Control device for internal combustion engine

Abstract

To avoid an erroneous determination in abnormality determination for a regenerative function of a filter.SOLUTION: Provided is a control device for an internal combustion engine that is equipped with a filter for collecting PM in an exhaust pipe connected to an engine body, and that includes a PM regenerative function for regenerating the filter with the PM collected thereon. The control device for the internal combustion engine includes: a filter differential pressure acquisition unit for acquiring a filter differential pressure, which is a differential pressure across the filter; a pre-and post-regeneration differential pressure difference acquisition unit for acquiring a differential pressure difference before and after regeneration, which is a difference between a pre-regeneration filter differential pressure acquired by the filter differential pressure acquisition unit before the regeneration of the filter and a post-regeneration filter differential pressure acquired by the filter differential pressure acquisition unit after the regeneration of the filter; and a PM generative function determination unit for performing abnormality determination on the PM regenerative function when the pre-and post-regeneration differential pressure difference acquired by the pre-and post-regeneration differential pressure difference acquisition unit is equal to or less than a preset threshold value.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] Conventionally, internal combustion engines have been known that are provided with a filter in an exhaust passage of the internal combustion engine that captures particulate matter (PM) in the exhaust gas. After capturing a predetermined amount of PM, the filter is subjected to a regeneration process. During the regeneration process, the filter is exposed to high temperatures, which can cause damage or melting of the filter. For example, Patent Document 1 proposes determining whether or not the filter has failed based on the pressure difference between the upstream and downstream sides of the filter after the regeneration process is complete. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-220233 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, when an internal combustion engine is equipped with a PM regeneration function, it is sometimes necessary to determine whether or not an abnormality has occurred in this regeneration function. One method for determining whether or not an abnormality has occurred in the regeneration function is to use the pressure difference between the upstream and downstream sides of a filter, as disclosed in Patent Document 1. However, the pressure difference between the upstream and downstream sides of the filter can be affected by variations in tolerances during filter manufacturing and by changes in the filter over time. If the pressure difference between the upstream and downstream sides of the filter is affected by the variations in tolerances and changes over time, as described above, there is a possibility that an abnormality in the regeneration function will be erroneously determined.

[0005] Therefore, an object of the invention disclosed in this specification is to avoid erroneous determinations in determining whether the regeneration function of a filter is abnormal. [Means for solving the problem]

[0006] The above-mentioned object is achieved by a control device for an internal combustion engine in which a filter that captures PM is provided in an exhaust pipe connected to an engine body, and which has a PM regeneration function that regenerates the filter that has captured the PM, the control device including: a filter differential pressure acquisition unit that acquires a filter differential pressure, which is the differential pressure before and after the filter; a pre-regeneration differential pressure difference acquisition unit that acquires a pre-regeneration differential pressure difference, which is the difference between the pre-regeneration filter differential pressure acquired by the filter differential pressure acquisition unit before regeneration of the filter and the post-regeneration filter differential pressure acquired by the filter differential pressure acquisition unit after regeneration of the filter; and a PM generation function determination unit that determines an abnormality in the PM regeneration function when the pre-regeneration differential pressure difference acquired by the pre-regeneration differential pressure difference acquisition unit is equal to or less than a preset threshold value.

[0007] The filter differential pressure acquisition unit may acquire the pre-regeneration filter differential pressure when the PM accumulation amount estimated by the PM accumulation amount estimation unit is equal to or greater than a first predetermined value, and may acquire the post-regeneration filter differential pressure when the PM accumulation amount estimated by the PM accumulation amount estimation unit after the PM regeneration function starts operating is equal to or less than a second predetermined value that is smaller than the first predetermined value.

[0008] The filter differential pressure difference acquisition unit may include a volumetric flow rate calculation unit that calculates the volumetric flow rate when the pre-regeneration filter differential pressure is acquired and the volumetric flow rate when the post-regeneration filter differential pressure is acquired, and may further include a filter differential pressure correction unit that corrects the pre-regeneration filter differential pressure and the post-regeneration filter differential pressure so that the volumetric flow rates calculated by the volumetric flow rate calculation unit are the same value, and the pre- and post-regeneration differential pressure difference acquisition unit may acquire the difference between the pre-regeneration filter differential pressure and the post-regeneration filter differential pressure corrected by the filter differential pressure correction unit.

