Control device for internal combustion engine

Abstract

To suppress deterioration in insulation property of an electric heating type catalyst.SOLUTION: An internal combustion engine comprises an electric heating type first catalyst 26 that is housed in a case 24 provided in an exhaust passage and heated by energization, and a second catalyst 27 that is provided on an exhaust downstream side with respect to the first catalyst 26. A controller device 100 executes a preheating process of warming up the first catalyst 26 by energizing the first catalyst 26 prior to starting the internal combustion engine, and a start delay process of starting the internal combustion engine after a predetermined period of time has elapsed since the preheating process is completed.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] A catalyst that purifies exhaust gas from an internal combustion engine exhibits sufficient performance at an activation temperature after the engine has been warmed up. Therefore, if the catalyst temperature is below the activation temperature, the catalyst may not be able to purify exhaust gas sufficiently.

[0003] In view of this, an electrically heated catalyst is known that is housed in a case provided in the exhaust passage of the internal combustion engine and heated by passing electricity through it (for example, Patent Document 1, etc.). The electrically heated catalyst can be warmed up prior to engine start-up by executing a preheat process in which electricity is passed through it before starting the internal combustion engine. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2012-72665 A Summary of the Invention [Problem to be solved by the invention]

[0005] When the engine starts, exhaust gas containing moisture flows into the case. This can cause the moisture in the exhaust gas to condense on the inner wall of the case. If this condensation occurs, the insulating properties of the electrically heated catalyst can be reduced. [Means for solving the problem]

[0006] The control device for an internal combustion engine that solves the above problems is applied to an internal combustion engine that includes an electrically heated first catalyst that is housed in a case provided in an exhaust passage and is heated by passing electricity through it, and a second catalyst that is provided downstream of the first catalyst in the exhaust gas. Can This control device is In this case, the rotating shaft of the internal combustion engine is drivenA preheat process is performed in advance to warm up the first catalyst by energizing the first catalyst, and the internal combustion engine is started after a predetermined period of time has elapsed since the end of the preheat process. In this case, the driving of the rotating shaft of the internal combustion engine and executes a start-up delay process which initiates

[0007] Even after the preheat process is completed, the temperature of the case continues to rise due to the preheating of the first catalyst warmed by the preheat process. Therefore, when engine start is started after a certain period of time has passed since the preheat process is completed, the temperature of the case is higher than when engine start is started immediately after the preheat process is completed. Therefore, the internal combustion engine can be started in a state where condensation is less likely to occur on the inner wall of the case. Therefore, in this configuration, the internal combustion engine is started after a predetermined period of time has passed since the preheat process is completed. Therefore, deterioration of the insulation of the electrically heated catalyst can be suppressed compared to when engine start is started immediately after the preheat process is completed.

[0008] Furthermore, even if condensation has already formed on the inner wall of the case before the engine is started, the condensed water will evaporate due to the temperature rise of the case as described above, improving the insulation resistance of the electrically heated catalyst at the time the engine is started. This also makes it possible to suppress deterioration of the insulation properties of the electrically heated catalyst.

[0009] In the control device, the predetermined period may be a period until a wall temperature of the case becomes equal to or higher than a predetermined judgment temperature. In addition, in the control device, the default period is the period until the elapsed time from the end of the preheat process becomes equal to or greater than a default judgment time, and a process of acquiring the temperature of the first catalyst at the time the preheat process is ended and a process of setting the judgment time to a longer time the lower the temperature of the first catalyst may be executed.

[0010] After the preheat process is completed, the time required for the temperature of the case to reach a temperature at which condensation is unlikely to occur is longer the lower the temperature of the first catalyst at the time the preheat process is completed. Also, after the preheat process is completed, the time required for the condensed water adhering to the inner wall of the case to evaporate sufficiently is longer the lower the temperature of the first catalyst at the time the preheat process is completed.

[0011] In this configuration, the preset period is a period until the elapsed time from the end of the preheat process becomes equal to or greater than a preset judgment time, and a process of acquiring the temperature of the first catalyst at the time of the end of the preheat process and a process of setting the judgment time to a longer time as the temperature of the first catalyst is lower are executed. Therefore, the judgment time is appropriately set according to the temperature of the first catalyst at the time of the end of the preheat process, and thus the engine start can be appropriately initiated by the start delay process.

[0012] In addition, in the control device, the predetermined period is the period until the elapsed time since the end of the preheat process becomes equal to or greater than a predetermined judgment time, and a process of acquiring an insulation resistance value of the first catalyst before the start of execution of the preheat process and a process of setting the judgment time to a longer time the lower the insulation resistance value are may be executed.

[0013] The lower the insulation resistance value of the first catalyst before the start of the preheat process, the more likely it is that condensed water will be attached to the inner wall of the case. Therefore, the lower the insulation resistance value, the longer it takes for the condensed water attached to the inner wall of the case to evaporate sufficiently after the end of the preheat process.

[0014] Therefore, in this configuration, a process for acquiring an insulation resistance value of the first catalyst before the start of the preheat process and a process for setting the determination time to a longer time as the insulation resistance value is lower are executed. Therefore, the determination time is appropriately set according to the insulation resistance value of the first catalyst before the start of the preheat process, and thus the engine start can be appropriately started by the start delay process.

[0015] Moreover, the control device may execute a post-heat process of energizing the first catalyst in synchronization with the start of startup of the internal combustion engine. According to this configuration, even after the preheat process is completed and the engine start is started, the first catalyst is energized by the postheat process. By executing the postheat process, the temperature drop of the first catalyst that has completed warming up is suppressed, and therefore the deterioration of emissions immediately after the engine start is suppressed.

