Internal combustion engine control device

Abstract

An internal combustion engine is provided with a filter that collects PM contained in exhaust gas flowing through an exhaust passage. A CPU of a control device executes: a calculation process for calculating a PM deposition amount, which is the amount of PM collected by a filter, on the basis of the operating conditions of an internal combustion engine and the ethanol content of fuel supplied into a cylinder; and a regeneration process for combusting the PM collected by the filter when the PM deposition amount exceeds a predetermined amount.

Description

Technical Field

[0001] This invention relates to an internal combustion engine control device suitable for an internal combustion engine with a filter installed in the exhaust passage. Background Technology

[0002] Japanese Patent Application Publication No. 2023-37344 discloses a control device applicable to an internal combustion engine with a filter installed in the exhaust passage. This control device performs: a calculation process to calculate the amount of particulate matter trapped by the filter, i.e., the PM deposition amount; and a regeneration process to burn the particulate matter trapped by the filter if the PM deposition amount exceeds a predetermined amount.

[0003] In the above calculation process, the control device calculates the PM deposition amount based on operating conditions including the intake air volume and fuel injection volume of the internal combustion engine. Summary of the Invention

[0004] When using ethanol-containing fuel as the fuel for the aforementioned internal combustion engine, the amount of particulate matter generated in the engine varies depending on the ethanol content of the fuel. Therefore, if the aforementioned control device is applied to an internal combustion engine using ethanol-containing fuel, the control device may lead to a deterioration in the fuel economy of the internal combustion engine due to the inability to perform filter regeneration at appropriate times.

[0005] The internal combustion engine control device according to the first aspect of the present invention is applicable to an internal combustion engine having a cylinder, an exhaust passage for exhaust flow from said cylinder, and a filter for capturing particulate matter contained in the exhaust flowing in said exhaust passage.

[0006] The internal combustion engine control unit has a processing circuit.

[0007] The processing circuit performs:

[0008] The calculation process, based on the operating conditions of the internal combustion engine and the ethanol content in the fuel supplied to the cylinder, calculates the amount of particulate matter (PM) captured by the filter, i.e., the PM deposition amount; and

[0009] The regeneration process involves burning the particulate matter captured by the filter when the PM deposition exceeds a predetermined amount.

[0010] The aforementioned internal combustion engine control device, by performing filter regeneration at appropriate times, can suppress the deterioration of the internal combustion engine's fuel economy. Attached Figure Description

[0011] Hereinafter, with reference to the accompanying drawings, the features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described, in which the same reference numerals denote the same elements, and wherein:

[0012] Figure 1 This is a schematic structural diagram showing a control device as one embodiment of an internal combustion engine control device and an internal combustion engine to which the control device is applied.

[0013] Figure 2 It means in Figure 1 A block diagram of the computational processing performed in the control device.

[0014] Figure 3 It means Figure 2 The flowchart for calculating and processing the generation amount.

[0015] Figure 4 It means in Figure 1 The flowchart shows a series of processes performed during the regeneration process in the control device. Detailed Implementation

[0016] according to Figures 1 to 4 An embodiment of the internal combustion engine control device will be described.

[0017] Figure 1 This refers to a control device 40 as an example of an internal combustion engine control device and an internal combustion engine 10 to which the control device 40 is applied. The internal combustion engine 10 is mounted in a vehicle.

[0018] Structure of an internal combustion engine

[0019] The internal combustion engine 10 is an internal combustion engine capable of operating using fuel containing ethanol. The internal combustion engine 10 includes multiple cylinders 11, a crankshaft 12, an intake passage 13, multiple fuel injection valves 14, multiple spark plugs 15, and an exhaust passage 16. The intake passage 13 is a passage for introducing airflow into the multiple cylinders 11. A throttle valve 17, which operates to adjust the intake air volume, is provided in the intake passage 13. The fuel injection valves 14 inject supplied fuel into the corresponding cylinders 11. In the multiple cylinders 11, a mixture containing air and fuel is burned by spark discharge from the corresponding spark plugs 15. This causes the crankshaft 12 to rotate. Furthermore, exhaust gas is generated in the multiple cylinders 11 through combustion of the mixture. Then, the exhaust gas discharged from the multiple cylinders 11 flows through the exhaust passage 16.

[0020] The internal combustion engine 10 includes a three-way catalytic converter 18 and a filter 19 disposed in the exhaust passage 16. The three-way catalytic converter 18 is disposed in the exhaust passage 16 upstream of the filter 19. The three-way catalytic converter 18 purifies the exhaust gas flowing in the exhaust passage 16. Specifically, the three-way catalytic converter 18 purifies hydrocarbons, carbon monoxide, and nitrogen oxides in the exhaust gas. The filter 19 captures particulate matter contained in the exhaust gas flowing in the exhaust passage 16. Hereinafter, particulate matter will be referred to as "PM". "PM" is an abbreviation for "Particulate Matter".

