Internal combustion engine control apparatus

Abstract

To suppress generation of particulate materials caused by an increase of fuel injection rate from an in-cylinder injection valve.SOLUTION: An internal combustion engine control apparatus performs acquisition processing for acquiring, as an operating state, an engine revolution speed of an internal combustion engine and an engine load ratio thereof; and residual degree calculation processing for calculating residual degree of a cleaning agent residual in a cylinder on the basis of the operating state. Further in a case where a fuel injection rate from a port injection valve is equal to or more than a predetermined standard rate, with the residual degree calculated in the residual degree calculation processing equaling or exceeding a predetermined standard ratio, the control apparatus performs change processing. The change processing is processing that perform one of more processing selected from one to advance timing of fuel injection from the port injection valve in comparison with the case of the residual degree being less than the standard degree and one to increase a valve overlap amount, where an intake valve and exhaust valve are both opened, in comparison with the case of the residual degree being less than the standard degree.SELECTED DRAWING: Figure 2

Description

Technical Field

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

Background Art

[0002] The internal combustion engine described in Patent Document 1 includes an in-cylinder injection valve that injects fuel directly into the cylinder. Further, the control device described in Patent Document 1 targets the internal combustion engine for control. The control device determines whether the operating state of the internal combustion engine is a state in which the emission amount of particulate matter increases. And when it is determined that the emission amount of particulate matter is in an increasing state, the control device changes the control of the internal combustion engine according to the generation state of the particulate matter.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In an internal combustion engine, in addition to an in-cylinder injection valve such as that of the internal combustion engine described in Patent Document 1, there may be a port injection valve that injects fuel into the intake passage. In an internal combustion engine equipped with such two types of injection valves, it may be switched from a state of injecting fuel from the port injection valve to a state of injecting fuel from the in-cylinder injection valve. In this case, depending on the operating state of the internal combustion engine, the generation amount of particulate matter may increase immediately after switching to fuel injection from the in-cylinder injection valve.

Means for Solving the Problems

[0005] In order to solve the above problems, the present invention is applied to an internal combustion engine including a cylinder, an in-cylinder injection valve that injects fuel into the cylinder, a port injection valve that injects fuel into an intake passage, and a valve timing adjustment mechanism capable of adjusting one or more selected from the opening and closing timing of an intake valve and the opening and closing timing of an exhaust valve. An acquisition process for acquiring the engine speed and the engine load factor of the internal combustion engine as an operating state, a residence degree calculation process for calculating the residence degree of a cleaning agent retained in the cylinder based on the operating state, a fuel injection ratio from the port injection valve being equal to or greater than a predetermined ratio, and when both the residence degree calculated in the residence degree calculation process is equal to or greater than a predetermined degree are satisfied, a process of advancing the fuel injection timing from the port injection valve compared to when the residence degree is less than the predetermined degree, and a valve overlap amount in which both the intake valve and the exhaust valve are opened is compared to when the residence degree is less than the predetermined degree. A control device for an internal combustion engine that executes one or more selected from the processes of increasing.

Effect of the Invention

[0006] According to the above configuration, when the fuel injection ratio from the in-cylinder injection valve increases, generation of particulate matter can be suppressed.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Embodiment for Carrying Out the Invention

[0008] <Schematic Configuration of Internal Combustion Engine> As shown in FIG. 1, the vehicle includes an internal combustion engine 10. The internal combustion engine 10 is a drive source of the vehicle. The internal combustion engine 10 includes a cylinder 11, a piston 12, a connecting rod 13, a crankshaft 14, and a spark plug 15. Further, the internal combustion engine 10 includes an in-cylinder injection valve 21 and a port injection valve 31. Further, the internal combustion engine 10 includes an intake valve 41, an exhaust valve 61, and a valve timing adjustment mechanism. The valve timing adjustment mechanism includes an intake VVT mechanism 42 and an exhaust VVT mechanism 62. Therefore, the valve timing adjustment mechanism can adjust both the opening and closing timing of the intake valve 41 and the opening and closing timing of the exhaust valve 61. Note that the configuration related to these internal combustion engines 10 is the same as the configuration disclosed in Japanese Patent Application Laid-Open No. 2023-133802.

[0009] Here, the length of the period during which both the intake valve 41 and the exhaust valve 61 are open is defined as the "valve overlap amount". The valve overlap amount is changed by operating at least one of the intake VVT mechanism 42 and the exhaust VVT mechanism 62.

