Control device for an internal combustion engine

Abstract

A control device of an internal combustion engine adapted to an internal combustion engine on which an electrically heated catalyst system having an EHC is mounted. The control device executes a preheating process when it is determined that the temperature of an exhaust purification catalyst is less than an activation temperature, the preheating process being a process of preheating the exhaust purification catalyst by supplying electric power to the EHC before the internal combustion engine is started. The control device executes a determination process of whether or not water is attached to a catalyst carrier. The control device causes the internal combustion engine to start without executing the preheating process even when it is determined that the temperature of the exhaust purification catalyst is less than the activation temperature, in a case where it is determined through the determination process that water is attached to the catalyst carrier.

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 optimally at their activation temperature. Therefore, during cold starts, when the catalyst's temperature is below the activation temperature, it may not be able to adequately purify the exhaust.

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

[0004] Furthermore, the catalyst support for electrically heated catalysts is formed from raw materials such as ceramics that generate heat due to resistance when electricity is applied. Japanese Patent Application Publication No. 2011-231710 describes the following issue: if preheating is performed while moisture is present in the micropores of a porous ceramic support, a sudden boiling phenomenon occurs due to thermal expansion caused by the inability to expel the moisture.

[0005] Furthermore, in the control device disclosed in Japanese Patent Application Publication No. 2011-231710, when it is determined that there is moisture inside the ceramic carrier, a low-power control is implemented to reduce the amount of supplied power in order to prevent damage to the ceramic carrier caused by sudden boiling. Japanese Patent Application Publication No. 2011-231710 describes the following: By implementing low-power control in this way, the moisture inside the ceramic carrier can be gradually evaporated, thus suppressing damage caused by sudden boiling. Summary of the Invention

[0006] If preheating is performed while the catalyst support is covered with water, the heat is lost due to the latent heat of vaporization before the water evaporates and disappears. Therefore, the temperature of the water-covered portion is difficult to rise. On the other hand, the temperature of the portion without water adheres continues to rise during this period due to the heat generated by the energization. Consequently, if energization continues, the temperature difference between the water-covered and water-free portions increases, generating thermal stress. Therefore, even with the low-power control disclosed in Japanese Patent Application Publication No. 2011-231710, it is impossible to sufficiently suppress the generation of thermal stress caused by this temperature difference between the water-covered and water-free portions. As a result, the catalyst support may crack.

[0007] The technical solutions used to solve the above problems and their effects are described below.

[0008] 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 that is heated by electricity. The control device performs a preheating process when it determines that the temperature of the exhaust gas purification catalyst is lower than its activation temperature. This preheating process involves supplying electricity to the electrically heated catalytic converter via a power supply device before starting the internal combustion engine. Furthermore, the control device performs a determination process to determine whether water is adhering to the catalyst carrier. If the determination process determines that water is adhering to the catalyst carrier, the control device starts the internal combustion engine without performing the preheating process, even if the temperature of the exhaust gas purification catalyst is determined to be lower than its activation temperature.

[0009] In the preheating treatment where the catalyst support is heated by applying electricity, heat is transferred from the catalyst support to the water adhering to it. On the other hand, when the internal combustion engine is running and exhaust gas passes through the exhaust gas to purify the catalyst, the water adhering to the catalyst support is also heated by the exhaust gas flowing around it. Therefore, the water evaporates rapidly. Furthermore, the catalyst support also heats up due to the heat of the exhaust gas. Therefore, compared to the case where preheating is performed solely by heating the catalyst support by applying electricity, it is less likely to create a temperature difference between the parts with and without water adhering to them. That is, according to the above configuration, thermal stress generated in the catalyst support can be suppressed. Even the possibility of the catalyst support cracking due to thermal stress can be suppressed.

[0010] In one technical solution of the control device for an internal combustion engine, the control device prohibits the supply of electricity to the catalyst carrier when it is determined through the determination process that water is attached to the catalyst carrier.

[0011] Based on the above configuration, energizing is no longer performed when the catalyst support may be contaminated with water. Therefore, it is possible to suppress the cracking of the catalyst support caused by the thermal stress generated during energizing.

[0012] In one technical solution of the control device for an internal combustion engine, after the control device starts the internal combustion engine without performing the preheating treatment based on the determination process that water is attached to the catalyst carrier, it applies electricity to the catalyst carrier.

[0013] As described above, when the internal combustion engine is running and exhaust gas passes through the catalyst carrier, heat is also applied to the water adhering to the catalyst carrier from the exhaust gas, making the water easily evaporate. Therefore, it is difficult for the catalyst carrier to crack due to thermal stress. Therefore, in the above configuration, after starting the internal combustion engine without performing preheating treatment, electricity is applied to the catalyst carrier while the internal combustion engine is running. As a result, preheating of the exhaust gas purification catalyst can be completed quickly while suppressing catalyst carrier cracking.

[0014] In one technical solution of the control device for an internal combustion engine, when the control device starts the internal combustion engine without performing the preheating treatment based on the determination process that water is attached to the catalyst carrier, it delays the ignition timing compared to when the internal combustion engine is started after performing the preheating treatment.

[0015] By operating the internal combustion engine with ignition timing delayed, the exhaust temperature increases. Therefore, based on the above configuration, the temperature of the exhaust gas passing through the catalyst carrier can be increased, enabling rapid removal of moisture and preheating of the exhaust purification catalyst.

[0016] In one technical solution of the control device for an internal combustion engine, when the control device starts the internal combustion engine without performing the preheating treatment based on the determination process that water is attached to the catalyst carrier, the fuel injection quantity is increased compared to when the internal combustion engine is started after the preheating treatment is performed.

[0017] By increasing the fuel injection quantity, the internal combustion engine speed increases, leading to a greater flow rate of exhaust gas through the catalyst carrier and an increase in the heat generated by combustion. Consequently, the amount of water adhering to the catalyst carrier and the amount of heat applied to the catalyst carrier per unit time increase, thus enabling rapid removal of moisture and preheating of the exhaust gas purification catalyst.

[0018] In one technical solution of the control device for an internal combustion engine, the control device calculates the amount of water contained in the catalyst carrier, i.e., the water content. Furthermore, in the determination process, the control device determines that water is attached to the catalyst carrier if the calculated water content is above a threshold, and determines that no water is attached to the catalyst carrier if the calculated water content is below the threshold.

[0019] Whether the catalyst support is attached to water can be determined based on the calculated water content value, as described above.

[0020] In one technical solution of the control device for an internal combustion engine, the control device calculates the amount of water generated and the amount of water evaporated. The amount of water generated is the amount of water produced in the catalyst carrier during the period when the internal combustion engine is in a stopped state. The amount of water evaporated is the amount of water evaporated in the catalyst carrier during the period when the internal combustion engine is running, as well as the amount of water evaporated in the catalyst carrier by energizing the catalyst carrier. Furthermore, the control device calculates the water content based on the amount of water generated and the amount of water evaporated.

[0021] The water content can be calculated, for example, by calculating the amount generated and the amount evaporated, as described above. 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 showing the relationship between the control device, which is a control device for an internal combustion engine according to the first embodiment, 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 graph showing the temperature changes of the portion of the catalyst support without attached water and the portion with attached water.

[0026] Figure 4 It is a graph showing the change in temperature difference ΔT between the part of the catalyst support without water and the part with water.

