Control device for internal combustion engine

Abstract

To suppress the enrichment of an air fuel ratio when performing deposit removing control.SOLUTION: A control device 70 executes fuel injection by a port injection valve 16 only during idling operation of an internal combustion engine 10, and when the fuel injection is continuously executed over a predetermined period by the port injection valve 16 only, performs deposit removing control to stop the fuel injection from the port injection valve 16 and execute fuel injection by a cylinder injection valve 22 only. When the required injection amount of the internal combustion engine 10 is smaller than the minimum injection amount of the cylinder injection valve 22 during performing the deposit removing control, the control device 70 executes a treatment to change the operating condition of the internal combustion engine 10 so as to increase the required injection amount.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] For example, the internal combustion engine described in Patent Document 1 includes a port injection valve that injects fuel into an intake port and an in-cylinder injection valve that injects fuel into a cylinder. During idling operation, fuel injection is performed only through the port injection valve. Furthermore, when fuel injection only through the port injection valve has been performed continuously for a predetermined period during idling operation, deposit removal control is performed. The deposit removal control is a control for removing deposits adhering to the in-cylinder injection valve by stopping fuel injection from the port injection valve and performing fuel injection from the in-cylinder injection valve. The deposit removal control is also a control for suppressing the accumulation of deposits in the in-cylinder injection valve. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2010-37959 A Summary of the Invention [Problem to be solved by the invention]

[0004] For example, in a vehicle equipped with a vehicle drive motor and an internal combustion engine that receive power from a high-voltage battery, i.e., a vehicle equipped with a so-called HEV system, the load of accessories such as an air conditioner and an alternator on the internal combustion engine is smaller than that of a vehicle equipped with only an internal combustion engine. Therefore, the engine load during idling is smaller than that of a vehicle equipped with only an internal combustion engine. In such an internal combustion engine with a small engine load during idling, the required injection amount is small. Here, when the deposit removal control is executed, it is necessary to increase the fuel pressure of the fuel supplied to the in-cylinder injection valve to a certain extent. However, if the fuel pressure of the fuel is increased, the minimum injection amount of the in-cylinder injection valve increases, and the required injection amount may become smaller than the minimum injection amount. If the required injection amount becomes smaller than the minimum injection amount, an excess of fuel is injected by the difference between the required injection amount and the minimum injection amount, and the air-fuel ratio may become richer than the theoretical air-fuel ratio. [Means for solving the problem]

[0005] A control device for an internal combustion engine that solves the above problems includes a port injection valve that injects fuel into an intake port and an in-cylinder injection valve that injects fuel into a cylinder, and during idling operation, performs fuel injection only through the port injection valve, and when fuel injection only through the port injection valve has been continuously performed for a predetermined period of time, performs deposit removal control by stopping fuel injection from the port injection valve and performing fuel injection only through the in-cylinder injection valve. This control device performs a change process when a required injection amount of the internal combustion engine is less than a minimum injection amount of the in-cylinder injection valve during the execution of the deposit removal control, and the change process changes the operating state of the internal combustion engine so that the required injection amount is increased compared to before the change process was performed.

[0006] A control device for an internal combustion engine that solves the above problems includes a port injection valve that injects fuel into an intake port and an in-cylinder injection valve that injects fuel into a cylinder, and during idling operation, performs fuel injection only through the port injection valve, and when fuel injection only through the port injection valve has been continuously performed for a predetermined period of time, performs deposit removal control that stops fuel injection from the port injection valve and performs fuel injection only through the in-cylinder injection valve. This control device performs air-fuel ratio feedback control that corrects the amount of fuel supplied to the internal combustion engine with an air-fuel ratio correction value, and performs an adjustment process to adjust the fuel pressure of the fuel supplied to the in-cylinder injection valve when the required injection amount of the internal combustion engine is less than the minimum injection amount of the in-cylinder injection valve during the deposit removal control. Then, as the adjustment process, the control device adjusts the fuel pressure to a pressure at which the fuel injection amount of the in-cylinder injection valve is minimized, and then executes a process to gradually increase the fuel pressure if the logical product of the condition that the air-fuel ratio of the mixture detected by the sensor is an air-fuel ratio richer than the stoichiometric air-fuel ratio and the condition that the air-fuel ratio correction value is a value that corrects the fuel to reduce the amount of fuel is not true. Effect of the Invention

