Control device for internal combustion engine

Abstract

To optimize combustion at the time of engine start.SOLUTION: A control device 100 executes increase correction of fuel at the time of engine start of an internal combustion engine 10 including a catalyst in an exhaust passage. The control device 100 selects either one of high revolution start control and low revolution start control at the time of engine start. The high revolution start control is control of starting fuel injection and ignition in a state that an engine rotation speed is high compared to the low revolution start control. The control device 100 executes processing of setting a value of at least one of the initial value of increase correction of fuel and the attenuation of increase correction of fuel to a value different between the high revolution start control and the low revolution start control.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] For example, as described in Patent Document 1, fuel increment correction is performed at the time of engine startup.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, as a method of starting the engine, there are a high-speed start control in which fuel injection and ignition are started in a state where the engine rotation speed by cranking is high, and a low-speed start control in which fuel injection and ignition are started in a state where the engine rotation speed by cranking is lower than that of the high-speed start control. The high-speed start control is characterized in that, for example, the shock at the time of engine startup is small compared to the low-speed start control. Further, the low-speed start control is characterized in that, for example, the time from when a start request occurs until the engine startup is actually completed is short, that is, the so-called start response is good, compared to the high-speed start control.

[0005] Here, in the high-speed start control and the low-speed start control, the amount of air in the cylinder and the amount of oxygen occluded by the catalyst at the time of engine startup are different. Therefore, if the initial value and the attenuation amount regarding the fuel increment correction at the time of engine startup are made the same for the high-speed start control and the low-speed start control, it may be difficult to optimize combustion at the time of engine startup.

Means for Solving the Problems

[0006] The control device for an internal combustion engine that solves the above problems performs fuel increment correction at the start of the engine equipped with a catalyst in the exhaust passage. This control device selects either high-speed start control or low-speed start control at the start of the engine. The high-speed start control is a control that starts fuel injection and ignition in a state where the engine rotation speed is higher than that of the low-speed start control. Then, the control device executes a process of setting at least one of the initial value of the increment correction and the attenuation amount of the increment correction to different values between the high-speed start control and the low-speed start control.

[0007] According to the same configuration, when performing fuel increment correction at the start of the engine, at least one of the initial value and the attenuation amount regarding the increment correction is set to a value corresponding to the method of starting the engine. Therefore, it becomes possible to optimize combustion at the start of the engine.

[0008] In addition, when varying the initial value of the increment correction, it is possible to perform a fuel increment according to the amount of air in the cylinder at the start of the engine. Therefore, it is possible to optimize combustion so that there is no shock at startup due to an excess or deficiency of engine torque at the start of the engine.

[0009] Also, when varying the attenuation amount of the increment correction, it is possible to perform a fuel increment according to the amount of oxygen stored in the catalyst at the start of the engine. Therefore, it is possible to optimize combustion so that the oxygen storage amount of the catalyst becomes an appropriate amount.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Best Mode for Carrying Out the Invention

[0011] Hereinafter, an embodiment of a control device for an internal combustion engine will be described with reference to FIGS. 1 to 4. <Configuration of Vehicle> As shown in FIG. 1, the vehicle 500 is equipped with two prime movers such as an internal combustion engine 10 and an electric motor 30. The internal combustion engine 10 is provided with a fuel injection valve 12 for supplying fuel to the cylinders. The internal combustion engine 10 is provided with an intake passage 13. An electric throttle valve 14 for adjusting the intake air amount is provided in the intake passage 13. The internal combustion engine 10 is provided with an exhaust passage 16. A catalyst 17 for purifying the exhaust is provided in the exhaust passage 16. In the combustion chamber of the internal combustion engine 10, an engine output is obtained by burning a mixture of the inhaled air and the fuel injected from the fuel injection valve 12.

[0012] An electric starter motor 85 driven by receiving power supply from a low-voltage battery 310 is provided on the crankshaft 18 which is the output shaft of the internal combustion engine 10. Further, the crankshaft 18 is connected to the output shaft 41 of the electric motor 30 via a hydraulic clutch mechanism 20. A mechanical oil pump (hereinafter referred to as MOP) 50 driven by the electric motor 30 is provided on the output shaft 41. In addition, the vehicle 500 is also provided with an electric oil pump (hereinafter referred to as EOP) 80.