[0027] Figure 5 This is a flowchart illustrating the process involved in the routine of the preheating process performed by the aforementioned control device.

[0028] Figure 6 This is a flowchart illustrating the process involved in calculating the moisture content Q when the aforementioned control device is activated.

[0029] Figure 7 This is a flowchart illustrating the storage process of water content Q performed when the aforementioned control device stops.

[0030] Figure 8 This is a flowchart illustrating the process of moisture content update treatment performed by the aforementioned control device during catalyst preheating.

[0031] Figure 9This is a flowchart illustrating the series of processes involved in the evaporation promotion control performed by the aforementioned control device during catalyst preheating.

[0032] Figure 10A This is a timeline showing the system operating state when the aforementioned vehicle was started with water attached to the catalyst carrier.

[0033] Figure 10B This is a time graph showing the EHC water content Q of the above-mentioned vehicle system when it was started with water attached to the catalyst carrier.

[0034] Figure 10C This is a timeline showing the progression of the power-on prohibition requirement when the system of the aforementioned vehicle is started with water attached to the catalyst carrier.

[0035] Figure 10D This is a time graph showing the shift of the internal combustion engine speed NE when the system of the aforementioned vehicle is started with water attached to the catalyst carrier.

[0036] Figure 10E This is a time graph showing the shift of evaporation promotion control when the system of the aforementioned vehicle is started with water attached to the catalyst carrier.

[0037] Figure 10F This is a time graph showing the shift of catalyst preheating control when the system of the aforementioned vehicle is started with water attached to the catalyst carrier.

[0038] Figure 10G This is a time diagram showing the ignition timing shift when the system of the aforementioned vehicle is started with water attached to the catalyst carrier.

[0039] Figure 10H This is a time-shifting graph showing the output of the internal combustion engine when the system of the aforementioned vehicle is started with water attached to the catalyst carrier.

[0040] Figure 10I This is a time graph showing the shift of catalyst temperature T when the system of the aforementioned vehicle is started with water attached to the catalyst carrier.

[0041] Figure 10J This is a time graph showing the temperature difference ΔT shift when the system of the aforementioned vehicle is started with water attached to the catalyst carrier.

[0042] Figure 11 This is a flowchart illustrating the process flow of the routine involved in the prohibition of preheating treatment performed by the control device of the second embodiment.

[0043] Figure 12This is a flowchart illustrating the process involved in the catalyst preheating control performed by the control device of the second embodiment. Detailed Implementation

[0044] (First Embodiment)

[0045] The following is for reference Figures 1 to 10 The control device 100, which is the control device of the internal combustion engine in the first embodiment, will be described.

[0046] <Vehicle Composition>

[0047] First, refer to Figure 1 The configuration of a vehicle 10 equipped with a control device 100 as a control device according to the first embodiment will be described.

[0048] 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 a plug-in hybrid vehicle capable of connecting to an external power source 60 to charge battery 50. Therefore, an external charger 51 is connected to battery 50. Moreover, battery 50 is, for example, a 400V high-voltage battery. Additionally, the second electric generator 32 is, for example, a three-phase AC electric generator.

[0049] The internal combustion engine 11 includes an intake passage 12 and an exhaust passage 21. Furthermore, in Figure 1 In 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. Furthermore, 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.

[0050] 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 is heated by electricity. 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 catalyst system 200, including the electrically heated catalyst 210, will be described.

[0051] 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.

[0052] 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.

[0053] 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 driving 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 supply from the battery 50.

[0054] 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 a converter.

[0055] Additionally, the DC power from battery 50 is converted into AC power by power control unit 35 and supplied to the second electric generator 32. Furthermore, 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 charged into battery 50. That is, regenerative charging is performed in 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 into DC power by power control unit 35 and charged into battery 50.

[0056] 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.

[0057] <Control Device>

[0058] 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 for controlling 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 catalytic converter system 200. In short, control device 100 is also a control device for controlling internal combustion engine 11. Furthermore, as described later, control device 100 diagnoses malfunctions of electrically heated catalytic converter system 200. In short, control device 100 is also an malfunction diagnosis device for diagnosing malfunctions of electrically heated catalytic converter system 200.

[0059] 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 of the coolant in the internal combustion engine 11, i.e., water temperature Tw. Furthermore, a system switch 102 is connected to the control device 100 for the driver of the vehicle 10 to start and stop the vehicle's systems. Therefore, the control device 100 determines the starting status of the vehicle 10's systems based on the input signal from the system switch 102. An 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, i.e., exhaust temperature Tex. Moreover, the exhaust temperature sensor 103 is located upstream of the catalytic converter 29 in the exhaust passage 21. In addition, an air flow meter 104 is connected to the control device 100 to detect the temperature of the air drawn into the internal combustion engine 11, i.e., the intake temperature Tin, and the mass of the air drawn into the internal combustion engine 11, i.e., the intake air volume.

[0060] The vehicle 10 configured as described above uses the electricity stored in the battery 50 to drive the second electric generator 32, thereby enabling it to drive the drive wheels 40 using only the second electric generator 32. Alternatively, it can also perform hybrid driving using both the internal combustion engine 11 and the second electric generator 32 to drive the drive wheels 40.

[0061] <Composition of an electrically heated catalyst system>

[0062] Next, refer to Figure 2 The configuration of the electrically heated catalyst system 200 will be described.

[0063] 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.

[0064] 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 gasket 28 is provided between the first exhaust purification catalyst 26 and the second exhaust purification catalyst 27 and the housing 24. The gasket 28 is an insulator, for example, formed of inorganic fibers with alumina as the main component.

[0065] The gasket 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 gasket 28.

[0066] 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.

[0067] 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.

[0068] 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.

[0069] 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 is lower at higher temperatures than at lower temperatures.

[0070] 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.

[0071] 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.

[0072] 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 layer is applied by coating the inner circumferential surface of the housing 24 with an insulating material. That is, an insulating coating layer 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 layer can be used as the insulating coating layer. Thus, the first exhaust purification catalyst 26 is electrically insulated from the housing 24. In addition, the insulating coating layer has the characteristic of having lower electrical resistance at higher temperatures than at lower temperatures.

[0073] 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.

[0074] Furthermore, when the internal combustion engine 11 is operating 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.

[0075] The first electrode 211 and the second electrode 212 are connected to the power supply unit 220 via a power cable. 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-gate bipolar transistor and power switching elements, 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.

[0076] 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 layer. Leakage current is detected based on a low insulation resistance Rt.

[0077] 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.

[0078] <About Preheating Treatment>

[0079] 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.

[0080] 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.

[0081] In order to fully utilize the exhaust purification capabilities immediately after switching to hybrid driving mode, it is preferable to energize the EHC210 before starting the internal combustion engine 11 when switching to hybrid driving mode, so as to preheat the first exhaust purification catalyst 26.

[0082] Therefore, the control device 100 performs a preheating process, which is a process of supplying power from the battery 50 to the EHC 210 to preheat the first exhaust purification catalyst 26 before the internal combustion engine 11 is started.

[0083] If preheating is performed on the catalyst carrier of the first exhaust purification catalyst 26 while water is attached to it, the catalyst carrier may crack. That is, heat is lost due to the latent heat of vaporization before the attached water evaporates and disappears. Therefore, the temperature of the part with attached water is difficult to rise. On the other hand, the part without attached water also experiences a continuous temperature rise during this period due to the heat generated by the energization. As a result, if the energization continues, the temperature difference ΔT between the part with attached water and the part without attached water will increase.