[0016] Here, the above-mentioned start delay processing prevents the deterioration of the insulating properties of the electrically heated catalyst after the engine is started, so that even if electricity is passed through the catalyst by such post-heat processing, the occurrence of leakage current or the like can be prevented. [Brief description of the drawings]

[0017] [Figure 1] 1 is a schematic diagram showing a configuration of a vehicle equipped with a control device for an internal combustion engine; [Diagram 2] FIG. 2 is a schematic diagram showing the system configuration of an electrically heated catalyst mounted on the vehicle. [Diagram 3] 4 is a flowchart showing a procedure of a process executed by the control device of the embodiment. [Figure 4] 4 is a graph showing the relationship between the maximum oxygen storage amount and the activation temperature of the catalyst. [Diagram 5] 4 is a graph showing a relationship between a first catalyst temperature and a maximum oxygen storage amount, and a target electric power amount. [Figure 6] 1 is a graph showing the relationship between the maximum oxygen storage amount and a judgment value. [Figure 7]7 is a time chart showing the transition of various states when the vehicle system is started up, in which Fig. 7(a) shows the engine output, Fig. 7(b) shows the electrified state of the electrically heated catalyst, Fig. 7(c) shows the first catalyst temperature and the second catalyst temperature, and Fig. 7(d) shows the transition of each. [Figure 8] 10 is a flowchart showing a part of a procedure of a process executed by a control device in a modified example of the embodiment. [Figure 9] 4 is a graph showing the relationship between the first catalyst temperature and the determination time. [Figure 10] 1 is a graph showing the relationship between insulation resistance value and determination time. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, one embodiment of a control device for an internal combustion engine will be described with reference to Figs. <Vehicle configuration> The configuration of a vehicle 10 equipped with an internal combustion engine control device 100 will be described with reference to FIG.

[0019] The vehicle 10 includes an internal combustion engine 11 and a second motor generator 32 as power sources. In other words, the vehicle 10 is a hybrid vehicle. The vehicle 10 is a plug-in hybrid vehicle that can be connected to an external power source 60 to charge the battery 50. Therefore, a charger 51 for external charging is connected to the battery 50. The battery 50 is, for example, a 400V high-voltage battery. The second motor generator 32 is, for example, a three-phase AC motor generator.

[0020] The internal combustion engine 11 includes an intake passage 12 and an exhaust passage 21. In the example shown in FIG. 1, the internal combustion engine 11 includes four cylinders. The intake passage 12 includes a throttle valve 13 for adjusting the flow rate of intake air flowing through the intake passage 12. The internal combustion engine 11 includes a plurality of fuel injection valves 14 for injecting fuel during intake, one for each cylinder. The plurality of fuel injection valves 14 may be provided for each cylinder, or the number of the fuel injection valves 14 provided for each cylinder may differ. The internal combustion engine 11 includes a spark plug 15 for igniting a mixture of fuel and intake air by spark discharge, one for each cylinder. The plurality of spark plugs 15 may be provided for each cylinder, or the number of the spark plugs provided for each cylinder may differ.

[0021] A catalytic converter 29 is installed in the exhaust passage 21 of the internal combustion engine 11. The catalytic converter 29 is equipped with an electrically heated catalyst 210 that generates heat in response to the passage of current. The electrically heated catalyst 210 is connected to a battery 50 via a power supply device 220. A detailed configuration of an electrically heated catalyst system 200 including the electrically heated catalyst 210 will be described later with reference to FIG. 2.

[0022] In addition, a filter 36 is provided downstream of the catalytic converter 29 in the exhaust passage 21. The filter 36 collects particulate matter contained in the exhaust gas. The particulate matter is fine particulate matter produced by combustion and composed mainly of carbon.

[0023] The second motor generator 32 is connected to a battery 50 via a power control unit 35. In addition, the second motor generator 32 is linked to driving wheels 40 via a reduction mechanism .

[0024] The internal combustion engine 11 is connected to drive wheels 40 via a power split mechanism 30 and a reduction mechanism 34. A first motor generator 31 is also connected to the power split mechanism 30. The first motor generator 31 is, for example, a three-phase AC motor generator. The power split mechanism 30 is a planetary gear mechanism, and can split the driving force of the internal combustion engine 11 between the first motor generator 31 and the drive wheels 40.

[0025] The first motor generator 31 generates electricity by receiving driving force from the internal combustion engine 11 and driving force from the drive wheels 40. The first motor generator 31 also serves as a starter that drives the rotating shaft of the internal combustion engine 11 when starting the internal combustion engine 11. At that time, the first motor generator 31 functions as a motor that generates driving force in response to the supply of electric power from the battery 50.

[0026] The first motor generator 31 and the second motor generator 32 are connected to a battery 50 via a power control unit 35. AC power generated by the first motor generator 31 is converted to DC power by the power control unit 35 and charged into the battery 50. In other words, the power control unit 35 functions as an inverter.

[0027] Moreover, the DC power of the battery 50 is converted to AC by the power control unit 35 and supplied to the second motor generator 32. When the vehicle 10 is decelerated, the second motor generator 32 generates power by utilizing the driving force from the drive wheels 40. The generated power is then charged to the battery 50. That is, the vehicle 10 performs regenerative charging. At this time, the second motor generator 32 functions as a generator. At this time, the AC power generated by the second motor generator 32 is converted to DC by the power control unit 35 and charged to the battery 50.

[0028] When the first motor generator 31 is caused to function as a starter, the power control unit 35 converts the DC power of the battery 50 into AC power and supplies it to the first motor generator 31.

[0029] <Control device> The control device 100 controls the internal combustion engine 11, the first motor generator 31, and the second motor generator 32. In other words, the control device 100 is a control device that controls the powertrain of the vehicle 10, which is a plug-in hybrid vehicle. Therefore, the control device 100 controls the internal combustion engine 11 including the electrically heated catalyst system 200. The control device 100 also controls the electrically heated catalyst system 200.

[0030] The control device 100 receives detection signals from sensors provided in various parts of the vehicle 10. The detection signals input to the control device 100 include the vehicle speed SP, the accelerator pedal opening degree ACCP, and the state of charge SOC according to the remaining capacity of the battery 50. The control device 100 is connected to a water temperature sensor 101 that detects a water temperature Tw, which is the temperature of the cooling water of the internal combustion engine 11. The control device 100 is also connected to a power switch 102 that allows the driver of the vehicle 10 to start and stop the system of the vehicle 10. Therefore, the control device 100 grasps the start-up state of the system of the vehicle 10 based on an input signal from the power switch 102. The control device 100 is connected to an upstream air-fuel ratio sensor 103 that detects an upstream air-fuel ratio AFu, which is the air-fuel ratio of the exhaust gas flowing into the catalytic converter 29. The upstream air-fuel ratio sensor 103 is disposed in the exhaust passage 21 upstream of the catalytic converter 29. The control device 100 is connected to a downstream air-fuel ratio sensor 104 that detects a downstream air-fuel ratio AFd, which is the air-fuel ratio of the exhaust gas that has passed through the catalytic converter 29. The downstream air-fuel ratio sensor 104 is disposed in the exhaust passage 21 downstream of the catalytic converter 29 and upstream of the filter 36. The control device 100 is connected to an air flow meter 105 that detects the intake air temperature Tin, which is the temperature of the air taken into the internal combustion engine 11, and the intake air amount GA, which is the mass, and a crank angle sensor 106 that detects the rotation angle of the crankshaft of the internal combustion engine 11. The control device 100 calculates the engine speed NE based on the output signal Scr of the crank angle sensor 106. The control device 100 also calculates an engine load factor KL based on the engine speed NE and the intake air amount GA. The engine load factor KL is a parameter that determines the amount of air filled in the combustion chamber of the internal combustion engine 11, and is the ratio of the amount of inflow air per combustion cycle of one cylinder to a reference amount of inflow air. The reference inflow air amount is variably set according to the engine speed NE.