[0007] According to the present invention, it is possible to suppress the air-fuel ratio from becoming rich when deposit removal control is performed. [Brief description of the drawings]

[0008] [Figure 1] 1 is a schematic diagram showing the configuration of an internal combustion engine, a drive system, and a control device in a first embodiment. [Diagram 2] 4 is a flowchart showing the procedure of a process executed by the control device of the embodiment. [Diagram 3] 10 is a flowchart showing the procedure of a process executed by a control device of a second embodiment. [Figure 4] 13 is a flowchart showing the procedure of a process executed by a control device according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] (First embodiment) Hereinafter, a first embodiment of a control device for an internal combustion engine will be described with reference to the drawings. <Configuration of the internal combustion engine, drive system, and control device> As shown in FIG. 1, an internal combustion engine 10 mounted on a vehicle is, for example, an in-line four-cylinder internal combustion engine having four cylinders, #1 to #4.

[0010] A throttle valve 14 is provided in an intake passage 12 of the internal combustion engine 10. An intake port 12a, which is a downstream portion of the intake passage 12, is provided with a port injection valve 16 for performing port injection, which injects fuel into the intake port 12a. Air drawn into the intake passage 12 and fuel injected from the port injection valve 16 flow into a combustion chamber 20 when an intake valve 18 opens. Fuel is also injected into the combustion chamber 20 from an in-cylinder injection valve 22 for in-cylinder injection. A fuel pressure P, which is the pressure of the fuel supplied to the in-cylinder injection valve 22, is adjusted by a high-pressure pump 25. The mixture of air and fuel in the combustion chamber 20 is burned in association with spark discharge from an ignition plug 24. The combustion energy generated at this time is converted into the rotational energy of a crankshaft 26.

[0011] The air-fuel mixture burned in the combustion chamber 20 is discharged as exhaust gas into an exhaust passage 30 when the exhaust valve 28 opens. A catalyst 32 having an oxygen storage capacity is provided in the exhaust passage 30. When combustion is performed near the theoretical air-fuel ratio, the catalyst 32 oxidizes HC and CO in the exhaust gas and reduces NOx in the exhaust gas to purify the exhaust gas. A filter 34 that collects particulate matter in the exhaust gas is provided downstream of the catalyst 32. The filter 34 in this embodiment supports a catalyst for purifying the exhaust gas.

[0012] A first air-fuel ratio sensor 87 is provided on the exhaust upstream side of the catalyst 32. The first air-fuel ratio sensor 87 is a sensor that detects an upstream air-fuel ratio AFf, which is the air-fuel ratio of the exhaust gas flowing into the catalyst 32. In addition, a second air-fuel ratio sensor 88 is provided on the exhaust downstream side of the catalyst 32. The second air-fuel ratio sensor 88 is a sensor that detects a downstream air-fuel ratio AFr, which is the air-fuel ratio of the exhaust gas after passing through the catalyst 32.

[0013] The first air-fuel ratio sensor 87 and the second air-fuel ratio sensor 88 are well-known limiting current oxygen sensors. This limiting current oxygen sensor is a sensor that obtains an output current according to the oxygen concentration in the exhaust gas by providing a ceramic layer called a diffusion-controlling layer in the detection section of a concentration cell type oxygen sensor. When the air-fuel ratio, which is closely related to the oxygen concentration in the exhaust gas, is the stoichiometric air-fuel ratio, the output current of the limiting current oxygen sensor becomes "0". In addition, as the air-fuel ratio becomes richer, the output current becomes larger in the negative direction, and as the air-fuel ratio becomes leaner, the output current becomes larger in the positive direction. Therefore, the degree to which the air-fuel ratio is lean or rich can be detected based on the outputs of these air-fuel ratio sensors.