[0084] exist Figure 3 The figure shows the change in temperature of the first exhaust gas purification catalyst 26, i.e., catalyst temperature T, under preheating treatment. Figure 3 The solid line in the figure represents the temperature T change of the catalyst in the portion of the catalyst carrier of the first exhaust gas purification catalyst 26 that is free of adhering water. Furthermore, Figure 3 The dashed line in the figure represents the change in catalyst temperature T of the water-bearing portion of the catalyst carrier in the first exhaust purification catalyst 26.

[0085] like Figure 3 As shown by the dashed line, when the temperature T of the catalyst portion with attached water rises, the water easily evaporates. During water evaporation, heat is lost to the heat of vaporization; therefore, if the water evaporates actively, it will... Figure 3 As shown by the dashed line, the catalyst temperature T does not rise even if the current continues to be applied.

[0086] In addition, such as Figure 3 As shown by the solid line, during this period, the temperature T of the catalyst in the portion without attached water also continues to rise. Consequently, during this period, as... Figure 4 As shown, the temperature difference ΔT between the water-attached and water-free parts of the catalyst support increases, and thermal stress is applied to the catalyst support.

[0087] Therefore, if the EHC210 is energized while still in a preheated state with water attached, the temperature difference ΔT will become too large, leading to increased thermal stress. Furthermore, if the thermal stress becomes too large, the catalyst support may crack.

[0088] Therefore, in the control device 100 of the first embodiment, if it is determined that water is attached to the catalyst carrier, the internal combustion engine 11 is started without performing preheating treatment, and the water attached to the catalyst carrier is removed by exhaust gas.

[0089] <Routines related to the prohibition of preheating treatment>

[0090] Next, refer to Figure 5 The routines related to the prohibition of preheating treatment are explained.

[0091] This routine is executed by the control device 100 when the system switch 102 is operated from OFF to ON, and the control device 100 is activated, thus putting the vehicle 10 into a state where the system is in operation.

[0092] like Figure 5 As shown, when this routine begins, the control device 100 first reads information for confirming the system's status during the processing of step S100. Specifically, the control device 100 reads information indicating the result of the abnormality diagnosis processing that has been performed. That is, abnormality diagnosis processing is performed on various parts during diagnostic operation in the vehicle 10. When the control device 100 diagnoses that an abnormality has occurred during the abnormality diagnosis processing, it stores a flag indicating that an "abnormality has occurred." During the processing of step S100, the control device 100 reads information from this flag. For example, such flags include flags indicating an abnormality in the internal combustion engine 11, flags indicating an abnormality in the power supply unit 220, etc.

[0093] Furthermore, in this step S100, the control device 100 reads information about the water content Q, which is an estimated value of the amount of water present in the catalyst carrier of the first exhaust purification catalyst 26. (See below for further details.) Figures 6-7 The calculation of the water content Q will be described. Additionally, in this step S100, the control device 100 reads the catalyst temperature T and the insulation resistance Rt of EHC210. ​​The catalyst temperature T read here is an estimated value calculated by the control device 100 based on the temperature of the first exhaust gas purification catalyst 26.

[0094] When the internal combustion engine 11 is stopped, the control device 100 stores the catalyst temperature T at that time as the stop temperature Toff and starts a timeout timer. Furthermore, the control device 100 continues timing based on the timeout timer while the internal combustion engine 11 is in a stopped state. When the internal combustion engine 11 is started, the control device 100 calculates the product obtained by multiplying the difference between the outside air temperature and the stop temperature Toff by the convergence rate. It also calculates the sum obtained by adding the stop temperature Toff to this product. This sum is set as the catalyst temperature T at the start of the internal combustion engine. Furthermore, the convergence rate is calculated based on the timeout period. The convergence rate is a value between 0 and 1. The longer the timeout period, the closer the convergence rate is to 1. For example, when the convergence rate is 1, the catalyst temperature T becomes the same as the outside air temperature. This means that when the convergence rate is 1, the catalyst temperature T converges to the outside air temperature. In addition, the control device 100 regards the intake air temperature Tin detected by the air flow meter 104 as the outside air temperature and uses it to calculate the catalyst temperature T.

[0095] During the operation of the internal combustion engine, the control device 100 calculates the temperature change dT. Furthermore, it adds the temperature change dT to the most recently calculated catalyst temperature T to calculate the latest catalyst temperature T. In addition, the temperature change dT is affected by exhaust heat. Therefore, the control device 100 uses parameters that affect the thermal energy of the exhaust, such as the internal combustion engine speed NE, internal combustion engine load, coolant temperature Tw, intake air volume, and intake air temperature Tin, to calculate the temperature change dT.

[0096] Additionally, in the 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, at this time, power from the auxiliary battery 55 is supplied to the EHC 210 to detect the insulation resistance Rt. During the processing of this step S100, the control device 100 also reads the insulation resistance Rt detected when the system is started.

[0097] Then, in the next step S110, the control device 100 determines whether the vehicle 10's system is normal. Specifically, in this step S110, the control device 100 determines whether the vehicle 10's system is normal based on a flag indicating the result of the abnormality diagnosis process read in step S100. That is, if a flag indicating an abnormality has occurred is stored, the control device 100 determines that the system is abnormal. On the other hand, if no flag indicating an abnormality has occurred is stored, the control device 100 determines that the system is normal.

[0098] If the system is determined to be normal in step S110 (step S110: Yes), the control device 100 proceeds the process to step S120. Then, in step S120, the control device 100 determines whether the insulation resistance Rt read in step S100 is greater than a threshold Rt_x. The threshold Rt_x is a threshold used to determine that the resistance of the insulating coating layer is sufficient to suppress leakage current based on the condition that the insulation resistance Rt is greater than the threshold Rt_x.

[0099] If, during the processing in step S120, it is determined that the insulation resistance Rt is greater than the threshold Rt_x (step S120: Yes), the control device 100 advances the processing to step S130.

[0100] In step S130, the control device 100 determines whether water adheres to the catalyst support of the first exhaust gas purification catalyst 26. Specifically, the control device 100 determines whether the water content Q of the EHC 210 is less than a threshold Q_x. The threshold Q_x is a threshold used to determine, based on the case that the water content Q is less than the threshold Q_x, that the water content Q is so low that even if preheating treatment is performed, it will not generate large thermal stress that would cause the catalyst support to crack.

[0101] Reference Figure 3 and Figure 4 As explained, the temperature difference ΔT increases during the period until the water adhering to the catalyst support evaporates, resulting in greater thermal stress. Therefore, if the water content Q is low, the water evaporates completely before generating the large thermal stress that would cause the catalyst support to crack, eliminating the temperature difference ΔT. Thus, if the water content Q is sufficiently low, even preheating will not generate thermal stress sufficient to cause the catalyst support to crack. That is, when the water content Q is sufficiently low, it can be considered that there is no water adhering to the catalyst support that would cause cracks due to preheating. The threshold value Q_x is set based on the results of prior experiments and calculations based on the various elements (specifications) of the catalyst support.

[0102] If the control device 100 determines in step S130 that the water content Q is less than the threshold Q_x (step S130: Yes), it determines that there is no water adhering to the catalyst support based on this result. Then, the control device 100 advances the process to step S140.

