Control device for a hybrid vehicle

Abstract

A control device for a hybrid vehicle. During driving in the EV driving mode, when the remaining capacity of the main battery drops below the optimal energization remaining capacity set based on the driving load, the control device starts energizing the catalyst device. And when the driving load decreases after the start of energization, the control device corrects the input power of the catalyst device to a value smaller than the value at the start of energization.

Description

Technical Field

[0001] The present invention relates to a control device for a hybrid vehicle having two power sources, an engine and a motor. Background Art

[0002] As such a hybrid vehicle, there is a hybrid vehicle having two driving modes, an EV driving mode and a hybrid driving mode. The EV driving mode is a driving mode in which the engine is stopped and only the power of the motor is used for driving. The hybrid driving mode is a driving mode in which both the engine and the motor are used as power sources for driving. In such a hybrid vehicle, when there is a surplus in the remaining capacity of the battery, it is driven in the EV driving mode. And, when the remaining capacity of the battery becomes equal to or less than a certain value, the driving mode is switched from the EV driving mode to the hybrid driving mode.

[0003] As a control device for a hybrid vehicle, a device described in Japanese Patent Application Laid-Open No. 2003-269208 is known. The control device described in this document is applied to a hybrid vehicle having "an engine provided with an electrically heated catalyst device in the exhaust passage" and "a motor that generates power by power supply from a battery" as power sources for driving. During EV driving in which the engine is stopped and only the motor is used as a power source for driving, when the remaining capacity of the battery becomes equal to or less than a predetermined preheating determination value, the electric heating of the catalyst device is started. And, when the remaining capacity of the battery becomes equal to or less than a predetermined start determination value smaller than the preheating determination value, the engine is started. In this way, in the above-described conventional control device, preheating of the catalyst device before engine start, that is, so-called preheating, is performed. Summary of the Invention

[0004] When the reduction rate of the remaining capacity of the battery after the start of preheating of the catalyst device is slower than expected, there may be a long time from the completion of preheating to engine start. In such a case, the catalyst device cools before engine start, and it is necessary to perform electric heating again, so the efficiency of electric heating deteriorates.

[0005] The control device for a hybrid vehicle that solves the above problems is a device for controlling a hybrid vehicle. The hybrid vehicle includes an engine and a motor as power sources for traveling, and has a first driving mode in which only the motor is used as the power source for traveling, and a second driving mode in which at least the engine is used as the power source for traveling as driving modes. The engine is provided with an electro-heated catalyst device in the exhaust passage that is heated by energization, and the motor generates power according to the power supply from the battery. And this control device performs the following processes: a switching process that switches the driving mode to the second driving mode when the remaining capacity of the battery becomes equal to or less than a predetermined mode switching remaining capacity during the driving in the first driving mode; a preheating process that is a process of electrically heating the catalyst device during the driving in the second driving mode, and starts energization of the catalyst device when the remaining capacity becomes equal to or less than an optimal energization remaining capacity that is larger than the mode switching remaining capacity; an arithmetic process that, when the driving load of the hybrid vehicle is large, calculates a larger value as the value of the optimal energization remaining capacity compared to when the driving load is small; and a correction process that reduces the input power of the catalyst device when the driving load decreases compared to when the energization of the catalyst device starts.

[0006] The engine stops during the first driving mode, but may start when the second driving mode starts. In the above control device, in order to preheat the catalyst device before the start of the second driving mode, a preheating process of electrically heating the catalyst device is performed.

[0007] The reduction rate of the remaining capacity of the battery is obtained based on the driving load of the hybrid vehicle during the driving in the first driving mode. If the reduction rate of the remaining capacity is known, the timing when the remaining capacity reaches the mode switching determination value can be predicted. Thus, by determining the remaining capacity at which energization starts according to the driving load, the start timing of the energization of the catalyst device is determined so that the preheating of the catalyst device is completed when the second driving mode starts. In the above control device, the remaining capacity of the battery at which such energization starts is obtained as the optimal energization remaining capacity.

[0008] In addition, if the driving load decreases after the start of power supply and the power consumption of the motor decreases, the start timing of the second driving mode will be delayed compared to the prediction at the start of power supply. On the other hand, if the input power to the catalyst device during the electric heating process is reduced, the completion timing of the preheating of the catalyst device will be delayed. Therefore, in the above control device, when the driving load decreases compared to the start of power supply to the catalyst device, the input power to the catalyst device is reduced. Therefore, even when the driving load decreases after the start of power supply, the power supply to the catalyst device can be implemented in such a way that the preheating is completed at an appropriate timing corresponding to the start of the second driving mode. Therefore, the efficiency of the electric heating of the catalyst device before engine start can be improved.