[0014] The crankshaft 26 is mechanically connected to a carrier C of a planetary gear mechanism 50 constituting a power split device. A rotating shaft 52a of a first motor generator 52 is mechanically connected to a sun gear S of the planetary gear mechanism 50. A rotating shaft 54a of a second motor generator 54 and a driving wheel 60 are mechanically connected to a ring gear R of the planetary gear mechanism 50. An AC voltage is applied to a terminal of the first motor generator 52 by an inverter 56. An AC voltage is applied to a terminal of the second motor generator 54 by an inverter 58. The inverter 56 and the inverter 58 are connected to a converter 59 that increases and decreases the voltage. A high-voltage battery 40 is connected to the converter 59. An auxiliary device 200 to which the decreased voltage is supplied is connected to the converter 59. The auxiliary device 200 is, for example, a compressor of an air conditioner provided in the vehicle.

[0015] The control device 70 controls the internal combustion engine 10, and operates operating parts of the internal combustion engine 10, such as the throttle valve 14, the port injection valve 16, the in-cylinder injection valve 22, the spark plug 24, and the high-pressure pump 25, in order to control the torque and the exhaust component ratio as the controlled variable of the internal combustion engine 10. The control device 70 also controls the first motor generator 52, and operates the inverter 56 in order to control the rotation speed as the controlled variable of the first motor generator 52. The control device 70 also controls the second motor generator 54, and operates the inverter 58 in order to control the torque as the controlled variable of the second motor generator 54. The control device 70 also operates the converter 59. FIG. 1 shows operation signals MS1 to MS8 of the throttle valve 14, the port injection valve 16, the in-cylinder injection valve 22, the spark plug 24, the high-pressure pump 25, the inverters 56 and 58, and the converter 59, respectively.

[0016] The control device 70 refers to the intake air amount GA detected by the air flow meter 80 and the output signal Scr of the crank angle sensor 82 in order to control the control amount of the internal combustion engine 10. The control device 70 also refers to the coolant temperature THW, which is the temperature of the coolant of the internal combustion engine 10 detected by the water temperature sensor 86. The control device 70 also refers to the upstream air-fuel ratio AFf detected by the first air-fuel ratio sensor 87 and the downstream air-fuel ratio AFr detected by the second air-fuel ratio sensor 88. The control device 70 also refers to the output signal Sp of the output side rotation angle sensor 89 that detects the rotation angle of the ring gear R. The control device 70 also refers to the output signal Sm1 of the first rotation angle sensor 90 that detects the rotation angle of the first motor generator 52 in order to control the control amount of the first motor generator 52. The control device 70 also refers to the output signal Sm2 of the second rotation angle sensor 92 that detects the rotation angle of the second motor generator 54 in order to control the control amount of the second motor generator 54. The control device 70 also refers to an accelerator operation amount ACCP, which is the amount of depression of the accelerator pedal detected by an accelerator sensor 94.

[0017] The control device 70 calculates the engine speed NE based on the output signal Scr of the crank angle sensor 82. The control device 70 also calculates an engine load factor KL based on the engine speed NE and the intake air amount GA. The engine load factor KL represents the ratio of the current amount of air flowing into the cylinder to the amount of air flowing into the cylinder when the internal combustion engine 10 is steadily operated under full load. The amount of air flowing into the cylinder is the amount of air flowing into each cylinder during the intake stroke. The control device 70 also calculates the vehicle speed SP of the vehicle equipped with the internal combustion engine 10 based on the output signal Sp of the output side rotation angle sensor 89.

[0018] The control device 70 includes a CPU 72, a ROM 74, a storage device 75, and a peripheral circuit 76, which are capable of communicating with each other via a communication line 78. Here, the peripheral circuit 76 includes a circuit that generates a clock signal that regulates the internal operation, a power supply circuit, a reset circuit, etc. The control device 70 controls the controlled variable by the CPU 72 executing a program stored in the ROM 74.

[0019] The control device 70 performs fuel injection control of the port injection valve 16 and the in-cylinder injection valve 22. The control device 70 also performs ignition timing control of the spark plug 24. The control device 70 also calculates a required torque required for the vehicle to travel based on the accelerator operation amount ACCP and the vehicle speed SP. The control device 70 also controls the required output Pe of the internal combustion engine 10 and the output torque of the first motor generator 52 and the second motor generator 54 so as to satisfy the required torque of the vehicle. The control device 70 controls the engine rotation speed NE so as to obtain the required output Pe, and also calculates a required injection amount Qd. The required injection amount Qd is a target value of the fuel supplied from the port injection valve 16 and the in-cylinder injection valve 22 to the combustion chamber 20. The control device 70 then controls the port injection valve 16 and the in-cylinder injection valve 22 so as to obtain the required injection amount Qd.