[0031] The vehicle 10 configured as described above can perform EV running in which the drive wheels 40 are driven using only the second motor generator 32 by using the power stored in the battery 50 to drive the second motor generator 32. In addition, the vehicle 10 can also perform hybrid running in which the drive wheels 40 are driven using the internal combustion engine 11 and the second motor generator 32.

[0032] <Configuration of Electrically Heated Catalyst System> Next, the configuration of the electrically heated catalyst system 200 will be described with reference to FIG. As shown in Fig. 2, the catalytic converter 29 is equipped with a second catalyst 27 for exhaust gas purification in addition to a first catalyst 26 for exhaust gas purification constituting an electrically heated catalyst 210. Both the first catalyst 26 and the second catalyst 27 are three-way catalysts supported on a honeycomb-structured catalyst carrier in which multiple passages extending in the exhaust gas flow direction are defined. The second catalyst 27 is provided downstream of the first catalyst 26 in the exhaust gas flow direction.

[0033] The first catalyst 26 and the second catalyst 27 are housed in a case 24. The case 24 is a cylinder made of metal, for example, stainless steel. The case 24 constitutes a part of the exhaust passage 21. Inside the case 24, a mat 28 is interposed between the case 24 and the first catalyst 26 and second catalyst 27. The mat 28 is an insulator, and is made of, for example, inorganic fibers containing alumina as a main component.

[0034] The mat 28 is interposed in a compressed state between the first catalyst 26 and the second catalyst 27 and the case 24. Therefore, the first catalyst 26 and the second catalyst 27 are held in the case 24 by the restoring force of the compressed mat 28.

[0035] An upstream connecting pipe 23, the diameter of which decreases toward the upstream side, is fixed to the upstream side of the case 24. A downstream connecting pipe 25, the diameter of which decreases toward the downstream side, is fixed to the downstream side of the case 24.

[0036] 2, the upstream connecting pipe 23 connects the upstream exhaust pipe 22, which has a smaller diameter than the case 24, to the case 24. Similarly, the downstream connecting pipe 25 connects the downstream exhaust pipe, which has a smaller diameter than the case 24, to the case 24. In this manner, the case 24, which contains the first catalyst 26 and the second catalyst 27, the upstream connecting pipe 23, and the downstream connecting pipe 25 constitute a catalytic converter 29 that constitutes a part of the exhaust passage 21.

[0037] The diameter of the upstream end of case 24 becomes smaller as it approaches upstream exhaust pipe 22, and the diameter of the part closest to upstream exhaust pipe 22 is approximately equal to the diameter of upstream exhaust pipe 22.

[0038] The second catalyst 27 is located downstream of the first catalyst 26 in the exhaust gas flow. The catalyst carrier of the first catalyst 26 is made of a material that becomes electrically resistant and generates heat when electricity is applied. For example, silicon carbide can be used as such a material. The catalyst carrier has the property that its electrical resistance is smaller when the temperature is high than when the temperature is low.

[0039] A first electrode 211 and a second electrode 212 are attached to the first catalyst 26. The first electrode 211 is a positive electrode, and the second electrode 212 is a negative electrode. A current flows through the first catalyst 26 by applying a voltage between the first electrode 211 and the second electrode 212. When a current flows through the first catalyst 26, the catalyst support generates heat due to the electrical resistance of the catalyst support.

[0040] In order to pass current uniformly through the entire catalyst carrier, the first electrode 211 and the second electrode 212 extend in the circumferential and axial directions along the outer circumferential surface of the catalyst carrier. Two openings 24K are formed in the case 24, and an insulator 213 made of an insulating material such as alumina is fitted into each opening 24K. The first electrode 211 and the second electrode 212 each pass through the insulator 213 fitted into the opening 24K.

[0041] The opening 24K is closed by a metallic electrode chamber 80. A terminal 85 provided at the end of a power line that supplies power to the first electrode 211 and the second electrode 212 is inserted into this electrode chamber 80. The terminal 85 is connected to the first electrode 211 and the second electrode 212.

[0042] An insulating coating is applied to the inner peripheral surface of the case 24. For example, a glass coating can be used as the insulating coating. As a result, the first catalyst 26 is electrically insulated from the case 24.

[0043] As described above, the first catalyst 26 is equipped with the first electrode 211 and the second electrode 212. This makes the first catalyst 26 an electrically heated catalyst 210 that generates heat when supplied with electric power. Hereinafter, the electrically heated catalyst 210 is referred to as EHC 210. The catalyst support generates heat when electricity is applied, thereby heating the first catalyst 26 and promoting activation.

[0044] Furthermore, when the internal combustion engine 11 starts operating and exhaust gas begins to flow, the exhaust gas is warmed as it passes through the EHC 210, and the heat is transferred to the second catalyst 27 as well. This also facilitates the warming up of the second catalyst 27.

[0045] The first electrode 211 and the second electrode 212 are connected to the battery 50 via a power circuit 221 of the power supply device 220. The power supply device 220 includes a power circuit 221 including an isolation transistor and a power switching element, and a power supply microcomputer 222 that controls the power supply circuit 221. The power supply circuit 221 is provided with a current sensor 224 and a voltage sensor 225. 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 a signal output by the current sensor 224. In addition, the power supply microcomputer 222 detects the voltage applied to the EHC 210 based on a signal output by the voltage sensor 225. An auxiliary battery 55 is connected to the power supply device 220.

