Internal combustion engine control device

Abstract

An internal combustion engine control device is provided, applicable to an internal combustion engine in which an exhaust gas concentrator (EHC) and a filter are arranged in the order of EHC and filter from the upstream side. The control device performs a regeneration process and a recovery process. The regeneration process removes particulate matter accumulated in the filter by oxidizing it. The recovery process removes particulate matter accumulated at the front end of the EHC by oxidizing it when the insulation resistance of the EHC is determined to be below a predetermined value. The recovery process is performed after the regeneration process when both the insulation resistance and the amount of particulate matter accumulated in the filter are determined to be above a predetermined amount.

Description

Technical Field

[0001] This invention relates to a control device for an internal combustion engine. Background Technology

[0002] Exhaust purification catalysts for internal combustion engines function effectively at their activation temperature. Therefore, if the temperature of the exhaust purification catalyst is below the activation temperature during cold starts, it may not be able to adequately purify the exhaust.

[0003] Therefore, as an exhaust purification catalyst installed in the exhaust passage of an internal combustion engine, an electrically heated catalyst is known to have a heater that heats up by supplying electricity. If it is an electrically heated catalyst, a preheating treatment can be performed, which involves supplying electricity to preheat the exhaust purification catalyst before starting the internal combustion engine.

[0004] In electrically heated catalysts, a sufficiently high insulation resistance is required to suppress leakage. Japanese Patent Application Publication No. 2012-72665 discloses a control device for controlling the energization of an electrically heated catalyst. The control device in Japanese Patent Application Publication No. 2012-72665 performs a recovery process to restore the insulation resistance when it detects that the insulation resistance of the electrically heated catalyst is low.

[0005] Furthermore, as a recovery process for removing particulate matter deposited at the front end of an electrically heated catalyst by oxidizing it, Japanese Patent Application Publication No. 2012-72665 discloses a process of heating an exhaust gas purification catalyst by operating an internal combustion engine and supplying exhaust gas.

[0006] In addition, filters are sometimes installed in the exhaust passage to capture particulate matter in the exhaust. If particulate matter accumulates in the filter, the resistance to exhaust in the exhaust passage will increase. Therefore, a regeneration process is sometimes performed, which involves raising the temperature of the exhaust flowing into such a filter to oxidize the particulate matter accumulated in the filter and remove it, thereby regenerating the filter. Summary of the Invention

[0007] The particulate matter deposited at the front end of the electrically heated catalyst is removed by oxidation through a recovery process. When a filter is installed downstream of the electrically heated catalyst in the exhaust passage, exhaust gas at a higher temperature than that fed into the electrically heated catalyst is introduced into the filter due to the heat of oxidation of the particulate matter generated by the recovery process and the heat of reaction of the electrically heated catalyst. As a result, the oxidation reaction of the particulate matter deposited in the filter may proceed in a chain reaction, and the filter temperature may rise excessively.

[0008] The technical solutions used to solve the above problems and their effects are described below.

[0009] The control device for solving the above-mentioned problems is applicable to an internal combustion engine equipped with an electrically heated catalytic converter system. This system includes an electrically heated catalytic converter, which is an exhaust gas purification catalyst supported on a catalyst carrier heated by electricity. The catalyst carrier is heated by electricity. The electrically heated catalytic converter and a filter for capturing particulate matter contained in the exhaust gas are arranged in the exhaust passage in the order of the electrically heated catalytic converter and the filter, starting from the upstream side. The control device performs a regeneration process and a recovery process. The regeneration process removes the particulate matter accumulated on the filter by oxidation. The recovery process removes the particulate matter accumulated at the front end of the electrically heated catalytic converter by oxidation when the insulation resistance of the electrically heated catalytic converter is determined to be below a predetermined value. The regeneration process raises the temperature of the exhaust gas discharged from the combustion chamber of the internal combustion engine compared to before the regeneration process began. Furthermore, the recovery process involves raising the temperature of the exhaust gas exiting the combustion chamber to a higher temperature than that under the regeneration process. Additionally, the control device performs the recovery process after the regeneration process when it determines that the insulation resistance is below a predetermined value and that the amount of particulate matter accumulated in the filter is above a predetermined amount.

[0010] Based on the above configuration, a regeneration process is performed first, so the amount of particulate matter accumulated in the filter has decreased before the recovery process. Even if the exhaust gas, heated to a high temperature due to the upstream reaction heat generated by the recovery process, is introduced into the filter, the particulate matter will burn off completely and the chain oxidation reaction will easily converge as long as the amount of accumulated matter has decreased. Therefore, it is possible to prevent the filter temperature from becoming too high.

[0011] In one technical solution of the control device for an internal combustion engine, the amount of buildup is estimated based on the exhaust pressure detected by an exhaust pressure sensor located downstream of the electrically heated catalyst and upstream of the filter in the exhaust passage.

[0012] If particulate matter accumulates in the filter, it becomes clogged, hindering exhaust flow. Consequently, the exhaust pressure upstream of the filter increases. The exhaust pressure detected by the exhaust pressure sensor, located downstream of the electrically heated catalyst and upstream of the filter, increases with the increased flow resistance caused by the accumulation of such particulate matter. Therefore, the amount of accumulation can be estimated based on the exhaust pressure detected as described above, and based on the estimated amount of accumulation, it can be determined that the amount of particulate matter accumulation is above a predetermined amount.

[0013] In one technical solution of the control device for an internal combustion engine, the electrically heated catalyst system includes a leakage current detection circuit for detecting the insulation resistance, and the leakage current detection circuit is used to detect the insulation resistance.

[0014] When the electrically heated catalyst system is equipped with a leakage current detection circuit for detecting the insulation resistance, it is possible to determine that the insulation resistance is below a predetermined value based on the insulation resistance detected by the leakage current detection circuit.

[0015] In one technical solution of the control device for an internal combustion engine, the exhaust temperature is increased by delaying the ignition timing of the internal combustion engine during the regeneration process and the recovery process.

[0016] In the regeneration process and the recovery process, as configured above, the exhaust temperature can be increased by delaying the ignition timing of the internal combustion engine.

[0017] In one technical solution of the control device for an internal combustion engine, if the regeneration process is performed before the recovery process because it is determined that the insulation resistance is below the predetermined value and the accumulation amount is above the predetermined value, the regeneration process ends and the recovery process begins when the accumulation amount is greater than the accumulation amount when the regeneration process is performed without determining that the insulation resistance is below the predetermined value.

[0018] When regeneration is performed before recovery processing, high-temperature exhaust gas is continuously introduced into the filter during the recovery processing following regeneration. Therefore, particulate matter accumulated in the filter can be oxidized during the recovery processing. Thus, even if the regeneration process is terminated when the accumulation amount is greater than that when regeneration is performed without determining that the insulation resistance is below a predetermined value, the accumulation amount can be sufficiently reduced. Based on the above configuration, the execution period of regeneration processing can be shortened, and the process can quickly transition to recovery processing.

[0019] In one technical solution of the control device for an internal combustion engine, the more oxygen contained in the exhaust gas discharged from the combustion chamber, the shorter the execution period of the recovery process.

[0020] The more oxygen there is, the easier it is for particulate matter to oxidize. Therefore, the more oxygen contained in the exhaust gas, the shorter the recovery process. Based on the above configuration, and in this practical situation, the more oxygen contained in the exhaust gas, the shorter the recovery process, thus suppressing unnecessary recovery processes.

