Controller for internal combustion engine, control method for internal combustion engine, and storage medium

Abstract

The present invention relates to a controller for an internal combustion engine, a control method for an internal combustion engine, and a storage medium. A controller, a control method, and a storage medium for an internal combustion engine are provided. In an initial combustion cylinder, when the engine is restarted from a state in which fuel combustion in the cylinder is suspended, initial combustion is caused by a control circuit. When a predetermined condition is satisfied, an automatic stop process suspends fuel combustion in the cylinder and controls the throttle valve to a closed state. In the case where the rotational speed of the crankshaft obtained when the restart is requested is zero, a first calculation process calculates the amount of fuel injected into the initial combustion cylinder based on the position of the piston in the initial combustion cylinder. In the case where the rotational speed obtained when the restart is requested is higher than zero, a second calculation process calculates the injection amount based on the rotational speed.

Description

Technical Field

[0001] The present disclosure relates to a controller for an internal combustion engine, a control method for an internal combustion engine, and a storage medium. Background Art

[0002] Japanese Patent Publication No. 2013-095155 discloses an internal combustion engine comprising cylinders, an intake passage, an exhaust passage, pistons, a crankshaft, fuel injection valves, and a throttle valve. Each cylinder is a space for burning fuel. The intake passage draws intake air into the cylinder. The exhaust passage exhausts exhaust gas from the cylinder. Each piston reciprocates in its corresponding cylinder. The crankshaft rotates due to the reciprocating motion of the pistons. Each fuel injection valve supplies fuel to its corresponding cylinder. The throttle valve is located in the intake passage. The throttle valve regulates the amount of intake air flowing through the intake passage. Summary of the Invention

[0003] This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

[0004] The internal combustion engine disclosed in the above document includes a controller that can pause fuel combustion in cylinders of the internal combustion engine and then perform a restart process to restart the internal combustion engine.

[0005] Conventionally, the restart process of an internal combustion engine requires that the crankshaft be at rest as a prerequisite. Therefore, if a conventional restart process is performed in a state when the rotational speed of the crankshaft is not zero, the internal combustion engine is not always restarted in an advantageous manner.

[0006] One aspect of the present disclosure provides a controller for an internal combustion engine. The controller includes a control circuit and is used in an internal combustion engine. The internal combustion engine includes: cylinders in which fuel is combusted; intake passages through which intake air is drawn in; and exhaust passages through which exhaust gas is discharged from the cylinders. The internal combustion engine further includes: pistons, each of which reciprocates in a corresponding one of the cylinders; a crankshaft, which rotates as the pistons reciprocate; fuel injection valves, each of which supplies fuel to a corresponding one of the cylinders; and a throttle located in the intake passages to regulate the amount of intake air flowing through the intake passages. The control circuit is configured to restart the internal combustion engine from a state in which fuel combustion in the cylinders is suspended. The cylinders include an initial combustion cylinder, and when the internal combustion engine is restarted from a state in which fuel combustion in the cylinders is suspended, the control circuit induces initial combustion in the initial combustion cylinder. The control circuit is configured to perform: an automatic stop process, which suspends fuel combustion in the cylinder and controls the throttle valve to a closed state when predetermined conditions are met; a first calculation process, which calculates the amount of fuel injected into the initial combustion cylinder based on the position of the piston in the initial combustion cylinder when the rotational speed of the crankshaft obtained when restart is requested is zero; and a second calculation process, which calculates the amount of fuel injected into the initial combustion cylinder based on the rotational speed when the rotational speed obtained when restart is requested is higher than zero.

[0007] Even during the automatic stop process, as the crankshaft rotates, gas flows through the intake passage, cylinder, and exhaust passage in the following order. This flow of gas through the intake passage, cylinder, and exhaust passage causes the pressure of the gas on the downstream side of the intake passage, as viewed from the throttle valve, to tend to change in accordance with the rotational speed of the crankshaft. This causes a change in the amount of intake air drawn into the primary combustion cylinder when the internal combustion engine restarts, and therefore a change in the amount of fuel to be supplied to the primary combustion cylinder. In the above configuration, the amount of fuel to be supplied to the primary combustion cylinder, which changes in accordance with the rotational speed of the crankshaft, is taken into account when calculating the amount of fuel injected into the primary combustion cylinder. This ensures that the internal combustion engine can be restarted even if the crankshaft rotates.

[0008] In the above configuration, N is an integer greater than or equal to 2. The cylinder may include a second combustion cylinder and an Nth combustion cylinder. The control circuit may be further configured to perform: an intermediate calculation process that calculates the amount of fuel injected into the second combustion cylinder to the Nth combustion cylinder when the internal combustion engine is restarted; and a normal calculation process that calculates the amount of fuel injected into the (N+1)th and subsequent combustion cylinders. The control circuit may be configured to set the value of N used in a case where the rotation speed obtained when the restart is requested is higher than zero to a value smaller than the value of N used in a case where the rotation speed obtained when the restart is requested is zero.

[0009] In the above configuration, when the crankshaft rotational speed obtained when restarting the internal combustion engine is higher than zero, the mode for calculating the fuel injection amount is switched to the normal calculation process more quickly than when the crankshaft rotational speed is zero. That is, the restart of the internal combustion engine, in which the amount of injected fuel is calculated to be relatively large, is quickly completed, and the control of the internal combustion engine returns to normal control. This reduces the amount of fuel consumed by the restarted internal combustion engine.

[0010] In the above configuration, the control circuit may be configured to set the value of N used in a case where the rotation speed obtained when the restart is requested is higher than zero to be smaller as the rotation speed obtained when the restart is requested becomes higher.

