Exhaust emission control system for internal combustion engine

Abstract

To provide an exhaust emission control system for an internal combustion engine capable of appropriately detecting an accumulation amount even in a non-uniform accumulation state where an accumulation amount of particulate matters in some regions of a filter is larger than that in other regions and capable of selectively regenerating a region that requires regeneration during regeneration.SOLUTION: An exhaust emission control system for an internal combustion engine includes a filter 62 that collects particulate matters in exhaust gas, a control device 50, and a storage device (53). Block division information on virtual division of an inflow surface of the filter into a plurality of blocks is stored in the storage device. The control device includes: an each block accumulation amount storage section 51a that calculates and stores an accumulation amount of particulate matters in each block in accordance with an operating state of an internal combustion engine 10; and a specific region regeneration control execution section 51b that executes specific region regeneration control for, when determining that there is a regeneration target block in which the accumulation amount of the particulate matters exceeds a regeneration start threshold value, specifying a regeneration target region including at least the regeneration target block and burning and incinerating particulate matters accumulated in the specified regeneration target region.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The technology disclosed in this specification relates to an exhaust gas purification system for an internal combustion engine that traps particulate matter contained in the exhaust gas of the internal combustion engine and combusts the trapped particulate matter. [Background technology]

[0002] In recent years, vehicles equipped with diesel engines as internal combustion engines have been fitted with filters (DPF: Diesel Particulate Filter) that trap particulate matter contained in exhaust and repeatedly combust and incinerate the trapped particulate matter.Furthermore, in recent years, an increasing number of vehicles equipped with gasoline engines as internal combustion engines have been fitted with filters (GPF: Gasoline Particulate Filter) that trap particulate matter contained in exhaust and repeatedly combust and incinerate the trapped particulate matter.

[0003] In both filters, when the amount of accumulated trapped particulate matter exceeds a predetermined threshold, the particulate matter accumulated on the filter is burned and incinerated to regenerate the filter in order to prevent clogging, etc. Both filters require detection of the amount of accumulated trapped particulate matter and a regeneration process in which the accumulated particulate matter is burned and incinerated.

[0004] For example, in Patent Document 1, in a hybrid vehicle powered by an internal combustion engine and a first motor, pressure sensors are provided in an exhaust pipe upstream (upstream) of a filter installed in the exhaust path and in an exhaust pipe downstream (downstream) of the filter, respectively, to determine the pressure difference between the pressure upstream and the pressure downstream of the filter, and to estimate the amount of particulate matter deposited in the filter based on the pressure difference. If it is determined based on the pressure difference that the amount of particulate matter deposited on the filter exceeds a predetermined threshold, the internal combustion engine is forcibly motored by a second motor connected to the internal combustion engine while the vehicle is running using the first motor as a power source. This motoring provides oxygen to a filter installed in the exhaust path, thereby implementing regeneration control to combust and incinerate the particulate matter deposited in the filter. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-126940 Summary of the Invention [Problem to be solved by the invention]

[0006] Particulate matter is captured and deposited on a filter installed in the exhaust path of an internal combustion engine, but it is often not deposited uniformly across the entire filter, resulting in uneven deposition where the amount of deposition in some areas of the filter is greater than the amount of deposition in other areas.When particulate matter is deposited unevenly, some areas of the filter have a large amount of particulate matter deposited and a large pressure loss, while other areas of the filter have a small amount of particulate matter deposited and a small pressure loss.

[0007] When particulate matter accumulates unevenly, even if the pressure difference between the upstream (upstream) and downstream (downstream) stages of the filter is calculated, a small pressure difference is detected due to the influence of areas where the accumulation amount is small and the pressure loss is small. In this case, the control device will erroneously recognize that the accumulation amount is small even though it is large in some areas. Furthermore, in filter regeneration control to burn and incinerate accumulated particulate matter, the conventional method of heating the entire filter to a high temperature exposes areas with a low accumulation amount of particulate matter to higher temperatures than necessary, accelerating deterioration of the entire filter. Heating only the areas of the filter that require regeneration to a high temperature is preferable because it suppresses deterioration of the entire filter.

[0008] In Patent Document 1, particulate matter is considered to be deposited almost uniformly throughout the filter, and the amount of particulate matter deposited on the filter is estimated based on the pressure difference between the pressure upstream and downstream of the filter. Therefore, if particulate matter is deposited unevenly, with a high deposition amount in some areas and a low deposition amount in other areas, the deposition amount may be erroneously recognized as low due to the influence of other areas with low pressure loss. Furthermore, in Patent Document 1, the entire filter is heated to a high temperature during filter regeneration control. Therefore, if particulate matter is deposited unevenly, areas with low particulate matter deposition may also be exposed to higher temperatures than necessary, which may accelerate deterioration of the entire filter, which is undesirable.

[0009] The objective of the technology disclosed in this specification to solve the above problems is to provide an exhaust purification system for an internal combustion engine that can properly detect the amount of particulate matter deposited even when the amount of particulate matter deposited in some areas of the filter is greater than the amount deposited in other areas, and that can selectively regenerate the areas that need to be regenerated during regeneration. [Means for solving the problem]

[0010] In order to solve the above problems, the exhaust gas purification system for an internal combustion engine disclosed in this specification takes the following measures.

[0011] The first means is an exhaust gas purification system for an internal combustion engine, the system including a filter disposed in an exhaust path of the internal combustion engine and trapping particulate matter contained in the exhaust gas, a control device for controlling the internal combustion engine, and a storage device. The storage device stores block division information that virtually divides the exhaust gas inlet surface of the filter into a plurality of blocks. The control device further includes a block-by-block accumulation amount storage unit that calculates the amount of particulate matter deposited in each block according to the operating state of the internal combustion engine and stores the amount of particulate matter deposited in each block in the storage device, and a specific area regeneration control execution unit that, when it is determined that there is a regeneration target block in which the amount of particulate matter deposited exceeds a regeneration start threshold, identifies a regeneration target area that is at least a part of the inlet surface of the filter that includes at least the regeneration target block, and executes specific area regeneration control to combust and burn the particulate matter deposited in the identified regeneration target area.

[0012] According to the first means, the exhaust gas inlet surface of the filter is virtually divided into a plurality of blocks, and the particulate matter deposition amount storage unit calculates and stores the deposition amount of particulate matter for each divided block. This makes it possible to appropriately detect the deposition amount even if the deposition amount of particulate matter is unevenly distributed in some areas of the filter, where it is greater than the deposition amount in other areas. Furthermore, the specific area regeneration execution unit combusts and incinerates the particulate matter deposited in the specified regeneration target area, thereby selectively regenerating the area that needs to be regenerated.

[0013] The second means is an exhaust gas purification system for an internal combustion engine according to the first means, wherein the storage device stores a particulate matter generation amount characteristic in which the amount of particulate matter contained in exhaust gas is set according to the operating state, and a block-by-block exhaust gas distribution rate characteristic in which the distribution rate of exhaust gas for each block according to the operating state is set. The control device calculates, in the block-by-block deposition amount storage unit, the amount of particulate matter generated corresponding to the operating state based on the operating state and the particulate matter generation amount characteristic, calculates the distribution rate of exhaust gas for each block corresponding to the operating state based on the operating state and the block-by-block exhaust gas distribution rate characteristic, and calculates the deposition amount of particulate matter for each block based on the calculated amount of particulate matter generated and the distribution rate of exhaust gas for each block.

[0014] According to the second means, it is possible to calculate the distribution of the generated particulate matter at which positions (block positions) on the inlet surface of the filter, and therefore the amount of particulate matter deposited in each block can be determined appropriately.