[0046] In addition, the power supply device 220 is provided with a leakage detection circuit 223 that is connected to the power supply circuit 221 and detects the insulation resistance of the EHC 210 to detect leakage. For example, the leakage detection circuit 223 includes a reference resistor. The auxiliary battery 55 supplies power to the power supply circuit 221 including the leakage detection circuit 223. The power supply microcomputer 222 calculates the insulation resistance value Rt of the EHC 210 based on the current value and voltage value detected by the current sensor 224 and voltage sensor 225 at this time.

[0047] The power supply device 220 is connected to the control device 100 so as to be mutually communicable, and the insulation resistance value Rt calculated by the power supply microcomputer 222 is output to the control device 100. Further, the control device 100 outputs a command to the power supply device 220 and controls the energization of the EHC 210 via the power supply device 220.

[0048] <Regarding the energization of the EHC> In the vehicle 10 which is a plug-in hybrid vehicle, when there is sufficient margin in the state of charge SOC of the battery 50, it travels in the EV travel mode using only the second motor generator 32 as the driving power source for traveling. The control device 100 at this time maintains the internal combustion engine 11 in a stopped state. Then, the control device 100 controls the power control unit 35 so that the second motor generator 32 generates torque that can obtain the driving force corresponding to the required driving force.

[0049] Further, when the state of charge SOC of the battery 50 falls below a certain value during traveling in the EV travel mode, the control device 100 switches the travel mode of the vehicle 10 from the EV travel mode to the hybrid travel mode. The hybrid travel mode is a travel mode that uses both the internal combustion engine 11 and the second motor generator 32 as the driving power source for traveling.

[0050] In order to be able to exhibit sufficient exhaust purification ability immediately after switching to the hybrid travel mode, it is desirable to energize the EHC 210 and warm up the first catalyst 26 before shifting to the hybrid travel mode and starting the internal combustion engine 11.

[0051] Therefore, prior to starting the internal combustion engine 11, the control device 100 executes a preheating process of warming up the first catalyst 26 by energizing the EHC 210. Further, the control device 100 executes a post-heating process of energizing the EHC 210 even after the start of the internal combustion engine 11. Note that warming up a catalyst means raising the temperature of the catalyst to the activation temperature.

[0052] Even after the preheating process is completed and the engine start is initiated in this way, the first catalyst 26 is energized by the post-heating process. By executing such a post-heating process, a decrease in the temperature of the first catalyst 26 after the warm-up is completed is suppressed, so that deterioration of emissions immediately after the engine start is suppressed.

[0053] Further, if the temperature of the second catalyst 27 has reached the activation temperature, the exhaust gas is purified by this second catalyst 27, so that the exhaust gas can be purified even if the energization of the first catalyst 26 is stopped. Therefore, in the present embodiment, the energization of the first catalyst 26 by the post-heating process is performed until the second catalyst 27 reaches the activation temperature. Accordingly, even if the energization of the first catalyst 26 is stopped, deterioration of emissions is suppressed.

[0054] Incidentally, when the engine start is initiated, exhaust gas containing moisture flows into the case 24. Therefore, there is a possibility that moisture in the exhaust gas condenses on the inner wall of the case 24 or the inner wall of the electrode chamber 80. When such condensation occurs, there is a possibility that the insulation of the EHC 210 decreases. Further, when the temperature of the first catalyst 26 rises due to the preheating process, the moisture absorbed by the mat 28 evaporates. There is also a possibility that the insulation of the EHC 210 decreases due to the evaporated moisture condensing again on the inner wall of the case 24 or the inner wall of the electrode chamber 80.

[0055] Therefore, in order to suppress such a decrease in the insulation of the EHC 210, the control device 100 executes the process shown in FIG. 3. <Processing related to energization of EHC> The procedure for energizing the EHC, including the pre-heat process and the post-heat process, will be described with reference to Fig. 3. The process shown in Fig. 3 is repeatedly executed by the control device 100 when the power switch 102 is ON and the system of the vehicle 10 is operating. In the following, step numbers are represented by numbers preceded by the letter "S."

[0056] 3, when this main process starts, the control device 100 first determines in the process of S100 whether or not an EHC energization request is ON. An EHC energization request is a request for energization of the EHC 210. Specifically, the control device 100 determines that the EHC energization request is ON when either of the following two conditions is satisfied:

[0057] There is a request to start the internal combustion engine 11. Note that a request to start the internal combustion engine 11 may occur, for example, when the state of charge SOC is below a threshold for switching to the hybrid driving mode, or when the vehicle driving torque required by the vehicle driver cannot be obtained in EV driving.

[0058] The first catalyst temperature Tcat1, which is the temperature of the first catalyst 26, is equal to or lower than a predetermined temperature that is lower than the activation temperature. The control device 100 estimates the first catalyst temperature Tcat1. For example, when the operation of the internal combustion engine 11 is stopped, the control device 100 stores the first catalyst temperature Tcat1 at that time as the first temperature at stop Toff1 and starts the soak timer. Then, the control device 100 continues the time measurement by the soak timer while the internal combustion engine 11 is stopped. When the internal combustion engine 11 is started, the control device 100 calculates a product obtained by multiplying the difference obtained by subtracting the first temperature at stop Toff1 from the outside air temperature by a convergence rate. Then, the control device 100 calculates a sum by adding the product to the first temperature at stop Toff1. The sum thus calculated is set as the first catalyst temperature Tcat1 at the time of engine start. The convergence rate is calculated based on the soak time. The convergence rate is a value between 0 and 1. The convergence rate approaches 1 as the soak time becomes longer. For example, when the convergence rate is 1, the catalyst temperature T becomes equal to the outside air temperature. This indicates that when the convergence rate is 1, the first catalyst temperature Tcat1 converges to the outside air temperature. The control device 100 regards the intake air temperature Tin detected by the air flow meter 105 as the outside air temperature and uses it to calculate the first catalyst temperature Tcat1.

[0059] During engine operation, the control device 100 calculates a first temperature change amount dT1, which is a temperature change amount of the first catalyst temperature Tcat1. The first temperature change amount dT1 is added to the first catalyst temperature Tcat1 calculated immediately before to calculate the latest first catalyst temperature Tcat1. The first temperature change amount dT1 changes due to the influence of exhaust heat and the amount of heat generated by the EHC 210. Therefore, the control device 100 calculates the first temperature change amount dT1 using parameters that affect the amount of thermal energy of the exhaust gas and parameters that affect the amount of heat generated by the EHC 210. Examples of parameters that affect the amount of thermal energy of the exhaust gas include the engine speed NE, the engine load factor KL, the water temperature Tw, the intake air amount GA, the vehicle speed SP, and the intake air temperature Tin. Examples of parameters that affect the amount of heat generated by the EHC 210 include the amount of electric power input to the EHC 210.