[0013] When the clutch mechanism 20 is in the engaged state, the crankshaft 18 and the output shaft 41 of the electric motor 30 are connected, while when in the released state, the connection between the crankshaft 18 and the output shaft 41 of the electric motor 30 is released.

[0014] The electric motor 30 exchanges electric power with a high-voltage battery 300 for driving via a PCU (Power Control Unit) 200. The PCU 200 includes a boost converter 210, an inverter 220, a DC-DC converter 230, etc. The boost converter 210 boosts and outputs the DC voltage input from the high-voltage battery 300. The inverter 220 converts the DC voltage boosted by the boost converter 210 into an AC voltage and outputs it to the motor 30. The DC-DC converter 230 steps down the DC voltage of the high-voltage battery 300 to a voltage for auxiliary drive.

[0015] The vehicle 500 includes the above-mentioned low-voltage battery 310 that stores the power stepped down by the DC-DC converter 230. Also, the PCU 200 detects the state of charge SOC of the high-voltage battery 300 (SOC = remaining capacity of the battery [Ah] / fully charged capacity of the battery [Ah] × 100%) and the state of charge SOC of the low-voltage battery 310.

[0016] The output shaft 41 of the motor 30 is connected to the input shaft of a torque converter 42 having a lock-up clutch 45. The output shaft of the torque converter 42 is connected to the input shaft of an automatic transmission 48. The output shaft of the automatic transmission 48 is connected to a differential gear 60. The drive wheels 65 of the vehicle 500 are connected to the output shaft of the differential gear 60.

[0017] The vehicle 500 includes a hydraulic adjustment mechanism 90 using the MOP 50 and the EOP 80 as a hydraulic source. Connected to the hydraulic adjustment mechanism 90 as destinations for hydraulic supply are the automatic transmission 48, the lock-up clutch 45, the clutch mechanism 20, etc. By controlling the hydraulic pressure supplied from the hydraulic adjustment mechanism 90, the shifting operation by the automatic transmission 48, the operation of the lock-up clutch 45, the operation of the clutch mechanism 20, etc. are controlled.

[0018] Various controls such as the control of the internal combustion engine 10, the control of the motor 30, and the control of the hydraulic adjustment mechanism 90 are executed by a control device 100 mounted on the vehicle 500. The control device 100 includes a central processing unit (hereinafter referred to as CPU) 110 and a memory 120 that stores control programs and data. Then, the CPU 110 executes the programs stored in the memory 120 to perform various controls. Although not shown in the figure, the control device 100 is composed of a plurality of control units such as a control unit for an internal combustion engine and a control unit for a PCU.

[0019] Connected to the control device 100 are a crank angle sensor 70 that detects the rotation angle of the crankshaft 18, and a rotation speed sensor 71 that detects the motor rotation speed Nm which is the rotation speed of the electric motor 30. Connected to the control device 100 are an air flow meter 72 that detects the intake air amount GA of the internal combustion engine 10, and a water temperature sensor 73 that detects the cooling water temperature THW which is the temperature of the cooling water of the internal combustion engine 10. Connected to the control device 100 are a throttle sensor 74 that detects the throttle opening TA which is the opening degree of the throttle valve 14, and an accelerator position sensor 75 that detects the accelerator operation amount ACCP which is the operation amount of the accelerator pedal. Connected to the control device 100 is a vehicle speed sensor 76 that detects the vehicle speed SP of the vehicle 500. Also, connected to the control device 100 is a power switch 77 for the driver of the vehicle 500 to start and stop the system of the vehicle 500. The control device 100 grasps the start request of the system of the vehicle 500 based on the input signal from the power switch 77. Note that the control device 100 calculates the engine rotation speed Ne based on the output signal Scr of the crank angle sensor 70. Also, the control device 100 calculates the engine load factor KL based on the engine rotation speed Ne and the intake air amount GA.