[0015] A third means is an exhaust gas purification system for an internal combustion engine according to the second means, wherein the storage device stores per-cylinder exhaust region characteristics that set per-cylinder exhaust regions, which are regions where exhaust gas from each cylinder of the internal combustion engine hits the inlet surface of the filter, according to the operating state. When the specific region regeneration control execution unit executes the specific region regeneration control, the control device specifies the per-cylinder exhaust region including the regeneration target block as the regeneration target region based on the operating state, the per-cylinder exhaust region characteristics, and the regeneration target block, specifies a cylinder corresponding to the specified regeneration target region, and adjusts the amount of fuel supplied to the specified cylinder so that the exhaust from the specified cylinder has a higher oxygen content or a higher exhaust temperature than the exhaust from other cylinders.

[0016] According to the third means, it is possible to properly determine the regeneration target area where the accumulated particulate matter is to be burned and incinerated, and to properly burn and incinerate the particulate matter accumulated in each block of the regeneration target area.

[0017] A fourth aspect of the present invention is an exhaust gas purification system for an internal combustion engine according to the third aspect, wherein the internal combustion engine is a gasoline engine and an injector for supplying fuel is provided for each cylinder, and the control device executes the specific region regeneration control using the specific region regeneration control execution unit, and when adjusting the amount of fuel supplied to the specific cylinder so that the exhaust from the specific cylinder has a higher oxygen content than the exhaust from other cylinders, controls the air-fuel ratio of the specific cylinder to be lean, thereby increasing the oxygen content of the exhaust from the specific cylinder.

[0018] According to the fourth means, by adjusting the fuel supply amount to the specific cylinder so that the air-fuel ratio of the specific cylinder becomes lean, the oxygen content of the exhaust gas from the specific cylinder can be made higher than the oxygen content of the exhaust gas from the other cylinders.

[0019] A fifth means is an exhaust gas purification system for an internal combustion engine according to the fourth means, wherein the control device is capable of detecting an intake air amount of the internal combustion engine, and when the specific region regeneration control execution unit executes the specific region regeneration control, the control device determines a regeneration target air-fuel ratio that makes the air-fuel ratio of the specific cylinder lean, and adjusts the fuel amount of the specific cylinder based on the regeneration target air-fuel ratio and the intake air amount, or cuts fuel to the specific cylinder, to control the air-fuel ratio of the specific cylinder to be lean, and determines the amount of intake air of the specific cylinder based on the intake air amount of the internal combustion engine and the regeneration target air-fuel ratio, or the intake air amount of the internal combustion engine. An exhaust purification system for an internal combustion engine that calculates the oxygen content of the exhaust of a cylinder, calculates an oxygen supply amount per block within the region, which is the amount of oxygen supplied to each block within the per-cylinder exhaust region of the specific cylinder, based on the calculated oxygen content, the operating state, the per-cylinder exhaust region corresponding to the specific cylinder, and the per-block exhaust distribution ratio characteristic, calculates the amount of particulate matter burned and incinerated for each block within the per-cylinder exhaust region of the specific cylinder based on the per-region oxygen supply amount per block, and reduces the amount of deposition for each block within the per-cylinder exhaust region of the specific cylinder.

[0020] According to the fifth means, it is possible to appropriately calculate the oxygen supply amount for each block in the regeneration target region (the exhaust region for each cylinder of a specific cylinder), which is the oxygen supply amount to each block in the regeneration target region (the exhaust region for each cylinder of a specific cylinder). This makes it possible to appropriately calculate the combustion amount for each block in the exhaust region for each cylinder of a specific cylinder, and to reduce the deposition amount for each block in the exhaust region for each cylinder of a specific cylinder.

[0021] The sixth means is an exhaust purification system for an internal combustion engine according to any one of the first to fifth means, wherein the operating state includes the rotation speed of the internal combustion engine and an internal combustion engine load-related quantity related to the load on the internal combustion engine.

[0022] According to the sixth means, it is possible to appropriately set the particulate matter generation amount characteristics, the exhaust distribution ratio characteristics for each block, the exhaust region characteristics for each cylinder, and the like, in accordance with the operating state. [Effects of the Invention]

[0023] By adopting the above-mentioned measures, the exhaust purification system for an internal combustion engine disclosed in this specification can appropriately detect uneven deposition of particulate matter in some areas of the filter, where the amount of deposition is greater than the amount of deposition in other areas, and can selectively regenerate the areas that need to be regenerated during regeneration. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a diagram illustrating an example of the overall configuration of an internal combustion engine system. [Figure 2] FIG. 2 is a diagram illustrating a schematic configuration of a filter. [Figure 3] 10A and 10B are diagrams illustrating examples of regions with a large amount of particulate matter deposited and regions with a small amount of particulate matter deposited on the exhaust gas inflow surface of the filter. [Figure 4] 10 is a flowchart illustrating an example of a processing procedure of the control device (an example of [overall processing]). [Figure 5] 5 is a flowchart illustrating details of the process of "calculating and storing the amount of deposited particulate matter for each block" shown in the "overall process" of FIG. 4. [Figure 6] FIG. 10 is a diagram illustrating an example of [block division information] in which the exhaust gas inflow surface of the filter is virtually divided into a plurality of blocks. [Figure 7] FIG. 2 is a diagram illustrating an example of the characteristics of the amount of particulate matter generated according to the operating state of the internal combustion engine. [Figure 8] 10 is a diagram illustrating an example of the "exhaust region characteristics for each cylinder" according to the operating state of the internal combustion engine. FIG. [Figure 9] 10A and 10B are diagrams illustrating examples of the "exhaust gas distribution ratio characteristics for each block" according to the operating state of the internal combustion engine. [Figure 10] FIG. 10 is a diagram illustrating an example of the “distribution amount per block” showing the distribution amount of particulate matter per block. [Figure 11] FIG. 10 is a diagram illustrating an example of the “accumulation amount per block” showing the accumulation amount of particulate matter per block. [Figure 12]5 is a flowchart illustrating details of the process of "identifying a cylinder that is a cylinder-by-cylinder exhaust region including a regeneration target block and storing the identified cylinder" shown in "Overall process" in FIG. 4. [Figure 13] 5 is a flowchart illustrating details of the process of "calculating the amount of combustion for each block in the exhaust region for each cylinder of a specific cylinder" shown in "Overall process" in FIG. 4. [Figure 14] FIG. 10 is a diagram illustrating an example of the exhaust distribution ratio for each block within the exhaust region for each cylinder of a specific cylinder. [Figure 15] FIG. 10 is a diagram illustrating an example of the oxygen supply amount for each block in the exhaust region for each cylinder of a specific cylinder. [Figure 16] FIG. 10 is a diagram illustrating an example of the amount of combustion per block in the exhaust region per cylinder of a specific cylinder. [Figure 17] 5 is a flowchart illustrating details of the process of "reducing and storing the deposit amount of each block in the exhaust region for each cylinder of a specific cylinder" shown in "Overall process" in FIG. 4. [Figure 18] 10 is a flowchart illustrating an example of a fuel injection process. [Figure 19] 10 is a flowchart illustrating an example of throttle valve control. DETAILED DESCRIPTION OF THE INVENTION

[0025] <<Overall configuration of internal combustion engine system 1 (Fig. 1)>> Hereinafter, an embodiment will be described with reference to the drawings. Fig. 1 shows an example of the overall configuration of an internal combustion engine system 1 mounted on a vehicle. Note that the internal combustion engine 10 of the internal combustion engine system 1 in the example of Fig. 1 is a so-called gasoline engine. The exhaust purification system 2 has a control device 50 (including a storage device 53) and a filter 62 (particulate matter collection filter). Below, the configuration of the internal combustion engine system 1 will be described in order from the intake side to the exhaust side.

[0026] An intake air flow rate detecting device 31 (e.g., an intake air flow rate sensor) is provided on the inflow side of the intake pipe 12a. The intake air flow rate detecting device 31 outputs a detection signal corresponding to the flow rate [g / sec] of air taken in by the internal combustion engine 10 to the control device 50. The intake air flow rate detecting device 31 is also provided with an intake air temperature detecting device 33a (e.g., an intake air temperature sensor) and an atmospheric pressure detecting device 32a (e.g., an atmospheric pressure sensor). The intake air temperature detecting device 33a outputs a detection signal corresponding to the intake air temperature to the control device 50, and the atmospheric pressure detecting device 32a outputs a detection signal corresponding to the atmospheric pressure to the control device 50. The outflow side of the intake pipe 12a is connected to the inflow side of a throttle device 41.