[0009] The correction process in the above control device may be as follows: when the value of the optimal remaining power supply capacity at the start of power supply to the catalyst device under the preheating process is set as the initial value of the power supply of the optimal remaining power supply capacity, and the value of the optimal remaining power supply capacity recalculated through arithmetic processing after the start of power supply to the catalyst device is set as the recalculated value of the optimal remaining power supply capacity, when the difference obtained by subtracting the recalculated value from the remaining capacity at the start of power supply is large, the input power is set to a smaller value compared to when the difference is small. If the correction process of the input power after the start of power supply is performed in this way, the completion timing of the preheating of the catalyst device based on electric heating can be adjusted according to the delay of the start timing of the second driving mode accompanying the decrease in the driving load. Furthermore, preferably, the correction process in such a case is a process of setting the value of the ratio of the value at the start of power supply to the input power to be “ΔS / (S0 - SHV)” as the value of the input power. Here, “S0” represents the initial value of the power supply, “ΔS” represents the difference obtained by subtracting the recalculated value from the initial value of the power supply, and “SHV” represents the remaining capacity for mode switching.

[0010] Sometimes the driving load decreases significantly after the start of power supply. If the input power is corrected corresponding to the significant decrease in the driving load, sometimes the input power is less than the energy taken away from the catalyst device due to heat dissipation to the outside air, etc., and the catalyst device cannot be heated up. Therefore, in the preheating process in the above control device, it is preferable to stop the power supply to the catalyst device when the above difference is larger than a predetermined interruption determination value.

[0011] In the switching process in the above control device, it may be that when the remaining capacity becomes less than or equal to the remaining capacity for mode switching, and when the preheating of the catalyst device based on electric heating is not completed, the driving mode is switched to the second driving mode when the preheating is completed. In such a case, the second driving mode is not started in the state where the preheating of the catalyst device is not completed. Description of the Drawings

[0012] Hereinafter, the features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described with reference to the accompanying drawings. In the drawings, the same reference numerals denote the same elements, and:

[0013] Figure 1 FIG. is a diagram schematically showing the configuration of an embodiment of a control device for a hybrid vehicle.

[0014] Figure 2 FIG. is a flowchart showing the processing steps of a driving mode switching control routine executed by the control device of this embodiment.

[0015] Figure 3 FIG. is a flowchart showing a part of the processing steps of a power-on control routine executed by the control device of this embodiment.

[0016] Figure 4 FIG. is a flowchart showing the remaining part of the processing steps of this power-on control routine.

[0017] Figure 5 In, (a) is a time chart showing the transition of the driving mode when the driving load has decreased after the start of power-on, (b) is a time chart showing the transition of the driving load when the driving load has decreased after the start of power-on, (c) is a time chart showing the transition of the power-on flag when the driving load has decreased after the start of power-on, (d) is a time chart showing the transition of the remaining capacity and the optimal power-on remaining capacity when the driving load has decreased after the start of power-on, (e) is a time chart showing the transition of the input power of the catalyst device when the driving load has decreased after the start of power-on, and (f) is a time chart showing the transition of the catalyst temperature when the driving load has decreased after the start of power-on. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, with reference to Figures 1 to 5 An embodiment of a control device for a hybrid vehicle will be described in detail.

[0019] <Configuration of Hybrid Vehicle>

[0020] First, with reference to Figure 1 , the configuration of a hybrid vehicle to which the control device 10 of this embodiment is applied will be described. As Figure 1 shown, the hybrid vehicle includes an engine 20 and a motor 21 as power sources. In addition, a main battery 22 for supplying power for driving and an auxiliary battery 23 for supplying power to auxiliary equipment of the engine 20 are mounted on the hybrid vehicle. Further, a charging connector 222 for external charging is connected to the main battery 22 via a DC-AC conversion circuit 221. In this way, the control device 10 of this embodiment is applied to a plug-in hybrid vehicle capable of external charging.

[0021] An electro-heated catalyst device 202 that generates heat according to energization is provided in the exhaust passage 201 of the engine 20. A substrate 203 carrying a catalyst for exhaust purification is accommodated in the catalyst device 202. For the substrate 203, a conductive porous material that generates heat according to energization is used. The substrate 203 of such a catalyst device 202 is connected to the auxiliary battery 23 via a power control circuit 204.

[0022] The motor 21 generates power according to the power supply from the main battery 22. That is, in the present embodiment, the main battery 22 among the above two batteries becomes the battery that supplies power to the motor 21. The motor 21 is connected to the drive wheels 25 via a reduction mechanism 24. On the other hand, the engine 20 is connected to the drive wheels 25 via a planetary gear mechanism 26 and a reduction mechanism 24.