[0020] The above PCU 200 is connected to the control device 100, and the control device 100 controls the electric motor 30 through the control of the PCU 200. <Regarding the control device> The control device 100 calculates the vehicle required torque, which is the required value of the driving force of the vehicle 500, from the accelerator operation amount ACCP and the vehicle speed SP. Further, the control device 100 calculates, based on the vehicle required torque, the state of charge SOC, etc., the engine required torque, which is the required value of the output torque of the internal combustion engine 10, and the motor required torque, which is the required value of the power running torque of the electric motor 30, respectively. Then, the control device 100 performs output control of the internal combustion engine 10 according to the engine required torque and torque control of the electric motor 30 according to the motor required torque, thereby performing torque control necessary for the running of the vehicle 500.

[0021] When the control device 100 uses the internal combustion engine 10 as the prime mover of the vehicle 500, the clutch mechanism 20 is engaged to transmit the output torque of the internal combustion engine 10 to the automatic transmission 48. Also, in some cases, the electric motor 30 is also made to perform a power running operation, so that not only the output torque of the internal combustion engine 10 but also the power running torque of the electric motor 30 is transmitted to the automatic transmission 48. On the other hand, when the control device 100 uses only the electric motor 30 as the prime mover of the vehicle 500, the clutch mechanism 20 is released to cut off the torque transmission between the internal combustion engine 10 and the automatic transmission 48. Then, by making the electric motor 30 perform a power running operation, the power running torque of the electric motor 30 is transmitted to the automatic transmission 48. Thus, when only the electric motor 30 is used as the prime mover of the vehicle 500, the operation of the internal combustion engine 10 is stopped. In this way, during the operation of the vehicle 500, intermittent operation and intermittent stop in which the operation and the stop of the internal combustion engine 10 are repeated are carried out.

[0022] The control device 100 performs regenerative control during coasting (inertial running) when the accelerator is off (the state where the accelerator operation amount ACCP is "0") and during braking by depressing the brake pedal. This regenerative control is control that uses the kinetic energy transmitted from the drive wheels 65 to rotate the electric motor 30 so that the electric motor 30 functions as a generator, and stores the generated electric power in the high-voltage battery 300. When performing regenerative control, the control device 100 engages the lock-up clutch 45 and basically releases the clutch mechanism 20 in order to reduce the rotational resistance.

[0023] When there is a starting request for the internal combustion engine 10, the control device 100 selects one of a plurality of engine starting modes described later and starts cranking the internal combustion engine 10. Then, fuel injection and ignition are started to start the engine.

[0024] Note that the starting requests include a first starting request and an intermittent starting request. The first starting request is the first starting request after the power switch 77 is turned on. At the time when the first starting request occurs, the electric motor 30 is not rotating yet.

[0025] The intermittent starting request is a starting request due to the above-described intermittent operation. At the time when the intermittent starting request occurs, the electric motor 30 is in a rotating state. Examples of when the intermittent starting request occurs include, for example, when a vehicle driving torque that cannot be compensated only by the torque of the electric motor 30 is required when the operation of the internal combustion engine 10 is stopped. Further, examples of when the intermittent starting request occurs include, for example, when a charging request for the high-voltage battery 300 occurs, when a charging request for the low-voltage battery 310 occurs, and the like.

[0026] And the control device 100 performs an increment correction of fuel during fuel injection at engine start. This increment correction of fuel is performed as follows. That is, the control device 100 calculates the fuel injection amount Q every predetermined calculation cycle based on the following formula (1) until a predetermined period elapses after starting the engine start. Then, the fuel injection valve 12 is controlled so that the calculated fuel injection amount Q is injected.

[0027] Fuel injection amount Q = basic injection amount Qb × increment coefficient K... (1) The basic injection amount Qb is a value calculated based on the coolant temperature THW when the engine starting request occurs. The control device 100 calculates the basic injection amount Qb so that the value of the basic injection amount Qb becomes larger as the coolant temperature THW is lower.

[0028] The increment coefficient K is a coefficient for performing fuel increment correction until a predetermined period elapses after the start of engine startup, and a value of "1" or more is set. Then, the increment coefficient K is calculated for each predetermined calculation cycle based on the following formula (2).

[0029] Increment coefficient K = Previous increment coefficient K × Decay coefficient Kg…(2) The calculation of the initial increment value Ks, which is the initial value of the increment coefficient K, will be described later.