[0027] The throttle device 41 includes a throttle valve 41c that adjusts the opening of the intake pipe 12a, a motor 41a that drives the throttle valve 41c, an opening detection device 41b (e.g., an opening sensor) that detects the opening of the throttle valve 41c, etc. The control device 50 detects the accelerator pedal depression amount from the driver using a depression amount detection device 37 (e.g., an accelerator depression amount sensor), determines a target throttle valve opening amount based on the detected depression amount, etc., and drives the motor 41a so that the throttle valve 41c opens to the target opening amount.

[0028] The outlet side of the throttle device 41 is connected to the inlet side of the intake pipe 12b, and the outlet side of the intake pipe 12b is connected to the inlet side of a compressor 44b of the turbocharger 44. A purge pipe 45a is connected to a canister 45 via a purge valve 42 on the downstream side of the throttle device 41. When the control device 50 opens the purge valve 42, evaporated fuel generated in the fuel tank 46 and adsorbed in the canister 45 is sucked into the intake pipe 12b. Although the example in FIG. 1 shows an example in which the throttle device 41 and the purge pipe 45a are arranged upstream of the compressor 44b, the throttle device 41 and the purge pipe 45a may also be arranged downstream of the compressor 44b.

[0029] The discharge side of the compressor 44b is connected to the inlet side of the intake pipe 12c. The outlet side of the intake pipe 12c is connected to the inlet side of the intake manifold 12d. An intake air temperature detection device 33b (e.g., an intake air temperature sensor) is provided in the intake pipe 12c near the compressor 44b, and outputs a detection signal corresponding to the temperature of the intake air to the control device 50.

[0030] The outlet side of the intake manifold 12d is connected to an intake port that guides intake air to cylinders #1 to #4 of the internal combustion engine 10. The intake air guided to the intake manifold 12d is drawn into cylinders #1 to #4 of the internal combustion engine 10 and is used for combustion together with fuel injected from injectors 11a provided for each cylinder. Spark plugs are not shown. The intake manifold 12d is also provided with a pressure detection device 32b (e.g., a pressure sensor) that outputs a detection signal corresponding to the pressure of the intake air in the intake manifold 12d to the control device 50.

[0031] The internal combustion engine 10 is provided with a rotation detection device 35a and a cylinder detection device 35b. The rotation detection device 35a (for example, a crankshaft rotation sensor) outputs a detection signal (crank angle signal) corresponding to the rotation angle of the crankshaft of the internal combustion engine 10 to the control device 50. The cylinder detection device 35b (for example, a camshaft rotation sensor) outputs a detection signal (cylinder discrimination signal) to the control device 50, for example, when the piston of the first cylinder reaches top dead center of compression. The internal combustion engine 10 is also provided with a coolant temperature detection device 34 (for example, a water temperature sensor) that outputs a detection signal corresponding to the temperature of the coolant (cooling water) that cools the internal combustion engine 10 to the control device 50.

[0032] The control device 50 determines the rotation speed of the internal combustion engine based on the detection signal from the rotation detection device 35a, and can recognize the compression top dead center of each cylinder based on the detection signal from the cylinder detection device 35b. The control device 50 then controls the injector 11a at a predetermined timing to inject a fuel amount according to the operating state of the internal combustion engine 10 into each of cylinders #1 to #4.

[0033] An inlet side of an exhaust manifold 22a is connected to an exhaust port of the internal combustion engine 10. The outlet side of the exhaust manifold 22a is connected to the inlet side of an exhaust pipe 22b, and the outlet side of the exhaust pipe 22b is connected to the inlet side of a turbine 44a of a turbocharger 44. The exhaust manifold 22a or the exhaust pipe 22b is provided with an air-fuel ratio detection device 38 (e.g., an A / F sensor) that detects the air-fuel ratio of the exhaust.

[0034] The inlet side of EGR pipe 23, which returns part of the exhaust gas to the intake air, is connected to exhaust manifold 22a or exhaust pipe 22b. The outlet side of EGR pipe 23 is connected to intake pipe 12c or intake manifold 12d. EGR pipe 23 is provided with EGR valve 43, which is controlled by control device 50 to adjust the opening of the EGR pipe.

[0035] The inlet side of an exhaust pipe 22c is connected to the outlet side of the turbine 44a, and the outlet side of the exhaust pipe 22c is connected to the inlet side of a three-way catalyst 61. The inlet side of an exhaust pipe 22d is connected to the outlet side of the three-way catalyst 61, and the outlet side of the exhaust pipe 22d is connected to the inlet side of a filter 62. The outlet side of the filter 62 is connected to the inlet side of an exhaust pipe 22e. The three-way catalyst 61 purifies carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOx) contained in the exhaust gas from the internal combustion engine 10. The filter 62 traps particulate matter contained in the exhaust gas from the internal combustion engine 10 and combusts the trapped particulate matter under regeneration control from the control device 50.

[0036] An exhaust gas temperature detecting device 36a (for example, an exhaust gas temperature sensor) is provided on the inflow side of the three-way catalyst 61, which outputs a detection signal corresponding to the exhaust gas temperature to the control device 50, and an exhaust gas temperature detecting device 36b (for example, an exhaust gas temperature sensor) is provided on the outflow side of the three-way catalyst 61 (or the inflow side of the filter 62), which outputs a detection signal corresponding to the exhaust gas temperature to the control device 50. An exhaust gas temperature detecting device 36c (for example, an exhaust gas temperature sensor) is provided on the outflow side of the filter 62, which outputs a detection signal corresponding to the exhaust gas temperature to the control device 50.

[0037] Also provided is a differential pressure detection device 32c (e.g., a differential pressure sensor) that outputs a detection signal corresponding to the differential pressure across the filter, which is the pressure difference between the pressure on the upstream side and the pressure on the downstream side of the filter 62. Note that the differential pressure detected by the differential pressure detection device 32c shown in Fig. 1 is not used to estimate the amount of particulate matter deposited on the filter 62, but is used for other purposes.

[0038] The control device 50 is a well-known device including a CPU 51, a RAM 52, a ROM 53 (storage device), a timer 54, a non-volatile storage device 55 (e.g., EEPROM), etc. The CPU 51 executes various calculation processes based on various programs and maps stored in the ROM 53 (e.g., Flash-ROM). The RAM 52 temporarily stores the calculation results of the CPU and data input from each detection device, and the non-volatile storage device 55 stores data to be saved when the internal combustion engine 10 is stopped, for example. The block-by-block deposition amount storage unit 51a and the specific region regeneration control execution unit 51b will be described later.

[0039] The control device 50 can detect the operating state of the internal combustion engine 10 based on the various detection signals input thereto. The control device 50 also outputs control signals for controlling various actuators such as the injector 11a, the motor 41a of the throttle device 41, the purge valve 42, the EGR valve 43, etc., in response to the detected operating state of the internal combustion engine 10 and a request from the driver based on a detection signal from the depression amount detection device 37.

[0040] <<Schematic structure of filter 62 (Figs. 2 and 3)>> FIG. 2 shows a schematic diagram of the structure of filter 62. FIG. 3 shows inflow surface 62m in FIG. 2 as viewed from the front. Filter 62 houses filter body 62a, and exhaust gas flowing in from exhaust pipe 22d strikes inflow surface 62m of filter body 62a, passes through filter body 62a, and flows into exhaust pipe 22e, with particulate matter contained in the exhaust gas being collected by filter body 62a. Note that the exhaust gas striking inflow surface 62m does not strike inflow surface 62m uniformly over the entire surface, and therefore, as shown in the example of FIG. 3, the amount of particulate matter deposited in region A on inflow surface 62m is greater than the amount of particulate matter deposited in region B. The positions and sizes of region A, where the amount of deposition is high, and region B, where the amount of deposition is low, vary depending on the curved shape and length of the exhaust pipe, etc.