[0011] In the above configuration, the restart of the internal combustion engine ends quickly due to the relatively high rotation speed of the crankshaft obtained when the restart of the internal combustion engine is requested. In this case, the mode of calculating the fuel injection amount is switched to the normal calculation process more quickly.

[0012] In the above configuration, the control circuit can be configured to set the cylinder allowing initial fuel injection after requesting restart as the initial combustion cylinder in the case where the rotation speed obtained when restart is requested is higher than zero, regardless of the position of the piston obtained when restart is requested.

[0013] For example, if the rotational speed of the crankshaft obtained when the internal combustion engine is restarted is zero, a process can be executed to postpone fuel injection into the cylinder based on the position of the piston obtained when the internal combustion engine is restarted. The above configuration prohibits execution of the postponement process, etc. This restricts the case where the cylinder into which fuel can be injected due to the postponement process is not processed as the initial combustion cylinder.

[0014] Another aspect of the present disclosure may provide a control method for an internal combustion engine that performs various processes according to any one of the above controllers.

[0015] A further aspect of the present disclosure may provide a non-transitory computer-readable storage medium storing a program causing a processor to execute various processes according to any one of the above controllers.

[0016] Other features and aspects will be apparent from the following detailed description, drawings, and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram showing the configuration of a vehicle.

[0018] Figure 2 It shows Figure 1 A schematic diagram of the configuration of an internal combustion engine.

[0019] Figure 3 It is used to indicate Figure 2 Flowchart of the restart control of the internal combustion engine in FIG.

[0020] Throughout the drawings and detailed description, like reference numerals refer to like elements. The drawings may not be to scale, and the relative sizes, proportions, and depictions of elements in the drawings may be exaggerated for clarity, illustration, and convenience. DETAILED DESCRIPTION

[0021] This detailed description provides a comprehensive understanding of the described methods, devices, and / or systems. Modifications and equivalents to the described methods, devices, and / or systems will be apparent to those skilled in the art. The order of operations is exemplary and, except for operations that necessarily occur in a particular order, may be varied as will be apparent to those skilled in the art. Descriptions of functions and configurations well known to those skilled in the art may be omitted.

[0022] Exemplary embodiments may have different forms and are not limited to the described examples. However, the described examples are thorough and complete, and will convey the full scope of the disclosure to those skilled in the art.

[0023] In this specification, "at least one of A and B" should be understood to mean "only A, only B, or both A and B."

[0024] Vehicle mechanical configuration

[0025] Now refer to Figures 1 to 3 An embodiment according to the present disclosure will be described. First, a mechanical configuration of the vehicle 100 will be described.

[0026] As in Figure 1 As shown in FIG, a vehicle 100 includes an internal combustion engine 10. Figure 2As shown in FIG, an internal combustion engine 10 includes a cylinder 11, an intake passage 12, an exhaust passage 13, a piston 16, a connecting rod 17, and a crankshaft 18. Figure 2 One of the cylinders 11 , one of the pistons 16 , and one of the connecting rods 17 are shown.

[0027] As in Figure 2 As shown in , the cylinder 11 is a space for burning an air-fuel mixture of fuel and intake air. In this embodiment, the internal combustion engine 10 includes six cylinders 11. The internal combustion engine 10 is an inline six-cylinder engine in which the six cylinders 11 are arranged in line. Hereinafter, when described together, the six cylinders 11 are simply referred to as (a plurality of) cylinders 11. When the six cylinders 11 are distinguished from each other, the six cylinders 11 are referred to as a first cylinder 11A, a second cylinder 11B, a third cylinder 11C, a fourth cylinder 11D, a fifth cylinder 11E, and a sixth cylinder 11F in the order in which the six cylinders 11 are arranged. Figure 2 Only one of the cylinders 11 is shown as a representative cylinder.

[0028] Each piston 16 is located in a corresponding cylinder 11. The piston 16 is coupled to a crankshaft 18 via a connecting rod 17. When an air-fuel mixture of fuel and intake air is combusted in the cylinder 11, the piston 16 reciprocates in the cylinder 11. The reciprocating motion of the piston 16 rotates the crankshaft 18.

[0029] An intake passage 12 is connected to the cylinder 11. The intake passage 12 draws intake air from outside the internal combustion engine 10 into each cylinder 11. An exhaust passage 13 is connected to the cylinder 11. The exhaust passage 13 discharges exhaust gas from each cylinder 11 to the outside of the internal combustion engine 10.

[0030] The internal combustion engine 10 includes a throttle valve 21 , a port injection valve 22 , a direct injection valve 23 , an ignition device 24 , an intake valve 26 , and an exhaust valve 27 .

[0031] A 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. Each port injection valve 22 is located in the intake passage 12 adjacent to the corresponding cylinder 11. The port injection valve 22 supplies fuel to the cylinder 11 through the intake passage 12 by injecting the fuel into the intake passage 12. The internal combustion engine 10 includes six port injection valves 22 corresponding to the six cylinders 11. The portion including the top end of each direct injection valve 23 is located in the corresponding cylinder 11. The direct injection valve 23 supplies fuel to the cylinder 11 by injecting the fuel into the cylinder 11. The internal combustion engine 10 includes six direct injection valves 23 corresponding to the six cylinders 11. In this embodiment, the port injection valves 22 and the direct injection valves 23 are fuel injection valves that supply fuel to the cylinder 11.