[0010] The internal combustion engine 10 includes a crank position sensor 71, an air flow meter 72, a water temperature sensor 73, and an air-fuel ratio sensor 74. The crank position sensor 71 detects the rotational position Scr of the crankshaft 14. The air flow meter 72 detects the intake air amount GA flowing into the intake passage 40 from the outside. The water temperature sensor 73 detects the cooling water temperature TW, which is the outlet temperature of the cooling water flowing through the water jacket partitioned inside the internal combustion engine 10. The air-fuel ratio sensor 74 detects the air-fuel ratio AF of the exhaust gas passing through the exhaust passage 60.

[0011] As shown in FIG. 1, the vehicle includes a control device 90. The control device 90 controls the internal combustion engine 10. The control device 90 repeatedly acquires signals corresponding to the information detected by each sensor from the crank position sensor 71, the air flow meter 72, the water temperature sensor 73, and the air-fuel ratio sensor 74.

[0012] The control device 90 calculates the engine speed NE, which is the rotational speed of the crankshaft 14, based on the rotational position Scr detected by the crank position sensor 71. Further, the control device 90 calculates the engine load ratio based on the engine speed NE and the intake air amount GA detected by the air flow meter 72. The engine load ratio indicates the ratio of the current intake air amount GA to the intake air amount GA when the internal combustion engine 10 is in steady operation with the throttle valve fully open at the current engine speed NE.

[0013] The control device 90 calculates the target fuel injection amount, which is the target value of the fuel injection amount, based on the intake air amount GA, the engine speed NE, the engine load ratio, etc. The control device 90 calculates the target fuel injection amount so that, for example, the air-fuel ratio AF becomes the stoichiometric air-fuel ratio. Further, the control device 90 calculates the PFI injection ratio, which is the ratio of the fuel injection amount injected from the port injection valve 31. The control device 90 calculates the port injection amount, which is the fuel injection amount injected from the port injection valve 31, by multiplying the target fuel injection amount by the PFI injection ratio. Then, the control device 90 calculates the in-cylinder injection amount, which is the fuel injection amount injected from the in-cylinder injection valve 21, by subtracting the port injection amount from the target fuel injection amount. Note that the PFI injection ratio can be changed according to the operating state of the internal combustion engine 10.

[0014] Also, the control device 90 calculates the fuel injection timing and the fuel injection time from each injection valve based on the calculated port injection amount, in-cylinder injection amount, etc. Note that the control device 90 may calculate the in-cylinder injection amount to be zero. In this case, the control device 90 controls so that the entire amount of the target fuel injection amount is injected from the port injection valve 31. Similarly, the control device 90 may calculate the port injection amount to be zero. In this case, the control device 90 controls so that the entire amount of the target fuel injection amount is injected from the in-cylinder injection valve 21.

[0015] <Regarding the residence suppression control> The control device 90 executes each process of the residence suppression control. Note that the residence suppression control is repeatedly executed when the vehicle power supply is in the ON state. Hereinafter, a series of processes of the residence suppression control will be described.

[0016] As shown in FIG. 2, when the control device 90 starts the residence suppression control, first, the process of step S11 is executed. In step S11, the control device 90 executes an acquisition process. The acquisition process is a process of acquiring the operating state of the internal combustion engine 10. In this embodiment, the operating state is the engine speed NE, the engine load factor, the coolant temperature TW, the PFI injection ratio, the fuel injection time from the port injection valve 31, and the valve overlap amount. Note that the "acquisition" here also includes calculating parameters based on the detection values from each sensor. After acquiring the operating state of the internal combustion engine 10, the control device 90 executes the process of step S12.

[0017] In step S12, the control device 90 executes a first determination process. The first determination process determines whether the PFI injection ratio acquired in the acquisition process is equal to or greater than a predetermined specified ratio. That is, the control device 90 determines whether the fuel injection ratio from the port injection valve 31 is equal to or greater than a predetermined specified ratio. The specified ratio can be determined as follows. For example, first, the PFI ejection ratio at which a detergent in an amount that can cause the generation of particulate matter can remain in the cylinder 11 is determined through experiments, simulations, etc. Then, the specified ratio can be determined as a value slightly smaller than the determined PFI ejection ratio. In the case of a negative determination in step S12, the control device 90 ends the residence suppression control. On the other hand, in the case of an affirmative determination in step S12, the control device 90 executes the process of step S13.