[0041] Conventionally, when determining the amount of particulate matter deposited on the filter 62, the particulate matter is assumed to be deposited almost uniformly across the entire filter 62, and the amount of deposition is estimated based on the differential pressure across the filter detected by the differential pressure detection device 32c. However, with this method, if particulate matter is deposited unevenly, as described above, even if the differential pressure across the filter is determined, a small pressure difference is detected due to the influence of an area where the deposition amount is small and the pressure loss is small (area B in FIG. 3). In this case, the control device erroneously determines that the deposition amount is small, even though it is large in some areas (area A in FIG. 3). Furthermore, during filter regeneration control, if particulate matter is deposited unevenly, raising the temperature of the entire filter is undesirable because it may expose areas with low particulate matter deposition to higher temperatures than necessary, which may accelerate deterioration of the entire filter. Therefore, the above problem is solved by the processing of the control device 50 described below.

[0042] <<Processing of the control device 50 (FIGS. 4 to 18)>> <<Processing procedure for [Full Processing] (Figure 4)>> Next, the "overall processing" which is the processing of the control device 50 will be described with reference to Fig. 4. For example, the control device 50 (CPU 51 of the control device 50) starts the "overall processing" shown in Fig. 4 at predetermined time intervals (intervals of several [ms] to several hundred [ms]), and the processing proceeds to step S10.

[0043] As shown in the block division information (stored in the storage device) in Figure 6, the inlet surface 62m of the filter is virtually divided into multiple blocks, and the control device 50 stores (stores in a non-volatile storage device) the amount of particulate matter deposited for each block. In Figure 6, blocks at least partially inside the inlet surface 62m (such as block

[12] and block

[13] enclosed in [ ]) are valid blocks, while blocks entirely outside the inlet surface 62m (such as block 00 and block 01 without [ ]) are invalid blocks and will not be used in subsequent control. Hereinafter, unless otherwise specified, the term "block" refers to a valid block enclosed in [ ].

[0044] In step S10, the control device 50 detects various operating conditions of the internal combustion engine, and then proceeds to step S12. The operating conditions to be detected include, for example, the internal combustion engine speed based on a detection signal from the rotation detection device 35a, the accelerator pedal depression amount based on a detection signal from the depression amount detection device 37, the coolant temperature based on a detection signal from the coolant temperature detection device 34, the air-fuel ratio based on a detection signal from the air-fuel ratio detection device 38, and the exhaust temperature based on detection signals from the exhaust temperature detection devices 36a, 36b, and 36c.

[0045] In step S12, the control device 50 executes the process of "determining and storing the amount of particulate matter deposited for each block," which will be described later, and proceeds to step S22. The control device 50 (CPU 51) that executes the process of step S12 corresponds to the block-by-block deposition amount storage unit 51a (see FIG. 1), which determines the amount of particulate matter deposited for each block according to the operating state of the internal combustion engine 10 and stores the amount of deposition for each block in a storage device.

[0046] In step S22, the control device 50 determines whether the regeneration in progress flag is ON. The "regeneration in progress flag" is set to "ON" when regeneration control of the filter 62 (control to regenerate the filter by burning and incinerating accumulated particulate matter) is started in step S38 or step S48 of Fig. 4, and is set to "OFF" when the filter regeneration control is completed in step S64 of Fig. 4. If the regeneration in progress flag is set to ON (Yes), the control device 50 proceeds to step S52, and if the regeneration in progress flag is set to OFF (No), the control device 50 proceeds to step S24.

[0047] If the process proceeds to step S24, the control device 50 reads the amount of particulate matter deposited in each block shown in Fig. 6 and determines whether there is a block to be regenerated where the amount of deposition is greater than the regeneration start threshold. The "regeneration start threshold" is an amount of deposition less than the amount of deposition at which the block becomes clogged with particulate matter, and is a value selected through experiments, simulations, etc. using an actual vehicle. If there is a block to be regenerated where the amount of deposition is greater than the regeneration start threshold (Yes), the control device 50 proceeds to step S26, and if there is no block to be regenerated where the amount of deposition is greater than the regeneration start threshold (No), the control device 50 ends the process shown in Fig. 4.

[0048] If the process proceeds to step S26, the control device 50 determines whether or not a regeneration start condition (a regeneration start condition other than the accumulation amount) is satisfied. Examples of the regeneration start conditions include: after warming up of the internal combustion engine is complete; the internal combustion engine rotation speed is within a range from a first predetermined rotation speed to a second predetermined rotation speed; the rotation speed fluctuation amount is within a ± predetermined rotation speed range; the accelerator pedal depression amount (load) is within a range from a first predetermined depression amount to a second predetermined depression amount; the accelerator pedal depression amount fluctuation amount is within a ± predetermined depression amount range; and the exhaust gas temperatures before and after the filter are equal to or higher than a predetermined exhaust gas temperature. If the regeneration start condition is satisfied (Yes), the control device 50 proceeds to step S28; if the regeneration start condition is not satisfied (No), the control device 50 ends the process shown in FIG. 4.

[0049] If the process proceeds to step S28, the control device 50 executes a process to "identify a cylinder that is part of the per-cylinder exhaust region that includes the block to be regenerated, and store the specific cylinder," which will be described later, and then proceeds to step S32. Note that the "specific cylinder" and "per-cylinder exhaust region" will be described later, but for example, if the internal combustion engine 10 has four cylinders, cylinders #1 to #4, the exhaust from each cylinder impinges on the inlet surface 62m of the filter as shown in the "per-cylinder exhaust region characteristics" in Figure 8.

[0050] Figure 8 shows an example in which the exhaust from cylinder #1 falls within per-cylinder exhaust region R1, the exhaust from cylinder #3 falls within per-cylinder exhaust region R3, the exhaust from cylinder #4 falls within per-cylinder exhaust region R4, and the exhaust from cylinder #2 falls within per-cylinder exhaust region R2. The "per-cylinder exhaust region" in the per-cylinder exhaust region characteristics varies depending on the number of cylinders, the length and curvature of the exhaust path from the internal combustion engine 10 to the filter 62, the exhaust velocity (exhaust flow rate), and other factors. For example, if the amount of particulate matter deposited in block

[53] in Figure 8 is greater than the regeneration start threshold, block

[53] is the "regeneration target block," the per-cylinder exhaust region R1 that includes block

[53] is the "per-cylinder exhaust region" that is the regeneration target, and cylinder #1 that corresponds to this per-cylinder exhaust region R1 is the "specific cylinder."

[0051] In step S32, the control device 50 determines whether or not there are any blocks where the accumulation amount is greater than the predetermined threshold among the regeneration target blocks where the accumulation amount is greater than the regeneration start threshold in step S24. The "predetermined threshold" is a threshold that switches whether or not to speed up the combustion of particulate matter, and is a value selected through experiments, simulations, etc. using an actual vehicle. If there are any regeneration target blocks where the accumulation amount is greater than the predetermined threshold (Yes), the control device 50 proceeds to step S34, where regeneration is performed with a large oxygen supply amount for quick combustion and incineration. If there are no regeneration target blocks where the accumulation amount is greater than the predetermined threshold (No), the control device 50 proceeds to step S42, where regeneration is performed with a small oxygen supply amount for gentle combustion and incineration.

[0052] In gasoline engines, a three-way catalyst is used to purify HC, CO, and NOx, and the air-fuel ratio is controlled close to the theoretical value, so there is almost no oxygen in the exhaust. In order to regenerate the filter, oxygen must be added to the exhaust in order to burn off the particulate matter that has accumulated inside the filter.

[0053] If the process proceeds to step S34, the control device 50 predicts the torque decrease amount of the internal combustion engine when fuel is cut off from the specific cylinder identified in step S28 (when a relatively large amount of oxygen is contained in the exhaust), and proceeds to step S36. For example, the torque decrease amount corresponds to the torque that would have been generated by the combustion stroke of the specific cylinder if fuel was not cut off from the specific cylinder.