[0020] The control device 70 also executes a known air-fuel ratio feedback control. In the air-fuel ratio feedback control, an air-fuel ratio correction value FH, which is a feedback value for making the actual air-fuel ratio coincide with the target air-fuel ratio AFt, is calculated based on the upstream air-fuel ratio AFf, the downstream air-fuel ratio AFr, and the target air-fuel ratio AFt of the mixture. The amount of fuel injected from the port injection valve 16 and the in-cylinder injection valve 22 is feedback corrected by the air-fuel ratio correction value FH, so that the actual air-fuel ratio converges to the target air-fuel ratio AFt. When the air-fuel ratio correction value FH is a positive value, the amount of fuel is increased, whereas when the air-fuel ratio correction value FH is a negative value, the amount of fuel is decreased. The target air-fuel ratio AFt is basically the theoretical air-fuel ratio.

[0021] <About deposit removal control> Furthermore, during idling operation, the control device 70 executes fuel injection only through the port injection valve 16. Then, when fuel injection only through the port injection valve 16 has been executed continuously for a predetermined period of time, deposit removal control is implemented. The deposit removal control is a control for suppressing the accumulation of deposits in the in-cylinder injection valve 22 and removing any deposited deposits by stopping fuel injection from the port injection valve 16 and executing fuel injection from the in-cylinder injection valve 22.

[0022] Fig. 2 shows the procedure for deposit removal control executed by the control device 70. The process shown in Fig. 2 is realized by the CPU 72 executing a program stored in the ROM 74. The process shown in Fig. 2 is repeatedly executed when there is a request for deposit removal. Deposit removal is requested when the internal combustion engine 10 is idling and fuel injection only by the port injection valve 16 has been performed continuously for a predetermined period of time. When the deposit removal process has been performed for the predetermined period of time, the request for deposit removal is canceled.

[0023] In the following, the step number of each process will be represented by a number preceded by the letter "S". 2 starts, the control device 70 determines whether the required injection amount Qd is less than the minimum injection amount Qmin (S100). The minimum injection amount Qmin is the minimum injection amount of the direct injection valve 22 when the fuel pressure P is set to the pressure required for deposit removal.

[0024] When the controller 70 determines that the required injection amount Qd is less than the minimum injection amount Qmin (S100: YES), it executes a change process (S110). The change process is a process for changing the operating state of the internal combustion engine 10 so that the required injection amount Qd is increased compared to before the change process was executed. More specifically, the change process is a process for lowering the engine speed NE during idling operation compared to before the change process was executed while maintaining the required output Pe of the internal combustion engine 10. In the process of S110, the controller 70 executes a process for setting a value obtained by subtracting a preset value α from the base rotation speed NEb during idling operation to the target rotation speed NEt of the internal combustion engine 10, thereby lowering the engine speed NE during idling operation.

[0025] Here, the required output Pe is a value expressed as the product of the engine speed NE and the output torque Te of the internal combustion engine 10. Therefore, if the engine speed NE is reduced while maintaining the required output Pe, the required output torque Te becomes larger, and therefore the required injection amount Qd increases.

[0026] The base rotation speed NEb is a basic value of the engine rotation speed NE of the internal combustion engine 10 during idling operation. The default value α is a value for reducing the engine rotation speed during idling operation. For example, it is preferable to set the default value α to a reduction in the engine rotation speed NE required for the required injection amount Qd to be equal to or greater than the minimum injection amount Qmin.

[0027] Next, the control device 70 executes the deposit removal process by switching the fuel injection mode from port injection to in-cylinder injection, thereby stopping fuel injection only by the port injection valve 16 and executing fuel injection only by the in-cylinder injection valve 22 (S120). When the process of S120 is executed, the control device 70 adjusts the actual fuel pressure P to the pressure Pd by substituting the pressure Pd required for deposit removal for the target fuel pressure Pt, which is the target value of the fuel pressure P.