[0030] Also, the calculation of the decay coefficient Kg corresponding to the decay amount for gradually reducing the fuel increment correction amount will be described later. Note that the decay coefficient Kg is a value greater than "0" and less than "1". When the value of the decay coefficient Kg is large, the value of the increment coefficient K calculated from the above formula (2) becomes larger compared to the case where the value of the decay coefficient Kg is small. When the value of the increment coefficient K becomes large, the value of the fuel injection amount Q calculated from the above formula (1) becomes larger compared to the case where the value of the increment coefficient K is small. That is, when the value of the decay coefficient Kg is large, the decay amount per unit time for the fuel increment correction amount becomes small.

[0031] <Regarding the engine startup mode> FIG. 2 shows a first mode, a second mode, a third mode, and a fourth mode, which are a plurality of engine startup modes implemented by the control device 100.

[0032] The first mode and the second mode are engine startup modes selected at the first startup implemented due to the occurrence of the first startup request. The first mode is the mode selected when the coolant temperature THW is equal to or higher than a predetermined temperature. In the first mode, when a first start request occurs, the clutch mechanism 20 is engaged. Then, when the engagement of the clutch mechanism 20 is completed, the motor 30 is driven, so that both the engine rotation speed Ne and the motor rotation speed Nm increase, and cranking of the internal combustion engine 10 is performed. Then, when the engine rotation speed Ne reaches a predetermined rotation speed, fuel injection and ignition are started, and the engine is started. In this first mode, the engagement shock of the clutch mechanism 20 is less likely to occur. Also, since fuel injection and ignition are started after the engine rotation speed Ne has increased to a certain extent, the mixing of the air-fuel mixture proceeds easily, and thus the exhaust emission is improved.

[0033] The second mode is the mode selected when the coolant temperature THW is lower than the above-mentioned predetermined temperature. In the second mode, when a first start request occurs, the clutch mechanism 20 is released. If the clutch mechanism 20 is in the released state when the first start request occurs, that released state is maintained. Then, when the starter motor 85 is driven, cranking of the internal combustion engine 10 is started. Then, when the crank angle of the crankshaft 18 is determined, fuel injection and ignition are started, and the engine is started. In this second mode, cranking is performed using the starter motor 85. This is because in a low-temperature environment, the torque of the motor 30 decreases, making it difficult to increase the engine rotation speed Ne to the above-mentioned predetermined rotation speed. Thus, the second mode is a mode for starting in a low temperature.

[0034] The above-mentioned first mode is a control in which fuel injection and ignition are started in a state where the engine rotation speed is higher compared to the above-mentioned second mode. The first mode is high-speed start control, and the second mode is low-speed start control.

[0035] The third mode and the fourth mode are engine start modes selected during intermittent starting that is implemented due to an intermittent start request occurring. The third mode is a mode selected when an intermittent start request without urgency occurs, for example, when a charging request for the high-voltage battery 300 occurs, or when a charging request for the low-voltage battery 310 occurs. In the third mode, when an intermittent start request occurs, the clutch mechanism 20 that was in the released state is put into the slip state. When the clutch mechanism 20 is in the slip state, torque transmission from the electric motor 30 to the internal combustion engine 10 is performed and cranking of the internal combustion engine 10 is performed, whereby the engine rotational speed Ne increases. Then, when the engine rotational speed Ne reaches the motor rotational speed Nm and their rotational speeds are synchronized, the state of the clutch mechanism 20 is changed from the slip state to the engaged state and fuel injection and ignition are started, thereby starting the engine. This third mode is easy to synchronize the clutch mechanism 20 and is less likely to cause shock during starting.

[0036] The fourth mode is a mode selected when an intermittent start request with urgency occurs, for example, when a vehicle drive torque that cannot be compensated only by the torque of the electric motor 30 is requested when the operation of the internal combustion engine 10 has stopped. In the fourth mode, when an intermittent start request occurs, the clutch mechanism 20 that was in the released state is put into the slip state. When the clutch mechanism 20 is in the slip state, torque transmission from the electric motor 30 to the internal combustion engine 10 is performed and cranking of the internal combustion engine 10 is started. Then, when the crank angle of the crankshaft 18 is determined, fuel injection and ignition are started, thereby starting the engine. This fourth mode is difficult to synchronize the clutch mechanism 20 and is likely to cause shock during starting, but it has the characteristic that the time from when the start request occurs until the engine start is actually completed is short, that is, the so-called starting response is good.