[0060] The control device 100 also estimates the second catalyst temperature Tcat2, which is the temperature of the second catalyst 27. For example, when the control device 100 stops the operation of the internal combustion engine 11, it stores the second catalyst temperature Tcat2 at that time as the second temperature at stop Toff2 and starts the soak timer. Then, the control device 100 continues the time measurement by the soak timer while the internal combustion engine 11 is stopped. When the internal combustion engine 11 is started, the control device 100 calculates the product of the difference obtained by subtracting the second temperature at stop Toff2 from the outside air temperature and multiplying it by the convergence rate. Then, it calculates the sum by adding the product to the second temperature at stop Toff2. The sum calculated in this way is set as the second catalyst temperature Tcat2 at the time of engine start. The convergence rate is calculated based on the soak time. The convergence rate is a value between 0 and 1. The convergence rate approaches 1 as the soak time becomes longer. For example, when the convergence rate is 1, the catalyst temperature T becomes equal to the outside air temperature. This indicates that when the convergence rate is 1, the second catalyst temperature Tcat2 converges to the outside air temperature.

[0061] During engine operation, the control device 100 calculates a second temperature change amount dT2, which is the amount of temperature change in the second catalyst temperature Tcat2. The second temperature change amount dT2 is then added to the previously calculated second catalyst temperature Tcat2 to calculate the latest second catalyst temperature Tcat2. The second temperature change amount dT2 changes due to the influence of exhaust heat. Therefore, the control device 100 calculates the second temperature change amount dT2 using parameters that affect the amount of thermal energy of the exhaust gas. Examples of parameters that affect the amount of thermal energy of the exhaust gas flowing into the second catalyst 27 include the first catalyst temperature Tcat1, the intake air amount GA, and the intake air temperature Tin.

[0062] In the process of S100, when it is determined that the EHC energization request is not ON (S100: NO), the control device 100 ends this process once. That is, in this case, the control device 100 does not execute the pre-heat process and the post-heat process.

[0063] On the other hand, when it is determined in the process of S100 that the EHC energization request is ON (S100: YES), the control device 100 advances the process to S110. In the process of S110, the control device 100 prohibits the internal combustion engine 11 from starting.

[0064] Next, in the process of S112, the control device 100 obtains the insulation resistance value Rt at this time point. Then, in the process of S114, the control device 100 determines whether the insulation resistance value Rt is greater than a threshold value A1. The threshold value A1 is a threshold value for determining whether the insulation resistance, which is the electrical resistance of the EHC 210, is large enough to suppress leakage current.

[0065] When it is determined in the process of S114 that the insulation resistance value Rt is equal to or less than the threshold value A1 (S114: NO), the control device 100 advances the process to S116. Then, in the process of S116, the control device 100 releases the inhibition of starting the internal combustion engine 11 and starts the starting of the internal combustion engine 11. Then, this process is temporarily ended.

[0066] On the other hand, when it is determined in the process of S114 that the insulation resistance value Rt is greater than the threshold value A1 (S140: YES), the control device 100 advances the process to S120. In the process of S120, the control device 100 calculates a target electric power amount Q0. Specifically, the control device 100 calculates the target electric power amount Q0 according to the first catalyst temperature Tcat1 estimated when the process of S100 was executed and the maximum oxygen storage amount Cmax calculated during the previous operation of the internal combustion engine 11.

[0067] The maximum oxygen storage amount Cmax is the maximum amount of oxygen that can be stored by the two catalysts provided in the catalytic converter 29, i.e., the first catalyst 26 and the second catalyst 27, when the two catalysts are regarded as one catalyst. The control device 100 estimates the maximum oxygen storage amount Cmax based on, for example, the values ​​of the upstream air-fuel ratio AFu and the downstream air-fuel ratio AFd during engine operation. Here, as the deterioration of the first catalyst 26 and the second catalyst 27 progresses and their degree of deterioration increases, the maximum oxygen storage amount Cmax decreases. Therefore, the maximum oxygen storage amount Cmax is deterioration information that is information related to the degree of deterioration of the first catalyst 26 and the second catalyst 27.

[0068] As shown in FIG. 4, when the maximum oxygen storage amount Cmax decreases due to an increase in the degree of deterioration of the first catalyst 26 or the second catalyst 27, the activation temperatures of the first catalyst 26 or the second catalyst 27 tend to increase.

[0069] In the preheat process, the first catalyst 26 is heated to or above its activation temperature by continuing to supply electricity to the EHC 210 until the amount of electricity Q, which is the integrated value of the input power, reaches a target amount of electricity Q0, thereby warming up the first catalyst 26. In other words, the target amount of electricity Q0 is the amount of electricity required to heat the first catalyst 26 from the temperature before the start of electricity supply until the warm-up is completed.

[0070] Therefore, as shown in Fig. 5, in the process of S120, the control device 100 calculates a larger value as the target electric power amount Q0 as the first catalyst temperature Tcat1 is lower. Note that the electric power amount Q is an integrated value of the electric power actually supplied to the EHC 210. Also, as shown in Fig. 5, in the process of S120, the control device 100 calculates a larger value as the target electric power amount Q0 as the maximum oxygen storage amount Cmax is smaller and the activation temperature is higher.

[0071] Next, in the process of S130, the control device 100 sets the power supplied to the EHC 210 to the first power W1. In this embodiment, the power supplied to the EHC 210 in the pre-heat process and the post-heat process is both the first power W1. However, the power supplied to the EHC 210 in the pre-heat process and the post-heat process may be different.

[0072] Next, the control device 100 advances the process to S140. In the process of S140, the control device 100 starts energizing the EHC 210. In the preheat process, the control device 100 controls the power supply circuit 221 so that the input power becomes a set value, converts the voltage of the battery 50, and supplies power to the EHC 210. When the temperature of the first catalyst 26 rises due to the preheat process, the insulation resistance value Rt gradually decreases. Therefore, the control device 100 lowers the voltage in accordance with the decrease in the insulation resistance value Rt to maintain the input power at the first power W1. In addition, the control device 100 controls the voltage within a range equal to or less than the upper limit voltage so that the voltage does not exceed a preset upper limit voltage value. That is, the upper limit voltage is the upper limit value of the voltage when controlling the voltage in the preheat process. In addition, when energization is started, 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 starts integrating the input power. While power is being applied to the EHC 210, the control device 100 continues to calculate the amount of power Q input to the EHC 210 by integrating the input power.