[0023] In addition, a generator 27 (motor generator) is connected to the planetary gear mechanism 26. The generator 27 receives the driving force of the engine 20 or the drive wheels 25 and generates electricity. In addition, the generator 27 also functions as a starter that drives the engine 20 to rotate when the engine 20 is started. At this time, the generator 27 functions as a motor that generates power according to the power supply from the main battery 22.

[0024] The generator 27 and the motor 21 are connected to the main battery 22 via an inverter 28. The AC power generated by the generator 27 is converted into DC by the inverter 28 and charged into the main battery 22. The DC power of the main battery 22 is converted into AC by the inverter 28 and supplied to the motor 21.

[0025] The control device 10 is configured as an electronic control unit for vehicle control having a CPU, a ROM, a RAM, etc. Detection signals of sensors provided in various parts of the hybrid vehicle are input to the control device 10. These include the detection signals of the vehicle speed V, the accelerator pedal opening ACC, the remaining capacity SOC of the main battery 22, and the catalyst temperature TMP of the catalyst device 202. The control device 10 controls the operating state of the engine 20. In addition, the control device 10 controls the power running / regenerative torque of the motor 21 and the generator 27 by driving control of the inverter 28.

[0026] <Switching process of driving mode>

[0027] During the running of the hybrid vehicle, the control device 10 obtains the required driving force, which is the required value of the driving force of the hybrid vehicle, according to the vehicle speed V and the accelerator pedal opening ACC. And the drive control of the engine 20, the motor 21, and the generator 27 is performed in such a way as to obtain the driving force in an amount of the required driving force.

[0028] When the remaining capacity SOC of the main battery 22 has sufficient margin, the control device 10 travels in an EV driving mode that uses only the motor 21 as a driving power source. At this time, the control device 10 maintains the state where the engine 20 is stopped. And the control device 10 performs drive control of the converter 28 in such a way that the motor 21 generates a torque of a driving force amount that obtains the required driving force.

[0029] In addition, during the travel in the EV driving mode, when the remaining capacity SOC of the main battery 22 is lower than a certain value, the control device 10 switches the driving mode of the hybrid vehicle from the EV driving mode to a hybrid driving mode (hereinafter, referred to as the HV driving mode). The HV driving mode is a driving mode that uses both the engine 20 and the motor 21 as driving power sources. The control device 10 in the HV driving mode performs charge / discharge control of the main battery 22 in order to keep the remaining capacity SOC of the main battery 22 within a certain range. Charging of the main battery 22 in the charge / discharge control is performed by regenerative power generation of the motor 21. In addition, discharging of the main battery 22 in the charge / discharge control is performed by power running drive of the motor 21. The control device 10 calculates the driving force required for regenerative power generation of the motor 21 in the charge / discharge control, or the driving force generated by power running drive, as the value of the battery required driving force. And the control device 10 performs output control of the engine 20 in such a way as to obtain a driving force amount that is the sum of the required driving force and the battery required driving force. In addition, when the sum of the required driving force and the battery required driving force becomes 0 or less, the control device 10 stops the engine 20. In addition, in the present embodiment, the EV driving mode corresponds to the first driving mode that uses only the motor as a driving power source. In addition, the HV driving mode corresponds to the second driving mode that uses at least the engine as a driving power source.

[0030] Figure 2 It is a flowchart of a driving mode switching routine executed by the control device 10 in order to switch the driving mode from the EV driving mode to the HV driving mode. The control device 10 repeatedly executes this routine at every predetermined control cycle during the travel in the EV driving mode.

[0031] When starting this routine, the control device 10 first determines in step S100 whether the remaining capacity SOC of the main battery 22 is below a predetermined mode switching remaining capacity SHV. And when the remaining capacity SOC is above the mode switching remaining capacity SHV (No), the control device 10 directly ends the processing of this routine this time. In contrast, when the remaining capacity SOC is below the mode switching remaining capacity SHV (Yes), the control device 10 advances the processing to step S110.

[0032] When proceeding to the process of step S110, the control device 10 determines in this step S110 whether the catalyst temperature TMP is equal to or higher than a predetermined purification start temperature TMP2. When the catalyst temperature TMP is less than the purification start temperature TMP2 (No), the control device 10 directly ends the processing of this example routine. In contrast, when the catalyst temperature TMP is equal to or higher than the purification start temperature TMP2 (Yes), the control device 10 switches the driving mode from the EV driving mode to the HV driving mode in step S120.

[0033] In this way, the control device 10 switches from the EV driving mode to the HV driving mode on the condition that the remaining capacity SOC of the main battery 22 is lower than the mode switching remaining capacity SHV and the catalyst temperature TMP is equal to or higher than the purification start temperature TMP2. For the purification start temperature TMP2, the following temperature is set.