[0037] The above third mode is a control in which fuel injection and ignition are started in a state where the engine rotational speed is higher compared to the above fourth mode. The third mode is high-speed start control, and the fourth mode is low-speed start control.

[0038] When performing high-speed start control (first mode and third mode), the opening degree of the throttle valve 14 is adjusted so that the amount of air in the cylinder when starting the engine is less than when performing low-speed start control (second mode and fourth mode). This is, for example, to suppress the surging of the engine rotation speed during engine starting by high-speed start control.

[0039] High-speed start control is characterized by, for example, less shock during engine starting compared to low-speed start control. Also, low-speed start control is characterized by, for example, a short so-called start response time, that is, the time from when a start request occurs until the engine actually starts is short, compared to high-speed start control.

[0040] Here, in high-speed start control and low-speed start control, as described above, the amount of air in the cylinder at the time of engine starting is different. Also, when performing high-speed start control, compared to when performing low-speed start control, the number of rotations of the crankshaft 18 from the start of cranking until the engine start is initiated increases. When the number of rotations of the crankshaft 18 during this cranking increases, the amount of fresh air passing through the catalyst 17 increases, so there is a possibility that the oxygen storage amount of the catalyst 17 becomes more than the appropriate amount.

[0041] Therefore, if the initial increment value Ks and the attenuation coefficient Kg regarding the fuel increment correction at the time of engine starting are made the same for high-speed start control and low-speed start control, it may become difficult to optimize combustion at the time of engine starting.

[0042] For example, if the initial increment value Ks is made the same, it is not possible to perform fuel increment according to the amount of air in the cylinder at the time of engine starting. Therefore, combustion cannot be optimized, and there is a possibility that an excess or deficiency of engine torque occurs at the time of engine starting and a shock occurs during starting.

[0043] In addition, if the attenuation coefficient Kg is made the same for high-speed start control and low-speed start control, there is a concern that the following inconveniences may occur. That is, the oxygen stored in the catalyst 17 at the time of engine start is released when the catalyst 17 is exposed to a reducing atmosphere due to an increase in fuel. Therefore, when the amount of oxygen stored in the catalyst 17 at the time of engine start is large, it is desirable to increase the attenuation coefficient Kg. As described above, when the attenuation coefficient Kg is increased, the attenuation amount per unit time of the fuel increment correction amount becomes smaller compared to the case where the attenuation coefficient Kg is decreased. This is because when the attenuation amount per unit time decreases, the period during which the fuel increment correction is executed becomes longer, and thereby the amount of oxygen released from the catalyst 17 increases.

[0044] Therefore, if the attenuation coefficient Kg is made the same for high-speed start control and low-speed start control, it is not possible to perform a fuel increment corresponding to the amount of oxygen stored in the catalyst 17 at the time of engine start. Therefore, there is a possibility that combustion cannot be optimized so that the oxygen storage amount of the catalyst 17 becomes an appropriate amount.

[0045] Therefore, the control device 100 executes a process of setting different values for the increment initial value Ks and the attenuation coefficient Kg for high-speed start control and low-speed start control. <Calculation process of increment initial value> FIG. 3 shows the procedure of the calculation process of the increment initial value Ks executed by the control device 100. When a start request for the internal combustion engine 10 occurs, the control device 100 starts executing this process. In the following, step numbers are represented by numbers preceded by "S".

[0046] When starting the process shown in FIG. 3, the control device 100 determines whether the current start request is the first start request (S100). If it is determined that it is the first start request (S100: YES), the control device 100 determines whether the currently selected start mode is the first mode (S110). If it is determined that it is the first mode (S110: YES), the control device 100 calculates the increment initial value Ks based on the first initial value map (S120).

[0047] The first initial value map is map data prepared in advance to calculate the increment initial value Ks optimized for engine starting in the first mode. In this first initial value map, data for calculating the increment initial value Ks based on the coolant water temperature THW at the time when a start request occurs and the throttle opening TA at the time of engine starting is recorded. And in this first initial value map, the value of the increment initial value Ks is set such that the lower the coolant water temperature THW or the larger the throttle opening TA, the larger the calculated value of the increment initial value Ks. The reason why the value of the increment initial value Ks is increased as the coolant water temperature THW is lower is that the amount of fuel contributing to combustion decreases as the coolant water temperature THW is lower. Also, the reason why the value of the increment initial value Ks is increased as the throttle opening TA is larger is that the amount of air in the cylinder increases as the throttle opening TA is larger, and thus it is necessary to supply an amount of fuel corresponding to that air amount into the cylinder.