[0028] Then, when the process of S120 has been executed, or when a negative determination is made in the process of S100, the control device 70 ends this process in the current execution cycle. <Action and Effects> The operation and effects of this embodiment will be described.

[0029] (1-1) When the required injection amount Qd is less than the minimum injection amount Qmin when deposit removal control is being performed, the above-mentioned change process is executed. This change process is a process for changing the operating state of the internal combustion engine 10 so that the required injection amount Qd is increased compared to before the change process was executed. Therefore, when the required injection amount Qd is less than the minimum injection amount Qmin when deposit removal control is being performed, the operating state of the internal combustion engine 10 is changed so that the required injection amount Qd is increased. By increasing the required injection amount Qd in this manner, the deviation between the required injection amount Qd and the minimum injection amount Qmin becomes smaller, so that the enrichment of the air-fuel ratio when deposit removal control is being performed can be suppressed.

[0030] (1-2) The change process is a process for lowering the engine speed NE during idling operation compared to before the change process was executed, while maintaining the required output Pe of the internal combustion engine 10. Therefore, by executing the change process, the engine speed NE is lowered while maintaining the required output Pe, and therefore the required injection amount Qd is increased so as to increase the output torque of the internal combustion engine 10. Therefore, the change process can be executed appropriately.

[0031] Second embodiment Next, a second embodiment of a control device for an internal combustion engine will be described with reference to the drawings. The internal combustion engine of this embodiment is a V-type internal combustion engine having two banks. Also, the processing content of the change processing is different from that of the first embodiment. The change processing of this embodiment will be described below, focusing on the differences from the first embodiment.

[0032] Fig. 3 shows the procedure for deposit removal control executed by the control device 70 of this embodiment. The process shown in Fig. 3 is realized by the CPU 72 executing a program stored in the ROM 74. The process shown in Fig. 3 is repeatedly executed when there is a request for deposit removal. Deposit removal is requested when the internal combustion engine 10 is idling and fuel injection only by the port injection valve 16 has been performed continuously for a predetermined period of time. Then, when the deposit removal process has been performed for the predetermined period of time, the request for deposit removal is canceled.

[0033] 3 starts, the control device 70 determines whether the required injection amount Qd is less than the minimum injection amount Qmin (S200). The minimum injection amount Qmin is the minimum injection amount of the direct injection valve 22 when the fuel pressure P is set to the pressure Pd required for deposit removal.

[0034] When the control device 70 determines that the required injection amount Qd is less than the minimum injection amount Qmin (S200: YES), it executes a change process (S210). The change process is a process for changing the operating state of the internal combustion engine 10 so that the required injection amount Qd is increased compared to before the change process was executed. More specifically, it is a cylinder deactivation process for stopping the combustion of the air-fuel mixture in some of the cylinders of the internal combustion engine. In this embodiment, the cylinders for which the cylinder deactivation process is executed are all cylinders in one of the two banks described above, and cylinder deactivation of one bank is executed.

[0035] Next, the control device 70 executes the deposit removal process by switching the fuel injection mode from port injection to in-cylinder injection, thereby stopping fuel injection only by the port injection valve 16 and executing fuel injection only by the in-cylinder injection valve 22 (S220). When the process of S220 is executed, the control device 70 adjusts the actual fuel pressure P to the pressure Pd by substituting the pressure Pd required for deposit removal for the target fuel pressure Pt.

[0036] Then, when the process of S220 has been executed, or when a negative determination is made in the process of S200, the control device 70 ends this process in the current execution cycle. <Action and Effects> The operation and effects of this embodiment will be described.

[0037] (2-1) When the required injection amount Qd is less than the minimum injection amount Qmin when deposit removal control is being performed, the above-mentioned change process is executed. This change process is a process for changing the operating state of the internal combustion engine 10 so that the required injection amount Qd is increased compared to before the change process was executed. Therefore, when the required injection amount Qd is less than the minimum injection amount Qmin when deposit removal control is being performed, the operating state of the internal combustion engine 10 is changed so that the required injection amount Qd is increased. By increasing the required injection amount Qd in this manner, the deviation between the required injection amount Qd and the minimum injection amount Qmin becomes smaller, so that the enrichment of the air-fuel ratio when deposit removal control is being performed can be suppressed.