[0021] In one technical solution of the control device for an internal combustion engine, when it is determined that the insulation resistance is below a predetermined value, a counter is set to a predetermined value. Furthermore, during the recovery process, a reduction amount is repeatedly subtracted from the counter, and the recovery process ends when the counter drops below a termination determination value. The higher the oxygen content, the larger the reduction amount is set to. By adopting this configuration, it is possible to achieve a situation where the higher the oxygen content in the exhaust gas discharged from the combustion chamber, the shorter the execution period of the recovery process. Attached Figure Description

[0022] The features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, in which the same reference numerals denote the same elements, and wherein:

[0023] Figure 1 This is a schematic diagram illustrating the relationship between a control device as an embodiment of a control device for an internal combustion engine and a vehicle equipped with an internal combustion engine controlled by the control device.

[0024] Figure 2 This is a schematic diagram showing the general configuration of the electrically heated catalyst system installed in the aforementioned vehicle.

[0025] Figure 3 It is a flowchart illustrating a series of processes in a routine related to the operation of insulation restoration requirements.

[0026] Figure 4 This is a flowchart illustrating a series of processes performed when the insulation restoration requirement becomes active (ON).

[0027] Figure 5 A shows the state transition of insulation recovery requirements in a time graph representing the transition of various states when the accumulation amount PM is above a predetermined value PM_x and the insulation resistance Rt is below a predetermined value Rt_x.

[0028] Figure 5 B shows the progression of the accumulation amount PM in a time graph representing the various states when the accumulation amount PM is above a predetermined value PM_x and the insulation resistance Rt is below a predetermined value Rt_x.

[0029] Figure 5 C shows the target temperature progression in a time graph representing the progression of various states when the accumulation amount PM is above a predetermined value PM_x and the insulation resistance Rt is below a predetermined value Rt_x.

[0030] Figure 5D shows the time progression of the counter CNT in a time graph representing the progression of various states when the accumulation amount PM is above a predetermined value PM_x and the insulation resistance Rt is below a predetermined value Rt_x.

[0031] Figure 6 A shows the state transition of insulation recovery requirements in a time graph representing the transition of various states when the accumulation amount PM is less than a predetermined amount PM_x and the insulation resistance Rt is less than a predetermined value Tt_x.

[0032] Figure 6 B shows the progression of the accumulation amount PM in a time graph representing the various states when the accumulation amount PM is less than a predetermined amount PM_x and the insulation resistance Rt is below a predetermined value Tt_x.

[0033] Figure 6 C shows the target temperature progression in a time graph representing the progression of various states when the accumulation amount PM is less than a predetermined amount PM_x and the insulation resistance Rt is below a predetermined value Tt_x.

[0034] Figure 6 D shows the time progression of the counter CNT in a time graph representing the progression of various states when the accumulation amount PM is less than a predetermined amount PM_x and the insulation resistance Rt is less than a predetermined value Tt_x. Detailed Implementation

[0035] The following is for reference Figures 1-6 D describes the control device 100, which is a control device for an internal combustion engine according to one embodiment.

[0036] <Composition of Vehicle 10>

[0037] First, refer to Figure 1 The configuration of the vehicle 10 equipped with the control device 100 will be described.

[0038] like Figure 1 As shown, vehicle 10 is equipped with an internal combustion engine 11 and a second electric generator 32 as power sources. That is, vehicle 10 is a hybrid vehicle. Furthermore, vehicle 10 is also a plug-in hybrid vehicle that connects to an external power source 60 to charge battery 50. Therefore, an external charger 51 is connected to battery 50. In addition, battery 50 is, for example, a 400V high-voltage battery. Furthermore, the second electric generator 32 is, for example, a three-phase AC electric generator.

[0039] The internal combustion engine 11 includes an intake passage 12 and an exhaust passage 21. Furthermore, in Figure 1In the example shown, the internal combustion engine 11 has four cylinders. A throttle valve 13 is provided in the intake passage 12 to adjust the flow rate of the intake air flowing in the intake passage 12. In the internal combustion engine 11, one fuel injection valve 14 is provided for each cylinder, which injects fuel into the intake air. Alternatively, multiple fuel injection valves 14 can be provided for each cylinder, or a different number of fuel injection valves 14 can be provided for each cylinder. Additionally, in the internal combustion engine 11, one spark plug 15 is provided for each cylinder, which ignites the fuel-air mixture via spark discharge. Alternatively, multiple spark plugs 15 can be provided for each cylinder, or a different number of spark plugs 15 can be provided for each cylinder.

[0040] A catalytic converter 29 is provided in the exhaust passage 21 of the internal combustion engine 11. The catalytic converter 29 is equipped with an electrically heated catalytic converter 210 that heats up when energized. The electrically heated catalytic converter 210 is connected to a battery 50 via a power supply 220. See below. Figure 2 The detailed configuration of the electrically heated catalytic converter system 200, including the electrically heated catalytic converter 210, will be described. Furthermore, a filter 36 is provided downstream of the catalytic converter 29 in the exhaust passage 21. The filter 36 captures particulate matter contained in the exhaust gas. Particulate matter consists mainly of fine particles of carbon produced through combustion.

[0041] The second electric generator 32 is connected to the battery 50 via the power control unit 35. The second electric generator 32 is connected to the drive wheel 40 via the reduction gear 34.

[0042] Furthermore, the internal combustion engine 11 is connected to the drive wheel 40 via a power distribution mechanism 30 and a reduction gear 34. Additionally, a first electric generator 31 is connected to the power distribution mechanism 30. The first electric generator 31 is, for example, a three-phase AC electric generator. The power distribution mechanism 30 is a planetary gear mechanism capable of distributing the driving force of the internal combustion engine 11 to the first electric generator 31 and the drive wheel 40.

[0043] The first electric generator 31 generates electricity by receiving driving force from the internal combustion engine 11 and driving force from the drive wheel 40. Additionally, when starting the internal combustion engine 11, the first electric generator 31 also functions as a starter for the rotating shaft of the internal combustion engine 11. At this time, the first electric generator 31 functions as a motor that generates driving force based on the power supplied from the battery 50.

[0044] The first electric generator 31 and the second electric generator 32 are connected to the battery 50 via the power control unit 35. The alternating current (AC) power generated by the first electric generator 31 is converted into direct current (DC) power by the power control unit 35 and then charged into the battery 50. That is, the power control unit 35 functions as an inverter.

[0045] Furthermore, the DC power from battery 50 is converted to AC power by power control unit 35 and supplied to the second electric generator 32. Additionally, when the vehicle 10 decelerates, the second electric generator 32 generates electricity using the driving force from drive wheels 40. The generated electricity is then used to charge battery 50. In other words, regenerative charging is performed on the vehicle 10. At this time, the second electric generator 32 functions as a generator. The AC power generated by the second electric generator 32 is converted to DC power by power control unit 35 and then charged to battery 50.

[0046] Furthermore, when the first electric generator 31 is used as a starter, the power control unit 35 converts the DC power from the battery 50 into AC power and supplies it to the first electric generator 31.

[0047] <Regarding Control Device 100>

[0048] Control device 100 controls internal combustion engine 11, first electric generator 31, and second electric generator 32. That is, control device 100 is a control device that controls the powertrain system of vehicle 10, which is a plug-in hybrid electric vehicle. Therefore, control device 100 controls internal combustion engine 11, including electrically heated catalyst system 200. In short, control device 100 is also a control device that controls internal combustion engine 11.