[0073] In the next process of S150, the control device 100 determines whether the amount of power Q is equal to or greater than the target amount of power Q0. If the amount of power Q is determined to be less than the target amount of power Q0 in the process of S150 (S150: NO), the control device 100 repeats the process of S150.

[0074] On the other hand, when it is determined in the process of S150 that the electric energy Q is equal to or greater than the target electric energy Q0 (S150: YES), the control device 100 proceeds to the process of S152. Then, in the process of S152, the control device 100 stops the supply of electric energy to the EHC 210, thereby temporarily suspending the supply of electric energy to the EHC 210. Note that when suspending the supply of electric energy to the EHC 210, instead of stopping the supply of electric energy to the EHC 210, the input electric power may be made smaller than the first electric power W1 to keep the EHC 210 warm.

[0075] Next, the control device 100 acquires the current wall temperature Twall in the process of S154. It is determined whether the acquired wall temperature Twall is equal to or higher than a predetermined judgment temperature T0ref. The wall temperature Twall is the temperature of the case 24 around the first catalyst 26, and the control device 100 calculates the wall temperature Twall by referring to the first catalyst temperature Tcat1. The judgment temperature T0ref is a value for determining whether the wall temperature Twall is a sufficiently high temperature for suppressing condensation on the inner wall of the case 24. For example, the highest conceivable dew point temperature on the inner wall of the case 24 may be set as the judgment temperature T0ref.

[0076] Then, when it is determined in the process of S154 that the wall temperature Twall is lower than the reference temperature T0ref (S154: NO), the control device 100 repeats the process of S154. On the other hand, when it is determined in the process of S154 that the wall temperature Twall is equal to or higher than the reference temperature T0ref (S154: YES), the control device 100 advances the process to S156.

[0077] In the process of S156, control device 100 sets the power supplied to EHC 210 to first power W1, thereby restarting the supply of power to EHC 210. Next, the control device 100 advances the process to S160. In the process of S160, the control device 100 releases the start inhibition of the internal combustion engine 11 and starts the start of the internal combustion engine 11. Note that the processes of S152, S154, and S160 configure a start delay process that starts the start of the internal combustion engine 11 after a predetermined period has elapsed since the end of the preheat process.

[0078] Next, the control device 100 performs engine output limitation and ignition timing retardation in the process of S170. The engine output limitation is to control the engine output Pe of the internal combustion engine 11 so that the engine output Pe is constant at a preset default output Pec. Note that the default output Pec is set to a value slightly smaller than the engine output Pe at which the amount of exhaust gas discharged from the internal combustion engine 11 is appropriate for suppressing the occurrence of condensation in case 24. By performing such engine output limitation, the occurrence of condensation in case 24 caused by moisture in the exhaust gas is suppressed.

[0079] In addition, the ignition timing is retarded compared to when the engine is started without energizing the EHC 210. By retarding the ignition timing, the temperature of the exhaust gas discharged from the internal combustion engine 11 increases. This makes it possible to suppress a decrease in temperature of the first catalyst 26 due to the exhaust gas and to promote the warming up of the second catalyst 27.

[0080] Next, the control device 100 calculates the reference value Tref in the process of S180. The reference value Tref is the activation temperature of the second catalyst 27. As described above, the activation temperature of the second catalyst 27 changes depending on the deterioration level of the second catalyst 27. The deterioration level of the second catalyst 27 is correlated with the maximum oxygen storage amount Cmax. Therefore, in the process of S180, the control device 100 acquires the maximum oxygen storage amount Cmax, which is the deterioration information of the second catalyst 27. Then, the control device 100 calculates the reference value Tref based on the acquired maximum oxygen storage amount Cmax.

[0081] As shown in FIG. 6, the control device 100 calculates the reference value Tref so that the smaller the maximum oxygen storage amount Cmax is, the higher the reference value Tref becomes. Next, the control device 100 acquires the second catalyst temperature Tcat2 in the process of S190. Then, the control device 100 judges whether the second catalyst temperature Tcat2 is equal to or higher than the judgment value Tref. Then, in the process of S190, when it is judged that the second catalyst temperature Tcat2 is less than the judgment value Tref (S190: NO), the control device 100 repeats the process of S190.

[0082] On the other hand, in the process of S190, when it is determined that the second catalyst temperature Tcat2 is equal to or higher than the reference value Tref (S190: YES), the control device 100 advances the process to S200. In the process of S200, the control device 100 ends the engine output limitation and the ignition timing retardation described above.

[0083] Next, in the process of S210, the control device 100 stops the supply of electricity to the EHC 210. Then, this process ends for the time being. <effect> The operation of this embodiment will now be described.

[0084] Fig. 7 is a time chart showing the transition of various states when the above-mentioned vehicle system is started up. Fig. 7(a) shows the transition of the output of the internal combustion engine 11, Fig. 7(b) shows the current supply state of the EHC 210, Fig. 7(c) shows the transition of the first catalyst temperature Tcat1 and the second catalyst temperature Tcat2, and Fig. 7(d) shows the transition of the wall temperature Twall.

[0085] 7, when it is determined that the EHC power supply request is ON at time t1, power supply to the EHC 210 is started, causing the first catalyst temperature Tcat1 to rise. In addition, as the first catalyst temperature Tcat1 rises, the wall temperature Twall of the case 24 around the first catalyst 26 also rises.

[0086] Then, at time t2, the amount of electric power Q supplied to the EHC 210 becomes equal to or greater than the target amount of electric power Q0, and the warm-up of the first catalyst 26 is completed, and then the supply of electricity to the EHC 210 is stopped. The supply of electricity to the EHC 210 from time t1 to time t2 is a preheat process for warming up the first catalyst 26 by supplying electricity to the first catalyst 26 prior to the start of the internal combustion engine 11.