[0038] (2-2) The above-mentioned change process is a cylinder deactivation process that stops the combustion of the air-fuel mixture in some of the cylinders of the internal combustion engine. When this cylinder deactivation process is executed, the output torque of the cylinders in which the combustion of the air-fuel mixture continues is increased so as to compensate for the output torque of the cylinders in which the combustion of the air-fuel mixture has been stopped. Therefore, the required injection amount Qd is increased so as to increase the output torque. Therefore, the above-mentioned change process can be appropriately executed.

[0039] Third embodiment Next, an embodiment of the control device for an internal combustion engine will be described with reference to the drawings. The present embodiment differs from the first embodiment in the processing content of the deposit removal control. The change processing in this embodiment will be described below, focusing on the differences from the first embodiment.

[0040] Fig. 4 shows the procedure for deposit removal control executed by the control device 70 of this embodiment. The process shown in Fig. 3 is realized by the CPU 72 executing a program stored in the ROM 74. The process shown in Fig. 4 is repeatedly executed when there is a request for deposit removal. Deposit removal is requested when the internal combustion engine 10 is idling and fuel injection only by the port injection valve 16 has been performed continuously for a predetermined period of time. Then, when the deposit removal process has been performed for the predetermined period of time, the request for deposit removal is canceled.

[0041] 4 starts, the control device 70 judges whether the required injection amount Qd is less than the minimum injection amount Qmin (S300). The minimum injection amount Qmin increases as the fuel pressure P increases, but the minimum injection amount Qmin used as a judgment value in the process of S300 is the following value. That is, it is the minimum injection amount under the pressure at which the fuel injection amount of the direct injection valve 22 is minimized, that is, when the lowest value of the variable fuel pressure P is set to the first fuel pressure P1, it is the minimum injection amount at the first fuel pressure P1.

[0042] When it is determined that the required injection amount Qd is less than the minimum injection amount Qmin (S300: YES), the control device 70 determines whether or not the flag F is "0" (S310). The initial value of the flag F is "0". Then, in the process of S330 described later, the flag F is set to "1". When the deposit removal control is completed, the flag F is set to "0".

[0043] When it is determined that the flag F is "0" (S310: YES), the control device 70 assigns the first fuel pressure P1 to the target fuel pressure Pt, which is the target value of the fuel pressure P (S320). The control device 70 controls the drive of the high-pressure pump 25 so as to obtain the target fuel pressure Pt.

[0044] Next, the control device 70 sets the flag F to "1" (S330). Next, the control device 70 switches the fuel injection mode from port injection to in-cylinder injection, thereby stopping fuel injection only by the port injection valve 16 and performing fuel injection only by the in-cylinder injection valve 22 (S340).

[0045] After executing the process of S340, or if a negative determination is made in the process of S310, the control device 70 executes the process of S350. In the process of S350, the control device 70 determines whether the logical product of the following condition (a) and condition (b) is true (S350).

[0046] Condition (a): The upstream air-fuel ratio AFf, which indicates the air-fuel ratio of the mixture detected by the sensor, is a value smaller than the stoichiometric value. In other words, the upstream air-fuel ratio AFf is an air-fuel ratio richer than the stoichiometric air-fuel ratio.

[0047] Condition (b): The air-fuel ratio correction value FH is equal to or smaller than a threshold value FHref and is a value that corrects the fuel to a reduced amount. When it is determined that the logical product of the condition (a) and the condition (b) is true (S350: YES), the control device 70 executes the process of S340. In the process of S340, the control device 70 switches from in-cylinder injection to port injection, thereby stopping fuel injection only by the port injection valve 16 and executing fuel injection only by the in-cylinder injection valve 22.

[0048] On the other hand, when the logical product of the condition (a) and the condition (b) is not true, that is, when it is determined that the logical product is false (S350: YES), the control device 70 updates the target fuel pressure Pt in the process of S370. The target fuel pressure Pt is updated by adding a preset value β to the currently set target fuel pressure Pt and setting the new target fuel pressure Pt as the new target fuel pressure Pt. Each time the process of S370 is executed, the target fuel pressure Pt increases by the preset value β, so that the process of S370 gradually increases the fuel pressure. When the target fuel pressure Pt updated in S370 reaches the pressure Pd required for deposit removal, the value of the target fuel pressure Pt is maintained at the pressure Pd. Then, the process of deposit removal is executed by continuing in-cylinder injection while the value of the target fuel pressure Pt is maintained at the pressure Pd.