[0032] The portion including the top end of each ignition device 24 is located in the corresponding cylinder 11. The ignition device 24 ignites the air-fuel mixture of fuel and intake air through spark discharge. The internal combustion engine 10 includes six ignition devices 24 corresponding to the six cylinders 11. These 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 enters the combustion stroke in this order: 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. For every two revolutions of the crankshaft 18, each cylinder 11 repeats the intake stroke, compression stroke, combustion stroke, and exhaust stroke.

[0033] Each 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 using a driving force from a valve operating mechanism (not shown). The internal combustion engine 10 includes six intake valves 26 corresponding to the six cylinders 11. Each 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 using a driving force from a valve operating mechanism (not shown). The internal combustion engine 10 includes six exhaust valves 27 corresponding to the six cylinders 11.

[0034] As in Figure 1 As shown in , the vehicle 100 includes a clutch 31 , a motor generator 40 , an automatic transmission 61 , a differential mechanism 62 , and drive wheels 63 .

[0035] The motor generator 40 includes a rotating shaft 41. The rotating shaft 41 is connected to a rotor 40a of the motor generator 40. Therefore, the rotating shaft 41 is rotatable relative to a stator 40b of the motor generator 40. 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 clutch 31 switches the connection state of the clutch 31 from one of an engaged state and a disengaged state to the other depending on the hydraulic pressure supplied to the clutch 31.

[0036] Furthermore, the rotating shaft 41 of the motor generator 40 is connected to the drive wheels 63 via an automatic transmission 61 and a differential mechanism 62. The automatic transmission 61 is, for example, a stepped automatic transmission. The gear ratio of the automatic transmission 61 can be changed in steps. The differential mechanism 62 allows a difference in the rotational speed of the left and right drive wheels 63.

[0037] Vehicle electrical configuration

[0038] As in Figure 1As shown in FIG, vehicle 100 includes a battery 71 and an inverter 72. When motor generator 40 functions as a generator, battery 71 stores the power generated by motor generator 40. For example, when motor generator 40 performs regeneration, motor generator 40 functions as a generator. When motor generator 40 functions as a motor, battery 71 supplies power to motor generator 40. For example, when motor generator 40 performs power running, motor generator 40 functions as a motor. A second inverter 72 regulates the amount of power transferred between second motor generator 40 and battery 71.

[0039] As in Figure 1 As shown in FIG, the vehicle 100 includes 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 the driver. The vehicle speed sensor 82 detects a vehicle speed SP, which is the speed of the vehicle 100. The crank angle sensor 83 detects a crank angle SC, which is the angular position of the crankshaft 18.

[0040] As in Figure 1 As shown in FIG, vehicle 100 includes a controller 90. Controller 90 obtains a signal indicating an accelerator operation amount ACC from an accelerator operation amount sensor 81. Controller 90 obtains a signal indicating a vehicle speed SP from a vehicle speed sensor 82. Controller 90 obtains a signal indicating a crank angle SC from a crank angle sensor 83. Based on crank angle SC, controller 90 calculates an engine rotational speed NE. Engine rotational speed NE is the rotational speed of crankshaft 18.

[0041] Based on the accelerator operation amount ACC and the vehicle speed SP, the controller 90 calculates a vehicle requested driving force, which is a requested value of driving force for the vehicle 100 to travel. Based on the vehicle requested driving force, the controller 90 determines the torque distribution between the internal combustion engine 10 and the motor generator 40. Based on the torque distribution between the internal combustion engine 10 and the motor generator 40, the controller 90 controls the output of the internal combustion engine 10 and controls the power operation and regeneration of the motor generator 40.

[0042] The controller 90 outputs control signals to the internal combustion engine 10 to perform various controls, 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 direct injection valve 23, and adjusting the ignition timing of the ignition device 24. Furthermore, the controller 90 outputs control signals to the inverter 72 to control the motor generator 40. Furthermore, the controller 90 uses the inverter 72 to adjust the amount of electric power transferred between the second motor generator 40 and the battery 71, thereby controlling the motor generator 40.

[0043] The controller 90 outputs a control signal to the clutch 31 to control the connection state of the clutch 31. The controller 90 outputs a control signal to the automatic transmission 61 to control the gear ratio of the automatic transmission 61.

[0044] The controller 90 executes an automatic stop process of suspending combustion of fuel in the cylinder 11 and controlling the throttle valve 21 to be closed when a predetermined stop condition is satisfied. The stop condition is, for example, when the accelerator operation amount ACC becomes zero and the vehicle requested driving force becomes smaller than a predetermined value.

[0045] During the restart of the internal combustion engine 10, the controller 90 executes a delay process when a predetermined delay condition is satisfied. The delay process delays the injection of fuel into the cylinder 11 that has already entered the compression stroke at the time the delay condition is satisfied. For example, the delay condition is that the position of the piston 16 in the cylinder 11 that has already entered the compression stroke at the time the restart of the internal combustion engine 10 is requested is within a predetermined angular range. This predetermined angular range, for example, ranges from several tens of degrees of advancement of the injection start timing of the direct injection valve 23 to compression top dead center.

[0046] The controller 90 may be a circuit comprising one or more processors that execute various processes according to a computer program (software). The controller 90 may be a circuit comprising one or more dedicated hardware circuits such as application-specific integrated circuits (ASICs) that execute at least a portion of the various processes, or a combination thereof. The processor includes a CPU and a memory such as RAM and ROM. The memory stores program codes or instructions configured to cause the CPU to execute these processes. The memory or computer-readable medium includes any type of medium that can be accessed by general-purpose computers and special-purpose computers, such as tangible or non-transitory storage media.