[0018] In step S13, the control device 90 executes a residence degree calculation process. The residence degree calculation process is a process of calculating the residence degree of the cleaning agent retained in the cylinder 11 based on the operating state. Specifically, the control device 90 calculates such that the higher the engine speed NE, the greater the residence degree. The control device 90 calculates such that the higher the engine load ratio, the smaller the residence degree. The control device 90 calculates such that the higher the coolant temperature TW, the smaller the residence degree. The control device 90 calculates such that the longer the PFI injection time, the greater the residence degree. The control device 90 calculates such that the greater the valve overlap amount, the smaller the residence degree. After calculating the residence degree, the control device 90 executes the process of step S14.

[0019] In step S14, the control device 90 executes a second determination process. The second determination process is a process of determining whether the residence degree calculated in the residence degree calculation process is equal to or greater than a predetermined specified degree. The specified degree can be determined as follows. For example, through experiments and simulations, etc., when switching from fuel injection from the port injection valve 31 to fuel injection from the in-cylinder injection valve 21, the residence degree at which a certain amount or more of particulate matter is generated is determined. Then, the above-mentioned specified degree can be determined as a value slightly smaller than the residence degree. In the case of a negative determination in step S14, the control device 90 ends the residence suppression control. On the other hand, in the case of an affirmative determination in step S14, the control device 90 executes the process of step S15.

[0020] In step S15, the control device 90 executes a change process. That is, the control device 90 executes the change process when both the fuel injection ratio from the port injection valve 31 is equal to or greater than a specified ratio and the degree of residence calculated in the degree-of-residence calculation process is equal to or greater than a specified degree. In the change process, an advance angle process is performed in which the fuel injection timing from the port injection valve 31 is advanced compared to the case where the degree of residence is less than the specified degree. Also, in the change process, an increase process is performed in which the valve overlap amount is increased compared to the case where the degree of residence is less than the specified degree. Specifically, the control device 90 first calculates the advance angle amount of the fuel injection timing of the port injection valve 31 in the advance angle process and the increase amount of the valve overlap amount in the increase process. Note that the control device 90 calculates the advance angle amount and the increase amount as positive values. The advance angle amount and the increase amount are calculated based on the engine rotational speed NE, the engine load factor, and the degree of residence calculated in the degree-of-residence calculation process, etc., obtained in the acquisition process. For example, the control device 90 stores in advance a map showing the relationship between the engine rotational speed NE, the engine load factor, and the advance angle amount, and calculates the advance angle amount based on the map. Similarly, for example, the control device 90 stores in advance a map showing the relationship between the engine rotational speed NE, the engine load factor, and the increase amount, and calculates the increase amount based on the map. Note that the advance angle amount and the increase amount may be calculated based on the determination result of the failure diagnosis device of the air-fuel ratio sensor 74 that the vehicle has. The failure diagnosis device of the air-fuel ratio sensor 74 is a device that determines whether there is an abnormality in the air-fuel ratio sensor 74 according to the detected value of the air-fuel ratio sensor 74. For example, when the air-fuel ratio sensor 74 detects an excessively large or small air-fuel ratio AF, the failure diagnosis device may detect an abnormality in the air-fuel ratio sensor 74. On the other hand, due to the exhaust pulsation generated by an increase in the valve overlap amount or the like, the air-fuel ratio sensor 74 may temporarily detect an excessively large or small value. In that case, the failure diagnosis device may determine an abnormality in the air-fuel ratio sensor 74. The control device 90 may calculate the increase amount of the valve overlap amount so as to suppress such misjudgment.

[0021] Then, the control device 90 advances the fuel injection timing of the port injection valve 31 according to the calculated advance angle amount. Further, the control device 90 increases the valve overlap amount according to the calculated increase amount. Thereafter, the control device 90 ends the series of residence suppression controls.

[0022] <Operation of this embodiment (Particulate matter emission test)> When the advance angle amount of the fuel injection timing of the port injection valve 31 was changed, the number of particulate matters discharged was confirmed by a test. In the test, the number of particulate matters (hereinafter referred to as PN) when the advance angle amount was changed was confirmed at two different engine speeds NE. PN was defined as the maximum value of PN per unit time detected when switching from the state where fuel injection was performed only by the port injection valve 31 to the state where fuel injection was performed only by the in-cylinder injection valve 21. The engine load rate in the test was 40%.