[0034] The catalyst supported on the catalyst device 202 becomes inactive at low temperatures. At this time, the catalyst device 202 is in a state where it does not exhibit exhaust purification ability. When the catalyst temperature TMP is increased from this state, the catalyst soon becomes active, and the catalyst device 202 exhibits a certain exhaust purification ability. The value of the catalyst temperature TMP at this time is set as the purification start temperature TMP2. Here, the state where the catalyst temperature TMP has become equal to or higher than the purification start temperature TMP2 is referred to as a state where the catalyst device 202 is partially preheated.

[0035] Furthermore, if the catalyst temperature TMP is further increased from the purification start temperature TMP2, the catalyst is fully activated, and the catalyst device 202 exhibits the maximum exhaust purification ability. In the following description, the catalyst temperature TMP at this time is denoted as the catalyst activation temperature TMP1. Here, the state where the catalyst temperature TMP has become equal to or higher than the catalyst activation temperature TMP1 is referred to as a state where the catalyst device 202 is fully preheated.

[0036] The engine 20 stops in the EV driving mode. And when the driving mode is switched from the EV driving mode to the HV driving mode, the engine 20 may start at that time point. On the other hand, if the catalyst temperature TMP at the time of starting the engine 20 is equal to or higher than the purification start temperature TMP2, the catalyst device 202 exhibits a certain level or more of exhaust purification ability immediately after starting. For this, in the present embodiment, "the catalyst temperature TMP is equal to or higher than the purification start temperature TMP2", that is, "the partial preheating of the catalyst device 202 is completed" is included in the switching condition from the EV driving mode to the HV driving mode. And thereby, the engine 20 is always started in a state where a certain level or more of exhaust purification ability can be obtained.

[0037] <Power supply control of the catalyst device>

[0038] In addition, the control device 10 performs a preheating process of electrically heating the catalyst device 202 before switching from the EV driving mode to the HV driving mode. Hereinafter, the energization control of the catalyst device 202 for such a preheating process will be described.

[0039] In Figure 3 and Figure 4 FIGs. are shown flowcharts of an energization control routine executed by the control device 10 to perform such energization control. The control device 10 repeatedly executes this routine at every predetermined control cycle during the running in the EV driving mode.

[0040] In addition, after the end of this routine, the control device 10 confirms whether the energization flag is in the set state. And, in the case where the energization flag is in the cleared state, the control device 10 sets to the state of stopping the energization of the catalyst device 202. On the other hand, in the case where the energization flag is in the set state, the control device 10 supplies the amount of power E of the input power set in this routine to perform the energization to the catalyst device 202.

[0041] When starting this routine, the control device 10 first calculates the running load W based on the vehicle speed V and the accelerator pedal opening ACC in step S200. In the EV driving mode, the driving force of the hybrid vehicle is generated solely by the motor 21. The running load W is an index value of the magnitude of the load of such a motor 21. In the present embodiment, the power consumption of the motor 21 is used as the value of the running load W.

[0042] Next, the control device 10 calculates the optimum energization remaining capacity SOP based on the running load W calculated in step S200 in step S210. The optimum energization remaining capacity SOP is calculated as the following value. Here, it is assumed that the running load W is maintained at the current value until the start of the HV driving mode. In addition, it is assumed that the preheating process is performed in such a manner that the catalyst temperature TMP reaches the catalyst activation temperature TMP1 at the same time as the start of the HV driving mode. The optimum energization remaining capacity SOP represents the remaining capacity SOC of the main battery 22 at the start of the energization of the catalyst device 202 in the preheating process at this time. In addition, of course, the optimum energization remaining capacity SOP is a value larger than the mode switching remaining capacity SHV.

[0043] In addition, as described below, in the present embodiment, the input power E of the catalyst device 202 at the start of the preheating process is set such that the catalyst temperature TMP reaches the catalyst activation temperature TMP1 through energization for a certain period of time. In the following description, the above-mentioned certain period of time is denoted as the required energization time HT. In such a case, it is considered that if the energization of the catalyst device 202 is started before the required energization time HT prior to the start of the HV driving mode, the catalyst temperature TMP reaches the catalyst activation temperature TMP1 at the same time as the start of the HV driving mode. And if it is set that "the driving load W is maintained at the current value until the start of the HV driving mode", the power consumption of the motor 21 from the start of energization until the start of the HV driving mode becomes the product of the current value of the driving load W and the required energization time HT. Therefore, in the present embodiment, the value obtained by adding the product of "the driving load W and the required energization time HT" to "the remaining capacity SHV for mode switching" (= SHV + W × HT) is obtained as the value of the optimal remaining energization capacity SOP.