[0047] Restart control

[0048] The restart control executed by the controller 90 will now be described. When a restart of the internal combustion engine 10 is requested in a state where the internal combustion engine 10 is stopped by the automatic stop process, the controller 90 executes the restart control. Restart of the internal combustion engine 10 is requested when, for example, the accelerator operation amount ACC becomes greater than zero and the vehicle requested driving force becomes greater than a predetermined value.

[0049] As in Figure 3 As shown in FIG, when the restart control is started, the controller 90 proceeds to the process of step S11. In step S11, the controller 90 determines whether the engine rotation speed NE obtained when the restart of the internal combustion engine 10 is requested is zero. In step S11, if the controller 90 determines that the engine rotation speed NE obtained when the restart of the internal combustion engine 10 is requested is zero (S11: YES), the controller 90 proceeds to the process of step S31.

[0050] In step S31, the controller 90 executes a cranking process. Specifically, the controller 90 first outputs a control signal to the clutch 31 to control the clutch 31 to be in an engaged state. By outputting a control signal to the inverter 72, the controller 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. As a result, the engine rotational speed NE increases. In other words, the controller 90 uses the motor generator 40 to crank the internal combustion engine 10. The controller 90 then proceeds to step S32.

[0051] In step S32, the controller 90 performs a setting process. Specifically, the controller 90 sets N, which is used in the intermediate calculation process of step S34, which will be described later. Hereinafter, N is an integer greater than or equal to 2. N used in the intermediate calculation process of step S34 is an integer greater than or equal to 3 and is a fixed value that has been set in advance.

[0052] Furthermore, in step S32, the controller 90 sets the initial combustion cylinder. The initial combustion cylinder refers to the cylinder 11 in which initial combustion occurs when the internal combustion engine 10 is restarted from a combustion paused state. For example, the controller 90 typically sets the cylinder 11 that has already entered the compression stroke when the internal combustion engine 10 is requested to restart as the initial combustion cylinder. In this embodiment, if the engine rotational speed NE obtained when the internal combustion engine 10 is requested to restart is zero, the controller 90 allows the above-mentioned delay process to be executed. Therefore, when executing the delay process, the controller 90 sets the following cylinder 11 as the initial combustion cylinder: the cylinder 11 that will enter the compression stroke after the cylinder 11 that has already entered the compression stroke when the internal combustion engine 10 is requested to restart. Hereinafter, the cylinder 11 in which combustion occurs after the initial combustion cylinder is simply referred to as the second combustion cylinder 11. Where the initial combustion cylinder is defined as the cylinder in which combustion occurs at the first time, the cylinder 11 in which combustion occurs at the Nth time is simply referred to as the Nth combustion cylinder 11. After step S32, the controller 90 advances the process to step S33.

[0053] In step S33, the controller 90 performs a first calculation process to calculate the amount of fuel injected into the primary combustion cylinder based on the position of the piston 16 in the primary combustion cylinder obtained when the internal combustion engine 10 is restarted. For example, as the piston 16 in the primary combustion cylinder approaches top dead center, the controller 90 calculates a smaller value as the amount of fuel injected into the primary combustion cylinder. The controller 90 obtains the position of the piston 16 in the primary combustion cylinder based on the crank angle SC. Based on the amount of fuel injected into the primary combustion cylinder calculated by the first calculation process, the controller 90 controls the port injection valve 22 and the direct injection valve 23. As a result, fuel is supplied to the primary combustion cylinder. Therefore, when the process of step S33 is executed, the engine rotational speed NE increases. After step S33, the controller 90 advances the process to step S34.

[0054] In step S34, the controller 90 performs an intermediate calculation process to calculate the amount of fuel injected into the second through Nth combustion cylinders 11. For example, as the engine rotational speed (NE) increases at the time step S34 is executed, the controller 90 calculates a smaller value for the amount of fuel injected into the second through Nth combustion cylinders 11. The controller 90 controls the port injection valve 22 and the direct injection valve 23 based on the amount of fuel injected into the cylinders 11 calculated by the intermediate calculation process. As a result, fuel is supplied to the cylinders 11. After step S34, the controller 90 advances the process to step S35.

[0055] In step S35, the controller 90 determines whether a predetermined end condition is satisfied. The end condition is, for example, that fuel has been injected into the Nth combustion cylinder 11. In step S35, if it is determined that the end condition is not satisfied (S35: No), the controller 90 performs the process of step S35 again. In step S35, if it is determined that the end condition is satisfied (S35: Yes), the controller 90 advances the process to step S36.

[0056] In step S36, the controller 90 performs a normal calculation process for calculating the amount of fuel injected into the (N+1)th and subsequent combustion cylinders. For example, as the engine rotational speed NE increases or as the vehicle requested driving force decreases, the controller 90 calculates a smaller value for the amount of fuel injected into the (N+1)th and subsequent combustion cylinders. The controller 90 controls the port injection valve 22 and the direct injection valve 23 based on the amount of fuel injected into the cylinder 11 calculated by the normal calculation process. As a result, fuel is supplied to the cylinder 11. After step S36, the controller 90 ends the current restart control. Even after the restart control ends, the controller 90 calculates the fuel injection amount by performing the normal calculation process.

[0057] In step S11 , in a case where the controller 90 determines that the engine rotation speed NE obtained when the restart of the internal combustion engine 10 is requested is higher than zero ( S11 : NO), the controller 90 advances the process to step S21 .