[0054] In step S36, the control device 50 calculates and stores the throttle valve opening increase amount for increasing the amount of intake air and the fuel increase amount to compensate for the torque decrease amount with other cylinders, and proceeds to step S38. For example, if the specific cylinder to be fuel-cut is cylinder #1 and the torque decrease amount is torque X, the torque is increased by X / 3 in each of cylinders #2, #3, and #4. The increase in fuel amount required for this is the fuel increase amount, and the increase in the throttle valve opening amount that realizes the increase in intake air amount corresponding to the fuel increase amount is the throttle valve opening increase amount.

[0055] In step S38, the control device 50 sets the regeneration in progress flag to ON, sets the fuel cut regeneration flag to ON, and ends the processing shown in Fig. 4. Note that the "fuel cut regeneration flag (and regeneration in progress flag)" is used in the [fuel injection processing] shown in Fig. 18.

[0056] When the process proceeds to step S42, the control device 50 sets a target initial value to the regeneration target air-fuel ratio, which is the target air-fuel ratio when the air-fuel ratio of the specific cylinder identified in step S28 is made lean and combustion is performed (when a relatively small amount of oxygen is contained in the exhaust), and proceeds to step S44. For example, in the case of a gasoline engine, since the stoichiometric air-fuel ratio is about 14.7, the target initial value for making it lean is set to a value of about 16.0, which is larger than 14.7. The target initial value is set to a value selected through experiments, simulations, etc. using an actual vehicle.

[0057] In step S44, the control device 50 predicts the amount of NOx generated from a specific cylinder when the specific cylinder is subjected to lean control (lean burn) at the regeneration target air-fuel ratio, and proceeds to step S46. For example, the amount of NOx generated is predicted based on operating conditions such as the intake air amount of the specific cylinder, the fuel injection amount required to achieve the regeneration target air-fuel ratio, the engine speed, and the EGR amount. Although NOx increases because the specific cylinder is subjected to lean burn, the increase in NOx is suppressed to an allowable amount or less by the following processing.

[0058] In step S46, the control device 50 determines whether the predicted NOx generation amount, which is the predicted amount of NOx generation, is equal to or less than a preset allowable amount. If the predicted NOx generation amount is equal to or less than the allowable amount (Yes), the control device 50 proceeds to step S48, and if the predicted NOx generation amount is greater than the allowable amount (No), the control device 50 proceeds to step S47.

[0059] If the process proceeds to step S47, the control device 50 reduces the regeneration target air-fuel ratio by a predetermined air-fuel ratio ΔL, and returns the process to step S44. The predetermined air-fuel ratio ΔL to be subtracted is set to an appropriate value, for example, about 0.1 to 0.5.

[0060] If the process proceeds to step S48, the control device 50 sets the regeneration in progress flag to ON, sets the lean regeneration flag to ON, and ends the process shown in Fig. 4. The "regeneration in progress flag" is used in the [fuel injection process] shown in Fig. 18.

[0061] If the process proceeds to step S52, the control device 50 determines whether or not a regeneration continuation condition (a condition for continuing regeneration) is satisfied. Examples of the regeneration continuation conditions include: after warming up of the internal combustion engine is complete; the internal combustion engine rotation speed is within a range from a first predetermined rotation speed to a second predetermined rotation speed; the rotation speed fluctuation amount is within a ± predetermined rotation speed range; the accelerator pedal depression amount (load) is within a range from a first predetermined depression amount to a second predetermined depression amount; the accelerator pedal depression amount fluctuation amount is within a ± predetermined depression amount range; and the exhaust gas temperatures before and after the filter are equal to or higher than a predetermined exhaust gas temperature. If the regeneration continuation condition is satisfied (Yes), the control device 50 proceeds to step S54; if the regeneration continuation condition is not satisfied (No), the control device 50 proceeds to step S64 and stops the filter regeneration process.

[0062] If the process proceeds to step S54, the control device 50 executes a process to calculate the combustion amount of each block in the exhaust region for each cylinder of a specific cylinder, which will be described later, and then proceeds to step S56.

[0063] In step S56, the control device 50 executes a process to reduce and store the amount of (particulate matter) deposition in each block in the exhaust region for each cylinder of a specific cylinder, which will be described later, and then proceeds to step S62.

[0064] In step S62, the control device 50 determines whether the deposit amount (deposit amount after reduction by combustion) in each block within the per-cylinder exhaust region of a specific cylinder is less than the regeneration end threshold. The regeneration end threshold is a threshold for determining that regeneration is complete, and an appropriate value is selected through experiments, simulations, etc. using an actual vehicle. If the deposit amount in each target block is less than the regeneration end threshold (Yes), the control device 50 proceeds to step S64 and ends the regeneration process. If the deposit amount in each target block is equal to or greater than the regeneration end threshold (No), the control device 50 ends the process of FIG. 4 and continues regeneration.

[0065] If the process proceeds to step S64, the control device 50 sets the regeneration in progress flag to OFF, sets the fuel cut regeneration flag to OFF, and sets the lean regeneration flag to OFF in order to end the regeneration process, and then ends the process shown in FIG. 4.

[0066] In addition, the control device 50 (CPU 51) that executes the processing from step S22 onwards in Figure 4 corresponds to a specific area regeneration control execution unit 51b that, when it determines that there is a regeneration target block, which is a block in which the amount of particulate matter accumulated exceeds the regeneration start threshold, identifies a regeneration target area that is at least a part of the inlet surface of the filter that includes at least the regeneration target block, and executes specific area regeneration control to burn and incinerate the particulate matter accumulated in the identified regeneration target area.

[0067] <<Processing procedure for [Calculating and storing the amount of particulate matter deposited per block] (Figures 5 to 11)>> Fig. 5 is a flowchart illustrating the details of the process of "calculating and storing the amount of particulate matter deposited for each block" in step S12 in Fig. 4. When executing the process of step S12 in Fig. 4, the control device 50 advances the process to step T10 of "calculating and storing the amount of particulate matter deposited for each block" shown in Fig. 5. As described above, as shown in the block division information (stored in the storage device) in Fig. 6, the inlet surface 62m of the filter is virtually divided into a plurality of blocks.

[0068] In step T10, the control device 50 calculates the amount of particulate matter generated according to the operating state of the internal combustion engine 10, and proceeds to step T12. For example, the storage device stores the "particulate matter generation amount characteristics" shown in FIG. 7. The "particulate matter generation amount characteristics" set the amount of particulate matter generated in the exhaust gas according to the operating state of the internal combustion engine 10 (the amount generated during a predetermined time interval during which the overall processing shown in FIG. 4 is executed). In the example shown in FIG. 7, the amount of particulate matter generated according to the rotation speed of the internal combustion engine 10 (horizontal axis) and the load of the internal combustion engine (an internal combustion engine load-related quantity such as accelerator pedal depression amount) (vertical axis) is set. For example, using the "particulate matter generation amount characteristics" shown in FIG. 7, the control device 50 calculates the amount of particulate matter generated = P22 when the rotation speed = 2000 [rpm] and the accelerator pedal depression amount (load) = 20 [%].

[0069] In step T12, the control device 50 calculates the exhaust distribution ratio for each block according to the operating state of the internal combustion engine 10, and proceeds to step T14. For example, the memory device stores the "exhaust distribution ratio characteristics for each block" shown in FIG. 9. The "exhaust distribution ratio characteristics for each block" are prepared for each operating state, and for example, the characteristics of the exhaust distribution ratio for each block according to the internal combustion engine speed and load (internal combustion engine load-related quantities such as accelerator pedal depression) are stored. The "exhaust distribution ratio characteristics for each block" according to the operating state can be obtained by experiments or simulations using an actual vehicle. Note that, for ease of understanding, the example in FIG. 8 also shows the inlet surface 62m and the exhaust regions R1, R2, R3, and R4 for each cylinder in the "exhaust distribution ratio characteristics for each block."