[0044] When the optimal remaining energization capacity SOP is calculated in this way, in the next step S220, the control device 10 determines whether the energization flag is in the cleared state. As described below, the energization flag is a flag that is in the set state at the start of the energization of the catalyst device 202 during the preheating process and in the cleared state at the stop of energization. That is, in step S220, it is determined whether the energization of the catalyst device 202 is being performed. And when the energization flag is in the cleared state (Yes), the control device 10 advances the process to step S230, and when it is in the set state (No), the control device 10 advances the process to Figure 4 step S300. That is, Figure 3 The processing after step S230 is processing that is performed when the energization of the catalyst device 202 is not in progress. In addition, Figure 4 The processing after step S300 is processing that is performed when the energization of the catalyst device 202 is in progress.

[0045] Here, first, the processing when the energization is not in progress will be described. When the control device 10 advances the process to step S230, in this step S230, it is determined whether the current remaining capacity SOC of the main battery 22 is less than or equal to the optimal remaining energization capacity SOP. And when the current remaining capacity SOC is less than or equal to the optimal remaining energization capacity SOP (Yes), the control device 10 advances the process to step S240. In contrast, when the current remaining capacity SOC exceeds the optimal remaining energization capacity SOP (No), the processing of this example routine is directly ended as it is.

[0046] When the process proceeds to step S240, the control device 10 determines in this step S240 whether the catalyst temperature TMP is less than the purification start temperature TMP2. And, when the catalyst temperature TMP is less than the purification start temperature TMP2 (Yes), the control device 10 causes the process to proceed to step S250. In contrast, when the catalyst temperature TMP is equal to or higher than the purification start temperature TMP2 (No), the control device 10 directly ends the processing of this example routine as it is.

[0047] When causing the process to proceed to step S250, the control device 10 sets an energization flag in this step S250. Next, the control device 10 sets the value of the current optimal remaining energization capacity SOP to the value of the initial energization value S0 in step S260. In addition, in the next step S270, the control device 10 calculates the initial input power E0 based on the current catalyst temperature TMP. Here, the control device 10 calculates the value of "the input power E that can raise the catalyst temperature TMP from the current value to the catalyst activation temperature TMP1 when the input power E is kept constant and energization for the required energization time HT is performed" as the value of the initial input power E0. Specifically, the control device 10 first obtains the amount of electric power required to raise the catalyst temperature TMP from the current value to the catalyst activation temperature TMP1. In the following description, the amount of electric power required for "raising the temperature to the catalyst activation temperature TMP1" is denoted as the required electric power amount P. The control device 10 calculates the quotient obtained by dividing the required electric power amount P by the required energization time HT as the value of the initial input power E0 (E0 = P / HT). Then, the control device 10 sets the initial input power E0 to the input power E of the catalyst device 202 in the next step S280, and then ends the processing of this example routine. As described above, when the remaining capacity SOC of the main battery 22 is equal to or less than the optimal remaining energization capacity SOP and the catalyst temperature TMP is less than the purification start temperature TMP2, the energization of the catalyst device 202 is started.

[0048] Next, the processing in the case where energization is in progress is described. As described above, at this time, the control device 10 proceeds to Figure 4Processing of step S300. When the control device 10 advances the processing to step S300, it determines in this step S300 whether the catalyst temperature TMP is less than the catalyst activation temperature TMP1. And when the catalyst temperature TMP is less than the catalyst activation temperature TMP1 (yes), the control device 10 advances the processing to step S320. On the other hand, when the catalyst temperature TMP is equal to or higher than the catalyst activation temperature TMP1 (no), the control device 10 advances the processing to step S310. And the control device 10 clears the power-on flag in this step S310 and then ends the processing of this example routine. That is, when the catalyst temperature TMP reaches the catalyst activation temperature TMP1 after the power-on starts and the complete preheating of the catalyst device 202 is completed, the control device 10 stops the power supply to the catalyst device 202.

[0049] In contrast, in the case of the processing advancing to step S310, the control device 10 determines in this step S310 whether the difference ΔS (= S0 - SOP) obtained by subtracting the optimal power-on remaining capacity SOP from the power-on initial value S0 is less than the interruption determination value ΔS1. A predetermined positive value is set for the interruption determination value ΔS1. And when the above difference ΔS is less than the interruption determination value ΔS1 (yes), the control device 10 advances the processing to step S330. In contrast, when the above difference ΔS is equal to or higher than the interruption determination value ΔS1 (no), the control device 10 advances the processing to the above step S310. Thus, in this case, the power-on flag is in a cleared state and the power supply to the catalyst device 202 is stopped. That is, the electric heating of the catalyst device 202 is interrupted in a state where the complete preheating is not completed.

