ignition timing based on the target torque and the engine speed, respectively, with reference to the intake air amount map, the injection amount map, and the ignition timing map.

[0048] Next, the drive control unit 69 controls the drive of the throttle valve 13, the fuel injector 15, and the spark plug 17 based on the set target intake air amount, target fuel injection amount, and target ignition timing (step S15). Specifically, the drive control unit 69 sets a target opening of the throttle valve 13 based on the target intake air amount and engine speed, and drives and rotates the throttle valve 13. The drive control unit 69 also sets a drive duty ratio of the fuel injector 15 based on the target fuel injection amount, and controls the current supplied to the fuel injector 15. The drive control unit 69 also supplies a current to the spark plug 17 in accordance with the target ignition timing.

[0049] Next, the power generation load prediction unit 65 determines whether or not a correction execution condition is satisfied (step S17). The process of determining whether or not a correction execution condition is satisfied corresponds to the process of determining whether or not an increase in the load of power generation by the alternator 31 is predicted.

[0050] FIG. 6 is a flowchart showing the correction execution condition satisfaction determination process. The power generation load prediction unit 65 determines whether or not there is a possibility that the battery voltage will drop due to reasons other than the consumption of a large current equal to or greater than a predetermined standard (step S51). The determination process in step S51 is a process for determining whether or not an abnormality has occurred in the power supply unit 2, such as a breakdown or deterioration of the battery 35 or a malfunction of the alternator 31.

[0051] When the power generation load prediction unit 65 does not determine that the battery voltage may decrease due to reasons other than the consumption of a large current equal to or greater than a predetermined standard (S51 / No), it determines whether or not the decrease rate of the battery voltage is equal to or greater than a predetermined first threshold based on the information on the battery voltage acquired from the power generation control device 30 (step S53). The determination process in step S51 is a process for determining that the decrease rate of the battery voltage is large and that the load of power generation will be excessive in order to maintain the SOC of the battery 35 at a predetermined target charge amount, and the first threshold is set to any appropriate value based on this viewpoint. For example, the power generation load prediction unit 65 may determine that the decrease rate of the battery voltage is equal to or greater than a predetermined first threshold when the difference (ΔV) obtained by subtracting the current value from the previous value of the battery voltage acquired at a predetermined sampling period (Δt) is equal to or less than a predetermined threshold (ΔV_thr). Note that the above threshold ΔV_thr indicates a negative value.

[0052] When the power generation load prediction unit 65 determines that the rate of decrease in the battery voltage is equal to or greater than a predetermined first threshold (S53 / Yes), it determines whether or not the power generation current value of the alternator 31 is equal to or greater than a predetermined second threshold based on the excitation current of the alternator 31 acquired from the power generation control device 30 (step S55). When the battery voltage is decreasing in conjunction with a decrease in the target voltage of the battery 35, the power generation current value of the alternator 31 decreases. Therefore, the determination process of step S55 is a process for determining such a situation and preventing unnecessary correction from being performed. From this viewpoint, the second threshold is set to any appropriate value.

[0053] When the power generation load prediction unit 65 determines that the power generation current value of the alternator 31 is equal to or greater than the second threshold value (S55 / Yes), that is, when the determination in step S51 is negative and the determinations in steps S53 to S55 are positive, it determines that the correction execution condition is satisfied since there is a risk of an increase in the power generation load of the alternator 31 (step S57). On the other hand, when the power generation load prediction unit 65 determines that the power generation load of the alternator 31 is negative (S51 / Yes or S53 / No or S55 / No), it determines that there is no risk of an increase in the power generation load of the alternator 31 and therefore determines that the correction execution condition is not satisfied (step S59).