[0070] The [Block-by-Block Exhaust Distribution Ratio Characteristics] shows the ratio of the exhaust gas hitting the inlet surface 62m to each block (the ratio at which it hits). For example, when the rotation speed is 2000 [rpm] and the accelerator pedal depression amount (load) is 20 [%], in the example shown in Figure 9, block

[53] receives an exhaust gas that is proportional to the total exhaust gas hitting the inlet surface 62m, which is "the value of block

[53] (= 1) / the sum of the values ​​of each block."

[0071] In step T14, the control device 50 calculates the block-by-block distribution amount of particulate matter according to the operating state of the internal combustion engine 10, and then proceeds to step T16. The control device 50 calculates the block-by-block distribution amount of particulate matter based on the amount of particulate matter generated in step T10 and the block-by-block exhaust distribution ratio calculated in step T12. The [Block-by-Block Distribution Amount] shown in FIG. 10 shows an example of the block-by-block distribution amount (Dmn). Note that for ease of understanding, the example in FIG. 10 adds the inlet surface 62m and the cylinder-by-cylinder exhaust regions R1, R2, R3, and R4 to the [Block-by-Block Distribution Amount]. For example, when the rotation speed is 2000 rpm, the accelerator pedal depression amount (load) is 20%, the amount of particulate matter generated is P22, and according to the [Block-by-Block Exhaust Distribution Ratio Characteristics] shown in FIG. 9, the particulate matter distribution amount (D53) in block

[53] is P22 * 1 / (the sum of the values ​​of each block in FIG. 9).

[0072] In step T16, the control device 50 calculates the deposition amount of particulate matter for each block, terminates the process shown in FIG. 5, and returns to step S22 shown in FIG. 4. The storage device (non-volatile storage device) stores the deposition amount for each block shown in FIG. 6. [Deposition amount per block] shown in FIG. 11 shows an example of the deposition amount of particulate matter for each block (Emn). Note that, for ease of understanding, the example in FIG. 11 adds the inlet surface 62m and the exhaust regions R1, R2, R3, and R4 for each cylinder to the [Deposition amount per block]. For example, when calculating and storing the deposition amount (E53) for block

[53] , the control device 50 calculates and stores "the deposition amount for the current block

[53] (the deposition amount stored in block

[53] ) + the distribution amount (D53) for this block

[53] " and stores it in the non-volatile storage device.

[0073] <<Processing procedure for [Identifying the cylinders in the cylinder-by-cylinder exhaust region that includes the block to be regenerated and storing the specific cylinders] (Fig. 12)>> Fig. 12 is a flowchart illustrating the details of the process of "identifying the cylinders that are part of the cylinder-by-cylinder exhaust region that includes the regeneration target block and storing the specific cylinders" in step S28 in Fig. 4. When executing the process of step S28 in Fig. 4, the control device 50 proceeds to step U10 in Fig. 12 of "identifying the cylinders that are part of the cylinder-by-cylinder exhaust region that includes the regeneration target block and storing the specific cylinders."

[0074] In step U10, the control device 50 extracts a cylinder-by-cylinder exhaust region corresponding to the operating state of the internal combustion engine 10 and proceeds to step U12. For example, the storage device stores the "cylinder-by-cylinder exhaust region characteristics" shown in FIG. 8. The "cylinder-by-cylinder exhaust region characteristics" are prepared for each operating state, and for example, the characteristics of the region where the exhaust gas from each cylinder hits the inlet surface of the filter corresponding to the engine speed and load (accelerator pedal depression amount) are stored. The "cylinder-by-cylinder exhaust region characteristics" indicate, for each block and filter inlet surface 62m, the cylinder-by-cylinder exhaust region R1, which is the region where the exhaust gas from cylinder #1 hits, the cylinder-by-cylinder exhaust region R3, which is the region where the exhaust gas from cylinder #3 hits, the cylinder-by-cylinder exhaust region R4, which is the region where the exhaust gas from cylinder #4 hits, and the cylinder-by-cylinder exhaust region R2, which is the region where the exhaust gas from cylinder #2 hits. Note that in the description of this embodiment, a four-cylinder gasoline engine is used as an example, and combustion occurs in the order of cylinder #1 > cylinder #3 > cylinder #4 > cylinder #2. The "exhaust region characteristics for each cylinder" according to the driving state can be obtained by experiments using an actual vehicle, simulations, etc.

[0075] In step U12, the control device 50 superimposes the per-cylinder exhaust regions R1, R2, R3, and R4 (see FIG. 8) on the per-block deposition amount (see FIG. 11) to identify the cylinder that is the per-cylinder exhaust region including the block to be regenerated, and stores the identified cylinder in the "identified cylinder" field. Note that the example in FIG. 11 shows an example in which the per-cylinder exhaust regions R1, R2, R3, and R4 (and inlet surface 62m) are superimposed on the per-block deposition amount (Emn). For example, if the control device 50 determines that block

[53] is the block to be regenerated (deposition amount > regeneration start threshold), it identifies the per-cylinder exhaust region (corresponding to the regeneration target region) including block

[53] as the "per-cylinder exhaust region R1," and the cylinder in the "per-cylinder exhaust region R1" as "cylinder #1," and stores "cylinder #1" in the "identified cylinder" field. The control device 50 then ends the process shown in FIG. 12 and returns to step S32 shown in FIG. 4.

[0076] <<Processing procedure for [Calculating the combustion amount of each block within the exhaust area of ​​each cylinder of a specific cylinder] (Figures 13 to 16)>> Fig. 13 is a flowchart illustrating the details of the process of "calculating the amount of combustion for each block in the exhaust region for each cylinder of a specific cylinder" in step S54 in Fig. 4. When executing the process of step S54 in Fig. 4, the control device 50 advances the process to step V10 of "calculating the amount of combustion for each block in the exhaust region for each cylinder of a specific cylinder" shown in Fig. 13.

[0077] In step V10, the control device 50 determines whether the fuel cut regeneration flag is ON. If the fuel cut regeneration flag is ON (Yes), the control device 50 proceeds to step V12, and if the fuel cut regeneration flag is not ON (No), the control device 50 proceeds to step V14.

[0078] If the process proceeds to step V12, the control device 50 calculates the oxygen content according to the intake air amount of the specific cylinder, and then proceeds to step V22. For example, if the "specific cylinder" is "cylinder #1," the control device 50 calculates the intake air amount of cylinder #1 and multiplies the intake air amount by the oxygen percentage in the atmosphere (approximately 21%]) to calculate the oxygen content.

[0079] If the process proceeds to step V14, the control device 50 calculates the oxygen content according to the intake air amount of the specific cylinder and the regeneration target air-fuel ratio, and then proceeds to step V22. For example, if the "specific cylinder" is "cylinder #1," the control device 50 calculates the intake air amount of cylinder #1, calculates the amount of excess intake air not used for combustion based on the intake air amount and the regeneration target air-fuel ratio, and multiplies the excess intake air amount by the oxygen percentage in the atmosphere (approximately 21%]) to calculate the oxygen content.

[0080] If the process proceeds to step V22, the control device 50 calculates the exhaust distribution ratio for each block according to the operating state of the internal combustion engine 10, and proceeds to step V24. The [exhaust distribution ratio for each block] is as explained using Fig. 9, and the control device 50 calculates the exhaust distribution ratio for each block from the exhaust distribution ratio for each block characteristic shown in the example of Fig. 9 when, for example, the internal combustion engine speed = 2000 [rpm] and the accelerator pedal depression amount (load) = 20 [%].

[0081] In step V24, the control device 50 extracts the exhaust gas distribution ratio per block in the region of the cylinder-by-cylinder exhaust region of the specific cylinder, and then proceeds to step V26. For example, if the "specific cylinder" is "cylinder #1," the rotation speed is 2000 rpm, and the load (accelerator pedal depression amount) is 20%, the control device 50 extracts the value in the "cylinder-by-cylinder exhaust region R1" corresponding to cylinder #1 from the "block-by-block exhaust gas distribution ratio characteristics" calculated in step V22. The extracted state is as shown in the "exhaust gas distribution ratio per block in the region of the cylinder-by-cylinder exhaust region of the specific cylinder" in Figure 14.