[0023] As shown in FIG. 3, in the case of a certain first engine speed, as the advance angle amount was increased, PN decreased substantially linearly. Also, at a second engine speed higher than the first engine speed, as the advance angle amount was increased, PN decreased substantially linearly. Thus, in the test, regardless of the engine speed NE, the tendency was obtained that PN decreased as the advance angle amount was increased. Although illustration is omitted, when the valve overlap amount was changed, the discharged PN was confirmed by a similar test. Also in this test, regardless of the engine speed NE, the tendency was obtained that PN decreased as the valve overlap amount was increased.

[0024] <Regarding the effects of this embodiment> (1) When fuel is injected from the port injection valve 31, the detergent added to the fuel vaporizes in the intake passage 40 and burns together with the fuel in the cylinder 11. On the other hand, if the detergent cannot be sufficiently vaporized in the intake passage 40, the non-vaporized detergent adheres to the top surface of the piston 12 and remains there. When fuel is injected from the in-cylinder injection valve 21 with a large amount of detergent remaining on the top surface of the piston 12, a part of the injected fuel is adsorbed by the detergent. Since the fuel adsorbed by the detergent in this way cannot burn normally, a large amount of particulate matter is generated.

[0025] In the above embodiment, when the fuel injection ratio from the port injection valve 31 is equal to or higher than a specified ratio and the degree of detergent retention is equal to or higher than a specified degree, an advance angle process for advancing the fuel injection timing from the port injection valve 31 is performed. By this process, the period from fuel injection until it flows into the cylinder 11 becomes longer, so that the detergent is more likely to vaporize in the intake passage 40. Also, when the above conditions are satisfied, an increase process for increasing the valve overlap amount is performed. By this process, the amount of exhaust gas flowing into the intake passage 40 increases, so that the inside of the intake passage 40 can be heated to a high temperature. Along with this, the detergent is more likely to vaporize in the cylinder 11. In this way, in either process, an increase in the amount of detergent remaining in the cylinder 11 can be suppressed. Therefore, even if a large amount of fuel is subsequently injected from the in-cylinder injection valve 21, an increase in the amount of particulate matter generated can be prevented.

[0026] (2) In the change process, if the advance angle amount for advancing the fuel injection timing from the port injection valve 31 is made excessively large, there is an inevitable risk that the injected fuel will be sucked into an unintended cylinder 11. In this case, a difference may occur in the air-fuel ratio AF for each cylinder 11, and torque fluctuations may occur. Also, if the increase amount of the valve overlap amount is made excessively large, the exhaust pulsation becomes large, and there is a risk that the failure diagnosis device of the air-fuel ratio sensor 74 will make a misjudgment. In the above embodiment, in the change process, by not relying on only one of the advance angle process and the increase process, torque fluctuations and misjudgments of the failure diagnosis device as described above can be suppressed.

[0027] <Modification Example> This embodiment can be implemented with the following modifications. This embodiment and the following modification examples can be implemented in combination with each other within a technically non - conflicting range.

[0028] · The valve timing adjustment mechanism of the above - described embodiment may have only one of the intake VVT mechanism 42 and the exhaust VVT mechanism 62. Even in this case, the valve overlap amount can be adjusted.

[0029] · The method for calculating the advance angle amount and the increase amount of the above - described embodiment is not limited to the examples of the above - described embodiment. · In the change process of the above - described embodiment, one or more selected from the advance angle process and the increase process may be executed.

Explanation of Reference Numerals

[0030] NE…Engine speed, 10…Internal combustion engine, 11…Cylinder, 21…In - cylinder injection valve, 31…Port injection valve, 40…Intake passage, 41…Intake valve, 61…Exhaust valve, 90…Control device

Claims

【Claim 1】 Applied to an internal combustion engine comprising a cylinder, an in-cylinder injection valve for injecting fuel into the cylinder, a port injection valve for injecting fuel into an intake passage, and a valve timing adjustment mechanism capable of adjusting one or more selected from the opening and closing timing of an intake valve and the opening and closing timing of an exhaust valve, an acquisition process for acquiring the engine speed and engine load factor of the internal combustion engine as an operating state, a residence degree calculation process for calculating the residence degree of the detergent retained in the cylinder based on the operating state, when both the fuel injection ratio from the port injection valve is equal to or greater than a predetermined ratio and the residence degree calculated in the residence degree calculation process is equal to or greater than a predetermined degree, a process of advancing the fuel injection timing from the port injection valve compared to the case where the residence degree is less than the predetermined degree, and one or more selected from a process of increasing the valve overlap amount in which both the intake valve and the exhaust valve are opened compared to the case where the residence degree is less than the predetermined degree are performed a control device for an internal combustion engine.

Images