[0054] Returning to FIG. 3, if the power generation load prediction unit 65 does not determine that the correction execution condition is satisfied in step S17 (S17 / No), the process returns to step S11, and the control of the internal combustion engine 11 continues. On the other hand, if the power generation load prediction unit 65 determines that the correction execution condition is satisfied (S17 / Yes), the correction unit 67 determines whether the operating state of the internal combustion engine 11 is an operating state in which the ignition timing can be retarded (step S19). For example, when the internal combustion engine 11 is in a lean burn control state, retarding the ignition timing may excessively reduce the combustion efficiency, which may cause misfire in the internal combustion engine 11. In other words, step S19 is a process for determining whether the internal combustion engine 11 is in an operating state that can withstand retarding the ignition timing, and a predetermined condition may be set other than the above-mentioned lean burn control state.

[0055] When the correction unit 67 determines that the operating state of the internal combustion engine 11 is an operating state in which the ignition timing can be retarded (S19 / Yes), the process proceeds to step S21. On the other hand, when the correction unit 67 determines that the operating state of the internal combustion engine 11 is not an operating state in which the ignition timing can be retarded (S19 / No), the process proceeds to step S41.

[0056] If the correction unit 67 determines that the operating state of the internal combustion engine 11 is an operating state in which the ignition timing can be retarded (S19 / Yes), similar to steps S11 to S13 described above, the target torque setting unit 61 sets the target torque of the internal combustion engine 11, and the operation target setting unit 63 sets the target intake air volume, the target fuel injection volume, and the target ignition timing (step S21).

[0057] Next, the correction unit 67 corrects the target intake air amount by increasing it (step S23). In this embodiment, the correction unit 67 calculates the increase correction amount by using an intake air amount correction map in which the increase correction amount of the intake air amount is set according to the rotation speed of the alternator 31, the field current of the alternator 31, and the battery voltage. The rotation speed of the alternator 31 may be detected by a rotation speed sensor provided in the alternator 31, or may be calculated by multiplying the engine rotation speed by the value of the ratio between the rotation speed of the crankshaft 11a and the rotation speed of the alternator 31. In addition, along with the increase correction of the target intake air amount, the target fuel injection amount is also corrected by increasing it.

[0058] Next, the correction unit 67 sets a target retard amount of the target ignition timing based on the difference between the estimated output torque estimated to be output by the target intake air amount after the increase correction and the target torque set in step S21 (step S25). In other words, when the intake air amount is increased, the output torque of the internal combustion engine 11 increases and an excessive torque exceeding the target torque is output, so an ignition timing retard amount capable of suppressing the excessive torque is set. In this embodiment, the correction unit 67 calculates the ignition timing retard amount using an ignition timing correction map in which the ignition timing retard amount is set according to the difference between the torque that can be output by the increased intake air amount and the target torque.

[0059] Next, similarly to step S15, the drive control section 69 controls the drive of the throttle valve 13, the fuel injector 15 and the spark plug 17 based on the corrected target intake air amount, the target fuel injection amount and the target ignition timing (step S27).

[0060] Next, the correction unit 67 determines whether the engine speed has become equal to or lower than a predetermined third threshold value based on the sensor signal output from the engine speed sensor 45 (step S29). The determination process of step S29 is a process for determining whether the engine speed has actually decreased to an engine speed at which a stall of the internal combustion engine 11 may occur. If the third threshold value is too small, the internal combustion engine 11 may stall before the torque output from the internal combustion engine 11 is increased, and therefore, from this viewpoint, the third threshold value is set to any appropriate value.

[0061] If the correction unit 67 does not determine that the engine speed is equal to or lower than the third threshold (S29 / No), the power generation load prediction unit 65 determines whether or not the state in which the correction execution condition is satisfied is maintained (step S31), similar to step S17. If the power generation load prediction unit 65 determines that the state in which the correction execution condition is satisfied is maintained (S31 / Yes), the process returns to step S21, where the target intake air amount, the target fuel injection amount, and the target ignition timing are corrected, and the drive of the throttle valve 13, the fuel injector 15, and the spark plug 17 is controlled.

[0062] On the other hand, if the power generation load prediction unit 65 does not determine that the state in which the correction execution condition is satisfied is maintained (S31 / No), the correction unit 67 cancels the execution of the correction (step S33). That is, the increase correction of the intake air amount is stopped, and the ignition timing is returned to the ignition timing according to the ignition timing map. At this time, since a time lag occurs before the intake air amount returns to the state before the increase, the ignition timing is gradually changed to the advance side at a predetermined change rate. This makes it possible to suppress an increase in the engine speed due to a sudden increase in the output torque of the internal combustion engine 11.