[0082] In step V26, the control device 50 calculates the oxygen supply amount per block within the cylinder-specific exhaust region of the specific cylinder, which is the oxygen supplied to each block within the cylinder-specific exhaust region, and then proceeds to step V28. The control device 50 calculates the "oxygen supply amount per block within the cylinder-specific exhaust region of the specific cylinder" (see FIG. 15), which is the amount of oxygen supplied to each block within the target cylinder-specific exhaust region, based on the "oxygen content" calculated in step V12 (or step V14) and the "exhaust distribution ratio per block within the region" calculated in step V24. For example, if the "specific cylinder" is "cylinder #1," the control device 50 calculates the oxygen supply amount (Fmn), which is the amount of oxygen supplied to each block within the cylinder-specific exhaust region R1, as shown in FIG. 15. For example, the oxygen supply amount (F53) to block

[53] can be calculated by dividing the "oxygen content in step V12 or V14" * 1 by the "sum of values ​​within the cylinder-specific exhaust region R1 in FIG. 14."

[0083] In step V28, the control device 50 calculates the combustion burn-up amount per block within the region, which is the combustion burn-up amount per block within the per-cylinder exhaust region of the specific cylinder, ends the process shown in FIG. 13, and returns to step S56 shown in FIG. 4. The control device 50 can calculate the combustion burn-up amount for each block based on, for example, the exhaust temperature and the oxygen supply amount for each block calculated in step V26. For example, if the "specific cylinder" is "cylinder #1," the control device 50 calculates the combustion burn-up amount (Gmn) for each block within the per-cylinder exhaust region R1, as shown in FIG. 16.

[0084] <<Processing procedure for [Reducing and storing the deposit amount for each block in the exhaust area for each specific cylinder] (Fig. 17)>> Fig. 17 is a flowchart illustrating the details of the process of "reducing and storing the deposition amount in each block within the per-cylinder exhaust region of a specific cylinder" in step S56 in Fig. 4. When executing the process of step S56 in Fig. 4, the control device 50 advances the process to step W10 of "reducing and storing the deposition amount in each block within the per-cylinder exhaust region of a specific cylinder" shown in Fig. 17.

[0085] In step W10, the control device 50 calculates and stores the "deposition amount - combustion burn amount" for each block within the cylinder-by-cylinder exhaust region of the specific cylinder, terminates the process shown in Figure 17, and returns to step S62 shown in Figure 4. For example, if the "specific cylinder" is "cylinder #1," the "cylinder-by-cylinder exhaust region" of cylinder #1 is the "cylinder-by-cylinder exhaust region R1" shown in Figure 8, and the combustion burn amount of each block within the "cylinder-by-cylinder exhaust region R1" is the "combustion burn amount per block within the cylinder-by-cylinder exhaust region of the specific cylinder" shown in Figure 16, the control device 50 updates the deposition amount (E53) of block

[53] to the deposition amount of block

[53] before the update (the value of E53 shown in Figure 11) - the combustion burn amount per block within the region of block

[53] (the value of G53 shown in Figure 16), and stores the updated value in the non-volatile storage device.

[0086] <<[Fuel injection processing] processing procedure (Fig. 18)>> As explained above, during filter regeneration, in order to supply oxygen to the block to be regenerated, it is necessary to cut fuel to a specific cylinder or control the air-fuel ratio of the specific cylinder to be lean. For this reason, the fuel injection amount of the specific cylinder is adjusted to be different from the fuel injection amount of the other cylinders in the "fuel injection process" shown in Figure 18. When injecting fuel at a predetermined fuel injection timing, the control device 50 starts the "fuel injection process" shown in Figure 18 and proceeds to step F10.

[0087] In step F10, the control device 50 calculates the normal fuel injection amount based on the operating state of the internal combustion engine 10 using existing processing, and proceeds to step F12. Note that the processing in step F10 is an existing processing for calculating the normal fuel injection amount, and therefore a detailed description thereof will be omitted.

[0088] In step F12, the control device 50 determines whether the regeneration in progress flag is set to ON. If the regeneration in progress flag is set to ON (Yes), the control device 50 proceeds to step F22, and if the regeneration in progress flag is not set to ON (No), the control device 50 proceeds to step F14.

[0089] If the process proceeds to step F14, the control device 50 injects the normal fuel injection amount from the injector of each cylinder at a predetermined timing using existing processes. Note that the process of step F14 is an existing process, so a detailed description will be omitted. Then, the control device 50 ends the process shown in FIG.

[0090] If the process proceeds to step F22, the control device 50 determines whether the fuel cut regeneration flag is set to ON. If the fuel cut regeneration flag is set to ON (Yes), the control device 50 proceeds to step F24, and if the fuel cut regeneration flag is not set to ON (No), the control device 50 proceeds to step F34.

[0091] If the process proceeds to step F24, the control device 50 stops fuel injection from the injector for the "specific cylinder" and proceeds to step F26. For example, if the "specific cylinder" is "cylinder #1," the control device 50 does not inject fuel into cylinder #1 even when the fuel injection timing for cylinder #1 arrives. This causes the oxygen content of the exhaust from cylinder #1 (which is the same as the intake air because fuel is cut) to be higher (increased) than the oxygen content of the exhaust from the other cylinders.

[0092] In step F26, for other cylinders (cylinders that are not the specified cylinder), the control device 50 injects from the injector the injection amount of "normal fuel injection amount + fuel increase amount (calculated in step S36 of Figure 4)" when the fuel injection timing for the target cylinder arrives, and then ends the processing shown in Figure 18.

[0093] If the process proceeds to step F34, the control device 50 changes the fuel injection amount for the "specific cylinder" to a target lean injection amount that is reduced based on the intake air amount and the regeneration target air-fuel ratio (calculated in steps S42 to S47 in FIG. 4), injects the target lean injection amount when the fuel injection timing for the specific cylinder arrives, and then proceeds to step F36. For example, if the "specific cylinder" is "cylinder #1," the control device 50 sets the fuel injection amount for cylinder #1 to the target lean injection amount. As a result, the oxygen content of the exhaust gas from cylinder #1 is made larger (increased) than the oxygen content of the exhaust gas from the other cylinders.

[0094] In step F36, the control device 50 injects the "normal fuel injection amount" from the injector for other cylinders (cylinders that are not the specific cylinder) when the fuel injection timing for the target cylinder arrives, and then ends the processing shown in Figure 18.

[0095] <<Throttle Valve Control Processing Procedure (Fig. 19)>> When fuel is cut off for a specific cylinder to supply oxygen to the regeneration target block during filter regeneration, the fuel injection amount for cylinders other than the specific cylinder is increased (by the amount of fuel increase) in the process shown in Fig. 18, and the throttle valve opening is increased (by the amount of throttle valve opening increase) to increase the intake amount in the process shown in Fig. 19. When controlling the throttle valve opening at time intervals of, for example, several milliseconds to several tens of milliseconds, the control device 50 activates "throttle valve control" shown in Fig. 19 and proceeds to step E10.

[0096] In step E10, the control device 50 calculates, by existing processing, a normal target opening, which is a target opening of the throttle valve 41c based on the operating state of the internal combustion engine 10, and proceeds to step E12. Note that the processing of step E10 is an existing processing for calculating the normal target opening, and therefore a detailed description thereof will be omitted.

[0097] In step E12, the control device 50 determines whether the regeneration in progress flag is set to ON. If the regeneration in progress flag is set to ON (Yes), the control device 50 proceeds to step E14, and if the regeneration in progress flag is not set to ON (No), the control device 50 proceeds to step E16.

[0098] When the process proceeds to step E14, the control device 50 determines whether the fuel cut regeneration flag is set to ON. If the fuel cut regeneration flag is set to ON (Yes), the control device 50 proceeds to step E18, and if the fuel cut regeneration flag is not set to ON (No), the control device 50 proceeds to step E16.