[0103] In step S140, the control device 100 determines whether the temperature of the first exhaust gas purification catalyst 26 is lower than the activation temperature. Specifically, the control device 100 determines whether the catalyst temperature T read in step S100 is lower than the threshold T_x. The threshold T_x is the activation temperature.

[0104] If, during the processing in step S140, the control device 100 determines that the catalyst temperature T is lower than the threshold T_x (step S140: Yes), based on this result, it determines that the temperature of the first exhaust gas purification catalyst 26 is lower than the activation temperature. Then, the control device 100 advances the processing to step S150.

[0105] In step S150, the control device 100 activates the power-on request to the EHC210. ​​Then, the control device 100 terminates the routine.

[0106] Furthermore, when the power-on requirement is set to active, the control device 100 begins a preheating process. During the preheating process, the control device 100 continuously supplies power to the EHC 210 until the cumulative value of the supplied power, i.e., the electrical force, reaches the target electrical force. This heats the first exhaust gas purification catalyst 26 to above the activation temperature for preheating. The target electrical force is set based on the electrical force required to heat the first exhaust gas purification catalyst 26 to the point where preheating is complete. Additionally, the electrical force is the cumulative value of the power actually supplied to the EHC 210.

[0107] During the preheating process, the control device 100 controls the power supply circuit 221 to convert 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 according to the decrease in resistance, maintaining the supplied power at a constant level. Furthermore, the control device 100 controls the voltage within a range below a preset upper limit voltage, ensuring that the voltage does not exceed this limit. That is, the upper limit voltage is the upper limit of the voltage value 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. Furthermore, the control device 100 accumulates the supplied power during the period when the EHC 210 is powered on, continuously calculating the electrical force supplied to the EHC 210.

[0108] 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 terminates the power supply to the EHC 210. That is, the control device 100 continues to supply power from the battery 50 until the electrical force reaches the target electrical force. Then, when the electrical force reaches the target electrical force, the control device 100 terminates the preheating process by stopping the power supply from the battery 50.

[0109] Then, when the preheating process is finished, the control device 100 allows the internal combustion engine 11 to start.

[0110] exist Figure 5If, during step S110 of the routine, the system of vehicle 10 is determined to be malfunctioning (step S110: No), the control device 100 proceeds the process to step S160. Additionally, if, during step S120, the control device 100 determines that the insulation resistance Rt is below the threshold value Rt_x (step S120: No), it also proceeds the process to step S160. In step S160, the control device 100 activates the power-on prohibition requirement. Then, the control device 100 terminates the routine. That is, if the system malfunctions and sufficient insulation resistance Rt cannot be ensured, the control device 100 prohibits power to the EHC210 and does not perform the preheating process.

[0111] Furthermore, if the control device 100 determines in step S130 that the water content Q of EHC210 is above the threshold Q_x (step S130: No), it also proceeds to step S160. In step S160, the control device 100 activates the power-on prohibition requirement. Then, the control device 100 terminates the routine. That is, if the control device 100 determines that water is attached to the catalyst carrier of the first exhaust gas purification catalyst 26, it also prohibits power supply to EHC210 and does not perform preheating treatment. This is because, as described above, if preheating treatment is performed while water is attached to the catalyst carrier of the first exhaust gas purification catalyst 26, the catalyst carrier may crack.

[0112] If, during the processing in step S140, the control device 100 determines that the catalyst temperature T is above the threshold T_x (step S140: No), it also proceeds to step S160. During the processing in step S160, the control device 100 activates the power-on prohibition requirement. Then, the control device 100 terminates the routine. That is, the control device 100 prohibits power to the EHC 210 and does not perform preheating treatment unless it determines that the temperature of the first exhaust gas purification catalyst 26 is below the activation temperature. This is because preheating of the first exhaust gas purification catalyst 26 is not required.

[0113] When the power-on prohibition requirement is activated, the control device 100 will not perform power-on to the EHC 210 even if the power-on requirement to the EHC 210 is activated. Furthermore, the power-on prohibition requirement is reset to inactive when the evaporation-promoting control described later ends.

[0114] With power to EHC210 disabled as described above, control device 100 allows the internal combustion engine 11 to start. (See below for further details.) Figure 9 The control of catalyst preheating control when starting the internal combustion engine 11 under the condition that preheating treatment is prohibited is described.

[0115] <Calculation of water content Q>

[0116] Next, refer to Figures 6-8 The calculation of the moisture content Q is explained.

[0117] Figure 6 The flowchart illustrates the process executed by the control device 100 in the routine when the system switch 102 is turned on and the control device 100 is activated.

[0118] like Figure 6 As shown, when the routine begins, the control device 100 first substitutes the moisture content Q stored in the storage device into the previous moisture content Q0 during the processing of step S200. Furthermore, in Figure 7 The diagram shows the process flow in the routine executed by the control device 100 when the system switch 102 is turned off and the control device 100 stops.

[0119] like Figure 7 As shown, the control device 100 executes step S300 until the system switch 102 is set to open and stops, storing the calculated moisture content Q in the storage device. That is, in Figure 6 In step S200, the moisture content Q is substituted into the previous moisture content Q0, which is obtained when the control device 100 stops. Figure 7 Step S300 processes and stores the water content Q value in the storage device.

[0120] When passing Figure 6 When the processing in step S200 updates the previous moisture content Q0, the control device 100 advances the processing to step S210. Then, in the processing of step S210, the control device 100 calculates the generation amount Q1. The generation amount Q1 is the amount of condensate generated in the catalyst carrier of the first exhaust purification catalyst 26 during the period when the system switch 102 is set to open and the system of the vehicle 10 is in a stopped state.

[0121] In step S210, the control device 100 calculates the generation quantity Q1 based, for example, on the water temperature Tw when the system switch 102 is set to open and the system stops, the current water temperature Tw, and the outside air temperature. The higher the temperature of the catalyst support, the easier it is to generate condensate when cooled rapidly. Therefore, the control device 100 calculates the generation quantity Q1 in a way that the higher the water temperature Tw when the system stops and the lower the current water temperature Tw, the greater the generation quantity Q1. Furthermore, the lower the outside air temperature, the easier it is to generate condensate, so the generation quantity Q1 is calculated in a way that the lower the outside air temperature, the greater the generation quantity Q1. In addition, the generation quantity Q1 in step S210 can be calculated, for example, by inputting the water temperature Tw when the system stops, the current water temperature Tw, and the outside air temperature into a computational mapping based on the results of a pre-conducted experiment, and then outputting the generation quantity Q1. Furthermore, it is not limited to a computational mapping; it can also be achieved by inputting the water temperature Tw when the system stops, the current water temperature Tw, and the outside air temperature into a pre-adjusted computational formula and then outputting the generation quantity Q1.

[0122] When the generated quantity Q1 is calculated through the processing in step S210, the control device 100 advances the processing to step S220. Then, in the processing of step S220, the control device 100 adds the generated quantity Q1 to the previous moisture content Q0 and substitutes the sum into the moisture content Q. When the moisture content Q is calculated by adding the generated quantity Q1 to the previous moisture content Q0 in this way, the control device 100 ends the routine.