[0009] The volumetric flow rate calculation unit can be configured to obtain the volumetric flow rate at the time the pre-regeneration filter differential pressure is obtained based on the temperature and flow rate of the gas that passed through the filter at the time the pre-regeneration filter differential pressure is obtained, and to obtain the volumetric flow rate at the time the post-regeneration filter differential pressure is obtained based on the temperature and flow rate of the gas that passed through the filter at the time the post-regeneration filter differential pressure is obtained.

[0010] The pre- and post-regeneration differential pressure difference acquiring unit may acquire the pre- and post-regeneration differential pressure difference in a region where the volumetric flow rate is equal to or greater than a predetermined value. [Effects of the Invention]

[0011] The invention disclosed in this specification can avoid erroneous determinations when determining whether the regeneration function of a filter is abnormal. [Brief explanation of the drawings]

[0012] [Figure 1] Fig. 1A is a schematic diagram showing an internal combustion engine incorporating a control device according to a first embodiment, and Fig. 1B is a functional block diagram of a control device according to a second embodiment. [Figure 2] 2A is a graph illustrating the relationship between the filter differential pressure before regeneration, the filter differential pressure after regeneration, and the differential pressure before and after regeneration, and FIG. 2B is a graph illustrating the determination of an abnormality in the PM regeneration function based on the differential pressure before and after regeneration. [Figure 3] FIG. 3 is a graph illustrating the difference in filter differential pressure before and after regeneration due to aging of the GPF. [Figure 4] FIG. 4 is a flowchart showing an example of control in the first embodiment. [Figure 5] Figure 5A is a graph showing the influence of the passing gas flow rate and passing gas temperature on the filter differential pressure. Figure 5B is a graph showing the influence of the volumetric flow rate on the filter differential pressure. Figure 5C is a graph showing how the difference in pressure before and after regeneration is obtained by correcting the filter differential pressure before and after regeneration so that the volumetric flow rates are the same. [Figure 6] FIG. 6 is a flowchart showing an example of control in the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0014] (First embodiment) [Internal combustion engine] As shown in FIG. 1A, an internal combustion engine 100 includes an intake pipe 11 and an exhaust pipe 14 connected to an engine body 10. An air flow meter 12 and a throttle valve 13 are provided in the intake pipe 11. A throttle valve opening sensor 13a is provided in the throttle valve 13. A first catalyst 15 and a second catalyst 16 are provided in the exhaust pipe 14, in this order from the side closest to the engine body 10. The internal combustion engine 100 also includes an ECU (Electronic Control Unit) 50 that functions as a control device. The internal combustion engine 100 is mounted on a vehicle. The vehicle may be a hybrid vehicle. In this case, the internal combustion engine 100 is combined with a motor and a battery (not shown) to form a hybrid system.

[0015] The engine body 10 in this embodiment is a gasoline engine that uses gasoline as fuel. Gasoline engines can generate PM due to direct fuel injection. The engine body 10 can also be a diesel engine that uses light oil as fuel. Diesel engines can also generate PM.

[0016] The air flow meter 12 detects the amount of intake air flowing through the intake pipe 11 and sent to the engine body 10. The throttle valve 13 adjusts the amount of intake air sent to the engine body 10. The throttle valve opening sensor 13a detects the opening of the throttle valve 13.

[0017] The first catalyst 15 is a three-way catalyst. The first catalyst 15 generates heat during regeneration control of the second catalyst 16. The temperature of the second catalyst 16 rises due to the heat generated by the first catalyst 15. As the temperature of the second catalyst 16 rises, PM accumulated on the second catalyst 16 is burned off. As a result, the second catalyst 16 is regenerated.

[0018] The second catalyst 16 is a GPF (Gasoline Particulate Filter). If the engine body 10 is a diesel engine, a DPF (Diesel Particulate Filter) is provided instead of the GPF. The GPF or DPF captures PM emitted from the engine body 10. If the second catalyst 16 becomes clogged with the captured PM, its PM capturing function will be reduced. For this reason, the second catalyst 16 is subjected to a regeneration treatment under predetermined conditions.

[0019] A first pressure sensor 18a is provided on the upstream side of the second catalyst 16. The first pressure sensor 18a detects the pressure P upst A second pressure sensor 18b is provided downstream of the second catalyst 16. The second pressure sensor 18b detects the pressure P downstream of the second catalyst 16. downst Detect.