[0099] If the process proceeds to step E16, the control device 50 controls the throttle valve opening to approach the normal target opening using existing processing, and ends the process shown in Fig. 19. Note that the process of step E16 is an existing process, so a detailed description thereof will be omitted.

[0100] If the process proceeds to step E18, the control device 50 controls the opening of the throttle valve so that it approaches the target opening plus the throttle valve opening increase amount (calculated in step S36 of FIG. 4), and then ends the process shown in FIG. 19.

[0101] <<Effects etc.>> As explained above, even if the amount of particulate matter deposited in some areas of the filter is greater than in other areas, the amount of deposition can be properly detected. Furthermore, by burning and incinerating the particulate matter deposited in the specified regeneration target area in the specific area regeneration execution unit, the area that needs to be regenerated can be selectively regenerated, so that unnecessary regeneration is not performed and filter deterioration can be suppressed.

[0102] <<Others>> The exhaust gas purification system 2 for an internal combustion engine according to the technology disclosed in this specification is not limited to the configuration, structure, processing procedures, etc. described in this specification, and various modifications, additions, and deletions are possible within the scope of not changing the gist of the technology disclosed in this specification. For example, although a four-cylinder gasoline engine system has been described as an example in this specification, the number of cylinders is not limited to four, and the system can also be applied to a diesel engine system.

[0103] In the explanation of this specification, a filter of a gasoline engine system that controls the fuel amount at the stoichiometric air-fuel ratio has been used as an example, and therefore an example of increasing the oxygen content of the exhaust gas during filter regeneration has been explained. Note that when regenerating a filter of a diesel engine system that controls the fuel amount in a lean air-excess state, fuel may be added to the exhaust gas to increase the exhaust temperature. Also, in the explanation of this specification, the accelerator pedal depression amount has been used as an example of a load-related quantity of an internal combustion engine, but the fuel injection amount or the like may also be used as a load-related quantity (the greater the fuel injection amount, the greater the load).

[0104] Furthermore, the numerical values ​​used in the explanation of this specification are merely examples and are not limited to these numerical values. Furthermore, terms such as greater than or equal to (≧), less than or equal to (≦), larger than (>), and less than (<) may or may not include an equals sign. [Explanation of symbols]

[0105] 1 Internal combustion engine system 2. Exhaust purification system 10 Internal combustion engine 11a injector 12a, 12b, 12c intake pipes 12d Intake manifold 22a Exhaust manifold 22b, 22c, 22d, 22e exhaust pipes 23 EGR piping 31 Intake flow rate detection device 32a Atmospheric pressure detector 32b Pressure detection device 32c Differential pressure detection device 33a, 33b Intake air temperature detection device 34 Coolant temperature detection device 35a Rotation detection device 35b Cylinder detection device 36a, 36b, 36c Exhaust temperature detection device 37 Pedal amount detection device 38 Air-fuel ratio detection device 41 Throttle device 41a Motor 41b Opening detection device 41c Throttle valve 42 Purge valve 43 EGR valve 44 Turbocharger 44a Turbine 44b compressor 45 canister 45a Purge tube 46 Fuel Tank 50 Control device 51 CPU 51a Block-by-block deposition amount memory unit 51b Specific area playback control execution unit 61 Three-way catalyst 62 filters 62a Filter body 62m inflow surface R1, R2, R3, R4 Exhaust area for each cylinder

Claims

1. An exhaust purification system for an internal combustion engine, comprising: a filter provided in an exhaust path of the internal combustion engine to capture particulate matter contained in exhaust; a control device that controls the internal combustion engine; and a storage device, The storage device includes: Block division information that virtually divides an exhaust gas inflow surface of the filter into a plurality of blocks is stored, The control device a block-by-block accumulation amount storage unit that calculates the accumulation amount of particulate matter for each block according to an operating state of the internal combustion engine and stores the accumulation amount for each block in the storage device; a specific area regeneration control execution unit that, when it is determined that there is a regeneration target block, which is the block in which the amount of particulate matter deposited exceeds a regeneration start threshold, identifies a regeneration target area that is at least a part of the inflow surface of the filter that includes at least the regeneration target block, and executes specific area regeneration control to combust and incinerate the particulate matter deposited in the identified regeneration target area; having Exhaust gas purification system for internal combustion engines.

2. 2. An exhaust gas purification system for an internal combustion engine according to claim 1, The storage device includes: a particulate matter generation amount characteristic in which the amount of particulate matter contained in the exhaust gas is set according to the operating state; a block-by-block exhaust distribution ratio characteristic in which a distribution ratio of exhaust for each block according to the operating state is set; is stored, The control device In the block-by-block deposition amount storage unit, determining the amount of particulate matter generated corresponding to the operating state based on the operating state and the particulate matter generation amount characteristic; determining a distribution rate of exhaust gas for each block corresponding to the operating state based on the operating state and the block-by-block exhaust gas distribution rate characteristic; determining the amount of particulate matter deposited in each block based on the determined amount of particulate matter generated and the distribution ratio of exhaust gas in each block; Exhaust gas purification system for internal combustion engines.

3. 3. An exhaust gas purification system for an internal combustion engine according to claim 2, The storage device includes: a cylinder-by-cylinder exhaust region characteristic is stored, which is set according to the operating state, and is a region where exhaust gas from each cylinder of the internal combustion engine hits the inlet surface of the filter; The control device When the specific area regeneration control execution unit executes the specific area regeneration control, Identifying the cylinder-by-cylinder exhaust region including the regeneration target block as the regeneration target region based on the operating state, the cylinder-by-cylinder exhaust region characteristics, and the regeneration target block, and identifying a cylinder corresponding to the identified regeneration target region; adjusting the amount of fuel supplied to the specified cylinder so that the exhaust gas from the specified cylinder has a higher oxygen content or a higher exhaust temperature than the exhaust gas from the other cylinders; Exhaust gas purification system for internal combustion engines.

4. 4. An exhaust gas purification system for an internal combustion engine according to claim 3, the internal combustion engine is a gasoline engine, and an injector for supplying fuel is provided for each cylinder; The control device When the specific region regeneration control execution unit executes the specific region regeneration control and adjusts the amount of fuel supplied to the specific cylinder so that the exhaust gas from the specific cylinder has a higher oxygen content than the exhaust gases from the other cylinders, controlling the air-fuel ratio of the specific cylinder to be lean, thereby increasing the oxygen content of the exhaust gas from the specific cylinder; Exhaust gas purification system for internal combustion engines.

5. 5. An exhaust gas purification system for an internal combustion engine according to claim 4, The control device The intake amount of the internal combustion engine can be detected, When the specific area regeneration control execution unit executes the specific area regeneration control, determining a regeneration target air-fuel ratio that makes the air-fuel ratio of the specific cylinder lean, and adjusting the fuel amount of the specific cylinder based on the regeneration target air-fuel ratio and the intake amount, or cutting the fuel of the specific cylinder, to control the air-fuel ratio of the specific cylinder to be lean; determining an oxygen content of exhaust gas from the specific cylinder based on the intake air amount of the internal combustion engine and the regeneration target air-fuel ratio, or based on the intake air amount of the internal combustion engine; calculating an intra-region block-by-block oxygen supply amount, which is the amount of oxygen supplied to each block within the per-cylinder exhaust region of the specific cylinder, based on the calculated oxygen content, the operating state, the per-cylinder exhaust region corresponding to the specific cylinder, and the per-block exhaust distribution ratio characteristic; determining a combustion and incineration amount of particulate matter for each block in the exhaust region of the specific cylinder based on the oxygen supply amount for each block in the region, and reducing the deposition amount for each block in the exhaust region of the specific cylinder; Exhaust gas purification system for internal combustion engines.

6. An exhaust gas purification system for an internal combustion engine according to any one of claims 1 to 5, The operating state includes a rotation speed of the internal combustion engine and an internal combustion engine load related quantity related to a load of the internal combustion engine. Exhaust gas purification system for internal combustion engines.

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