[0049] The control device 100 receives detection signals from sensors located in various parts of the vehicle 10. These detection signals include vehicle speed, accelerator pedal opening, and state of charge (SOC) corresponding to the remaining capacity of the battery 50. Additionally, a water temperature sensor 101 is connected to the control device 100 to detect the temperature (Tw) of the coolant in the internal combustion engine 11. Furthermore, a power switch 102, used by the driver of the vehicle 10 to start and stop the vehicle 10's systems, is also connected to the control device 100. Therefore, the control device 100 monitors the starting state of the vehicle 10's systems based on the input signal from the power switch 102. An upstream exhaust temperature sensor 103 is connected to the control device 100 to detect the temperature of the exhaust gas discharged from the internal combustion engine 11. The upstream exhaust temperature sensor 103 is located upstream of the catalytic converter 29 in the exhaust passage 21. A downstream exhaust temperature sensor 107 is located downstream of the catalytic converter 29 and upstream of the filter 36 in the exhaust passage 21. Downstream exhaust temperature sensor 107 detects the temperature of the exhaust gas passing through catalytic converter 29. Similarly, air-fuel ratio sensors 105 and 106 are provided upstream and downstream of catalytic converter 29, respectively, as are upstream exhaust temperature sensor 103 and downstream exhaust temperature sensor 107. Upstream air-fuel ratio sensor 105, located in the portion of exhaust passage 21 upstream of catalytic converter 29, detects the air-fuel ratio of the exhaust gas introduced into catalytic converter 29. Downstream air-fuel ratio sensor 106 is located in the portion of exhaust passage 21 downstream of catalytic converter 29 and upstream of filter 36. Downstream air-fuel ratio sensor 106 detects the air-fuel ratio of the exhaust gas passing through catalytic converter 29. Furthermore, an exhaust pressure sensor 104, which detects exhaust pressure, is located in the portion of exhaust passage 21 between catalytic converter 29 and filter 36. All of the above sensors are connected to control device 100. Detection signals from the above sensors are input to control device 100.

[0050] The vehicle 10, configured as described above, uses the electricity stored in the battery 50 to drive the second electric generator 32, enabling it to operate using only the second electric generator 32 to drive the drive wheels 40. Alternatively, it can operate in a hybrid mode, using both the internal combustion engine 11 and the second electric generator 32 to drive the drive wheels 40.

[0051] <Composition of the electrically heated catalyst system 200>

[0052] Next, refer to Figure 2 The configuration of the electrically heated catalyst system 200 will be described.

[0053] like Figure 2As shown, in addition to the first exhaust gas purification catalyst 26 constituting the electrically heated catalyst 210, the catalyst converter 29 also carries a second exhaust gas purification catalyst 27. Both the first exhaust gas purification catalyst 26 and the second exhaust gas purification catalyst 27 are composed of a three-way catalyst supported on a catalyst carrier with a honeycomb structure that divides multiple passages extending along the exhaust flow direction.

[0054] The first exhaust purification catalyst 26 and the second exhaust purification catalyst 27 are housed in a housing 24. The housing 24 is a cylinder made of metal, such as stainless steel. The housing 24 is an exhaust pipe that forms part of the exhaust passage 21. Inside the housing 24, a spacer 28 is provided between the first exhaust purification catalyst 26 and the second exhaust purification catalyst 27 and the housing 24. The spacer 28 is an insulator, for example, formed of inorganic fibers with alumina as the main component.

[0055] The spacer 28 is positioned in a compressed state between the first exhaust purification catalyst 26 and the second exhaust purification catalyst 27 and the housing 24. Therefore, the first exhaust purification catalyst 26 and the second exhaust purification catalyst 27 are held within the housing 24 by the restoring force of the compressed spacer 28.

[0056] On the upstream side of the housing 24, an upstream connecting pipe 23, whose diameter decreases as it moves upstream, is covered and fixed from the outside. Similarly, on the downstream side of the housing 24, a downstream connecting pipe 25, whose diameter decreases as it moves downstream, is covered and fixed from the outside.

[0057] like Figure 2 As shown, the upstream connecting pipe 23 connects the upstream exhaust pipe 22, which has a smaller diameter than the housing 24, to the housing 24. Similarly, the downstream connecting pipe 25 connects the downstream exhaust pipe, which has a smaller diameter than the housing 24, to the housing 24. In this way, the housing 24, which houses the first exhaust purification catalyst 26 and the second exhaust purification catalyst 27, the upstream connecting pipe 23, and the downstream connecting pipe 25 constitute a catalyst converter 29 that forms part of the exhaust passage 21.

[0058] Furthermore, the diameter of the upstream end of the housing 24 decreases as it approaches the upstream exhaust pipe 22, and the diameter of the portion closest to the upstream exhaust pipe 22 is approximately equal to the diameter of the upstream exhaust pipe 22.

[0059] The first exhaust gas purification catalyst 26 is located upstream of the second exhaust gas purification catalyst 27. The catalyst support of the first exhaust gas purification catalyst 26 is formed of a raw material that generates heat due to resistance when energized. For example, silicon carbide can be used as such a raw material. Furthermore, the catalyst support has the characteristic that its resistance decreases at higher temperatures compared to lower temperatures.

[0060] A first electrode 211 and a second electrode 212 are installed in the first exhaust gas purification catalyst 26. The first electrode 211 is a positive electrode, and the second electrode 212 is a negative electrode. By applying a voltage between the first electrode 211 and the second electrode 212, current flows in the first exhaust gas purification catalyst 26. When current flows in the first exhaust gas purification catalyst 26, the catalyst support heats up due to the resistance of the catalyst support.

[0061] To ensure that the current flows uniformly across the entire catalyst support, the first electrode 211 and the second electrode 212 extend circumferentially and axially along the outer peripheral surface of the catalyst support. Furthermore, the first electrode 211 and the second electrode 212 each penetrate the housing 24.

[0062] An insulating member 213, made of an insulating material such as alumina, is embedded between each of the first electrode 211 and the second electrode 212 and the housing 24. Furthermore, an insulating coating is applied to the inner circumferential surface of the housing 24 by coating it with an insulating material. That is, an insulating coating is applied to the portion of the housing 24, which serves as the exhaust pipe, where the catalyst carrier is disposed. For example, a glass coating can be used as the insulating coating. Thus, the first exhaust purification catalyst 26 is electrically insulated from the housing 24. In addition, the insulating coating has the characteristic that its resistance decreases at higher temperatures compared to lower temperatures.

[0063] As described above, a first electrode 211 and a second electrode 212 are installed on the first exhaust gas purification catalyst 26. Thus, the first exhaust gas purification catalyst 26 becomes an electrically heated catalyst 210 that is heated by an electrical supply. Hereinafter, the electrically heated catalyst 210 will be referred to as EHC 210. By applying electricity to heat the catalyst support, the first exhaust gas purification catalyst 26 is heated, thereby promoting activation.

[0064] Furthermore, when the internal combustion engine 11 operates and exhaust flows, the heat from the exhaust, which has been heated by the EHC 210, also moves towards the second exhaust purification catalyst 27. This also promotes the preheating of the second exhaust purification catalyst 27.