[0021] sensor

[0022] Multiple sensors input detection signals to the control unit 40. The multiple sensors include a crankshaft angle sensor 31, an air flow meter 32, an air-fuel ratio sensor 33, an exhaust temperature sensor 34, and an ethanol concentration sensor 35.

[0023] The crankshaft angle sensor 31 detects the rotation angle of the crankshaft 12. The rotational speed of the crankshaft 12 based on the detection signal from the crankshaft angle sensor 31 is recorded as "internal combustion engine speed NE".

[0024] Air flow meter 32 detects the air flow rate in the intake passage 13. The air flow rate based on the detection signal of air flow meter 32 is recorded as "intake air volume GA".

[0025] The air-fuel ratio sensor 33 is disposed in the exhaust passage 16 upstream of the three-way catalytic converter 18. The air-fuel ratio sensor 33 detects the oxygen concentration of the exhaust gas flowing in the exhaust passage 16. That is, the air-fuel ratio sensor 33 is capable of detecting the air-fuel ratio of the air-fuel mixture. The air-fuel ratio of the exhaust gas based on the detection signal of the air-fuel ratio sensor 33 is recorded as "air-fuel ratio AF".

[0026] An exhaust temperature sensor 34 is disposed in the portion of the exhaust passage 16 between the three-way catalytic converter 18 and the filter 19. The exhaust temperature sensor 34 detects the temperature of the exhaust gas flowing into the filter 19. The exhaust temperature based on the detection signal from the exhaust temperature sensor 34 is recorded as "exhaust temperature TO".

[0027] An ethanol concentration sensor 35 detects the ethanol content in the fuel supplied to multiple cylinders 11. The ethanol content based on the detection result of the ethanol concentration sensor 35 is recorded as "ethanol content Ra".

[0028] Control device

[0029] One example of the control device 40 is an electronic control device. In this case, the control device 40 includes a CPU 41, a first memory 42, and a second memory 43. The first memory 42 stores the control program executed by the CPU 41. The second memory 43 stores the calculation results of the CPU 41. In this embodiment, the CPU 41 corresponds to a "processing circuit". By executing the control program in the first memory 42, the CPU 41 can control the operation of the internal combustion engine 10.

[0030] CPU41 performs the following: calculation processing, calculating the amount of PM captured by filter 19, i.e., PM deposition amount Qdp; and regeneration processing, causing the PM captured by filter 19 to burn if the PM deposition amount Qdp exceeds a specified amount Th.

[0031] Calculation processing

[0032] refer to Figure 2 and Figure 3 A detailed explanation of a computational processing example will be provided.

[0033] Calculation process M10 is used to calculate the PM deposition amount Qdp based on the operating conditions of the internal combustion engine 10 and the ethanol content Ra. Calculation process M10 includes generation calculation process M11, regeneration calculation process M13, differential calculation process M15, and cumulative process M17.

[0034] CPU41 repeatedly executes the generation quantity calculation process M11 according to each prescribed operation cycle. In the generation quantity calculation process M11, CPU41 calculates the sum of the amount of PM generated in multiple cylinders 11 per unit time, which is the PM generation quantity Qgn. Here, "unit time" refers to the length of the operation cycle.

[0035] like Figure 3 As shown, in the PM generation calculation process M11, CPU41 calculates the PM generation amount based on the operating conditions of the internal combustion engine 10, i.e., the PM generation amount reference value QgnB (S11). The PM generation amount reference value QgnB is the PM generation amount assuming that the fuel injected by the multiple fuel injection valves 14 does not contain ethanol. CPU41 derives the PM generation amount reference value QgnB based on the intake air volume GA and the fuel injection amount Qf, etc.

[0036] Next, CPU41 calculates the PM generation amount Qgn by correcting the PM generation baseline value QgnB based on the ethanol content Ra (S13). For example, CPU41 calculates the PM generation amount Qgn as the product of the PM generation baseline value QgnB and the correction coefficient α corresponding to the ethanol content Ra.

[0037] The correction factor α is a value between 0 (zero) and 1. The higher the ethanol content Ra, the less likely PM is to be generated. Therefore, CPU41 sets the correction factor α so that the higher the ethanol content Ra, the smaller the value. Thus, the higher the ethanol content Ra, the smaller the PM generation Qgn can be generated by CPU41.

[0038] return Figure 2 The CPU41 repeatedly executes the regeneration amount calculation process M13 in each of the above-mentioned operation cycles. In the regeneration amount calculation process, the CPU41 calculates the amount of PM burned in the filter 19 per unit time, which is the PM regeneration amount Qrp.