[0087] Even after the preheating process is completed, the temperature of the case 24 continues to rise due to preheating of the first catalyst 26 that has been warmed by the preheating process, and the wall temperature Twall continues to rise. Then, when the wall temperature Twall becomes equal to or higher than the reference temperature T0ref at time t3, engine start is started. When engine start is started, the engine output Pe is maintained at the default output Pec by the above-mentioned engine output limitation, and the ignition timing is retarded. The period from time t2 to time t3 is a start delay period during which the start of the internal combustion engine 11 is started after the default period has elapsed since the end of the preheat process.

[0088] At time t3, power supply to the EHC 210 is resumed. Then, at time t4, when the second catalyst temperature Tcat2 becomes equal to or higher than the reference value Tref and the warm-up of the second catalyst 27 is completed, the above-mentioned engine output limitation and ignition timing retard are ended and power supply to the EHC 210 is stopped. Power supply to the EHC 210 from time t3 to time t4 is a post-heat process in which power is supplied to the first catalyst 26 after the internal combustion engine 11 has begun to start.

[0089] <About the effects> The effects of this embodiment will be described. (1) As described above, even after the preheat process is completed, the temperature of the case 24 continues to rise due to the preheating of the first catalyst 26 that has been warmed by the preheat process. Therefore, when engine start is initiated a certain period of time after the preheat process is completed, the temperature of the case 24 is higher than when engine start is initiated immediately after the preheat process is completed. Therefore, the internal combustion engine 11 can be initiated in a state in which condensation is less likely to form on the inner wall of the case 24.

[0090] Therefore, in this embodiment, a start delay process is performed in which the start of the internal combustion engine 11 is started after a predetermined period has elapsed since the end of the preheat process. More specifically, the preheat process is terminated at time t2 shown in Fig. 7. Then, after a start delay period (the period from time t2 to time t3 shown in Fig. 7) has elapsed, which is the period until the wall temperature Twall of the case 24 becomes equal to or higher than the above-mentioned reference temperature T0ref, the internal combustion engine 11 is started to start.

[0091] Therefore, compared to when engine start is started immediately after the end of the preheat process, start of the internal combustion engine 11 is started in a state where condensation is less likely to form on the inner wall of the case 24. Therefore, deterioration of the insulation property of the EHC 210 can be suppressed.

[0092] Furthermore, even if condensation has already formed on the inner wall of case 24 before engine start, the temperature rise of case 24 as described above promotes evaporation of the condensed water. This improves the insulation resistance of EHC 210 at the time engine start is initiated. This also makes it possible to suppress deterioration of the insulation properties of EHC 210.

[0093] (2) Even after the pre-heat process is completed and engine startup is initiated, the post-heat process continues to supply current to the first catalyst 26. Execution of the post-heat process in this manner suppresses a decrease in temperature of the first catalyst 26, which has completed warming up, and thus suppresses a deterioration in emissions immediately after engine startup.

[0094] Here, the start delay process described above prevents the insulation of the EHC 210 from deteriorating after the engine is started, so that even if current is passed through the EHC 210 due to the post-heat process, the occurrence of leakage current or the like can be prevented.

[0095] <Example of change> The above embodiment can be modified as follows: The above embodiment and the following modifications can be combined with each other to the extent that no technical contradiction occurs.

[0096] In the process of S120, the control device 100 calculates the target electric power amount Q0 according to the first catalyst temperature Tcat1 and the maximum oxygen storage amount Cmax. Alternatively, the target electric power amount Q0 may be calculated according to either the first catalyst temperature Tcat1 or the maximum oxygen storage amount Cmax. The target electric power amount Q0 may also be calculated according to other parameters.

[0097] The engine output limit is to control the engine output Pe so that the engine output Pe is constant at a preset default output Pec. Alternatively, the engine output limit may be to control the engine output Pe within a range equal to or less than the preset upper limit output Pem so that the engine output Pe does not exceed the preset upper limit output Pem. Note that the value of the upper limit output Pem may be the above-mentioned default output Pec.

[0098] In the process of S170, the engine output limit and the ignition timing retard are implemented. Alternatively, either the engine output limit or the ignition timing retard may be implemented. Also, by omitting the processes of S170 and S200, it is possible to avoid implementing both the engine output limit and the ignition timing retard.

[0099] The reference value Tref is changed according to the maximum oxygen storage amount Cmax, but may be a predetermined constant value, for example, the activation temperature when it is assumed that the deterioration level of the second catalyst 27 has reached an allowable limit.

[0100] Although the maximum oxygen storage amount Cmax is used as catalyst deterioration information, other values ​​may be used. For example, the longer the total operating time of the internal combustion engine 11, the higher the degree of catalyst deterioration tends to be. Therefore, the total operating time may be used as catalyst deterioration information.

[0101] In the process of S154 shown in FIG. 3, the wall temperature Twall is compared with the reference temperature T0ref, but other values ​​may be compared. The processing procedure of such a modified example is shown in Fig. 8. Note that Fig. 8 also shows the differences from the processing shown in Fig. 3.

[0102] As shown in FIG. 8, after completing the process of S152 described above, the control device 100 calculates the judgment time Tiref as the process of S300. The judgment time Tiref is the longer of the time A and the time B. The time A is the time required for the temperature of the case 24 to reach a temperature at which condensation is unlikely to occur after the end of the preheat process, and the lower the temperature of the first catalyst 26 at the time of the end of the preheat process, the longer the judgment time Tiref. The time B is the time required for the evaporation of the condensed water attached to the inner wall of the case 24 to proceed sufficiently after the end of the preheat process, and this time is also longer as the temperature of the first catalyst 26 at the time of the end of the preheat process is lower. Therefore, in the process of S300, the control device 100 acquires the first catalyst temperature Tcat1 at the time of the end of the preheat process. Then, the judgment time Tiref is calculated based on the acquired first catalyst temperature Tcat1.

[0103] As shown in FIG. 9, the control device 100 calculates the value of the determination time Tiref so that the determination time Tiref becomes longer as the first catalyst temperature Tcat1 becomes lower. Next, in the process of S310, the control device 100 acquires the elapsed time Ti. Then, it is determined whether or not the acquired elapsed time is equal to or greater than the judgment time Tiref. The elapsed time Ti is the time that has elapsed since the power supply to the EHC 210 was stopped in the process of S152 shown in FIG. 3 until the present. In other words, the elapsed time Ti is the time that has elapsed since the preheat process was ended until the present. Then, in the process of S310, when it is determined that the elapsed time Ti is less than the judgment time Tiref (S310: NO), the control device 100 repeats the process of S310.