[0065] The first electrode 211 and the second electrode 212 are respectively connected to the power supply unit 220 via power cables. In this way, the EHC 210 is connected to the battery 50 via the power circuit 221 of the power supply unit 220. The power supply unit 220 includes a power circuit 221 comprising an insulated transistor and a power switching element, and a power supply microcomputer 222 serving as a power control device for the power circuit 221. A current sensor 224 and a voltage sensor 225 are provided in the power circuit 221. The current sensor 224 and the voltage sensor 225 are connected to the power supply microcomputer 222. The power supply microcomputer 222 detects the current supplied to the EHC 210 based on the signal output by the current sensor 224. Additionally, the power supply microcomputer 222 detects the voltage applied to the EHC 210 based on the signal output by the voltage sensor 225. Furthermore, an auxiliary battery 55 is connected to the power supply unit 220.

[0066] Furthermore, a leakage detection circuit 223 is provided in the power circuit 221 of the power supply unit 220 to detect leakage current by detecting the insulation resistance Rt of the EHC 210. For example, the leakage detection circuit 223 includes a reference resistor. When leakage current is detected, power is supplied from the auxiliary battery 55 to the power circuit 221, which includes the leakage detection circuit 223. The power supply microcomputer 222 calculates the insulation resistance Rt of the EHC 210 based on the current and voltage values ​​detected by the current sensor 224 and voltage sensor 225 at this time. The insulation resistance Rt is the resistance value of the insulating coating. Leakage current is detected based on a low insulation resistance Rt.

[0067] The power supply unit 220 and the control unit 100 are connected in a manner that enables communication between them. The insulation resistance Rt calculated by the power supply microcomputer 222 is output to the control unit 100. In addition, the control unit 100 outputs commands to the power supply unit 220, thereby controlling the power supply to the EHC 210. That is, the control unit 100 supplies power from the battery 50 to the EHC 210 via the power supply unit 220.

[0068] <About Driving Modes>

[0069] In vehicle 10, which is a plug-in hybrid electric vehicle, when the state of charge (SOC) of battery 50 has sufficient margin, it operates in motor driving mode, using only the second electric generator 32 as the power source for driving. In this mode, control unit 100 keeps internal combustion engine 11 stationary. Furthermore, control unit 100 controls power control unit 35 in a manner that causes the second electric generator 32 to generate torque sufficient to provide the required driving force.

[0070] Furthermore, during operation in motor-driven mode, when the state of charge (SOC) of the battery 50 falls below a certain value, the control device 100 switches the vehicle 10's driving mode from motor-driven mode to hybrid driving mode. Hybrid driving mode is a driving mode that uses both the internal combustion engine 11 and the second electric generator 32 as power sources for driving.

[0071] <About Preheating Treatment>

[0072] In order to achieve sufficient exhaust purification capability immediately after switching to hybrid driving mode, it is preferable to energize EHC210 to preheat the first exhaust purification catalyst 26 before starting the internal combustion engine 11 when switching to hybrid driving mode.

[0073] Therefore, the control device 100 performs a preheating process by supplying power from the battery 50 to the EHC 210 before the internal combustion engine 11 is started, in order to preheat the first exhaust purification catalyst 26.

[0074] The control device 100 performs a preheating process when the EHC power-on requirement becomes active. Furthermore, the EHC power-on requirement is activated when both of the following conditions are met.

[0075] The first condition is that the State of Charge (SOC) is below the threshold for switching to hybrid driving mode.

[0076] Another condition is that the temperature of the first exhaust purification catalyst 26 is below a predetermined temperature lower than the activation temperature.

[0077] The control device 100 estimates the temperature of the first exhaust gas purification catalyst 26 based on the water temperature Tw detected by the water temperature sensor 101. For example, the control device 100 takes the water temperature Tw detected by the water temperature sensor 101 as the temperature of the first exhaust gas purification catalyst 26 and determines whether the temperature of the first exhaust gas purification catalyst 26 is below a predetermined temperature lower than the activation temperature.

[0078] When the power-on requirement is activated, the control device 100 begins a preheating process. Furthermore, the control device 100 prohibits the starting of the internal combustion engine 11 during the preheating process. During the preheating process, the control device 100 continuously powers the EHC 210 until the accumulated electrical power reaches the target electrical power. This heats the first exhaust gas purification catalyst 26 to above its activation temperature for preheating. The target electrical power is set based on the electrical power required to heat the first exhaust gas purification catalyst 26 to completion of preheating. Additionally, the electrical power is the accumulated value of the electricity actually supplied to the EHC 210.

[0079] During the preheating process, the control device 100 controls the power supply circuit 221 to change the voltage of the battery 50 and supply power to the EHC 210. As the temperature of the first exhaust gas purification catalyst 26 rises through the preheating process, the resistance of the EHC 210 gradually decreases. Therefore, the control device 100 reduces the voltage in response to the decrease in resistance, maintaining the supplied power (electrical power) at a constant level. Furthermore, the control device 100 controls the voltage within a range below the upper limit voltage, ensuring that the voltage does not exceed a preset upper limit voltage value. That is, the upper limit voltage is the upper limit value of the voltage when controlling the voltage during the preheating process. Additionally, when power is applied, the control device 100 reads the current value detected by the current sensor 224 and the voltage value detected by the voltage sensor 225, and begins accumulating the supplied power. Then, the control device 100 accumulates the supplied power during the period of powering the EHC 210, continuously calculating the electrical power supplied to the EHC 210.

[0080] The control device 100 determines whether the calculated electrical force has reached the target electrical force. If it determines that the electrical force has reached the target electrical force, it stops energizing the EHC 210. That is, the control device 100 continues to energize the battery 50 until the electrical force reaches the target electrical force. Furthermore, when the electrical force reaches the target electrical force, the control device 100 stops energizing the battery 50, thereby ending the preheating process.

[0081] Furthermore, when the preheating process ends, the control device 100 allows the internal combustion engine 11 to start.

[0082] Before starting the preheating process, the control device 100 checks the insulation resistance Rt of the EHC210.

[0083] In vehicle 10, when the system is started, as described above, the power supply microcomputer 222 uses the leakage current detection circuit 223 to detect the insulation resistance Rt. Furthermore, as described above, power from the auxiliary battery 55 is supplied to the EHC 210 at this time to detect the insulation resistance Rt.

[0084] When the EHC energization requirement is active, the control device 100 reads and obtains the insulation resistance Rt detected during system startup. Then, before starting the preheating process, it determines whether the insulation resistance Rt is higher than a predetermined value Rt_x. The predetermined value Rt_x is a threshold used to determine whether "the insulation resistance Rt is sufficient to suppress leakage current" based on the condition that the insulation resistance Rt is higher than the predetermined value Rt_x. When the insulation resistance Rt is below the predetermined value Rt_x, energizing the EHC210 is prohibited.

[0085] When energizing EHC210 is prohibited, even if the EHC energizing requirement is activated, the control device 100 will not energize EHC210. ​​That is, in this case, the control device 100 starts the internal combustion engine 11 without performing a preheating process.

[0086] <Regarding recovery processing>

[0087] The control device 100 performs a recovery process to restore the reduced insulation resistance Rt. Sometimes, when particulate matter contained in the exhaust gas adheres to the housing 24 coated with an insulating coating, carbon contained in the particulate matter forms a conductive path. That is, sometimes carbon adhering to the surface of the insulating coating connects to form a conductive path connecting the first exhaust gas purification catalyst 26, which is currently flowing with current, to the portion without an insulating coating. Furthermore, as... Figure 2 As shown, in the catalyst converter 29, the housing 24 extends upstream of the portion housing the first exhaust gas purification catalyst 26. Because the housing 24 extends beyond the portion of the first exhaust gas purification catalyst 26 where current flows, the surface area of ​​the housing 24 up to the portion without the insulating coating becomes larger. Therefore, the formation of a conduction path can be expected to be suppressed.