[0063] On the other hand, when the correction unit 67 determines that the engine speed is equal to or lower than the third threshold (S29 / Yes), the ignition timing is returned to the advance side (step S35). As a result, the ignition timing is advanced with the intake air amount corrected to be increased, and the output torque of the internal combustion engine 11 is increased. Therefore, it is possible to suppress a sudden drop in the engine speed and stall of the internal combustion engine 11 due to an increase in the power generation load of the alternator 31. At this time, by gradually changing the ignition timing to the advance side at a predetermined change rate, it is possible to prevent the engine speed from revving up.

[0064] After the ignition timing is returned to the advance side, the process returns to step S11, and the drive of the internal combustion engine 11 is controlled according to the target torque corresponding to the required acceleration or the target torque for maintaining the idle speed.

[0065] On the other hand, in step S19, when the correction unit 67 determines that the operating state of the internal combustion engine 11 is an operating state in which the ignition timing can be retarded (S19 / Yes), it corrects the target intake air amount to increase as in step S23 (step S43). Next, the drive control unit 69 controls the drive of the throttle valve 13, the fuel injector 15, and the ignition plug 17 based on the corrected target intake air amount, the target fuel injection amount, and the target ignition timing as in step S15 (step S45). In this case, the correction unit 67 does not correct the ignition timing because the internal combustion engine 11 is not in an operating state that can withstand the retardation of the ignition timing. However, since the intake air amount is corrected to increase, a sudden drop in the engine speed is suppressed even if the load of the power generation of the alternator 31 increases, and the stall of the internal combustion engine 11 can be suppressed.

[0066] Next, the power generation load prediction unit 65 determines whether or not the state in which the correction execution condition is satisfied is maintained, similarly to step S17 (step S47). If the power generation load prediction unit 65 determines that the state in which the correction execution condition is satisfied is maintained (S47 / Yes), the process returns to step S41, where the target intake air amount and the target fuel injection amount are corrected, and the drive of the throttle valve 13, the fuel injector 15, and the ignition plug 17 is controlled.

[0067] On the other hand, if the power generation load prediction unit 65 does not determine that the state in which the correction execution condition is satisfied is maintained (S47 / No), the correction unit 67 cancels the execution of the correction (step S49). After that, the process returns to step S11, and the drive of the internal combustion engine 11 is controlled according to the target torque according to the required acceleration or the target torque for maintaining the idle speed.

[0068] <4. Effect> Next, the operation of the present disclosure will be described with reference to FIG.

[0069] FIG. 7 shows the battery voltage, engine speed, intake air amount, and ignition timing when the battery voltage suddenly drops due to consumption of a large current.

[0070] The power generation of the alternator 31 is controlled so as to maintain the SOC of the battery 35 at a predetermined target charge amount, and when the control device 50 determines at time t1 that the correction execution condition is satisfied from a state in which the battery voltage is stable near a predetermined value, the control device 50 corrects the intake air amount to increase and retards the ignition timing. At this time, the output torque of the internal combustion engine 11 does not increase, so the engine speed does not increase. After that, when the engine speed suddenly drops at time t2, the control device 50 returns the ignition timing to the advance side between time t2 and time t3 while maintaining the state in which the intake air amount is corrected to increase. As a result, the output torque of the internal combustion engine 11 increases, the decrease in the engine speed is eliminated, and the stall of the internal combustion engine 11 is avoided.

[0071] <5. Effects> As described above, when an increase in the power generation load of the alternator 31 is predicted, the control device 50 for the internal combustion engine according to this embodiment increases the intake air amount in advance and retards the ignition timing to prepare for a sudden drop in the engine speed of the internal combustion engine 11 while maintaining the output torque of the internal combustion engine 11 at a target torque. When a sudden drop in the engine speed occurs, the control device 50 returns the ignition timing to the advance side to quickly increase the output torque of the internal combustion engine 11. This reduces the risk of the engine speed decreasing as the power generation load of the alternator 31 increases, making it possible to avoid stalling of the internal combustion engine 11.