[0020] The ECU 50 includes a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), a storage device, etc. The ECU 50 executes programs stored in the ROM and the storage device to control the internal combustion engine 100. Although a detailed description thereof will be omitted here, the ECU 50 is connected to a large number of sensors for controlling the internal combustion engine 100.

[0021] The ECU 50 functions as a PM regeneration control unit 51 and a PM accumulation amount estimation unit 52. The ECU 50 functions as a filter differential pressure acquisition unit 53, a pre-regeneration filter differential pressure storage unit 54, and a post-regeneration filter differential pressure storage unit 55. The ECU 50 functions as a pre-regeneration / post-regeneration differential pressure difference acquisition unit 56 and a PM regeneration function determination unit 57.

[0022] The PM regeneration control unit 51 performs control for PM regeneration in the second catalyst 16. The PM regeneration control unit 51 can employ various conventionally known methods for PM regeneration. For example, the PM regeneration control unit 51 can perform F / C (Fuel Cut) control or forcibly perform lean operation. Furthermore, the PM regeneration control unit 51 may instruct the driver to perform high-load operation to promote PM regeneration. If the engine body 10 is a diesel engine, the PM regeneration control unit 51 may perform post-injection.

[0023] The PM accumulation amount estimation unit 52 estimates the amount of PM accumulated in the second catalyst 16. The air flow meter 12 and the throttle valve opening sensor 13a are electrically connected to the PM accumulation amount estimation unit 52. The PM accumulation amount estimation unit 52 estimates the PM accumulation amount using an estimation model that uses the detection values ​​of these sensors as parameters. The estimation model is created through experiments or simulations. The PM accumulation amount estimation unit 52 can use a conventionally known estimation model. Therefore, a detailed description of the estimation model will be omitted in this specification. The PM accumulation amount estimation unit 52 also estimates the PM accumulation amount after PM regeneration has been performed. The PM accumulation amount after PM regeneration can be estimated, for example, based on the progress of PM regeneration performed by the PM regeneration control unit 51.

[0024] The first pressure sensor 18a and the second pressure sensor 18b are electrically connected to the filter differential pressure acquisition unit 53. The filter differential pressure acquisition unit 53 acquires the pressure P upst The pressure P downstream of the second catalyst 16 detected by the second pressure sensor 18b is downst The filter differential pressure is calculated by subtracting the above. As shown in FIG. 2A, there are two types of filter differential pressure: pre-regeneration filter differential pressure dP1 and post-regeneration filter differential pressure dP2. The pre-regeneration filter differential pressure dP1 is a differential pressure obtained before PM regeneration is performed, when a large amount of PM has accumulated in the second catalyst 16. The post-regeneration filter differential pressure dP2 is a differential pressure obtained after PM regeneration is performed, when PM processing has progressed.

[0025] The pre-regeneration filter differential pressure storage unit 54 stores the pre-regeneration filter differential pressure dP1.

[0026] The post-regeneration filter differential pressure storage unit 55 stores the post-regeneration filter differential pressure dP2.

[0027] The pre- and post-regeneration differential pressure difference acquisition unit 56 acquires the pre- and post-regeneration differential pressure difference ΔP. The pre- and post-regeneration differential pressure difference ΔP is the difference between the pre-regeneration filter differential pressure dP1 and the post-regeneration filter differential pressure dP2, as illustrated in FIG. 2A.

[0028] The PM regeneration function determination unit 57 determines whether the pre- and post-regeneration differential pressure difference ΔP is greater than a preset threshold value P. As shown in FIG. 2B, the PM regeneration function determination unit 57 determines that the PM regeneration function is normal when the pre- and post-regeneration differential pressure difference ΔP is greater than the threshold value P. The PM regeneration function determination unit 57 also determines that the PM regeneration function is abnormal when the pre- and post-regeneration differential pressure difference ΔP is equal to or less than the threshold value P. The threshold value P is set in advance through experiments or simulations. The threshold value P is set from the perspective of whether the pre- and post-regeneration differential pressure difference ΔP corresponding to the content of the executed PM regeneration control is obtained.