[0088] The recovery process utilizes the heat from the exhaust of the internal combustion engine 11 to burn off the conductive path formed by carbon. Sometimes, the insulation resistance Rt recovers after the recovery process is performed.

[0089] <About Recycling Process>

[0090] When particulate matter accumulates in filter 36, the resistance to exhaust in exhaust passage 21 increases. Therefore, control device 100 performs a regeneration process to remove the particulate matter accumulated in filter 36 and regenerate filter 36. During the regeneration process, control device 100 raises the temperature of the exhaust flowing into filter 36 to oxidize the particulate matter accumulated in filter 36.

[0091] Furthermore, the control device 100 estimates the amount of particulate matter (PM) accumulated in the filter 36 based on the exhaust pressure between the catalyst converter 29 and the filter 36 detected by the exhaust pressure sensor 104. The more particulate matter accumulates in the filter 36, the higher the exhaust pressure detected by the exhaust pressure sensor 104. Therefore, the higher the exhaust pressure detected by the exhaust pressure sensor 104, the greater the estimated amount of PM accumulation.

[0092] Furthermore, the control device 100 performs regeneration processing when the accumulated amount PM, estimated based on the exhaust pressure, is greater than the threshold PM_y. Additionally, the control device 100 terminates the regeneration processing when the accumulated amount PM becomes "0".

[0093] <Execution order of regeneration and recovery processing>

[0094] In this way, both regeneration and recovery processes remove particulate matter by oxidizing it. Particulate matter accumulated at the front end of the EHC210, i.e., the portion of the housing 24 upstream of the EHC210, is removed through the recovery process. In the vehicle 10, a filter 36 is provided downstream of the EHC210. ​​In this case, due to the heat of oxidation of the particulate matter generated by the recovery process and the heat of reaction in the EHC210, exhaust gas at a higher temperature than the exhaust gas fed into the EHC210 is introduced into the filter 36. As a result, the oxidation reaction of the particulate matter accumulated in the filter 36 may proceed in a chain reaction, and the temperature of the filter 36 may rise excessively.

[0095] Therefore, when the conditions for performing the recovery process are met, the control device 100 performs the regeneration process first if it determines that the accumulation amount PM is greater than or equal to a predetermined amount PM_x. That is, in the control device 100, if it determines that the insulation resistance Rt is less than or equal to a predetermined value Rt_x and that the accumulation amount PM is greater than or equal to a predetermined amount PM_x, the recovery process is performed after the regeneration process. Furthermore, the predetermined amount PM_x is a value smaller than the threshold PM_y. The predetermined amount PM_x is a threshold used to determine the situation where "if the particulate matter accumulated in the filter 36 reacts in a chain reaction after the recovery process has been performed, the temperature of the filter 36 may become too high."

[0096] Next, refer to Figure 3 and Figure 4 The process flow related to controlling the execution order of regeneration and recovery processes is described.

[0097] <Regarding Insulation Restoration Requirements>

[0098] First, refer to Figure 3 The routines related to the operation of the restoration process, i.e. the insulation restoration requirements, are described. Figure 3 The routine shown is repeatedly executed by the control device 100 during the operation of the internal combustion engine 11.

[0099] Upon initiation of the routine, the control device 100 first acquires the insulation resistance Rt in step S100. Specifically, the control device 100 reads and acquires the latest insulation resistance Rt after detection. For example, the control device 100 reads and acquires the insulation resistance Rt detected during system startup. Then, in the next step S110, the control device 100 determines whether the acquired insulation resistance Rt is below a predetermined value Rt_x.

[0100] If, during the processing in step S110, it is determined that the insulation resistance Rt is below a predetermined value Rt_x (step S110: Yes), the control device 100 proceeds the processing to step S120. Then, during the processing in step S120, the control device 100 activates the insulation restoration requirement. Furthermore, the insulation restoration requirement is initially inactive. Whenever the power switch 102 is turned off and the operation of the vehicle 10's system stops, the insulation restoration requirement is reset to inactive. Furthermore, when the insulation resistance Rt is below the predetermined value Rt_x, energizing the EHC 210 is prohibited as described above. Therefore, when the insulation restoration requirement is activated, energizing the EHC 210 is not performed, preheating is not executed, and starting of the internal combustion engine 11 is permitted.

[0101] On the other hand, if it is determined in step S110 that the insulation resistance Rt is higher than the predetermined value Rt_x (step S110: No), the control device 100 advances the process to step S130. Then, in the process of step S130, the control device 100 sets the insulation recovery requirement to inactive. As described later, when the recovery process ends, the control device 100 re-detects the insulation resistance Rt. Therefore, if the insulation resistance Rt is recovered through the recovery process, the insulation recovery requirement is reset to inactive through the process of step S130 in this routine. In addition, if the insulation resistance Rt is higher than the predetermined value Rt_x, the power-on restriction on EHC210 is lifted.

[0102] After performing the processing of step S120 or step S130 and performing the processing of updating the insulation restoration requirement, the control device 100 temporarily terminates the routine.

[0103] Furthermore, although the power restriction on EHC210 is lifted if the insulation resistance Rt recovers after the recovery process is completed, sometimes the insulation resistance Rt does not recover even after the recovery process is completed, and the insulation resistance Rt remains below the predetermined value Rt_x. In this case, it can also be determined that an insulation failure has occurred.

[0104] <Regarding insulation restoration requirements: restoration and regeneration treatment upon activation>

[0105] Figure 4 This illustrates the processing flow of a routine repeatedly executed by the control device 100 when the insulation restoration requirement is activated. For example... Figure 4 As shown, when the routine begins, the control device 100 first obtains the accumulation amount PM in the process of step S200. Specifically, the control device 100 reads and obtains the accumulation amount PM estimated based on the exhaust pressure detected by the exhaust pressure sensor 104, as described above. Then, the control device 100 advances the process to step S210.

[0106] In step S210, the control device 100 determines whether the accumulated amount PM is less than the predetermined amount PM_x. That is, in step S210, it determines whether the filter 36 will not overheat even if a recovery process is performed.

[0107] If, during the processing in step S210, it is determined that the accumulated amount of PM is less than the predetermined amount of PM_x (step S210: Yes), the control device 100 advances the processing to step S220. Then, during the processing in step S220, a first oxidation control is performed as a recovery process. That is, if it is determined that the accumulated amount of PM is less than the predetermined amount of PM_x, and overheating of the filter 36 will not occur even if a recovery process is performed, the control device 100 performs a recovery process.

[0108] On the other hand, if it is determined in step S210 that the accumulated amount of PM is greater than or equal to a predetermined amount of PM_x (step S210: No), the control device 100 advances the process to step S230. Then, in the process of step S230, a second oxidation control is performed as a regeneration process. That is, if it is determined that the accumulated amount of PM is greater than or equal to a predetermined amount of PM_x, and overheating of the filter 36 may occur when performing the recovery process, the control device 100 does not perform the recovery process, but performs the regeneration process instead.

[0109] As described above, both regeneration treatment and recovery treatment are oxidation controls that oxidize particulate matter by raising the temperature of the exhaust gas discharged from the combustion chamber of the internal combustion engine 11. The target temperature of the exhaust gas discharged from the combustion chamber differs between the first oxidation control performed as recovery treatment and the second oxidation control performed as regeneration treatment.