[0050] In addition, the power-on initial value S0 represents the value of the optimal power-on remaining capacity SOP at the start of power-on. The calculation of the optimal power-on remaining capacity SOP is performed each time this example routine is executed. Thus, if the driving load W changes after the power-on starts, the value of the optimal power-on remaining capacity SOP also changes from the value at the start of power-on. The smaller the driving load W, the smaller the value of the optimal power-on remaining capacity SOP. Thus, when the driving load W has decreased significantly after the power-on starts, the power supply to the catalyst device 202 is stopped.

[0051] On the other hand, in the case of proceeding to the process of step S330, the control device 10 determines in this step S330 whether the above difference ΔS is less than a predetermined misprediction determination value ΔS2. For the misprediction determination value ΔS2, a positive value smaller than the above interruption determination value ΔS1 is set. And when the above difference ΔS is less than the misprediction determination value ΔS2 (Yes), the control device 10 sets the initial input power E0 to the value of the input power E in step S340, and then ends the processing of this example routine. In contrast, when the above difference ΔS is equal to or more than the misprediction determination value ΔS2 (No), the control device 10 advances the process to step S350. And the control device 10 calculates, in this step S350, a value that satisfies the relationship of formula (1) as the value of the input power E, and then ends the processing of this example routine. In addition, the value of the input power E that satisfies the relationship of formula (1) is the input power E required to "raise the temperature of the catalyst device 202 to the catalyst activation temperature TMP1 at the start of the HV driving mode delayed due to the decrease in the driving load W".

[0052]

[0053] <Functions and effects of the embodiment>

[0054] The functions and effects of this embodiment configured as described above will be described.

[0055] In Figure 5 shows an example of an embodiment of the energization control in the case where the driving load W has decreased after the start of energization. In addition, in Figure 5 (a) shows the transition of the driving mode, in Figure 5 (b) shows the transition of the driving load W, in Figure 5 (c) shows the transition of the energization flag. In addition, in Figure 5 (d) shows the transition of the remaining capacity SOC of the main battery 22 and the optimal energization remaining capacity SOP, in Figure 5 (e) shows the transition of the input power E of the catalyst device 202, in Figure 5 (f) shows the transition of the catalyst temperature TMP. In addition, in Figure 5 the transitions of the driving mode, the driving load W, the energization flag, the remaining capacity SOC, the input power E, and the catalyst temperature TMP are shown together with a dashed line even when the driving load W does not change after the start of energization.

[0056] In Figure 5 , at time t1, the remaining capacity SOC of the main battery 22 becomes less than the optimal energization remaining capacity SOP, and the energization flag is set to the set state. If the driving load W remains the same as the value at time t1 after the start of energization, then in Figure 5At time t3, the remaining capacity SOC of the main battery 22 decreases to the remaining capacity SHV for mode switching. And at this time t3, the driving mode switches from the EV driving mode to the HV driving mode. At time t1, the input power E is set so that the catalyst temperature TMP becomes the catalyst activation temperature TMP1 at time t3, and the energization of the catalyst device 202 is started. The time t3 is the predicted start time of the HV driving mode based on the current driving load W.

[0057] At Figure 5 After time t1 when the energization starts, the driving load W decreases. When the driving load W decreases, the power consumption of the motor 21 decreases, so the decreasing speed of the remaining capacity SOC decreases. Therefore, at time t4 which is later than the predicted time t3 at the start of energization, the remaining capacity SOC decreases to the remaining capacity SHV for mode switching and the HV driving mode starts. In this regard, if the input power E of the catalyst device 202 is maintained at the value at the start of energization, the catalyst temperature TMP will reach the catalyst activation temperature TMP1 at time t3 and the energization of the catalyst device 202 will stop. Therefore, in such a case, the catalyst temperature TMP may drop before the start of the HV driving mode.

[0058] In addition, when the catalyst temperature TMP drops below the purification start temperature TMP2 after the energization stops, the catalyst device 202 is re-energized. Therefore, the catalyst temperature TMP at the start of the HV driving mode becomes equal to or higher than the purification start temperature TMP2, ensuring a certain degree of exhaust purification ability when the engine 20 starts. However, if re-energization is performed, the power consumption will increase accordingly and the efficiency of the electric heating deteriorates.

[0059] On the contrary, the control device 10 also recalculates the optimal energization remaining capacity SOP based on the current driving load W after the start of energization. When the value of the recalculated optimal energization remaining capacity SOP is smaller than the value calculated at the start of energization, the start of the HV driving mode is delayed compared to the prediction at the start of energization. Therefore, when the difference ΔS obtained by subtracting the optimal energization remaining capacity SOP from the initial energization value S0 is equal to or greater than the misprediction determination value ΔS2, the input power E is corrected. At Figure 5 In this case, at time t2, the difference ΔS becomes equal to or greater than the misprediction determination value ΔS2, and the input power E is corrected to a value smaller than the initial input power E0. After that, the input power E is also corrected according to the change in the driving load W. Therefore, the catalyst device 202 is energized so that the catalyst temperature TMP reaches the catalyst activation temperature TMP1 at time t4 when the HV driving mode starts.