[0039] The higher the temperature of the exhaust gas flowing into filter 19, the higher the temperature of filter 19. The higher the temperature of filter 19, the more PM is burned in filter 19. Furthermore, the more oxygen flows into filter 19, the more PM is burned in filter 19.

[0040] Therefore, in the regeneration calculation process M13, CPU41 derives the PM generation amount based on the temperature of filter 19 and the amount of oxygen in the exhaust gas flowing into filter 19. For example, CPU41 can estimate the temperature of filter 19 based on the exhaust temperature TO, the flow rate of the exhaust gas flowing into filter 19, and the ambient temperature. CPU41 can estimate the amount of oxygen in the exhaust gas flowing into filter 19 based on the air-fuel ratio AF, the intake air volume GA, and the fuel injection quantity Qf.

[0041] CPU41 repeatedly executes the differential calculation process M15 in each of the above-mentioned operation cycles. In the differential calculation process M15, CPU41 calculates the difference ΔQ from the value obtained by subtracting the PM regeneration amount Qrp from the PM generation amount Qgn.

[0042] Whenever the difference ΔQ is calculated through the differential calculation process M15, CPU41 executes the cumulative process M17. In the cumulative process M17, CPU41 calculates the latest value of PM deposition Qdp by summing the previous value of PM deposition Qdp with the difference ΔQ. That is, CPU41 calculates the cumulative value of the difference ΔQ as PM deposition Qdp.

[0043] Regeneration

[0044] refer to Figure 4 The execution time and content of the regeneration process are explained. CPU41 executes repeatedly. Figure 4 The series of processes shown.

[0045] In S21, CPU41 determines whether the PM deposition amount Qdp calculated in calculation process M10 is greater than a predetermined amount Th. The predetermined amount Th is the criterion for determining whether filter 19 needs regeneration. If the PM deposition amount Qdp is greater than the predetermined amount Th (S21: Yes), CPU41 transfers the process to S23. On the other hand, if the PM deposition amount Qdp is less than or equal to the predetermined amount Th (S21: No), CPU41 temporarily terminates the process. Figure 4 The series of processes shown.

[0046] In S23, CPU41 determines whether the execution conditions for the regeneration process are met. Details will be described later, but in the regeneration process, combustion of the air-fuel mixture within cylinder 11 is stopped. Therefore, the execution condition is considered met if the crankshaft 12 can be rotated by power from outside the internal combustion engine 10. For example, when the vehicle is inert, the crankshaft 12 rotates via power transmission from the wheels. Furthermore, for example, in the case of a hybrid electric vehicle where an electric motor is connected to the crankshaft 12, the crankshaft 12 can be rotated by driving the electric motor.

[0047] In S23, if CPU41 determines that the execution condition is met (S23: Yes), CPU41 transfers processing to S25. Conversely, if CPU41 determines that the execution condition is not met (S23: No), CPU41 temporarily terminates. Figure 4 The series of processes shown.

[0048] In S25, CPU41 performs a regeneration process. During the regeneration process, CPU41 stops the spark discharge of spark plug 15 and causes fuel injection through fuel injection valve 14, causing filter 19 to heat up to above the ignition point of PM.

[0049] If the spark plug 15 stops firing, unburned fuel injected from the fuel injection valve 14 flows out of the cylinder 11 into the exhaust passage 16. This unburned fuel, along with air, is supplied to the three-way catalytic converter 18. As a result, the unburned fuel burns in the three-way catalytic converter 18, thus increasing its temperature. At this time, due to the rotation of the crankshaft 12, the flow of gas through the three-way catalytic converter 18 and towards the filter 19 transfers heat from the three-way catalytic converter 18 to the filter 19. Therefore, if the temperature of the filter 19 is higher than the ignition point of the PM, the PM burns in the filter 19.

[0050] If the regeneration process takes longer than the specified time, CPU41 will terminate the regeneration process. Then, CPU41 will temporarily stop. Figure 4 The series of processes shown.

[0051] Additionally, if CPU41 performs a regeneration process in this way, CPU41 will, for example, reset the PM deposition amount Qdp to a specified value. One example of a specified value is 0 (zero).

[0052] The role and effect of the implementation method

[0053] (1) The rate of increase of the amount of PM adhering to the filter 19 varies depending on the ethanol content Ra of the fuel supplied to the cylinder 11.

[0054] Therefore, in addition to the operating conditions of the internal combustion engine 10, the CPU41 also considers the ethanol content Ra to calculate the PM deposition amount Qdp. Thus, even when the internal combustion engine 10 is operated using fuel containing ethanol, the CPU41 can accurately estimate the PM deposition amount in the filter 19.