[0058] In step S21, the controller 90 determines whether the engine rotation speed NE obtained when the restart of the internal combustion engine 10 is requested is less than or equal to the prescribed rotation speed A that has been set in advance. The prescribed rotation speed A is, for example, several hundred revolutions per minute (rpm). For example, the prescribed rotation speed A is determined as follows. In order to restart the internal combustion engine 10, a test is first performed to obtain a lower limit value of the engine rotation speed NE that does not require the internal combustion engine 10 to be cranked by the electric generator 40. The prescribed rotation speed A is set to a value that is a certain rotation speed greater than the lower limit value of the obtained engine rotation speed NE. In step S21, in the case where the controller 90 determines that the engine rotation speed NE obtained when the restart of the internal combustion engine 10 is requested is less than or equal to the prescribed rotation speed A (S21: Yes), the controller 90 advances the process to step S41.

[0059] In step S41, the controller 90 performs a cranking process. The cranking process performed in step S41 is the same as that performed in step S31. Then, the controller 90 advances the process to step S42.

[0060] In step S42, the controller 90 performs a setting process. Specifically, the controller 90 sets N to be used in the intermediate calculation process of step S44, which will be described later. N used in the intermediate calculation process of step S44 is an integer greater than or equal to 2 and smaller than N used in the intermediate calculation process of step S34. In other words, the value of N used when the engine speed NE obtained when the restart of the internal combustion engine 10 is requested is higher than zero is smaller than the value of N used when the engine speed NE obtained when the restart of the internal combustion engine 10 is requested is zero. Furthermore, as the engine speed NE obtained when the restart of the internal combustion engine 10 is requested becomes higher, the controller 90 sets N used in the intermediate calculation process of step S44 to a smaller value. In other words, as the engine speed NE obtained when the restart of the internal combustion engine 10 is requested becomes higher, the value of N used when the engine speed NE obtained when the restart of the internal combustion engine 10 is requested becomes smaller.

[0061] Furthermore, in step S42, the controller 90 sets the initial combustion cylinder in which initial combustion occurs when the internal combustion engine 10 is restarted from a state where fuel combustion in cylinder 11 is suspended. For example, the controller 90 sets the cylinder 11 that has already entered the compression stroke when the restart of the internal combustion engine 10 is requested as the initial combustion cylinder. In this embodiment, if the engine speed NE obtained when the restart of the internal combustion engine 10 is requested is higher than zero, the controller 90 prohibits execution of the postponement process. Therefore, regardless of the postponement condition used to execute the postponement process, the controller 90 sets the cylinder 11 in which initial fuel injection is permitted after the restart of the internal combustion engine 10 is requested as the initial combustion cylinder. In other words, if the engine speed NE obtained when the restart of the internal combustion engine 10 is requested is higher than zero, the controller 90 sets the cylinder in which initial fuel injection is permitted after the request is made as the initial combustion cylinder. In this case, the setting is made regardless of the position of the piston 16 obtained when the request is made. After step S42, the controller 90 advances the process to step S43.

[0062] In step S43, the controller 90 executes a second calculation process to calculate the amount of fuel injected into the primary combustion cylinder based on the engine speed NE obtained when the restart of the internal combustion engine 10 is requested. For example, as the engine speed NE increases, the controller 90 calculates a smaller value for the amount of fuel injected into the primary combustion cylinder. The controller 90 controls the port injection valve 22 and the direct injection valve 23 based on the amount of fuel injected into the primary combustion cylinder calculated by the second calculation process. As a result, fuel is supplied to the primary combustion cylinder. Therefore, when executing the process of step S43, the engine speed NE increases. After step S43, the controller 90 advances the process to step S44.

[0063] In step S44, the controller 90 performs an intermediate calculation process for calculating the amount of fuel injected into the second to Nth combustion cylinders 11. The intermediate calculation process of step S44 is the same as that of step S34. After step S44, the controller 90 advances the process to step S45.

[0064] In step S45, the controller 90 determines whether a predetermined end condition is satisfied. The process of step S45 is the same as that of step S35. In step S45, if it is determined that the end condition is not satisfied (S45: No), the controller 90 performs the process of step S45 again. In step S45, if it is determined that the end condition is satisfied (S45: Yes), the controller 90 advances the process to step S46.

[0065] In step S46, the controller 90 performs a normal calculation process to calculate the amount of fuel injected into the (N+1)th and subsequent combustion cylinders. The normal calculation process of step S46 is the same as that of step S36. After step S46, the controller 90 ends the current restart control. Even after the restart control ends, the controller 90 continues to calculate the fuel injection amount by performing the normal calculation process.

[0066] In step S21 , in a case where the controller 90 determines that the engine rotation speed NE obtained when the restart of the internal combustion engine 10 is requested is higher than the prescribed rotation speed A ( S21 : NO), the controller 90 advances the process to step S51 .

[0067] In step S51, the controller 90 executes a disengagement process. Specifically, the controller 90 outputs a control signal to the clutch 31 to control the clutch 31's connected state to a disengaged state. If the clutch 31 is already in the disengaged state at the time the process of step S51 is executed, the controller 90 maintains the clutch 31 in this connected state. Therefore, after the process of step S51 is executed, no torque is applied from the motor generator 40 to the crankshaft 18. The controller 90 then proceeds to step S52.

[0068] In step S52, the controller 90 performs a setting process. The setting process of step S52 is the same as that of step S42. Then, the controller 90 advances the process to step S53.

[0069] In step S53, the controller 90 performs a second calculation process to calculate the amount of fuel injected into the primary combustion cylinder based on the engine speed NE obtained when restarting the internal combustion engine 10 is requested. The second calculation process of step S53 is identical to that of step S43. Similarly, the controller 90 controls the port injection valve 22 and the direct injection valve 23 based on the amount of fuel injected into the primary combustion cylinder calculated by the second calculation process. As a result, fuel is supplied to the primary combustion cylinder. Therefore, when the process of step S53 is executed, the engine speed NE increases. After step S53, the controller 90 advances the process to step S54.