[0060] Even if the driving load W decreases after the start of power-on, when the decrease is small, the delay of the "start period of the HV driving mode" relative to the "period predicted at the start of power-on" is also small. In such a case, even if the input power E is maintained at the initial input power E0 for power-on, the HV driving mode can be started immediately after the preheating of the catalyst device 202 is completed. Therefore, when the difference ΔS is less than the misprediction determination value ΔS2, that is, when the decrease in the driving load W after the start of power-on is small, the control device 10 maintains the input power E at the initial input power E0 without correction.

[0061] In addition, sometimes the driving load W may decrease significantly when the hybrid vehicle stops after the start of power-on. If the input power E is corrected based on the decrease in the driving load W in such a case, the energy taken away from the catalyst device 202 due to heat dissipation to the outside air, etc. will be greater than the input power E, and sometimes the catalyst temperature TMP cannot be further increased. Therefore, when the difference ΔS becomes equal to or greater than the interruption determination value ΔS1 after the start of power-on, the control device 10 stops power-on and interrupts the electric heating.

[0062] In such a present embodiment, Figure 2 the processing of the driving mode switching control routine corresponds to the switching process. In addition, Figure 3 and Figure 4 the processing of the power-on control routine corresponds to the preheating process. Furthermore, in the power-on control routine, Figure 3 the processing of step S210 corresponds to the arithmetic process, Figure 4 and the processing of steps S340 and S350 corresponds to the correction process.

[0063] According to the control device 10 of the hybrid vehicle according to the above present embodiment, the following effects can be achieved.

[0064] (1) The control device 10 performs a preheating process of energizing the catalyst device 202 before switching from the EV driving mode to the HV driving mode. In the preheating process, the control device 10 sets the input power E at the start of energization in such a manner that the catalyst temperature TMP reaches the catalyst activation temperature TMP1 at the start of the HV driving mode predicted based on the driving load W. On the other hand, when the driving load W decreases after the start of energization of the catalyst device 202, the control device 10 corrects the input power E to a value smaller than that at the start of energization. If the driving load W decreases after the start of energization, the start period of the HV driving mode will be a period later than the period expected at the start of energization. If the input power E is reduced, the period for completing the full preheating of the catalyst device 202 by electric heating will be delayed. Therefore, even when the driving load W decreases after the start of energization, the "period for completing the full preheating of the catalyst device 202 by electric heating" and the "start period of the HV driving mode" will not deviate significantly. Therefore, the efficiency of electric heating of the catalyst device 202 can be improved.

[0065] (2) As a corrected value of the input power E when the driving load W decreases after the start of energization, a value satisfying the relationship of formula (1) is set. Therefore, the energization control can be performed in such a manner that "the full preheating of the catalyst device 202 to the catalyst activation temperature TMP1 is completed at the start of the HV driving mode delayed due to the decrease in the driving load W".

[0066] (3) After the start of energization, when the difference ΔS obtained by subtracting the recalculated value of the optimal remaining energization capacity SOP from the energization initial value S0 becomes equal to or greater than the interruption determination value ΔS1, the control device 10 interrupts the energization of the catalyst device 202. Therefore, energization is not unnecessarily continued when the start of the HV driving mode is significantly delayed due to a large decrease in the driving load W after the start of energization.

[0067] (4) Even when the remaining capacity SOC of the main battery 22 becomes less than or equal to the mode switching remaining capacity SHV, the control device 10 does not start the HV driving mode until the catalyst temperature TMP becomes equal to or greater than the purification start temperature TMP2. Therefore, the engine 20 is not started in a state where the catalyst device 202 does not exhibit the exhaust purification ability.

[0068] This embodiment can be implemented with the following modifications. This embodiment and the following modification examples can be combined and implemented within a range where there is no technical contradiction between them.

[0069] The operation map storing the value of the input power E that satisfies the relationship of Expression (1) for each combination of the two values, i.e., the initial energization value S0 and the recalculated value, for the optimal energization remaining capacity SOP, is stored in the ROM of the control device 10 in advance. Then, this operation map can be used to perform Figure 4 the calculation of the corrected value of the input power E in step S350 of

[0070] In the above-described embodiment, the running load W is obtained based on the vehicle speed V and the accelerator pedal opening ACC, but the running load W may also be obtained based on other parameters such as the generated torque, voltage, and current of the motor 21.