[0048] In the process of S110, when it is determined that it is not the first mode (S110: NO), the control device 100 calculates the increment initial value Ks based on the second initial value map (S130). The second initial value map is map data prepared in advance to calculate the increment initial value Ks optimized for engine starting in the second mode. In this second initial value map, data for calculating the increment initial value Ks based on the coolant water temperature THW at the time when a start request occurs and the throttle opening TA at the time of engine starting is recorded. And in this second initial value map, the value of the increment initial value Ks is set such that the lower the coolant water temperature THW or the larger the throttle opening TA, the larger the calculated value of the increment initial value Ks.

[0049] Also, even when the coolant water temperature THW and the throttle opening TA are the same, the increment initial value Ks calculated based on the first initial value map is preset to be smaller than the increment initial value Ks calculated based on the second initial value map. That is, the increment initial value Ks when high-speed start control is performed at the first start is calculated to be smaller than the increment initial value Ks when low-speed start control is performed at the first start.

[0050] In the process of S100, when it is determined that it is not the first start request (S100: NO), the control device 100 determines whether the currently selected start mode is the third mode (S140). And when it is determined that it is the third mode (S140: YES), the control device 100 calculates the increment initial value Ks based on the third initial value map (S150).

[0051] The third initial value map is map data prepared in advance to calculate the increment initial value Ks optimized for engine start in the third mode. In this third initial value map, data for calculating the increment initial value Ks based on the coolant water temperature THW when the start request occurs and the intermittent stop time Ts, which is the intermittent stop time before the current start request occurs, is recorded. And in this third initial value map, the value of the increment initial value Ks is set so that the lower the coolant water temperature THW or the longer the intermittent stop time Ts, the larger the calculated value of the increment initial value Ks. The reason why the value of the increment initial value Ks is increased as the coolant water temperature THW is lower is that the lower the coolant water temperature THW, the less the amount of fuel contributing to combustion. Also, the reason why the value of the increment initial value Ks is increased as the intermittent stop time Ts is longer is as follows. That is, the longer the intermittent stop time Ts, the more oxygen the catalyst 17 stores during engine stop. Therefore, more fuel is required to release more oxygen from the catalyst 17.

[0052] In the process of S140, when it is determined that it is not the third mode (S140: NO), the control device 100 calculates the increment initial value Ks based on the fourth initial value map (S160). The fourth initial value map is map data prepared in advance to calculate the increment initial value Ks optimized for engine start in the fourth mode. In this fourth initial value map, data for calculating the increment initial value Ks based on the coolant water temperature THW at the time when a start request occurs and the above intermittent stop time Ts is recorded. And in this fourth initial value map, the value of the increment initial value Ks is set such that the lower the coolant water temperature THW or the longer the intermittent stop time Ts, the larger the calculated value of the increment initial value Ks.

[0053] Also, even if the coolant water temperature THW and the intermittent stop time Ts are the same, the increment initial value Ks calculated based on the third initial value map is set in advance to be smaller than the increment initial value Ks calculated based on the fourth initial value map. That is, the increment initial value Ks when high-speed start control is performed during intermittent start is calculated to be smaller than the increment initial value Ks when low-speed start control is performed during intermittent start.

[0054] And when any one of the processes of S120, S130, S150, and S160 is completed, the control device 100 ends this process. <Calculation process of attenuation coefficient> FIG. 4 shows the procedure for the calculation process of the attenuation coefficient Kg executed by the control device 100. When a start request for the internal combustion engine 10 occurs, the control device 100 repeatedly executes this process at a predetermined calculation cycle. When a predetermined end condition for ending the fuel increment at start is satisfied, the execution of this process ends.

[0055] When starting the process shown in FIG. 4, the control device 100 determines whether the current start request is the first start request (S200). And when it is determined that it is the first start request (S200: YES), the control device 100 determines whether the currently selected start mode is the first mode (S210). And when it is determined that it is the first mode (S210: YES), the control device 100 calculates the attenuation coefficient Kg based on the first attenuation coefficient map (S220).