[0049] If a negative determination is made in the processing of S300 (S300: NO), the control device 70 stops fuel injection only by the port injection valve 16 and performs fuel injection only by the direct injection valve 22 (S380). When the processing of S380 is performed, the control device 70 adjusts the actual fuel pressure P to the pressure Pd by substituting the pressure Pd required for deposit removal for the target fuel pressure Pt.

[0050] Then, when the control device 70 has executed any one of the processes of S360, S370, or S380, it ends this process in the current execution cycle. <Action and Effects> The operation and effects of this embodiment will be described.

[0051] (3-1) When the logical product of the condition (a) that the upstream air-fuel ratio AFf is an air-fuel ratio richer than the stoichiometric air-fuel ratio and the condition (b) that the air-fuel ratio correction value FH is a value that corrects the fuel to a reduced amount is true, it can be determined as follows. That is, it can be determined that the air-fuel ratio is enriched because the required injection amount Qd is smaller than the minimum injection amount min. Therefore, when the logical product of these conditions is not true, even if the minimum injection amount Qmin increases by increasing the fuel pressure P, it is possible to suppress the enrichment of the air-fuel ratio.

[0052] Therefore, in this embodiment, when the required injection amount Qd is less than the minimum injection amount Qmin during deposit removal control, an adjustment process is executed to adjust the fuel pressure P. As this adjustment process, in this embodiment, the fuel pressure P is once adjusted to a pressure at which the fuel injection amount of the direct injection valve 22 is minimized (processing of S320). Then, if the logical product of the above conditions is not true (S350: NO), the process of S370 is executed to gradually increase the fuel pressure P. This makes it possible to suppress the air-fuel ratio from becoming rich when deposit removal control is executed.

[0053] (3-2) There are individual differences in the injection amount of the direct injection valve 22. In this regard, in this embodiment, the fuel pressure is adjusted while monitoring the upstream air-fuel ratio AFf, which is the actual air-fuel ratio detected by the sensor, and the air-fuel ratio correction value FH calculated by air-fuel ratio feedback control (processing of S350 and S370). Therefore, the effect of such individual differences on the air-fuel ratio, etc. can be suppressed.

[0054] <Example of change> The above-described embodiments may be modified as follows: The above-described embodiments and the following modifications may be combined with each other to the extent that no technical contradiction occurs.

[0055] In the second embodiment, the banks for which the cylinder deactivation process is performed may be alternately switched. The timing of the switching may be set appropriately. For example, the timing may be set such that the cylinder deactivation process has been performed a preset number of times in one bank, or the cylinder deactivation process has been performed a preset time in one bank.

[0056] Although the internal combustion engine of the second embodiment has a V-shaped cylinder arrangement, the internal combustion engine may have another cylinder arrangement. Even in this case, the same action and effect can be obtained by executing a cylinder deactivation process that stops the combustion of the air-fuel mixture in some of the cylinders of the internal combustion engine.

[0057] The second air-fuel ratio sensor 88 may be a well-known concentration cell type oxygen sensor. This concentration cell type oxygen sensor produces an output of about 1 V when the air-fuel ratio is richer than the stoichiometric air-fuel ratio, and produces an output of about 0 V when the air-fuel ratio is leaner than the stoichiometric air-fuel ratio. In addition, this sensor produces a large change in output voltage near the stoichiometric air-fuel ratio. Therefore, this oxygen sensor is a sensor that can detect whether the air-fuel ratio is lean or rich.

[0058] The filter 34 is not limited to a filter carrying a catalyst, but may be a filter alone. Also, the filter 34 may be omitted from the exhaust passage 30. The control device is not limited to a device equipped with a CPU 72 and a ROM 74 and executing software processing. For example, the control device may be equipped with a dedicated hardware circuit such as an ASIC that performs hardware processing of at least a part of what was processed by software in the above embodiment. That is, the control device may have any of the following configurations (a) to (c). (a) A processing device that executes all of the above processing according to a program, and a program storage device such as a ROM that stores the program. (b) 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) A dedicated hardware circuit that executes all of the above processing. Here, there may be a plurality of software execution devices equipped with a processing device and a program storage device, and a plurality of dedicated hardware circuits.