[0123] exist Figure 8 The diagram illustrates the process flow of a routine repeatedly executed by the control device 100 during the period from when the system of vehicle 10 is operating until catalyst preheating control is completed. This routine updates the water content Q by reflecting the amount of water evaporated from the catalyst carrier of the first exhaust purification catalyst 26 during system operation in conjunction with catalyst preheating control. Furthermore, in this control device 100, catalyst preheating control is determined to be completed when preheating treatment is completed, or when catalyst preheating based on exhaust heat is completed (described later). Additionally, the control device 100 considers catalyst preheating control to be completed when the catalyst temperature T at system startup is above the threshold T_x.

[0124] When this routine begins, the control device 100 first reads the moisture content Q during the processing in step S400. This routine is executed repeatedly, so the value of the moisture content Q read here is the updated moisture content Q from the last execution of the routine. Additionally, the value of the moisture content Q read when the routine is first executed after system startup is the value obtained during system startup through... Figure 6 The water content Q is calculated by step S220.

[0125] When the moisture content Q is read in step S400, the control device 100 advances the process to step S410. Then, in step S410, the control device 100 determines whether the moisture content Q is above a threshold Q_x. Furthermore, the threshold Q_x is related to... Figure 5 The threshold Q_x used in step S130 is the same value.

[0126] If, during the processing in step S410, it is determined that the water content Q is above the threshold Q_x (step S410: Yes), the control device 100 proceeds the processing to step S420. Then, during the processing in step S420, the control device 100 determines whether the internal combustion engine 11 is operating.

[0127] If it is determined in step S420 that the internal combustion engine 11 is operating (step S420: Yes), the control device 100 advances the process to step S430. Then, in the process of step S430, the control device 100 calculates the evaporation amount Q2. Furthermore, the evaporation amount Q2 is a value representing the amount by which the water content Q decreases due to evaporation. Here, the evaporation amount Q2 is calculated as a negative value. That is, the greater the decrease in water content Q due to evaporation, the larger the absolute value of the evaporation amount Q2.

[0128] In step S430, the control device 100 calculates the evaporation amount Q2 based on the exhaust temperature Tex detected by the exhaust temperature sensor 103. Specifically, the evaporation amount Q2 is calculated using an operational mapping that stores the relationship between the exhaust temperature Tex as input and the evaporation amount Q2 as output. This operational mapping is created based on the results of prior experiments, etc. For example, in this operational mapping, the higher the exhaust temperature Tex, the larger the absolute value of the output evaporation amount Q2 becomes; that is, in this operational mapping, the higher the exhaust temperature Tex, the smaller the value of the output evaporation amount Q2.

[0129] When the evaporation amount Q2 is calculated through the process in step S430, the control device 100 advances the process to step S440. In step S440, the control device 100 substitutes the sum obtained by adding the evaporation amount Q2 calculated in step S430 to the moisture content Q into the moisture content Q. That is, in step S440, the control device 100 updates the moisture content Q by adding the evaporation amount Q2 to the moisture content Q. When the moisture content Q is updated in this way, the control device 100 temporarily terminates the routine. Furthermore, the lower limit value of the moisture content Q becomes zero.

[0130] On the other hand, if it is determined in step S420 that the internal combustion engine 11 is not working (step S420: No), the control device 100 advances the process to step S450. Then, in the process of step S450, the control device 100 determines whether the EHC210 is being energized.

[0131] If, during the processing in step S450, it is determined that power is being supplied to the EHC210 (step S450: Yes), the control device 100 advances the processing to step S460. Then, during the processing in step S460, the control device 100 calculates the evaporation amount Q4. Furthermore, the evaporation amount Q4, like the evaporation amount Q2, is a value representing the amount by which the water content Q decreases due to evaporation. The evaporation amount Q4 is also calculated as a negative value. That is, the greater the decrease in water content Q due to evaporation, the larger the absolute value of the evaporation amount Q4.

[0132] In step S460, the control device 100 calculates the evaporation amount Q4 by dividing the power supplied to the EHC 210 by the latent heat of vaporization of water. That is, the greater the power supplied, the greater the evaporation amount Q4. Furthermore, during the period when the power supply to the EHC 210 has just begun and the temperature of the EHC 210 is low, the reduction of water due to evaporation has not yet begun. Therefore, the control device 100 estimates the temperature of the EHC 210 based on the resistance of the EHC 210 estimated according to the values ​​of the current and voltage when the EHC 210 is energized. And, if the estimated temperature of the EHC 210 is such that the water will not decrease, the evaporation amount Q4 is set to "0".

[0133] When the evaporation amount Q4 is calculated through the process in step S460, the control device 100 advances the process to step S470. In step S470, the control device 100 adds the sum obtained by adding the evaporation amount Q4 calculated in step S460 to the moisture content Q and substitutes it into the moisture content Q. That is, in step S470, the control device 100 updates the moisture content Q by adding the evaporation amount Q4 to the moisture content Q. When the moisture content Q is updated in this way, the control device 100 temporarily terminates the routine.

[0134] Furthermore, if it is determined in step S450 that no power is supplied to EHC210 (step S450: No), the control device 100 temporarily terminates the routine. That is, in this case, the evaporation amount Q4 is not calculated, nor is the moisture content Q updated.

[0135] Furthermore, if it is determined in step S410 that the moisture content Q is less than the threshold Q_x (step S410: No), the control device 100 directly terminates the routine. That is, in this case, the moisture content Q is not updated. This is because if the moisture content Q is less than the threshold Q_x, there is no need to disable the preheating process, and there is no need to calculate the evaporation rate to update the moisture content Q.

[0136] By designing routines in a way that avoids calculating evaporation and updating moisture content Q when not needed, the computational load on the control device 100 can be reduced.

[0137] Next, refer to Figure 9 The catalyst preheating control when the energization prohibition requirement is activated will be explained. In this control device 100, when the energization prohibition requirement is activated, as described above, no energization is performed to the EHC 210. That is, preheating treatment is not performed. At this time, catalyst preheating control is performed, which controls the starting of the internal combustion engine 11 without performing preheating treatment and uses the heat of the exhaust gas for preheating. Figure 9 The routine shown is executed by the control device 100 when performing catalyst preheating control under such a power-on prohibition requirement to be activated.

[0138] When the internal combustion engine 11 is started to begin the routine, the control device 100 first reads the water content Q in step S500. Then, in the next step S510, it determines whether the water content Q is above or below the threshold Q_x. Furthermore, the threshold Q_x is related to... Figure 5 The threshold Q_x used in step S130 is the same value.

[0139] If, during the processing in step S510, it is determined that the water content Q is above the threshold Q_x (step S510: Yes), the control device 100 advances the processing to step S520. Then, during the processing in step S520, the control device 100 initiates evaporation promotion control.

[0140] Furthermore, evaporation promotion control is a control measure that increases the temperature and flow rate of the exhaust gas to promote the evaporation of water contained in the catalyst carrier of the first exhaust purification catalyst 26. In evaporation promotion control, the control device 100 delays the ignition timing compared to the case where evaporation promotion control is not performed. By delaying the ignition timing, combustion becomes slower, and the exhaust temperature increases. In addition, compared to the case where evaporation promotion control is not performed, the control device 100 increases the fuel injection quantity to increase the output of the internal combustion engine 11. This can compensate for the decrease in output caused by the delay in ignition timing. In addition, the exhaust flow rate can be increased, and the heat input per unit time to the water attached to the catalyst carrier and the catalyst carrier can be increased.