[0110] In the case of the second oxidation control, which is a regeneration process to oxidize the particulate matter accumulated on the filter 36, a low target temperature Ta is set by taking into account the heat of reaction in the first exhaust purification catalyst 26 and the second exhaust purification catalyst 27 located upstream of the filter 36.

[0111] Specifically, the target temperature Ta is set to a temperature at which "particulate matter can be oxidized by the exhaust gas flowing into the filter 36, whose temperature has risen due to the reaction heat in the first exhaust purification catalyst 26 and the second exhaust purification catalyst 27". In addition, the target temperature Ta is set to a degree to which the filter 36 will not overheat due to the chain oxidation of particulate matter accumulated on the filter 36.

[0112] On the other hand, in the case of the recovery treatment of the carbon contained in the particulate matter attached to the front end of EHC210, i.e., the portion of the shell 24 upstream of EHC210, it is necessary to oxidize the particulate matter thermally without relying on a catalyst. Therefore, the target temperature Tb in the first oxidation control performed as the recovery treatment is higher than the target temperature Ta. The target temperature Tb is set to a temperature at which the particulate matter can be oxidized.

[0113] Furthermore, in the control device 100, in both the first oxidation control (as the recovery process in step S220) and the second oxidation control (as the regeneration process in step S230), the exhaust temperature is increased by delaying the ignition timing. That is, the ignition timing is delayed compared to the case where oxidation control is not performed. By delaying the ignition timing, combustion becomes slower, and the exhaust temperature increases. In the first oxidation control, the exhaust temperature is increased by increasing the amount of ignition timing delay compared to the second oxidation control.

[0114] In this way, the ignition timing is delayed in the second oxidation control so that the temperature of the exhaust gas from the combustion chamber becomes the target temperature Ta, and the ignition timing is delayed even more significantly in the first oxidation control so that the temperature of the exhaust gas from the combustion chamber becomes the target temperature Tb.

[0115] Furthermore, the control device 100 increases the fuel injection quantity compared to the state without oxidation control, thereby increasing the output of the internal combustion engine 11. This compensates for the output reduction caused by ignition timing delay. Additionally, it increases exhaust flow and the amount of heat transferred per unit time.

[0116] After performing the second oxidation control as a regeneration process in step S230, the control device 100 temporarily terminates the series of processes. Through the regeneration process, the amount of PM accumulated in the filter 36 gradually decreases. Therefore, by repeatedly executing this routine, the amount of PM eventually becomes less than the predetermined amount of PM_x, thus determining "yes" in step S210 (Step S210: Yes). That is, the process eventually transitions from regeneration to recovery.

[0117] After performing the first oxidation control as a recovery process in step S220, the control device 100 advances the process to step S240 to update the counter CNT. The counter CNT is set to a predetermined value when the insulation resistance Rt is determined to be below a predetermined value Rt_x, thus prohibiting energization of the EHC 210. In step S240, the value of the counter CNT is updated by subtraction. The amount of subtraction of the counter CNT in step S240 (the amount of reduction of the counter CNT) is set according to the air-fuel ratio of the exhaust gas upstream of the catalytic converter 29 detected by the upstream air-fuel ratio sensor 105. Specifically, the higher the air-fuel ratio detected by the upstream air-fuel ratio sensor 105, that is, the more oxygen is contained in the exhaust gas, the larger the amount of subtraction is set to.

[0118] When the counter CNT is updated in the process of step S240, the control device 100 advances the process to step S250. Then, in the process of step S250, the control device 100 determines whether the counter CNT is below the threshold CNT_x, which is the end determination value.

[0119] If, during the processing in step S250, it is determined that the counter CNT is greater than the threshold CNT_x (step S250: No), the control device 100 temporarily terminates the routine. On the other hand, if, during the processing in step S250, it is determined that the counter CNT is less than the threshold CNT_x (step S250: Yes), the control device 100 advances the processing to step S260. Then, during the processing in step S260, the control device 100 performs resistance verification control.

[0120] In this resistance verification control, firstly, similar to system startup, the power supply microcomputer 222 uses the leakage current detection circuit 223 to detect the insulation resistance Rt. Next, the control device 100 executes the reference... Figure 3 The described routine. Furthermore, if the re-detected insulation resistance Rt is higher than the predetermined value Rt_x (step S110: No), the control device 100 updates the insulation recovery requirement to inactive (step S130). Then, the control device 100 terminates the resistance verification control, ending the routine.

[0121] When the insulation restoration requirement is set to inactive in this way, the routine is no longer executed, and the restoration process is not performed. That is, the control device 100 ends the restoration process by updating the insulation restoration requirement to inactive in the process of step S260.

[0122] On the other hand, if the re-detected insulation resistance Rt is still below the predetermined value Rt_x (step S110: Yes), the control device 100 will still set the insulation recovery requirement to active (step S120). Then, the control device 100 will end the resistance verification control and terminate the routine.

[0123] Since the insulation restoration requirement remains active, the restoration process is performed again in this case. Furthermore, if the insulation resistance Rt fails to recover even after repeated restoration processes, it can be determined that an anomaly has occurred in EHC210.

[0124] In this way, when the recovery process begins, the control device 100 repeatedly executes this routine to continue the recovery process until it is determined in the process of step S250 that the counter CNT is below the threshold CNT_x. The magnitude of the predetermined value set as the initial value of the counter CNT, the magnitude of the reduction, and the manner in which the recovery process can be continuously performed for the period required to restore the insulation resistance Rt are set based on the results of prior experiments, etc.

[0125] <Function>

[0126] Next, refer to Figure 5 A~ Figure 5 D and Figure 6 A~ Figure 6 D explains the function of the control device 100. Furthermore, Figure 5 A~ Figure 5 D and Figure 6 A~ Figure 6 D is a time graph showing the shift of the accumulation amount PM during the recovery process. Figure 5 B and Figure 6 B shows the shift in the accumulation amount PM. Figure 5 A and Figure 6 A illustrates the progression of the state of insulation restoration requirements. Figure 5 C and Figure 6 C indicates the progression of the target temperature in oxidation control. Figure 5 D and Figure 6 D indicates the progression of the counter CNT.

[0127] In addition, Figure 5 A~ Figure 5 D and Figure 6 A~ Figure 6 In D, a number is added after "t" to indicate the time. Figure 5 A~ Figure 5 D and Figure 6 A~ Figure 6 In D, the larger the number following "t", the later the time in time it represents. For example, Figure 5 A~ Figure 5In D, "t4" is Figure 6 A~ Figure 6 The moment after “t3” in D.

[0128] Figure 5 A~ Figure 5 D is a time graph showing the shift of values ​​when the insulation resistance Rt is determined to be below a predetermined value Rt_x and the accumulation amount PM is determined to be above a predetermined value PM_x. Figure 6 A~ Figure 6 D is a time graph showing the shift of values ​​when the insulation resistance Rt is determined to be below a predetermined value Rt_x and the accumulation amount PM is determined to be less than a predetermined amount PM_x.

[0129] When it is determined at time t1 that the insulation resistance Rt is below the predetermined value Rt_x (step S110: No), such as Figure 5 As shown in step A, the insulation restoration requirement is updated from inactive to active (step S120). Consequently, the counter CNT is set to a predetermined value.