[0070] In step S54, the controller 90 performs an intermediate calculation process for calculating the amount of fuel injected into the second to Nth combustion cylinders 11. The intermediate calculation process of step S54 is the same as that of step S34. After step S54, the controller 90 advances the process to step S55.

[0071] In step S55, the controller 90 determines whether a predetermined end condition is satisfied. The process of step S55 is the same as that of step S35. In step S55, if it is determined that the end condition is not satisfied (S55: No), the controller 90 performs the process of step S55 again. In step S55, if it is determined that the end condition is satisfied (S55: Yes), the controller 90 advances the process to step S56.

[0072] In step S56, the controller 90 performs a normal calculation process for calculating the amount of fuel injected into the (N+1)th and subsequent combustion cylinders. The normal calculation process of step S56 is the same as that of step S36. Then, the controller 90 advances the process to step S57.

[0073] In step S57, the controller 90 executes the engagement process. Specifically, the controller 90 outputs a control signal to the clutch 31 to control the clutch 31 to be in the engaged state. The controller 90 then ends the current restart control. Even after the restart control ends, the controller 90 calculates the fuel injection amount by executing the normal calculation process.

[0074] Operation of this embodiment

[0075] For example, in vehicle 100, the engine speed NE obtained when restarting the internal combustion engine 10 is requested may be higher than zero (S11: No). In this case, at the time when restarting the internal combustion engine 10 is requested, the throttle valve 21 is controlled to a closed state through the automatic stop process. Normally, even when the throttle valve 21 is controlled to a closed state, a small amount of gas can flow through the intake passage 12. Furthermore, in the internal combustion engine 10, the engine speed NE is higher than zero. Therefore, as each cylinder 11 repeats the intake stroke, compression stroke, combustion stroke, and exhaust stroke, gas flows through the intake passage 12, cylinder 11, and exhaust passage 13 in the following order. This flow of gas causes the pressure of the gas on the downstream side of the intake passage 12, as viewed from the throttle valve 21, to tend to decrease as the engine speed NE increases. As the engine speed NE increases, a smaller amount of intake air is drawn from the intake passage 12 into the cylinder 11. As a result, the amount of fuel to be supplied to the initial combustion cylinder is reduced.

[0076] Furthermore, as the engine rotational speed NE achieved when restarting the internal combustion engine 10 is requested becomes higher, the temperature in the cylinder 11 tends to increase. This makes it easier for the fuel supplied to the cylinder 11 to evaporate. Therefore, if the temperature in the cylinder 11 increases, the amount of fuel supplied to the cylinder 11 that collects on the inner wall surface of the cylinder 11 and the like due to non-evaporation of the fuel tends to decrease. As a result, the amount of fuel supplied to the cylinder that initially burns decreases.

[0077] Advantages of the embodiment

[0078] (1) In the event that the engine rotation speed NE obtained when the restart of the internal combustion engine 10 is requested is higher than zero (S11: No), the controller 90 uses the engine rotation speed NE (S21) to perform the second calculation process (S43 or S53) for calculating the amount of fuel injected into the first combustion cylinder. Therefore, the amount of fuel to be supplied to the first combustion cylinder, which changes according to the engine rotation speed NE, is taken into account to calculate the amount of fuel injected into the first combustion cylinder. This ensures that the restart of the internal combustion engine 10 is performed even if the engine rotation speed NE obtained when the restart of the internal combustion engine 10 is requested is higher than zero (S11: No).

[0079] (2) For example, in the vehicle 100, if the engine rotation speed NE obtained when the restart of the internal combustion engine 10 is requested is zero (S11: Yes) and the postponement condition for executing the postponement process is not satisfied, the cylinder 11 that has already entered the compression stroke when the restart of the internal combustion engine 10 is requested is set as the initial combustion cylinder. As the position of the piston 16 in the cylinder 11 that has already entered the compression stroke when the restart of the internal combustion engine 10 is requested becomes closer to the top dead center, the amount of intake air in the cylinder 11 that has already entered the compression stroke decreases. As a result, the amount of fuel to be supplied to the initial combustion cylinder decreases.

[0080] When the engine rotation speed NE obtained when the restart of the internal combustion engine 10 is requested is zero (S11: Yes), the controller 90 performs a first calculation process (S33) to calculate the amount of fuel injected into the first combustion cylinder based on the position of the piston 16 in the first combustion cylinder. Therefore, the amount of fuel to be supplied to the first combustion cylinder, which changes depending on the position of the piston 16 in the first combustion cylinder, is taken into consideration to calculate the amount of fuel injected into the first combustion cylinder.

[0081] (3) In the case where the engine rotation speed NE obtained when the restart of the internal combustion engine 10 is requested is zero (S11: Yes), the controller 90 performs the normal calculation process (S36) after the first calculation process (S33) and the intermediate calculation process (S34). In the case where the engine rotation speed NE obtained when the restart of the internal combustion engine 10 is higher than zero (S11: No), the controller 90 performs the normal calculation process after the second calculation process and the intermediate calculation process. In the intermediate calculation process, the controller 90 calculates the amount of fuel injected into the second combustion cylinder 11 to the N-th combustion cylinder 11. The value of N used in the case where the engine rotation speed NE obtained when the restart of the internal combustion engine 10 is higher than zero (S11: No) is smaller than the value of N used in the case where the engine rotation speed NE obtained when the restart of the internal combustion engine 10 is zero (S11: Yes). Therefore, when the engine speed NE obtained when the internal combustion engine 10 is requested to restart is higher than zero (S11: No), the calculation mode is switched from the intermediate calculation process to the normal calculation process (S46 or S56) more quickly than when the engine speed NE obtained when the internal combustion engine 10 is requested to restart (S11: Yes). That is, the restart of the internal combustion engine 10, in which the amount of injected fuel is calculated to be relatively large, is quickly completed, and the control of the internal combustion engine 10 returns to normal control. This reduces the amount of fuel consumed by restarting the internal combustion engine 10.