[0029] Here, referring to FIG. 3, the effect of determining the PM regeneration function using the pre- and post-regeneration differential pressure difference ΔP will be explained. In FIG. 3, the filter differential pressure at the second catalyst 16 of a vehicle with a low mileage is illustrated by a solid line. In FIG. 3, the filter differential pressure at the second catalyst 16 of a vehicle with a high mileage is illustrated by a dashed line. It is believed that the second catalyst 16 of a vehicle with a high mileage is subject to aging. The aging of the second catalyst 16 progresses, for example, due to the deposition of ash. Ash is, for example, a metal component contained in the fuel. Ash tends to accumulate as the mileage increases. Ash cannot be removed even when PM regeneration is performed. For this reason, the filter differential pressure may be detected as high even if the PM regeneration function is normal.

[0030] As shown in FIG. 3, it is assumed that the amount of PM deposited on the second catalyst 16 before regeneration is 4 g. The pre-regeneration filter differential pressure dP1′ in a vehicle with a high mileage is greater than the pre-regeneration filter differential pressure dP1 in a vehicle with a low mileage. It is also assumed that the amount of PM deposited on the second catalyst 16 after regeneration is 2 g. The pre-regeneration filter differential pressure dP1′ in a vehicle with a high mileage is greater than the pre-regeneration filter differential pressure dP1 in a vehicle with a low mileage. Here, it is assumed that the PM regeneration function is determined based on whether the post-regeneration filter differential pressure is greater than a threshold value P′. In this case, in a vehicle with a low mileage, the post-regeneration filter differential pressure dP2 is smaller than the threshold value P′, so the PM regeneration function is determined to be normal. On the other hand, in a vehicle with a high mileage, the post-regeneration filter differential pressure dP2′ is greater than the threshold value P′, so the PM regeneration function is determined to be abnormal. The PM regeneration amount in a vehicle with a high mileage is the same as the PM regeneration amount in a vehicle with a low mileage. In other words, the PM regeneration function in a vehicle with a high mileage may be erroneously determined to be abnormal even though it is actually normal. Such an erroneous determination may occur due to a manufacturing error (tolerance) that occurs during the manufacturing of the second catalyst 16.

[0031] As in this embodiment, by comparing the pre- and post-regeneration differential pressure difference ΔP with the threshold value P, erroneous determination can be avoided.

[0032] [PM playback function determination] The PM regeneration function determination in the first embodiment will be described with reference to the flowchart shown in Fig. 4. Fig. 2A and Fig. 2B will be referenced as appropriate.

[0033] In step S1, the ECU 50 determines whether the PM regeneration control unit 51 is performing PM regeneration control. This is because the PM regeneration function cannot be determined during PM regeneration control. If the ECU 50 makes a positive determination (Yes determination) in step S1, the ECU 50 proceeds to step S2. If the ECU 50 makes a negative determination (No determination) in step S1, the ECU 50 repeats the processing from step S1.

[0034] In step S2, the ECU 50 determines whether or not a first predetermined amount of PM or more has accumulated in the second catalyst 16, based on the PM accumulation amount estimated by the PM accumulation amount estimation unit 52. Specifically, the ECU 50 determines whether or not the estimated PM accumulation amount is within the pre-regeneration filter differential pressure detection range shown in FIG. 2A. The pre-regeneration filter differential pressure detection range is set as a range in which a pre-regeneration filter differential pressure dP1 is detected, from which the pre-regeneration filter differential pressure difference ΔP used in determining the PM regeneration function can be calculated. If the ECU 50 makes a positive determination in step S2, the process proceeds to step S3. If the ECU 50 makes a negative determination in step S1, the process proceeds to step S4.

[0035] In step S3, the filter differential pressure acquisition unit 53 acquires the pre-regeneration filter differential pressure dP1. The acquired pre-regeneration filter differential pressure dP1 is stored in the pre-regeneration filter differential pressure storage unit 54. After the process of step S3, the ECU 50 repeats the process from step S1.

[0036] In step S4, the ECU 50 determines whether regeneration has been completed in the second catalyst 16 to the extent that the PM accumulation amount is equal to or less than a second predetermined value, based on the PM accumulation amount estimated by the PM accumulation amount estimation unit 52. Specifically, the ECU 50 determines whether the estimated PM accumulation amount is within the post-regeneration filter differential pressure detection region shown in FIG. 2A. The post-regeneration filter differential pressure detection region is set as a region in which a post-regeneration filter differential pressure dP2 is detected, from which the pre-regeneration differential pressure difference ΔP used in determining the PM regeneration function can be calculated. If the ECU 50 determines yes in step S4, the process proceeds to step S5. If the ECU 50 determines no in step S4, the process repeats from step S1.