[0141] Next, in step S530, the control device 100 determines whether a predetermined time has elapsed since the start of the evaporation promotion control. This process determines whether "water has been removed from the catalyst support by catalyst preheating control accompanying the evaporation promotion control" has been completed. Therefore, the length of the predetermined time, which serves as a threshold, is set to a length such that, based on the condition that a predetermined time has elapsed since the start of the evaporation promotion control, it can be considered that "water has been sufficiently removed from the catalyst support of the first exhaust purification catalyst 26". For example, the length of the predetermined time is set based on the results of previously conducted experiments, etc. Furthermore, it is also possible that the higher the water content Q, the longer the length of the predetermined time, which serves as a threshold, will be.

[0142] If, in step S530, it is determined that no predetermined time has elapsed since the start of evaporation promotion control (step S530: No), the control device 100 repeatedly performs the process of step S520. Conversely, if, in step S530, it is determined that a predetermined time has elapsed since the start of evaporation promotion control (step S530: Yes), the process proceeds to the next step, S540. Then, in the process of step S540, the control device 100 terminates the evaporation promotion control. That is, the control device 100 terminates the delay in ignition timing and the increase in fuel injection quantity used to promote water evaporation. Specifically, when the water content Q is above the threshold Q_x, the control device 100 performs catalyst preheating control during the predetermined time period while the internal combustion engine operates under evaporation promotion control. When the process of step S540 ends, the control device 100 terminates the routine.

[0143] Furthermore, if the control device 100 determines in step S510 that the water content Q is less than the threshold Q_x (step S510: No), it will not execute the processes in steps S520 to S540, and will directly terminate the routine. That is, in this case, the control device 100 will not perform evaporation promotion control, and will use the heat of the exhaust gas associated with the operation of the internal combustion engine 11 to preheat the catalyst.

[0144] <Function of the first embodiment>

[0145] Next, refer to Figures 10A to 10J The function of the control device 100 will be explained. Furthermore, Figures 10A to 10J This is a time graph showing the progression of various states under catalyst preheating control when the system of vehicle 10 is operating under conditions where the water content Q is above the threshold Q_x.

[0146] like Figure 10A As shown, at time t1, when the system switch 102 of vehicle 10 is turned on and the system is working, the reference is executed. Figure 5 The example routines described. Figure 10BIn the example shown, the water content is high (Q) and above the threshold Q_x. Therefore, as... Figure 10C As shown, the power-on prohibition requirement becomes activation. Therefore, the internal combustion engine 11 is started without preheating. Then, as... Figure 10D As shown, the internal combustion engine speed NE increases.

[0147] When the internal combustion engine 11 completes starting at time t2, the reference is executed. Figure 9 The illustrated routines, such as Figure 10E and Figure 10F As shown, catalyst preheating control is initiated, accompanied by evaporation promotion control.

[0148] like Figure 10G As shown, ignition timing is delayed by evaporation-promoted control. Furthermore, in Figure 10G In the diagram, for comparison, the ignition timing without evaporation enhancement control is shown by dashed lines. Furthermore, with evaporation enhancement control, the fuel injection quantity is increased, and as... Figure 10H As shown, the output of the internal combustion engine increases. Furthermore, in Figure 10H In the diagram, for comparison purposes, the internal combustion engine output is shown in dashed lines when evaporation promotion control is not implemented.

[0149] like Figure 10I As shown, the catalyst temperature T of the first exhaust purification catalyst 26 increases through catalyst preheating control under internal combustion engine operation accompanied by evaporation promotion control. Figure 10I In the figure, the catalyst temperature T is shown as a solid line when catalyst preheating control accompanied by evaporation promotion control is implemented. Furthermore, for comparison, in... Figure 10I The dashed line indicates the catalyst temperature T when evaporation promotion control is not implemented, but catalyst preheating control is implemented through normal internal combustion engine operation. Additionally, in Figure 10I The figures show the catalyst temperature T1 for the portion without water and the catalyst temperature T2 for the portion with water. In the portion with water, heat is lost due to the latent heat of vaporization of the water. Therefore, the catalyst temperature T1 in the portion with water is difficult to rise. On the other hand, in the portion without water, the catalyst temperature T1 continues to rise during this period due to the heat generated associated with energization. Therefore, in Figure 10I In the diagram, the line representing the catalyst temperature T is divided into two lines starting from the middle. That is, the lower line represents the catalyst temperature T of the part with water attached, and the upper line represents the catalyst temperature T of the part without water attached.

[0150] Due to water evaporation accompanying the rise in catalyst temperature T during the implementation of catalyst preheating control, such as Figure 10B As shown, the water content Q gradually decreases. At this time, as... Figure 10JAs shown, the temperature difference ΔT between the portion of the catalyst support with attached water and the portion without attached water gradually increases. Consequently, thermal stress acts on the catalyst support. The greater the temperature difference ΔT, the greater the thermal stress. Figure 10J The temperature difference ΔT at which the catalyst support will break is indicated by a double-dotted line.

[0151] like Figure 10I and Figure 10J As shown by the dashed line, without evaporation promotion control, the temperature difference ΔT exceeds the level indicated by the double-dotted line. This is because insufficient heat is supplied to the first exhaust purification catalyst 26 via exhaust gas, causing water to evaporate and be removed in a time-consuming process during which the temperature difference ΔT becomes excessive.

[0152] On the other hand, when catalyst preheating control is performed with evaporation promotion control as in control device 100, the heat introduced into the first exhaust purification catalyst 26 via exhaust gas increases. Therefore, compared to the example shown by the dashed line, water can be removed in a shorter period of time. Thus, as... Figure 10J As shown by the solid line, the temperature difference ΔT will not exceed the level indicated by the double-dotted line.

[0153] When time t3 is determined to be the elapsed time since the start of evaporation-enhancing control, evaporation-enhancing control is stopped. This stops the ignition timing delay and the increase in fuel injection quantity. Furthermore, at this time, if... Figure 10B As shown, the water content Q becomes almost zero. Furthermore, at time t4, the catalyst preheating control ends.

[0154] <Effects of the first embodiment>

[0155] (1-1) As described above, the control device 100 determines whether water is adhering to the catalyst carrier through step S130, which is a determination process. If it is determined that water is adhering to the catalyst carrier, the control device 100 starts the internal combustion engine 11 without performing a preheating process, even if it is determined that the temperature of the first exhaust purification catalyst 26 is lower than the activation temperature. Furthermore, the water adhering to the catalyst carrier is removed using exhaust gas.

[0156] In the case of preheating treatment where the catalyst support is heated by electricity, heat is transferred from the catalyst support to the water adhering to it. On the other hand, when the internal combustion engine 11 is running and exhaust gas passes through the first exhaust purification catalyst 26, the water adhering to the catalyst support is also heated by the exhaust gas flowing around it. Therefore, the water evaporates rapidly. Furthermore, the temperature of the exhaust gas is higher than the temperature of the catalyst support in the case of preheating treatment. Additionally, the catalyst support is also heated by the heat of the exhaust gas. Therefore, compared to the case of preheating treatment where the catalyst support is heated only by electricity, it is difficult to generate a temperature difference ΔT between the water-adhered portion and the non-water-adhered portion. That is, according to the control device 100, thermal stress generated on the catalyst support can be suppressed. It is even possible to suppress the catalyst support from cracking due to thermal stress.

[0157] (1-2) Since catalyst preheating control is performed only when the moisture content Q is high without preheating treatment, the deterioration of exhaust characteristics can be suppressed.