[0071] In the above-described embodiment, the initial input power E0 is variably set according to the catalyst temperature TMP, but the initial input power E0 may also be set to a fixed value regardless of the catalyst temperature TMP.

[0072] In the above-described embodiment, "completion of partial preheating of the catalyst device 202" is included in the switching condition from the EV driving mode to the HV driving mode. Instead of partial preheating, "completion of full preheating" may be included in the switching condition. Additionally, "completion of 'partial preheating' or 'full preheating'" may not be included in the switching condition.

[0073] In the above-described embodiment, when the difference ΔS is less than the interruption determination value ΔS1 after the start of energization, i.e., when the running load W has significantly decreased, the energization of the catalyst device 202 is interrupted in a state where full preheating is not completed. The processing of such energization interruption may also be omitted.

[0074] In the above-described embodiment, as the corrected value of the input power E when the running load W decreases after the start of energization, a value that satisfies the relationship of Expression (1) is set, but the corrected value may also be calculated by other means. Also in this case, as long as the corrected value is set in such a way that the input power E is reduced when the above difference ΔS is large compared to when the difference ΔS is small, the efficiency of electric heating can be improved. Additionally, instead of using the recalculated value of the optimal energization remaining capacity SOP, the corrected value of the input power E may be obtained based on the running load W. In short, as long as the input power E is corrected to a value smaller than that at the start of energization when the running load W has decreased compared to the start of energization, the efficiency of electric heating is improved.

[0075] A hybrid vehicle that can consider an engine driving mode in which only the engine 20 is used as a driving power source instead of the HV driving mode is considered. When the control device of the above-described embodiment is applied to such a hybrid vehicle, the HV driving mode in the above-described embodiment is replaced with the engine driving mode. Also in this case, by applying the energization control routine in the above-described embodiment, the same operational effects as those of the above-described embodiment can be obtained. Further, in this case, the engine driving mode becomes a driving mode corresponding to the second driving mode.

[0076] Furthermore, a hybrid vehicle having three driving modes, namely an EV driving mode, an HV driving mode, and an engine driving mode, is also considered. In such a hybrid vehicle, in step S120 of the driving mode switching control routine, a switch is made to either the HV driving mode or the engine driving mode. Also in this case, as long as the energization control routine is implemented, the same operational effects as those of the above-described embodiment can be obtained. In such a case, both the HV driving mode and the engine driving mode become driving modes corresponding to the second driving mode.

Claims

1. A control device for a hybrid vehicle, which controls the hybrid vehicle, The hybrid vehicle includes an engine and a motor as power sources for traveling, and has a first traveling mode in which only the motor is used as a power source for traveling, and a second traveling mode in which at least the engine is used as a power source for traveling as traveling modes. The engine is provided with an electro-heated catalyst device in the exhaust passage that is heated by energization, and the motor generates power according to power supply from a battery. The control device performs the following processes: A switching process, during traveling in the first traveling mode, when the remaining capacity of the battery becomes equal to or less than a predetermined mode switching remaining capacity, the traveling mode is switched to the second traveling mode; A preheating process, which is a process of electrically heating the catalyst device during traveling in the first traveling mode, and starts energization of the catalyst device when the remaining capacity becomes equal to or less than an optimal energization remaining capacity that is larger than the mode switching remaining capacity; An arithmetic process, when the driving load of the hybrid vehicle is large, a larger value is calculated as the value of the optimal energization remaining capacity compared to when the driving load is small; And A correction process, when the driving load has decreased compared to when energization of the catalyst device started, reduces the input power of the catalyst device, The correction process is as follows: when the value of the optimal energization remaining capacity at the start of energization of the catalyst device in the preheating process is set as the energization initial value of the optimal energization remaining capacity, and the value of the optimal energization remaining capacity recalculated by the arithmetic process after the start of energization of the catalyst device is set as the recalculated value of the optimal energization remaining capacity, the energization initial value is set as "S0", the difference obtained by subtracting the recalculated value from the energization initial value is set as "ΔS", and the mode switching remaining capacity is set as "SHV", the value of the input power is set such that the ratio of the value at the start of energization to the input power becomes "ΔS / (S0 - SHV)".

2. The control device for a hybrid vehicle according to claim 1, In the preheating process, when the difference is larger than a predetermined interruption determination value, the energization of the catalyst device is stopped.

3. The control device for a hybrid vehicle according to claim 1 or 2, In the switching process, when the remaining capacity becomes equal to or less than the mode switching remaining capacity, if the preheating of the catalyst device based on the electric heating is not completed, the traveling mode is switched to the second traveling mode when the preheating is completed.

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