[0037] In step S5, the ECU 50 determines whether the pre-regeneration filter differential pressure dP1 has been acquired. If step S3 has been executed, the ECU 50 makes a positive determination. On the other hand, if step S3 has not been executed, the ECU 50 makes a negative determination. If the ECU 50 makes a positive determination in step S5, the ECU 50 proceeds to step S6. If the ECU 50 makes a negative determination in step S5, the ECU 50 repeats the processing from step S1.

[0038] In step S6, the filter differential pressure acquisition unit 53 acquires the post-regeneration filter differential pressure dP2. The acquired post-regeneration filter differential pressure dP2 is stored in the post-regeneration filter differential pressure storage unit 55. After processing in step S6, the ECU 50 proceeds to step S7.

[0039] In step S7, the pre- and post-regeneration differential pressure difference acquisition unit 56 acquires the pre- and post-regeneration differential pressure difference ΔP. The pre- and post-regeneration differential pressure difference acquisition unit 56 subtracts the post-regeneration filter differential pressure dP2 stored in the post-regeneration filter differential pressure storage unit 55 from the pre-regeneration filter differential pressure dP1 stored in the pre-regeneration filter differential pressure storage unit 54. After step S7, the ECU 50 proceeds to step S8.

[0040] In step S8, the PM regeneration function determination unit 57 determines whether the pre- and post-regeneration differential pressure difference ΔP is greater than the threshold value P. If the PM regeneration function determination unit 57 determines yes in step S8, the process proceeds to step S9, where it determines that the PM regeneration function is normal. After step S9, the ECU 50 repeats the process from step S1. If the PM regeneration function determination unit 57 determines no in step S8, the process proceeds to step S10, where it determines that the PM regeneration function is abnormal. After step S10, the ECU 50 repeats the process from step S1. If the ECU 50 determines that the PM regeneration function is abnormal, it may display a warning to that effect.

[0041] [effect] According to this embodiment, the differential pressure difference ΔP before and after regeneration is compared with the threshold value P, so that it is possible to avoid erroneous determination of whether the PM regeneration function is operating properly without being affected by changes over time in the second catalyst 16, etc.

[0042] (Second embodiment) In the second embodiment, an ECU 150 shown in Fig. 1B is provided instead of the ECU 50 in the first embodiment. The ECU 150 functions as each unit included in the ECU 50 and also functions as a filter differential pressure correction unit 58. The filter differential pressure correction unit 58 includes a passing gas temperature acquisition unit 60, a passing gas flow rate acquisition unit 61, and a volumetric flow rate calculation unit 62. The other configurations of the second embodiment are common to the configurations of the first embodiment.

[0043] FIG. 5A illustrates the influence of the passing gas flow rate and passing gas temperature on the filter differential pressure. In FIG. 5A, the filter differential pressure when the passing gas flow rate is 30 g / s is plotted for each passing gas temperature. In FIG. 5A, the filter differential pressure when the passing gas flow rate is 40 g / s is plotted for each passing gas temperature. In FIG. 5A, the filter differential pressure when the passing gas flow rate is 45 g / s is plotted for each passing gas temperature. The filter differential pressure increases as the passing gas flow rate increases. The filter differential pressure increases as the passing gas temperature increases. Therefore, in the second embodiment, the pressure difference before and after regeneration ΔP is calculated taking into account the influence of the passing gas flow rate and passing gas temperature. uni The PM regeneration function is determined using this.

[0044] The horizontal axis of the graph shown in Fig. 5B is the volumetric flow rate V of the passing gas passing through the second catalyst 16. The graph shown in Fig. 5B plots values ​​converted into volumetric flow rates V for each gas whose filter differential pressure is shown in Fig. 5A. Using the converted values ​​into volumetric flow rates V makes it possible to compare filter differential pressures under the same conditions. In other words, even if the passing gas flow rate or passing gas temperature is different, accurate PM regeneration function assessment can be performed by using the filter differential pressure corrected so that the volumetric flow rate V is the same.