[0056] The first attenuation coefficient map is map data prepared in advance to calculate the attenuation coefficient Kg optimized for engine starting in the first mode. In this first attenuation coefficient map, data for calculating the attenuation coefficient Kg based on the coolant water temperature THW acquired for each execution cycle of this process is recorded. And in this first attenuation coefficient map, the value of the attenuation coefficient Kg is set such that the lower the coolant water temperature THW, the larger the calculated value of the attenuation coefficient Kg. The reason why the value of the attenuation coefficient Kg is increased as the coolant water temperature THW decreases is that the amount of fuel contributing to combustion decreases as the coolant water temperature THW decreases, so it is necessary to perform fuel increment correction for a longer period.

[0057] In the process of S210, when it is determined that it is not in the first mode (S210: NO), the control device 100 calculates the attenuation coefficient Kg based on the second attenuation coefficient map (S230). The second attenuation coefficient map is map data prepared in advance to calculate the attenuation coefficient Kg optimized for engine starting in the second mode. In this second attenuation coefficient map, data for calculating the attenuation coefficient Kg based on the coolant water temperature THW acquired for each execution cycle of this process is recorded. And in this second attenuation coefficient map, the value of the attenuation coefficient Kg is set such that the lower the coolant water temperature THW, the larger the calculated value of the attenuation coefficient Kg.

[0058] Also, even when the coolant water temperature THW is the same, the attenuation coefficient Kg calculated based on the first attenuation coefficient map is set in advance to be a larger value than the attenuation coefficient Kg calculated based on the second attenuation coefficient map. That is, the attenuation coefficient Kg when high-speed starting control is performed at the first start is calculated to be a larger value than the attenuation coefficient Kg when low-speed starting control is performed at the first start.

[0059] In the process of S200, when it is determined that it is not the first startup request (S200: NO), the control device 100 determines whether the currently selected startup mode is the third mode (S240). And when it is determined that it is the third mode (S240: YES), the control device 100 calculates the attenuation coefficient Kg based on the third attenuation coefficient map (S250).

[0060] The third attenuation coefficient map is map data prepared in advance to calculate the attenuation coefficient Kg optimized for engine startup in the third mode. In this third attenuation coefficient map, data for calculating the attenuation coefficient Kg based on the coolant temperature THW acquired for each execution cycle of this process and the above intermittent stop time Ts is recorded. And in this third attenuation coefficient map, the value of the attenuation coefficient Kg is set so that the lower the coolant temperature THW or the longer the intermittent stop time Ts, the larger the calculated value of the attenuation coefficient Kg. The reason why the value of the attenuation coefficient Kg is increased as the coolant temperature THW is lower is that as the coolant temperature THW is lower, the amount of fuel contributing to combustion decreases, so it is necessary to perform the fuel increment correction for a longer period. Also, the reason why the value of the attenuation coefficient Kg is increased as the intermittent stop time Ts is longer is as follows. That is, as the intermittent stop time Ts is longer, the amount of oxygen adsorbed by the catalyst 17 during engine stop increases, so in order to release more oxygen from the catalyst 17, it is necessary to perform the fuel increment correction for a longer period.

[0061] In the process of S240, when it is determined that it is not the third mode (S240: NO), the control device 100 calculates the attenuation coefficient Kg based on the fourth attenuation coefficient map (S260). The fourth attenuation coefficient map is map data prepared in advance to calculate the attenuation coefficient Kg optimized for engine starting in the fourth mode. In this fourth attenuation coefficient map, data for calculating the attenuation coefficient Kg based on the coolant water temperature THW acquired for each execution cycle of this process and the above intermittent stop time Ts is recorded. And in this fourth attenuation coefficient map, the value of the attenuation coefficient Kg is set such that the lower the coolant water temperature THW or the longer the intermittent stop time Ts, the larger the calculated value of the attenuation coefficient Kg.

[0062] Also, even when the coolant water temperature THW and the intermittent stop time Ts are the same, the attenuation coefficient Kg calculated based on the third attenuation coefficient map is set in advance to be a larger value than the attenuation coefficient Kg calculated based on the fourth attenuation coefficient map. That is, the attenuation coefficient Kg when high-speed start control is implemented during intermittent starting is calculated to be a larger value than the attenuation coefficient Kg when low-speed start control is implemented during intermittent starting.