[0082] (4) In the intermediate calculation process, as the engine speed NE obtained when the restart of the internal combustion engine 10 is requested becomes higher, the value of N used in the case where the engine speed NE obtained when the restart of the internal combustion engine 10 is requested is higher than zero (S11: No) becomes smaller. Therefore, as the engine speed NE obtained when the restart of the internal combustion engine 10 is requested becomes higher, the calculation mode is switched from the intermediate calculation process to the normal calculation process more quickly. In other words, as the restart of the internal combustion engine 10 is completed more quickly, the mode of calculating the amount of consumed fuel is switched to the normal calculation process more quickly.

[0083] (5) In the case where the engine rotation speed NE obtained when the restart of the internal combustion engine 10 is requested is higher than zero (S11: No), the controller 90 prohibits the execution of the postponement process. Therefore, in the case where the engine rotation speed NE obtained when the restart of the internal combustion engine 10 is requested is higher than zero (S11: No), the controller 90 sets the cylinder in which the initial fuel injection is allowed after the request is made as the initial combustion cylinder. This setting is made regardless of the position of the piston 16 obtained when the request is made. If the postponement process is executed, there is a possibility that the cylinder 11 in which the fuel injection is allowed is not set as the initial combustion cylinder. This situation is prevented by the above configuration.

[0084] variants

[0085] The present embodiment can be modified as follows: The present embodiment and the following modifications can be combined as long as the combined modifications remain technically consistent with each other.

[0086] In the above embodiments, the processing contents of the restart control may be changed.

[0087] For example, N used in the intermediate calculation process may be changed. Specifically, in step S42, the controller 90 may set N used in the intermediate calculation process of step S44 to a fixed value regardless of the engine rotation speed NE obtained when the restart of the internal combustion engine 10 is requested. In this configuration, the value of N used in the intermediate calculation process of step S44 is preferably smaller than the value of N used in the intermediate calculation process of step S34.

[0088] Furthermore, for example, in step S42 , the controller 90 may set N used in the intermediate calculation process of step S44 to the same value as N used in the intermediate calculation process of step S34 .

[0089] For example, the end conditions of steps S35, S45, and S55 may be modified. Specifically, in addition to or in lieu of the condition that fuel has been injected into the Nth combustion cylinder 11, the end condition of step S35 may include a condition that the time period elapsed since the fuel was injected into the initial combustion cylinder reaches a predetermined time period that has been set in advance. The end conditions of steps S45 and S55 may be modified in the same manner. Alternatively, the end conditions of steps S35, S45, and S55 do not need to be the same and may be different from each other.

[0090] In the above embodiment, the controller 90 does not need to perform the delay process. That is, even when the engine speed NE obtained when the internal combustion engine 10 is requested to restart is zero (S11: Yes), the controller 90 can set the cylinder in which the initial fuel injection is allowed after the request is made as the initial combustion cylinder. This setting is made regardless of the position of the piston 16 when the request is made.

[0091] In the above embodiment, the configuration of the vehicle 100 may be changed.

[0092] For example, the vehicle 100 does not necessarily include the motor generator 40. Even in this configuration, in a case where the engine rotation speed NE obtained when the restart of the internal combustion engine 10 is requested is relatively high (S21: No), the internal combustion engine 10 can be restarted without applying torque from the motor generator 40. In a case where the engine rotation speed NE obtained when the restart of the internal combustion engine 10 is requested is zero (S11: Yes), the internal combustion engine 10 can be restarted by, for example, cranking using a starter motor.

[0093] For example, the internal combustion engine 10 may include five or fewer cylinders 11, or may include seven or more cylinders 11. Furthermore, for example, the internal combustion engine 10 does not necessarily need to include the port injection valve 22.

[0094] Various changes in form and detail may be made to the above examples without departing from the spirit and scope of the claims and their equivalents. The examples are for illustrative purposes only and are not intended to be limiting. The description of the features in each example should be considered applicable to similar features or aspects in other examples. Appropriate results may be achieved if the sequences are performed in a different order, and / or if the components in the described systems, systems, devices or circuits are combined differently, and / or replaced or supplemented by other components or their equivalents. The scope of this disclosure is not limited by the specific embodiments but by the claims and their equivalents. All changes within the scope of the claims and their equivalents are included in this disclosure.