[0158] (1-3) When the control device 100 determines that water is attached to the catalyst support, it prohibits the supply of electricity to the catalyst support. Therefore, electricity is not supplied when water may be attached to the catalyst support. Therefore, compared with the case where electricity is not prohibited, the cracking of the catalyst support caused by the thermal stress generated by the accompanying electricity supply can be suppressed more reliably.

[0159] (1-4) When the control device 100 starts the internal combustion engine 11 without performing preheating treatment based on the determination that water is attached to the catalyst carrier, it delays the ignition timing compared to when the internal combustion engine 11 is started after performing preheating treatment. By operating the internal combustion engine with the ignition timing delayed, the exhaust temperature Tex increases. Therefore, according to the control device 100, the temperature of the exhaust gas passing through the catalyst carrier can be increased, and the removal of moisture and the preheating of the first exhaust purification catalyst 26 can be completed quickly.

[0160] (1-5) When the control device 100 starts the internal combustion engine 11 without performing preheating treatment based on the determination that water is attached to the catalyst carrier, it increases the fuel injection quantity compared to when the internal combustion engine 11 is started after performing preheating treatment. By increasing the fuel injection quantity, the internal combustion engine speed NE increases. The increase in internal combustion engine speed NE increases the exhaust flow rate through the catalyst carrier and the heat generated by combustion. As a result, the amount of water attached to the catalyst carrier and the heat applied to the catalyst carrier per unit time increases. Therefore, the removal of water and the preheating of the exhaust purification catalyst can be completed quickly.

[0161] (Second Implementation)

[0162] In the control device 100 of the first embodiment, when the water content Q is above the threshold Q_x (step S130: No), energizing the EHC 210 is prohibited. In contrast, the control device 100 of the second embodiment does not perform preheating treatment when the water content Q is above the threshold Q_x; it energizes the EHC 210 while the internal combustion engine 11 is running, thereby removing water from the catalyst carrier and preheating the catalyst. That is, the difference between the control device 100 of the second embodiment and the control device 100 of the first embodiment is that energizing the EHC 210 is not prohibited even when the water content Q is above the threshold Q_x.

[0163] Figure 11 Show alternative Figure 5 The process flow of the routine executed by the control device 100 in the second embodiment is shown. Furthermore, in Figure 11 In the middle, to and Figure 5 The same processing methods are shown with the same labels.

[0164] This routine is executed by the control device 100 when the system switch 102 is operated from off to on, and the control device 100 is activated, thus putting the vehicle 10 into a state where the system is working.

[0165] like Figure 11 As shown, when the routine begins, the control device 100 first reads information for confirming the system's status during the processing of step S100. Furthermore, in the processing of step S100, similar to the first embodiment, information about the moisture content Q is also read. In the second embodiment, the moisture content Q is also measured by comparing it with a reference... Figures 6-8 The calculation process described in the first embodiment is performed in the same way.

[0166] In the next step S110, the control device 100 determines whether the system of the vehicle 10 is normal. If the system is determined to be normal in step S110 (step S110: Yes), the control device 100 proceeds the process to step S120. Then, in the process of step S120, the control device 100 determines whether the insulation resistance Rt read in step S100 is greater than the threshold value Rt_x.

[0167] If, during the processing in step S120, it is determined that the insulation resistance Rt is greater than the threshold Rt_x (step S120: Yes), the control device 100 advances the processing to step S140.

[0168] In step S140, the control device 100 determines whether the temperature of the first exhaust gas purification catalyst 26 is lower than the activation temperature. If the control device 100 determines in step S140 that the catalyst temperature T is lower than the threshold T_x (step S140: Yes), it determines that the temperature of the first exhaust gas purification catalyst 26 is lower than the activation temperature. Then, the control device 100 proceeds the process to step S150.

[0169] In step S150, the control device 100 activates the energizing request to the EHC 210. Then, the control device 100 terminates the routine. Furthermore, when the energizing request is activated, the control device 100 begins a preheating process. Upon termination of the preheating process, the control device 100 allows the internal combustion engine 11 to start.

[0170] exist Figure 11 If, during step S110 of the routine, the system of vehicle 10 is determined to be malfunctioning (step S110: No), the control device 100 proceeds the process to step S160. Additionally, if, during step S120, the control device 100 determines that the insulation resistance Rt is below the threshold value Rt_x (step S120: No), it also proceeds the process to step S160. In step S160, the control device 100 activates the power-on prohibition requirement. Then, the control device 100 terminates the routine. That is, if the system malfunctions and sufficient insulation resistance Rt cannot be ensured, the control device 100 prohibits power to the EHC210 and does not perform the preheating process.

[0171] Furthermore, if the control device 100 determines in step S140 that the catalyst temperature T is above the threshold T_x (step S140: No), it also proceeds to step S160. In step S160, the control device 100 activates the power-on prohibition requirement. Then, the control device 100 terminates the routine. That is, the control device 100 prohibits power to the EHC 210 and does not perform preheating treatment unless it determines that the temperature of the first exhaust gas purification catalyst 26 is below the activation temperature.

[0172] Next, refer to Figure 12 The preheating control of the catalyst is explained. Figure 12 The routine shown is executed by the control device 100 when the internal combustion engine 11 is required to start if the temperature of the first exhaust purification catalyst 26 is determined to be lower than the activation temperature.

[0173] When the routine begins, the control device 100 first reads the moisture content Q in step S600. Then, in the next step S610, it determines whether the moisture content Q is above a threshold Q_x. Furthermore, the threshold Q_x is related to... Figure 5 The threshold Q_x used in step S130 is the same value. In the control device 100 of the second embodiment, this step S620 is equivalent to a determination process for whether water is attached to the catalyst support.

[0174] If, during the processing in step S610, it is determined that the water content Q is above the threshold Q_x (step S610: Yes), the control device 100 advances the processing to step S620. Then, during the processing in step S620, the control device 100 starts the internal combustion engine 11 and begins evaporation promotion control. Furthermore, in this step S620, the control device 100 also performs energization control to the EHC 210 while the internal combustion engine 11 has finished starting and exhaust gas is flowing in the exhaust passage 21. That is, in the control device 100 of the second embodiment, in addition to exhaust gas heating, catalyst preheating control is performed by heating based on energization to the EHC 210. Furthermore, the content of the evaporation promotion control is the same as in the first embodiment.

[0175] Next, in step S630, the control device 100 determines whether a predetermined time has elapsed since the start of evaporation promotion control. This process determines whether the removal of water from the catalyst support has been completed. Therefore, the length of the predetermined time, which serves as a threshold, is set such that, based on the condition that a predetermined time has elapsed since the start of evaporation promotion control, it can be considered that water has been sufficiently removed from the catalyst support of the first exhaust gas purification catalyst 26. For example, the length of the predetermined time is set based on the results of prior experiments, etc. Alternatively, the higher the water content Q, the longer the predetermined time, which serves as a threshold, can be.

[0176] If, in step S630, it is determined that no predetermined time has elapsed since the start of evaporation promotion control (step S630: No), the control device 100 repeatedly performs the process of step S620. Conversely, if, in step S630, it is determined that a predetermined time has elapsed since the start of evaporation promotion control (step S630: Yes), the process proceeds to the next step, S640. Then, in the process of step S640, the control device 100 terminates the evaporation promotion control and the energization control of the EHC 210. That is, when the water content Q is above the threshold Q_x, the control device 100 performs energization control of the EHC 210 while simultaneously executing catalyst preheating control during internal combustion engine operation accompanying the evaporation promotion control for a predetermined period of time. When the process of step S640 is terminated in this manner, the control device 100 ends the routine.