[0055] CPU41 performs regeneration treatment when the PM deposition amount Qdp calculated above exceeds a predetermined amount Th. Therefore, by performing regeneration treatment at appropriate times, CPU41 can suppress the deterioration of the fuel economy of the internal combustion engine 10.

[0056] (2) CPU41 calculates PM deposition Qdp by the difference ΔQ between the cumulative PM generation Qgn and PM regeneration Qrp.

[0057] Here, the amount of PM generated in cylinder 11 varies depending on the ethanol content Ra of the fuel, while the combustion rate of PM in filter 19 is not significantly affected by the ethanol content Ra.

[0058] Therefore, CPU41 corrects the PM generation baseline value QgnB calculated based on the operating conditions of the internal combustion engine 10 according to the ethanol content Ra, thereby calculating the PM generation amount Qgn. Then, CPU41 calculates the PM deposition amount Qdp by accumulating the difference ΔQ between this PM generation amount Qgn and the PM regeneration amount Qrp. Therefore, CPU41 can estimate the PM deposition amount of filter 19 with high accuracy.

[0059] Change Example

[0060] The above-described embodiments can be implemented with the following modifications. The above-described embodiments and the following modifications can be combined with each other to implement them within the scope of technical inconsistency.

[0061] If the operating conditions of the internal combustion engine 10 are considered, the CPU 41 can calculate the PM generation amount Qgn without considering the ethanol content Ra. In this case, the CPU 41 can correct the difference ΔQ between the PM generation amount Qgn and the PM regeneration amount Qrp based on the ethanol content Ra. In this case, the CPU 41 calculates the PM deposition amount Qdp by accumulating the corrected difference ΔQ.

[0062] • If the filter 19 can be heated, the regeneration process can be a different process than that described in the above embodiments. For example, the regeneration process can be a process that includes at least one of the following: vibration control of each cylinder 11, fuel cut-off control of a portion of the plurality of cylinders 11, and control of delayed ignition timing.

[0063] The CPU41 can estimate the ethanol content using the air-fuel ratio (AF). In this case, the CPU41 can use the estimated ethanol content to calculate the PM deposition rate (Qdp).

[0064] • An internal combustion engine for which control device 40 is applicable only needs to have one or more cylinders 11.

[0065] • The control device 40 is not limited to a control device equipped with a CPU and ROM and capable of performing software processing. That is, the control device 40 may be any of the structures described in (a), (b) and (c) below.

[0066] (a) The control device 40 includes one or more processors that perform various processes according to a computer program. The processor includes a CPU and memories such as RAM and ROM. The memories store program code or instructions configured to cause the CPU to perform processes. Memory, or computer-readable medium, includes any available medium that can be accessed by a general-purpose or special-purpose computer.

[0067] (b) The control device 40 has one or more dedicated hardware circuits that perform various processes. Examples of dedicated hardware circuits include application-specific integrated circuits, i.e., ASICs or FPGAs. ASIC is an abbreviation for "Application Specific Integrated Circuit," and FPGA is an abbreviation for "Field Programmable Gate Array."

[0068] (c) The control device 40 includes: one or more processors that execute a portion of various processes according to a computer program; and one or more dedicated hardware circuits that execute the remaining processes in the various processes.

[0069] Furthermore, the term "at least one" as used in this specification indicates "more than one" of the desired options. For example, when there are two options, "at least one" means "only one option" or "both options". As another example, when there are three or more options, "at least one" means "only one option" or "any combination of two or more options".

Claims

1. An internal combustion engine control device adapted for an internal combustion engine that is provided with a cylinder, an exhaust passage through which exhaust gas discharged from the cylinder flows, and a filter that traps particulate matter contained in the exhaust gas flowing in the exhaust passage, characterized by comprising: a processing circuit, the processing circuit performs: a calculation process of calculating a PM deposition amount, which is an amount of the particulate matter trapped by the filter, in accordance with an operating condition of the internal combustion engine and a content rate of ethanol in fuel supplied into the cylinder; and a regeneration process of causing the particulate matter trapped by the filter to combust in a case where the PM deposition amount exceeds a prescribed amount.

2. The internal combustion engine control device according to claim 1, characterized in that: the processing circuit, in the calculation process, calculates, in accordance with the operating condition of the internal combustion engine and the content rate of ethanol in the fuel, a difference between a PM generation amount, which is an amount of the particulate matter generated in the cylinder, and a PM regeneration amount, which is an amount of the particulate matter combusted in the filter, at a prescribed each calculation cycle, calculates a cumulative value of the difference as the PM deposition amount, in a case of calculating the PM generation amount, the processing circuit calculates the PM generation amount in such a manner that the higher the content rate of ethanol in the fuel, the smaller the value.

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