Claims

1. A controller for an internal combustion engine, the controller comprising a control circuit, and the controller is used in the internal combustion engine, the internal combustion engine comprising: a cylinder in which fuel is burned, and an intake passage through which intake air is drawn in; an exhaust passage through which exhaust gas is discharged from the cylinder; a piston, each of which reciprocates in a corresponding one of the cylinders; a crankshaft, which rotates as the pistons reciprocate; a fuel injection valve, each of which supplies fuel to a corresponding one of the cylinders; and a throttle valve located in the intake passage to adjust an amount of intake air flowing through the intake passage, wherein The control circuit is configured to restart the internal combustion engine from a state where fuel combustion in the cylinders is suspended, wherein the cylinders include an initial combustion cylinder, and when the internal combustion engine is restarted from a state where fuel combustion in the cylinders is suspended, initial combustion is caused by the control circuit in the initial combustion cylinder, and The control circuit is configured to perform: an automatic stop process that, when a predetermined condition is satisfied, suspends fuel combustion in the cylinder and controls the throttle valve to a closed state; a first calculation process that calculates an amount of fuel injected into the first combustion cylinder based on a position of the piston in the first combustion cylinder in a case where a rotational speed of the crankshaft obtained when the restart is requested is zero; and a second calculation process of calculating, in a case where the rotation speed obtained when the restart is requested is higher than zero, the amount of fuel injected into the first combustion cylinder based on the rotation speed, in N is an integer greater than or equal to 2, The cylinders include a second combustion cylinder and an Nth combustion cylinder, The control circuit is further configured to perform: an intermediate calculation process that calculates an amount of fuel injected into the second combustion cylinder to the Nth combustion cylinder when restarting the internal combustion engine; and a general calculation process that calculates the amount of fuel injected into the (N+1)th combustion cylinder and subsequent combustion cylinders, and The control circuit is configured to set a value of N used in a case where the rotation speed obtained when the restart is requested is higher than zero to be smaller than a value of N used in a case where the rotation speed obtained when the restart is requested is zero.

2. The controller for an internal combustion engine according to claim 1, wherein The control circuit is configured to set the value of N used in a case where the rotation speed obtained when the restart is requested is higher than zero to be smaller as the rotation speed obtained when the restart is requested becomes higher.

3. The controller for an internal combustion engine according to claim 1 or 2, wherein: The control circuit is configured to set the cylinder for which initial fuel injection is permitted after requesting the restart as the initial combustion cylinder in a case where the rotational speed obtained when the restart is requested is higher than zero, the setting being independent of the position of the piston obtained when the restart is requested.

4. A control method for an internal combustion engine, the control method being used in the internal combustion engine, the internal combustion engine comprising: a cylinder in which fuel is burned, and an intake passage through which intake air is drawn in; an exhaust passage through which exhaust gas is discharged from the cylinder; a piston, each of the pistons reciprocating in a corresponding one of the cylinders; a crankshaft rotating as the pistons reciprocate; and a fuel injection valve, each of the fuel injection valves supplying fuel to a corresponding one of the cylinders; and a throttle valve located in the intake passage to adjust the amount of intake air flowing through the intake passage, the control method comprising: restarting the internal combustion engine from a state where fuel combustion in the cylinders is suspended, wherein the cylinders include an initial combustion cylinder in which initial combustion occurs when the internal combustion engine is restarted from a state where fuel combustion in the cylinders is suspended; When a predetermined condition is satisfied, suspending fuel combustion in the cylinder and controlling the throttle valve to be in a closed state; calculating an amount of fuel injected into the first combustion cylinder based on a position of the piston in the first combustion cylinder in a case where a rotational speed of the crankshaft obtained when the restart is requested is zero; and In the case where the rotational speed obtained when the restart is requested is higher than zero, the amount of fuel injected into the first combustion cylinder is calculated based on the rotational speed, wherein N is an integer greater than or equal to 2, The cylinders include a second combustion cylinder and an Nth combustion cylinder, The control method further includes: executing an intermediate calculation process that calculates an amount of fuel injected into the second combustion cylinder to the Nth combustion cylinder when restarting the internal combustion engine; and A normal calculation process is performed that calculates the amount of fuel injected into the (N+1)th combustion cylinder and subsequent combustion cylinders, and Here, the value of N used in a case where the rotation speed obtained when the restart is requested is higher than zero is set to be smaller than the value of N used in a case where the rotation speed obtained when the restart is requested is zero.

5. A non-transitory computer-readable storage medium storing a program for causing a processor to execute a control process for an internal combustion engine, the internal combustion engine comprising: a cylinder in which fuel is burned, and an intake passage through which intake air is drawn in; an exhaust passage through which exhaust gas is discharged from the cylinder; a piston, each of the pistons reciprocating in a corresponding one of the cylinders; a crankshaft rotating as the pistons reciprocate; and a fuel injection valve, each of the fuel injection valves supplying fuel to a corresponding one of the cylinders; and a throttle valve located in the intake passage to adjust the amount of intake air flowing through the intake passage, the control process comprising: restarting the internal combustion engine from a state where fuel combustion in the cylinders is suspended, wherein the cylinders include an initial combustion cylinder in which initial combustion occurs when the internal combustion engine is restarted from a state where fuel combustion in the cylinders is suspended; When a predetermined condition is satisfied, suspending fuel combustion in the cylinder and controlling the throttle valve to be in a closed state; calculating an amount of fuel injected into the first combustion cylinder based on a position of the piston in the first combustion cylinder in a case where a rotational speed of the crankshaft obtained when the restart is requested is zero; and In the case where the rotational speed obtained when the restart is requested is higher than zero, the amount of fuel injected into the first combustion cylinder is calculated based on the rotational speed, wherein N is an integer greater than or equal to 2, The cylinders include a second combustion cylinder and an Nth combustion cylinder, The control process also includes: executing an intermediate calculation process that calculates an amount of fuel injected into the second combustion cylinder to the Nth combustion cylinder when restarting the internal combustion engine; and A normal calculation process is performed that calculates the amount of fuel injected into the (N+1)th combustion cylinder and subsequent combustion cylinders, and Here, the value of N used in a case where the rotation speed obtained when the restart is requested is higher than zero is set to be smaller than the value of N used in a case where the rotation speed obtained when the restart is requested is zero.

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