[0045] The following equation (1) is used to convert each gas into a volumetric flow rate V. The conversion into a volumetric flow rate V is performed by a volumetric flow rate calculation unit 62. Ga in equation (1) is the flow rate of the passing gas. The passing gas flow rate Ga is a value detected by the air flow meter 12. A passing gas flow rate acquisition unit 61 acquires the value detected by the air flow meter 12. Gf in equation (1) is the amount of fuel injection. The value of the fuel injection amount is held by the ECU 50. The volumetric flow rate calculation unit 62 calculates the amount of substance n of the passing gas flow rate Ga and the amount of fuel injection Gf. The GPF internal temperature th in equation (1) ci is the internal temperature of the second catalyst 16. The internal temperature of the second catalyst 16 corresponds to the temperature of the passing gas. ci The GPF internal temperature th is obtained using a calculation model that has been established in advance through experiments and simulations. ci is acquired by the passing gas temperature acquisition unit 60. The upstream pressure P upst is the detection value of the first pressure sensor 18a. upst may be estimated from the flow rate of the passing gas Ga.

[0046] By converting to volumetric flow rate V, gases with different flow rates and temperatures can be plotted on roughly a single straight line, as shown in FIG. 5B.

[0047]

number

[0048] The PM regeneration function determination in the second embodiment will be described with reference to the flowchart shown in Fig. 6. However, the following description focuses on the differences from the first embodiment. The flowchart of the second embodiment shown in Fig. 6 differs from the first embodiment in the following points.

[0049] In the second embodiment, step S1a is performed between step S1 and step S2. In the second embodiment, steps S3' and S5' to S8' are performed instead of steps S3 and S5 to S8 in the first embodiment.

[0050] In step S1a, the ECU 50 determines whether the internal combustion engine 100 is in a regeneration state based on the pre-regeneration differential pressure ΔP uni Specifically, the ECU 50 determines whether the volume flow rate V is within the pre- and post-regeneration differential pressure difference detection region shown in FIG. 6C. If the volume flow rate V is small, the pre- and post-regeneration differential pressure difference ΔP uni Therefore, the detection area of ​​the differential pressure difference before and after regeneration is set to the differential pressure difference before and after regeneration ΔP uni If the ECU 50 determines in step S1a that the vehicle speed is within a certain range, the process proceeds to step S2. If the ECU 50 determines in step S1a that the vehicle speed is within a certain range, the process repeats the process from step S1.

[0051] In step S3', the filter differential pressure acquisition unit 53 acquires the pre-regeneration filter differential pressure dP1 corrected by the filter differential pressure correction unit 58. uni The obtained pre-regeneration filter differential pressure dP1 uni is stored in the pre-regeneration filter differential pressure storage unit 54. The acquired pre-regeneration filter differential pressure dP1 uni The data is stored in the pre-regeneration filter differential pressure storage unit 54. Pre-regeneration filter differential pressure dP1 uni By accumulating this data, the line segment L1 shown in Fig. 5C is drawn. After the process of step S3', the ECU 50 repeats the process from step S1.

[0052] In step S5', the ECU 50 calculates the pre-regeneration filter differential pressure dP1 uni If the ECU 50 determines in step S5' that the determination is affirmative, the ECU 50 proceeds to step S6'. If the ECU 50 determines in step S5' that the determination is negative, the ECU 50 repeats the processing from step S1.

[0053] In step S6', the filter differential pressure acquisition unit 53 calculates the post-regeneration filter differential pressure dP2 corrected by the filter differential pressure correction unit 58. uni The obtained post-regeneration filter differential pressure dP2 uni is stored in the post-regeneration filter differential pressure storage unit 55. The acquired post-regeneration filter differential pressure dP2uni The data is stored in the post-regeneration filter differential pressure storage unit 55. Post-regeneration filter differential pressure dP2 uni By accumulating this data, the line segment L2 shown in Fig. 5C is drawn. After processing step S6', the ECU 50 proceeds to step S7'.

[0054] In step S7', the pre- and post-regeneration differential pressure difference acquisition unit 56 calculates the pre- and post-regeneration differential pressure difference ΔP uni The pre- and post-regeneration differential pressure difference acquiring unit 56 acquires the pre-regeneration filter differential pressure dP1 at which the volumetric flow rate V is the same value from the line segment L1 and the line segment L2 in FIG. uni and post-regeneration filter differential pressure dP2 uni Extract the combination of the filter differential pressure before regeneration dP1 uni and post-regeneration filter differential pressure dP2 uni The combination of the pre-regeneration differential pressure difference dP1 is extracted from the pre-regeneration differential pressure difference detection region. uni After regeneration, the filter differential pressure dP2 uni After step S7', the ECU 50 proceeds to step S8'.