[0130] Starting at time t2 Figure 4 When the routine is shown, such as Figure 5 As shown in step B, the accumulated PM is above the predetermined amount of PM_x (step S210: No), so the second oxidation control is started as a regeneration process (step S230). Therefore, as... Figure 5 As shown in C, oxidation control is performed such that the temperature of the exhaust gas discharged from the combustion chamber of the internal combustion engine 11 is set to the target temperature Ta.

[0131] When regeneration begins at time t2, as shown below... Figure 5 As shown in B, the accumulated amount of PM gradually decreases. When the accumulated amount of PM at time t4 is lower than the predetermined amount of PM_x (step S210: Yes), the first oxidation control is performed as a recovery process (step S220). That is, the process performed by the control device 100 changes from a regeneration process to a recovery process. Thus, as Figure 5 As shown in C, a second oxidation control is performed such that the temperature of the exhaust gas discharged from the combustion chamber of the internal combustion engine 11 is a target temperature Tb that is higher than the target temperature Ta.

[0132] When the recovery process begins at time t4, the update of the counter CNT begins (step S250). Thus, as... Figure 5 As shown in D, the counter CNT gradually decreases after time t4.

[0133] At this time, the particulate matter at the front end of EHC210 is removed by oxidation through a recovery process, and the exhaust gas heated by the heat of oxidation and the heat of reaction in the catalyst converter 29 is introduced into the filter 36 located downstream of the catalyst converter 29. Therefore, the oxidation of particulate matter continues in the filter 36 as well. Thus, as... Figure 5 As shown in B, the accumulation amount PM continues to decrease after time t4. Furthermore, at... Figure 5 In B, the accumulation amount PM becomes "0" at time t7.

[0134] like Figure 5 As shown in step D, when it is determined at time t8 that the counter CNT has fallen below the threshold CNT_x (step S250: Yes), resistance verification control is executed (step S260). Furthermore, if the insulation resistance Rt is higher than the predetermined value Rt_x (step S110: No), then... Figure 5 As shown in Figure A, at time t9, the insulation restoration requirement is updated to inactive. Thus, the restoration process ends.

[0135] In this manner, according to the control device 100, when it is determined that the insulation resistance Rt is below a predetermined value Rt_x and the accumulation amount PM is above a predetermined value PM_x, a regeneration process is first performed. Then, after the accumulation amount PM is reduced through the regeneration process, a recovery process is performed.

[0136] Next, refer to Figure 6 A~ Figure 6 D explains the role of not determining the accumulation amount PM as being above the predetermined amount PM_x.

[0137] This is also true in this case, such as Figure 6 As shown in step A, when it is determined at time t1 that the insulation resistance Rt is below the predetermined value Rt_x (step S110: No), the insulation restoration requirement is updated from inactive to active (step S120). Therefore, the counter CNT is set to the predetermined value.

[0138] In this case, such as Figure 6 As shown in B, the accumulated amount PM is less than the predetermined amount PM_x (step S210: Yes). Therefore, in this case, starting at time t2... Figure 4 In the routine shown, the first oxidation control is performed as a recovery process (step S220). Thus, as... Figure 6 As shown in Figure C, the first oxidation control is performed such that the temperature of the exhaust gas discharged from the combustion chamber of the internal combustion engine 11 becomes the target temperature Tb. As described above, during the recovery process, the amount of PM deposited continuously decreases. Therefore, when the recovery process begins at time t2, as shown in Figure C... Figure 6 As shown in Figure B, the accumulated PM gradually decreases. Furthermore, in... Figure 6In B, at time t3, the accumulation amount PM becomes "0".

[0139] When the recovery process begins at time t2, the update of counter CNT begins (step S250). Thus, as... Figure 6 As shown in D, the counter CNT gradually decreases after time t2.

[0140] like Figure 6 As shown in step D, when it is determined at time t5 that the counter CNT has fallen below the threshold CNT_x (step S250: Yes), resistance verification control is executed (step S260). Furthermore, if the insulation resistance Rt is higher than the predetermined value Rt_x (step S110: No), then... Figure 6 As shown in Figure A, the insulation restoration requirement is updated to inactive at time t6. Thus, the restoration process ends.

[0141] In this way, according to the control device 100, when it is determined that the insulation resistance Rt is below a predetermined value Rt_x and it is not determined that the accumulation amount PM is above a predetermined amount PM_x, the regeneration process is not performed, but the recovery process is performed. Furthermore, the particulate matter at the front end of the EHC210 and the particulate matter accumulated on the filter 36 are removed by the recovery process.

[0142] <Effect>

[0143] The effects of this implementation method will be explained.

[0144] (1) In the control device 100, when it is determined that the insulation resistance Rt is below a predetermined value Rt_x and the accumulation amount PM is above a predetermined value PM_x, a regeneration process is performed first. Therefore, when the recovery process is performed, the accumulation amount PM of particulate matter in the filter 36 has decreased. Even if the exhaust gas, which has been heated to a high temperature due to the reaction heat generated upstream of the recovery process, is introduced into the filter 36, the particulate matter will burn out and the chain oxidation reaction will easily converge when the accumulation amount PM has decreased. Therefore, it is possible to prevent the temperature of the filter 36 from becoming too high.

[0145] (2) In the control device 100, if the insulation resistance Rt is determined to be below the predetermined value Rt_x and the accumulation amount PM is not determined to be above the predetermined amount PM_x, the regeneration process is not performed, but the recovery process is performed. Therefore, both the particulate matter at the front end of the EHC210 and the particulate matter accumulated on the filter 36 can be removed by a single recovery process.

[0146] (3) Figure 5 A~ Figure 5As shown in Figure D, in the control device 100, if a regeneration process is performed before a recovery process is initiated because the insulation resistance Rt is determined to be below a predetermined value Rt_x and the accumulation amount PM is above a predetermined value PM_x, the process switches from regeneration to recovery when the accumulation amount PM falls below the predetermined value PM_x. That is, the control device 100 ends the regeneration process before the accumulation amount PM becomes "0". In summary, in this case, the control device 100 ends the regeneration process and begins the recovery process when the accumulation amount PM is greater than the accumulation amount when regeneration was performed without determining that the insulation resistance Rt is below the predetermined value Rt_x.

[0147] When regeneration is performed before recovery processing, high-temperature exhaust gas is continuously introduced into filter 36 during the recovery processing following regeneration. Therefore, particulate matter accumulated in filter 36 can be oxidized during recovery processing. Thus, even if regeneration is terminated when the accumulation amount PM is greater than that when regeneration is performed without determining that the insulation resistance Rt is below a predetermined value Rt_x, the accumulation amount PM can be sufficiently reduced. Therefore, according to control device 100, the execution period of regeneration processing can be shortened, and recovery processing can be quickly transitioned to recovery processing.

[0148] (4) As mentioned above, it can be quickly converted into a recovery process, so the insulation resistance Rt can be quickly restored and the prohibition of energization can be quickly lifted.

[0149] (5) The more oxygen there is, the easier it is for particulate matter to oxidize. Therefore, the more oxygen contained in the exhaust gas, the shorter the execution period of the recovery process. In the control device 100, the more oxygen contained in the exhaust gas discharged from the combustion chamber, the shorter the execution period of the recovery process. Therefore, it is possible to suppress unnecessary execution of the recovery process.

[0150] <Example of Change>

[0151] This embodiment can be modified as follows. This embodiment and the following modifications can be combined with each other to implement them without technical inconsistencies.