[0059] The vehicle is not limited to a series-parallel hybrid vehicle, but may be, for example, a parallel hybrid vehicle or a series hybrid vehicle. However, the vehicle is not limited to a hybrid vehicle, and may be, for example, a vehicle whose prime mover is only an internal combustion engine 10. [Explanation of symbols]

[0060] 10... internal combustion engine, 12... intake passage, 12a... intake port, 14... throttle valve, 16... port injection valve, 18... intake valve, 20... combustion chamber, 22... in-cylinder injection valve, 24... spark plug, 25... high-pressure pump, 26... crankshaft, 28... exhaust valve, 30... exhaust passage, 32... catalyst, 34... filter, 40... high-pressure battery, 50... planetary gear mechanism, 52... first motor generator, 52a... rotating shaft, 54... second motor generator, 54a... Rotating shaft, 56... inverter, 58... inverter, 59... converter, 60... driving wheels, 70... control device, 72... CPU, 74... ROM, 75... storage device, 76... peripheral circuit, 78... communication line, 80... air flow meter, 82... crank angle sensor, 86... water temperature sensor, 87... first air-fuel ratio sensor, 88... second air-fuel ratio sensor, 89... output side rotation angle sensor, 90... first rotation angle sensor, 92... second rotation angle sensor, 94... accelerator sensor, 200... auxiliary device

Claims

1. A control device for an internal combustion engine which is provided with a port injection valve which injects fuel into an intake port and an in-cylinder injection valve which injects fuel into a cylinder, and which performs fuel injection only through the port injection valve during idling operation, and when fuel injection only through the port injection valve has been continuously performed for a predetermined period of time, performs a deposit removal control by stopping fuel injection from the port injection valve and performing fuel injection only through the in-cylinder injection valve, When the deposit removal control is performed and the required injection amount of the internal combustion engine is smaller than the minimum injection amount of the direct injection valve, a change process is executed; The change process is a process of changing the operating state of the internal combustion engine so that the required injection amount is increased compared to before the change process was executed. A control device for an internal combustion engine.

2. The change process is a process for decreasing the engine rotation speed during idling operation compared to before the change process was performed while maintaining the output of the internal combustion engine. The control device for an internal combustion engine according to claim 1.

3. The change process is a cylinder deactivation process that stops combustion of the air-fuel mixture in some of the cylinders of the internal combustion engine. The control device for an internal combustion engine according to claim 1.

4. The internal combustion engine is a V-type internal combustion engine having two banks, The cylinders for which the cylinder deactivation process is executed are all the cylinders in one of the two banks. The control device for an internal combustion engine according to claim 3.

5. A control device for an internal combustion engine which is provided with a port injection valve which injects fuel into an intake port and an in-cylinder injection valve which injects fuel into a cylinder, and which performs fuel injection only through the port injection valve during idling operation, and when fuel injection only through the port injection valve has been continuously performed for a predetermined period of time, performs a deposit removal control by stopping fuel injection from the port injection valve and performing fuel injection only through the in-cylinder injection valve, An air-fuel ratio feedback control is performed to correct an amount of fuel supplied to the internal combustion engine using an air-fuel ratio correction value, when a required injection amount of the internal combustion engine is smaller than a minimum injection amount of the direct injection valve during execution of the deposit removal control, an adjustment process is executed to adjust a fuel pressure of the fuel supplied to the direct injection valve; As the adjustment process, the fuel pressure is adjusted to a pressure at which the fuel injection amount of the in-cylinder injection valve is minimized, and then, if the logical product of the condition that the air-fuel ratio of the mixture detected by the sensor is an air-fuel ratio richer than the stoichiometric air-fuel ratio and the condition that the air-fuel ratio correction value is a value for correcting the fuel to the reduced side is not true, a process for gradually increasing the fuel pressure is executed. A control device for an internal combustion engine.

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