[0177] In addition, if the control device 100 determines in step S610 that the water content Q is less than the threshold Q_x (step S610: no), the process is advanced to step S650.

[0178] In step S650, the control device 100 performs start-up control with a preheating process. Specifically, in this case, the control device 100 performs a preheating process that controls the energization of the EHC 210 before starting the internal combustion engine 11. Then, when the catalyst preheating is complete through the preheating process, the internal combustion engine 11 is started. Finally, when step S650 ends, the control device 100 terminates the routine.

[0179] <Function of the Second Embodiment>

[0180] In the control device 100 of the second embodiment, based on the determination process indicating that water is attached to the catalyst carrier (step S610: Yes), the internal combustion engine is started without performing preheating treatment. Furthermore, evaporation promotion control is performed and the EHC 210 is energized (step S630). The first exhaust purification catalyst 26 is preheated using both the heat generated by energization and the heat from the exhaust gas.

[0181] <Effects of the Second Embodiment>

[0182] According to the control device 100 of the second embodiment, the same effects as those in the first embodiment (1-1), (1-2), (1-4), and (1-5) can be obtained. In addition, the following effects can be obtained instead of the effects (1-3) in the first embodiment.

[0183] (2-3) When the internal combustion engine 11 is running and exhaust gas passes through the catalyst carrier, heat is also applied from the exhaust gas to the water attached to the catalyst carrier, so the water evaporates easily. Therefore, it is difficult for the catalyst carrier to crack due to thermal stress. In the control device 100 of the second embodiment, after the internal combustion engine 11 is started without performing a preheating treatment, the EHC 210 is energized while the internal combustion engine 11 is running. As a result, the preheating of the first exhaust gas purification catalyst 26 can be completed quickly while suppressing the cracking of the catalyst carrier.

[0184] The above embodiments can be modified as follows. The above embodiments and the following modifications can be combined with each other within the scope of technical inconsistency.

[0185] The method for calculating the water content Q is not limited to the illustrated method and can be appropriately modified. For example, the amount of water generated in the catalyst carrier during the period when the internal combustion engine 11 is in a stopped state, i.e., the amount Q1 generated, can also be calculated and regarded as the water content Q.

[0186] • The criteria for determining whether water adheres to the catalyst support can be appropriately modified. For example, it is not necessarily necessary to calculate the water content Q for the determination. For example, it can also be determined that water has been generated on the catalyst support when the outside air temperature and the water temperature Tw are extremely low.

[0187] • The content of evaporation promotion control can be modified appropriately. For example, it is also possible to implement either the control that delays ignition timing or the control that increases the fuel injection quantity.

[0188] • Evaporation promotion control can also be omitted.

[0189] • A sensor can also be used to detect the temperature of the first exhaust purification catalyst 26 to determine if the temperature of the first exhaust purification catalyst 26 is lower than the activation temperature.

[0190] • It is also possible to determine that the temperature of the first exhaust gas purification catalyst 26 is below the activation temperature based on the fact that the water temperature Tw detected by the water temperature sensor 101 is below a threshold. If the preheating of the internal combustion engine 11 is completed and the water temperature Tw becomes sufficiently high, it can be assumed that the internal combustion engine has been running for a sufficient period of time. Furthermore, it can be assumed that the first exhaust gas purification catalyst 26 has been sufficiently heated by the exhaust gas, and its temperature has reached above the activation temperature. For a short period of time after the internal combustion engine 11 stops running, the water temperature Tw also remains at a high temperature, but if the state of the internal combustion engine 11 being stopped continues, the water temperature Tw gradually decreases. In addition, if the state of the internal combustion engine 11 being stopped continues, the temperature of the first exhaust gas purification catalyst 26 also gradually decreases. Therefore, when the water temperature Tw decreases, the temperature of the first exhaust gas purification catalyst 26 also decreases, which can be considered as being below the activation temperature. In this case, the threshold value for comparison with the water temperature Tw is set based on the results of prior experiments and calculations based on various factors of the catalyst carrier.

[0191] The power-on prohibition requirement can also be reset to inactive when system switch 102 is turned off and the system of vehicle 10 stops. Alternatively, the power-on prohibition requirement can also be reset to inactive when the water content Q becomes sufficiently low. For example, the power-on prohibition requirement can also be reset to inactive when the water content Q becomes less than the threshold Q_x.

[0192] • The internal combustion engine 11 can be a spark-ignition internal combustion engine or a compression-ignition internal combustion engine.

[0193] • 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.

[0194] • 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.

[0195] 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, or a vehicle that uses only the internal combustion engine 11 as a power source. In the example of the above-mentioned vehicles other than plug-in hybrid vehicles, 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.

[0196] 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 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.

[0197] Additionally, an example is shown where the control device for the internal combustion engine is specifically designed as a control device 100 for controlling the powertrain of the vehicle 10. Conversely, 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. This system includes an electrically heated catalytic converter, which is an exhaust purification catalyst supported on a catalyst carrier that heats up when energized. When the control device determines that the temperature of the exhaust gas purification catalyst is lower than the activation temperature, it performs a preheating process. This preheating process involves controlling the power supply device to supply electricity to the electrically heated catalyst before the internal combustion engine starts, thereby preheating the exhaust gas purification catalyst. The control device performs a determination process to determine whether water is attached to the catalyst carrier. If the determination process determines that water is attached to the catalyst carrier, the internal combustion engine is started without performing the preheating treatment, even if the temperature of the exhaust purification catalyst is determined to be lower than the activation temperature.

2. The control device for an internal combustion engine according to claim 1, If the determination process determines that water is attached to the catalyst carrier, the application of electricity to the catalyst carrier is prohibited.

3. The control device for an internal combustion engine according to claim 1, After starting the internal combustion engine without performing the preheating treatment, based on the determination process that water is attached to the catalyst carrier, the catalyst carrier is energized.

4. The control device for an internal combustion engine according to any one of claims 1 to 3, When the internal combustion engine is started without performing the preheating treatment based on the determination process indicating that water is attached to the catalyst carrier, the ignition timing is delayed compared to when the internal combustion engine is started after performing the preheating treatment.

5. The control device for an internal combustion engine according to any one of claims 1 to 4, When the internal combustion engine is started without performing the preheating treatment based on the determination process indicating that water is attached to the catalyst carrier, the fuel injection quantity is increased compared to when the internal combustion engine is started after performing the preheating treatment.

6. The control device for an internal combustion engine according to any one of claims 1 to 5, Calculate the amount of water contained in the catalyst support, i.e., the water content. In the determination process, if the calculated water content is above a threshold, it is determined that water is attached to the catalyst carrier; if the calculated water content is below the threshold, it is determined that no water is attached to the catalyst carrier.

7. The control device for an internal combustion engine according to claim 6, Calculate the amount produced and the amount evaporated. The amount generated is the amount of water produced within the catalyst carrier during the period when the internal combustion engine is stationary. The evaporation rate refers to the amount of water evaporated within the catalyst carrier during the operation of the internal combustion engine, as well as the amount of water evaporated within the catalyst carrier due to the application of electricity to the catalyst carrier. The water content is calculated based on the amount generated and the amount evaporated.

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