[0072] Although the preferred embodiment of the present disclosure has been described in detail above with reference to the attached drawings, the technology of the present disclosure is not limited to such examples. It is clear that a person having ordinary knowledge in the technical field to which the present disclosure belongs can conceive of various modified or amended examples within the scope of the technical ideas described in the claims, and it is understood that these also naturally belong to the technical scope of the present disclosure. [Explanation of symbols]

[0073] 1: Drive system 2: Power supply system 11: Internal combustion engine 11a: Crankshaft 13: Throttle valve 15: Fuel injector 17: Spark plug 20: Transmission 30: Power generation control device 31: Alternator 35: Battery 37: Battery voltage sensor 39: Battery current sensor 50: Internal combustion engine control device 61: Target torque setting section 63: Operation goal setting section 65: Power generation load forecasting section 67: Correction section 69: Drive control unit

Claims

1. A control device for controlling an internal combustion engine having a throttle valve for adjusting an intake air amount and an ignition plug for igniting an air-fuel mixture in a cylinder, an operational target setting unit that sets a target intake air amount and a target ignition timing based on a target torque corresponding to a required acceleration of a vehicle equipped with the internal combustion engine; a power generation load prediction unit that predicts an increase in a load of power generation by a generator that is connected to a power transmission system that transmits power from the internal combustion engine to drive wheels and is driven by an output torque output from the internal combustion engine to generate power; a correction unit which, when an increase in the load of power generation by the generator is predicted, sets an increase correction amount of the target intake air amount based on a power generation torque used to drive the generator, and sets an amount of retardation of the target ignition timing based on a difference between the output torque of the internal combustion engine realized by the intake air amount after the increase correction and the target torque, and returns the target ignition timing to the advance side when a sudden drop in the rotation speed of the internal combustion engine occurs; A control device for an internal combustion engine comprising:

2. The correction unit is calculating the power generation torque based on a rotation speed of the generator, a generated current of the generator, and a voltage of a battery that charges the generated current of the generator; The control device for an internal combustion engine according to claim 1.

3. The power generation load prediction unit is When there is no possibility that the voltage of the battery that charges the current generated by the generator will decrease due to reasons other than current consumption above a predetermined standard, the rate of decrease in the voltage of the battery that charges the current generated by the generator is equal to or greater than a predetermined first threshold, and the generated current of the generator is equal to or greater than a predetermined second threshold, it is predicted that the load of power generation by the generator will increase. The control device for an internal combustion engine according to claim 1.

4. The correction unit is when an increase in the load of power generation by the generator is predicted, it is further determined whether or not the operating state of the internal combustion engine is an operating state in which the target ignition timing can be retarded; When the engine is not in an operating state in which the target ignition timing can be retarded, the target intake air amount is increased without setting the increase correction amount of the target intake air amount and the delay amount of the target ignition timing. The control device for an internal combustion engine according to claim 1.

5. A method for controlling an internal combustion engine having a throttle valve for adjusting an intake air amount and an ignition plug for igniting an air-fuel mixture in a cylinder, comprising: setting a target intake air amount and a target ignition timing based on a target torque corresponding to a required acceleration of a vehicle equipped with the internal combustion engine; predicting an increase in a load of a generator that is connected to a power transmission system that transmits power from the internal combustion engine to drive wheels and is driven by an output torque output from the internal combustion engine to generate power; when an increase in the load of power generation by the generator is predicted, an increase correction amount of the intake air amount is set based on a power generation torque used to drive the generator, and an amount of retardation of the target ignition timing is set based on a difference between an output torque of the internal combustion engine realized by the intake air amount after the increase correction and the target torque, and when a sudden drop in the rotation speed of the internal combustion engine occurs, the target ignition timing is returned to the advance side; The control method for an internal combustion engine comprises:

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