[0104] On the other hand, when it is determined in the process of S310 that the elapsed time Ti is equal to or greater than the reference time Tiref (S310: YES), the control device 100 advances the process to the above-mentioned S156, thereby starting the engine start and post-heat process.

[0105] In this modification, the reference time Tiref is appropriately set in accordance with the first catalyst temperature Tcat1 at the time when the preheat process is completed. Therefore, in this modification, the engine start can be appropriately initiated by the start delay process.

[0106] 8, the determination time Tiref is calculated based on the first catalyst temperature Tcat1 at the time of completion of the preheat process, but the determination time Tiref may be calculated based on other values. For example, the lower the insulation resistance value Rt of the first catalyst 26 before the start of the preheat process, the more likely it is that condensed water is adhering to the inner wall of the case 24. Therefore, the lower the insulation resistance value Rt, the longer the time required for the condensed water adhering to the inner wall of the case 24 to evaporate sufficiently after the completion of the preheat process.

[0107] Therefore, in the processing of S300 shown in FIG. 8, the control device 100 executes a process of acquiring the insulation resistance value Rt of the first catalyst 26 before the start of the preheat processing, and a process of setting the judgment time Tiref based on the acquired insulation resistance value Rt.

[0108] As shown in FIG. 10, in the process of S300, the control device 100 calculates the determination time Tiref so that the lower the acquired insulation resistance value Rt, the longer the determination time Tiref. When the insulation resistance value Rt is equal to or greater than the default value Rt1, the amount of condensed water adhering to the inner wall of the case 24 is considered to be small, and the time required for the evaporation of the condensed water to proceed sufficiently is relatively short. Therefore, when the insulation resistance value Rt is equal to or greater than the default value Rt1, the control device 100 sets the determination time Tiref to a fixed value by substituting the shortest value Tiref1 among the values ​​set as the determination time Tiref. It is also possible to change the determination time Tiref according to the magnitude of the insulation resistance value Rt without fixing the determination time Tiref.

[0109] In this modification, the determination time Tiref is appropriately set in accordance with the insulation resistance value Rt before the start of the preheat process. Therefore, in this modification as well, the engine start can be appropriately initiated by the start delay process.

[0110] The catalyst supported on the catalyst carrier is not limited to a three-way catalyst, but may be, for example, an oxidation catalyst, a NOx storage reduction catalyst, or a NOx selective reduction catalyst. The vehicle 10 on which the electrically heated catalyst system 200 and the control device 100 are mounted is not limited to a plug-in hybrid vehicle, but may also be a hybrid vehicle without a plug-in function, or a vehicle powered only by an internal combustion engine 11.

[0111] The control device 100 may be configured as one or more dedicated hardware circuits, such as one or more processors that execute various processes according to a computer program (software) or an application specific integrated circuit (ASIC) that executes at least some of the various processes. The control device 100 may also be configured as a circuit including a combination of these. The processor includes a CPU and memory, such as RAM and ROM, which stores program code or instructions configured to cause the CPU to execute processes. Memory, i.e., computer-readable medium, includes any available medium that can be accessed by a general-purpose or special-purpose computer. [Explanation of symbols]

[0112] 10. Vehicle 11...Internal combustion engine 21...Exhaust passage 24…Case 24K…Aperture 26…First catalyst 27…Second catalyst 28…Matt 29…Catalytic converter 36…Filter 50…Battery 55…Auxiliary battery 80...Electrode chamber 100...Control device 101...Water temperature sensor 102…Power switch 103...Upstream air-fuel ratio sensor 104...Downstream air-fuel ratio sensor 105...Air flow meter 106...Crank angle sensor 200…Electrically heated catalyst system 210...Electrically heated catalyst (EHC) 220…Power supply device 221…Power circuit 222…Power supply microcomputer 224...Current sensor 225…Voltage sensor

Claims

1. A control device that is applied to an internal combustion engine including an electrically heated first catalyst that is housed in a case provided in an exhaust passage and is heated by passing current through it, and a second catalyst that is provided downstream of the first catalyst in the exhaust gas, a preheating process for warming up the first catalyst by energizing the first catalyst prior to driving a rotary shaft of the internal combustion engine when starting the internal combustion engine; a start delay process for starting the drive of a rotary shaft of the internal combustion engine when starting the internal combustion engine after a predetermined period of time has elapsed since the end of the preheat process; The predetermined period is a period until the wall temperature of the case reaches or exceeds a predetermined judgment temperature. A control device for an internal combustion engine.

2. A control device that is applied to an internal combustion engine including an electrically heated first catalyst that is housed in a case provided in an exhaust passage and is heated by passing current through it, and a second catalyst that is provided downstream of the first catalyst in the exhaust gas, a preheating process for warming up the first catalyst by energizing the first catalyst prior to driving a rotary shaft of the internal combustion engine when starting the internal combustion engine; a start delay process for starting the drive of a rotary shaft of the internal combustion engine when starting the internal combustion engine after a predetermined period of time has elapsed since the end of the preheat process; the predetermined period is a period until the elapsed time from the end of the preheat process becomes equal to or exceeds a predetermined determination time, A process of acquiring a temperature of the first catalyst at a time point when the preheat process is completed; and executing a process of setting the determination time to a longer time as the temperature of the first catalyst is lower. A control device for an internal combustion engine.

3. A control device that is applied to an internal combustion engine including an electrically heated first catalyst that is housed in a case provided in an exhaust passage and is heated by passing current through it, and a second catalyst that is provided downstream of the first catalyst in the exhaust gas, a preheating process for warming up the first catalyst by energizing the first catalyst prior to driving a rotary shaft of the internal combustion engine when starting the internal combustion engine; a start delay process for starting the drive of a rotary shaft of the internal combustion engine when starting the internal combustion engine after a predetermined period of time has elapsed since the end of the preheat process; the predetermined period is a period until the elapsed time from the end of the preheat process becomes equal to or exceeds a predetermined determination time, A process of acquiring an insulation resistance value of the first catalyst before starting execution of the preheat process; and executing a process of setting the determination time to a longer time as the insulation resistance value is lower. A control device for an internal combustion engine.

4. A post-heat process is performed to energize the first catalyst in synchronization with the start of the internal combustion engine. The control device for an internal combustion engine according to any one of claims 1 to 3.

Images