[0063] And when any one of the processes of S220, S230, S250, and S260 ends, the control device 100 temporarily ends this process. <Operation and Effect> According to this embodiment, the following operations and effects can be obtained.

[0064] (1) As described above, when high-speed start control (the first mode and the third mode) is implemented, the amount of air in the cylinder when starting the engine is less than when low-speed start control (the second mode and the fourth mode) is implemented. Therefore, the increment initial value Ks set when high-speed start control is implemented, where the amount of air in the cylinder when starting the engine is less than when low-speed start control is implemented, is calculated to be smaller than the value of the increment initial value Ks set when low-speed start control is implemented. Therefore, fuel increment correction according to the amount of air in the cylinder at engine start is performed, and thus combustion can be optimized so that no shock occurs at start due to an excess or deficiency of engine torque at engine start.

[0065] (2) As described above, when performing high-speed starting control (the first mode and the third mode), there is a possibility that the oxygen storage amount of the catalyst 17 may become larger than the appropriate amount compared to the case of performing low-speed starting control (the second mode and the fourth mode). Therefore, the attenuation coefficient Kg set during the execution of high-speed starting control is calculated to be larger than the value of the attenuation coefficient Kg set during the execution of low-speed starting control. Accordingly, the fuel increment is performed according to the amount of oxygen stored by the catalyst 17 at the time of engine starting, and the combustion can be optimized so that the oxygen storage amount of the catalyst 17 becomes an appropriate amount.

[0066] <Modified Example> Note that the above embodiment can be implemented with the following modifications. The above embodiment and the following modified examples can be implemented in combination with each other as long as there is no technical contradiction.

[0067] 》When calculating the increment initial value Ks, the throttle opening TA and the intermittent stop time Ts may be omitted. 》When calculating the attenuation coefficient Kg, the intermittent stop time Ts may be omitted.

[0068] 》The increment initial value Ks and the attenuation coefficient Kg may be calculated by a function formula. 》Either one of the increment initial value Ks and the attenuation coefficient Kg may be made different between high-speed starting control and low-speed starting control.

[0069] 》The hybrid system of the vehicle 500 is not limited to the one shown in FIG. 1, and other hybrid systems may also be used. · The control device 100 includes a CPU 110 and a memory 120, and is not limited to executing software processing. For example, it may include a dedicated hardware circuit (such as an ASIC, etc.) that processes at least a part of the software processing executed in the above embodiment. That is, the control device 100 may have any of the following configurations (a) to (c). (a) It includes a processing device that executes all of the above processing according to a program, and a program storage device such as a memory that stores the program. (b) It includes a processing device and a program storage device that execute a part of the above processing according to a program, and a dedicated hardware circuit that executes the remaining processing. (c) It includes a dedicated hardware circuit that executes all of the above processing. Here, there may be a plurality of software processing circuits and dedicated hardware circuits including a processing device and a program storage device. That is, the above processing may be executed by a processing circuit including at least one of one or more software processing circuits and one or more dedicated hardware circuits.

Explanation of Signs

[0070] 10… Internal combustion engine 12… Fuel injection valve 13… Intake passage 14… Throttle valve 16… Exhaust passage 17… Catalyst 18… Crankshaft 20… Clutch mechanism 30… Electric motor 42… Torque converter 45… Lock-up clutch 48… Automatic transmission 50… Mechanical oil pump 60… Differential gear 65… Driving wheel 80… Electric oil pump 85… Starter motor 90… Hydraulic adjustment mechanism 100… Control device 110… Central processing unit 120… Memory 200… PCU 500… vehicle

Claims

【Claim 1】 A control device that performs fuel increment correction at the start of an internal combustion engine equipped with a catalyst in an exhaust passage, selects either high-speed start control or low-speed start control at the start of the engine, and the high-speed start control is control to start fuel injection and ignition in a state where the engine rotation speed is higher than that of the low-speed start control, executes a process of setting the attenuation amount per unit time of the increment correction when the high-speed start control is performed to be less than the attenuation amount per unit time when the low-speed start control is performed A control device for an internal combustion engine.

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