[0055] In step S8', the PM regeneration function determination unit 57 determines the pre- and post-regeneration differential pressure difference ΔP uni It is determined whether or not is greater than the threshold value P. The subsequent processing is the same as in the first embodiment.

[0056] According to this embodiment, by using the filter differential pressure corrected so that the volumetric flow rate V has the same value, it is possible to accurately determine the PM regeneration function.

[0057] The above-described embodiments are merely examples for implementing the present invention, and the present invention is not limited to these. Various modifications of these embodiments are within the scope of the present invention. Furthermore, it is obvious from the above description that various other embodiments are possible within the scope of the present invention. [Explanation of symbols]

[0058] 10 engine body, 12 air flow meter, 13 throttle valve, 16 second catalyst, 53 filter differential pressure acquisition unit, 54 pre-regeneration filter differential pressure storage unit, 55 post-regeneration filter differential pressure storage unit, 56 pre-regeneration and post-regeneration differential pressure difference acquisition unit, 57 PM regeneration function determination unit, 60 passing gas temperature acquisition unit, 61 passing gas flow rate acquisition unit, 62 volumetric flow rate calculation unit

Claims

1. A control device for an internal combustion engine, the control device including a filter for trapping PM provided in an exhaust pipe connected to an engine body, and a PM regeneration function for regenerating the filter that has trapped the PM, a filter differential pressure acquisition unit that acquires a filter differential pressure, which is a differential pressure before and after the filter; a pre- and post-regeneration differential pressure difference acquisition unit that acquires a pre- and post-regeneration differential pressure difference, which is the difference between a pre-regeneration filter differential pressure acquired by the filter differential pressure acquisition unit before regeneration of the filter and a post-regeneration filter differential pressure acquired by the filter differential pressure acquisition unit after regeneration of the filter; a PM generation function determination unit that determines whether the PM regeneration function is abnormal when the pre- and post-regeneration differential pressure difference acquired by the pre- and post-regeneration differential pressure difference acquisition unit is equal to or less than a preset threshold value; A control device for an internal combustion engine, comprising:

2. the filter differential pressure acquisition unit acquires the pre-regeneration filter differential pressure when the PM accumulation amount estimated by the PM accumulation amount estimation unit is equal to or greater than a first predetermined value, and acquires the post-regeneration filter differential pressure when the PM accumulation amount estimated by the PM accumulation amount estimation unit after the start of operation of the PM regeneration function is equal to or less than a second predetermined value that is smaller than the first predetermined value. The control device for an internal combustion engine according to claim 1.

3. a volumetric flow rate calculation unit that calculates a volumetric flow rate when the pre-regeneration filter differential pressure is acquired and a volumetric flow rate when the post-regeneration filter differential pressure is acquired, and a filter differential pressure correction unit that corrects the pre-regeneration filter differential pressure and the post-regeneration filter differential pressure so that the volumetric flow rates calculated by the volumetric flow rate calculation unit are the same value; the pre- and post-regeneration differential pressure difference acquisition unit acquires the difference between the pre-regeneration filter differential pressure and the post-regeneration filter differential pressure, each corrected by the filter differential pressure correction unit. The control device for an internal combustion engine according to claim 1.

4. the volumetric flow rate calculation unit acquires the volumetric flow rate at the time of acquiring the pre-regeneration filter differential pressure based on the temperature and flow rate of the gas that passed through the filter at the time of acquiring the pre-regeneration filter differential pressure, and acquires the volumetric flow rate at the time of acquiring the post-regeneration filter differential pressure based on the temperature and flow rate of the gas that passed through the filter at the time of acquiring the post-regeneration filter differential pressure. The control device for an internal combustion engine according to claim 3.

5. the pre- and post-regeneration differential pressure difference acquisition unit acquires the pre- and post-regeneration differential pressure difference in a region where the volumetric flow rate is equal to or greater than a predetermined value. The control device for an internal combustion engine according to claim 3.

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