[0152] The higher the temperature, the easier it is for particulate matter to oxidize. For example, the higher the temperature of the exhaust gas from the combustion chamber of the internal combustion engine 11, the larger the decrease in the counter CNT should be set.

[0153] While a method for determining the timing to end the recovery process using a counter CNT is illustrated, this method is not limited to. Different methods can also be applied. Furthermore, although an example of decreasing the counter CNT is shown, the counter CNT can also be increased, and the recovery process can be terminated when the counter CNT reaches a threshold.

[0154] Although an example of subtracting the counter CNT only during the recovery process is shown, it is also possible to perform the subtraction during the regeneration process. Depending on the exhaust temperature, particulate matter at the front end of EHC210 may also oxidize during the regeneration process. The target temperature Ta in the second oxidation control of the regeneration process is set to a temperature at which overheating of filter 36 will not occur even when oxidative heat or reaction heat is applied.

[0155] During the regeneration process, oxygen supply to filter 36 can also be controlled simultaneously. For example, by stopping fuel injection and ignition in a portion of the cylinders and expelling air from those cylinders into exhaust passage 21, oxygen can be supplied to filter 36. With such an oxygen supply, even if oxygen is trapped in the three-way catalytic converter 29, sufficient oxygen can be supplied to filter 36. By supplying oxygen to filter 36, combustion can be promoted and regeneration can be completed quickly. Alternatively, the fuel injection quantity of other cylinders can be increased accordingly to maintain the average air-fuel ratio near the stoichiometric air-fuel ratio.

[0156] The method for determining whether the accumulated amount PM is above the predetermined amount PM_x can be appropriately modified. For example, it can also be determined that the accumulated amount PM is above the predetermined amount PM_x based on the condition that the exhaust pressure is above the threshold.

[0157] The amount of particulate matter (PM) deposited in filter 36 can also be estimated without relying on exhaust pressure. For example, the amount of PM can be calculated based on the exhaust flow rate. Furthermore, the amount of particulate matter flowing into filter 36 can be calculated by taking into account the effects of the reaction in the three-way catalytic converter. In addition, the amount of reduction in particulate matter in the exhaust due to oxidation based on the recovery treatment can also be calculated, and this reduction can also be reflected in the calculation of the amount of PM.

[0158] The configuration of the catalyst converter 29 can be modified appropriately. For example, it can also be configured without the second exhaust purification catalyst 27.

[0159] The catalyst supported on the catalyst carrier of the exhaust gas purification catalyst is not limited to a three-way catalyst. For example, it can also be an oxidation catalyst, a NOx-suppressing catalyst, or a selectively reduced NOx catalyst.

[0160] As an example of an electrically heated catalyst, the EHC210 is shown, which heats the exhaust gas purification catalyst by flowing an electric current within the catalyst itself. However, the configuration of an electrically heated catalyst is not limited to this configuration. For example, an electrically heated catalyst may also be configured such that a heater, which heats the exhaust gas purification catalyst by flowing an electric current, is disposed adjacent to the exhaust gas purification catalyst, and the exhaust gas purification catalyst is heated by the heater.

[0161] The vehicle 10 equipped with the electrically heated catalytic converter system 200 and control device 100 can be not only a plug-in hybrid vehicle, but also a hybrid vehicle without plug-in capability and a vehicle that uses only the internal combustion engine 11 as a power source. In the example of the above-mentioned vehicle other than a plug-in hybrid vehicle, the energization requirement of the EHC 210 is activated when there is a starting requirement of the internal combustion engine 11 and the temperature of the EHC 210 is below a predetermined value.

[0162] The control device 100 can be configured as one or more processors that perform various processes according to computer programs (software), and one or more application-specific integrated circuits (ASICs) that perform at least a portion of the various processes. Alternatively, the control device 100 can also be configured as a circuit comprising a combination of one or more of the aforementioned processors and one or more of the aforementioned dedicated hardware circuits. The processor includes a CPU and memories such as RAM and ROM, which store program code or instructions configured to cause the CPU to perform processes. Memory, or computer-readable medium, includes any available medium that can be accessed by a general-purpose or special-purpose computer.

[0163] Additionally, an example is shown where the control device for the internal combustion engine is specifically implemented as a control device 100 for controlling the powertrain system of the vehicle 10. In contrast, the control device for the internal combustion engine can also be configured as a dedicated control device for controlling the internal combustion engine 11.

Claims

1. A control device for an internal combustion engine, suitable for internal combustion engines. The internal combustion engine is equipped with an electrically heated catalytic converter system. The electrically heated catalyst system includes an electrically heated catalyst, which is an exhaust gas purification catalyst supported on a catalyst carrier that is heated by an electric current. The catalyst carrier is heated by an electric current. The electrically heated catalyst and the filter for capturing particulate matter contained in the exhaust gas are arranged in the exhaust passage in the following order from the upstream side: the electrically heated catalyst, the filter. The control device of the internal combustion engine performs regeneration and recovery processes. The regeneration process involves oxidizing the particulate matter accumulated in the filter to remove it. The recovery process involves removing the particulate matter accumulated at the front end of the electrically heated catalyst by oxidizing it when the insulation resistance of the catalyst is determined to be below a predetermined value. When it is determined that the amount of particulate matter accumulated in the filter is greater than or equal to a first predetermined amount, the regeneration process is performed. The regeneration process is a process that raises the temperature of the exhaust gas exiting the combustion chamber of the internal combustion engine compared to before the regeneration process begins. The recovery process involves raising the temperature of the exhaust gas exiting the combustion chamber to a higher temperature than that under the regeneration process. If it is determined that the insulation resistance is below the predetermined value and the accumulation amount of particulate matter in the filter is less than or greater than the second predetermined amount (less than the first predetermined amount), then the recovery process is performed after the regeneration process. If it is determined that the insulation resistance is below the predetermined value and the amount of particulate matter accumulated in the filter is less than the second predetermined amount, the regeneration process is not performed, but the recovery process is performed instead.

2. The control device for an internal combustion engine according to claim 1, The amount of buildup is estimated based on the exhaust pressure detected by an exhaust pressure sensor located downstream of the electrically heated catalyst and upstream of the filter in the exhaust passage.

3. The control device for an internal combustion engine according to claim 1, The electrically heated catalyst system includes a leakage current detection circuit for detecting the insulation resistance. The leakage current detection circuit is used to detect the insulation resistance.

4. The control device for an internal combustion engine according to any one of claims 1 to 3, In the regeneration process and the recovery process, the exhaust temperature is increased by delaying the ignition timing of the internal combustion engine.

5. The control device for an internal combustion engine according to any one of claims 1 to 3, If the regeneration process is performed before the recovery process because it is determined that the insulation resistance is below the predetermined value and the accumulation amount is above the second predetermined value, the regeneration process ends and the recovery process begins when the accumulation amount is greater than the accumulation amount when the regeneration process is performed without determining that the insulation resistance is below the predetermined value.

6. The control device for an internal combustion engine according to any one of claims 1 to 3, The more oxygen contained in the exhaust gas from the combustion chamber, the shorter the execution period of the recovery process.

7. The control device for an internal combustion engine according to claim 6, When it is determined that the insulation resistance is below the predetermined value, the counter is set to the predetermined value. During the recovery process, the reduction amount is repeatedly subtracted from the counter, and the recovery process ends when the counter drops below the termination determination value. The more oxygen there is, the larger the reduction amount is set to.

Images