Control device of hybrid vehicle

Abstract

To provide a control device of a hybrid vehicle that can prevent an EV mode and a hybrid mode from being switched frequently.SOLUTION: When a transitional condition is satisfied during running of a vehicle in an EV mode, a CTU (a control device) starts an engine after a first determination time ΔTa1 elapses to switch a running mode from the EV mode to an HV mode (a hybrid mode). When the transitional condition is satisfied during running of the vehicle in the HV mode, the CTU stops the engine after a second determination time ΔTa2 elapses to switch the running mode from the HV mode to the EV mode. When a maximum value (a maximum value Xmax or a minimum value Xmin) of a maximum value of an absolute value of an APS change rate X is a predetermined value Xs or higher, in a period of time during which the transitional condition was satisfied previously and subsequently satisfied this time, the CTU adds a delay time ΔTb to the first determination time ΔTa1 and the second determination time ΔTa2.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a control device for a hybrid vehicle. [Background technology]

[0002] Conventionally, there is known a technique related to a control device for a hybrid vehicle that can switch between an EV mode in which the vehicle runs using an electric motor as a power source and a hybrid mode in which the vehicle runs using an internal combustion engine and an electric motor as a power source. For example, Patent Document 1 describes a hybrid vehicle that is equipped with an EV priority switch that delays the timing of switching from the EV mode to the hybrid mode to give priority to the EV mode. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-008544 A Summary of the Invention [Problem to be solved by the invention]

[0004] When switching between the EV mode and the hybrid mode, the vehicle speed and the required output of the vehicle are taken into consideration. Therefore, for example, when the driver operates the accelerator to accelerate or decelerate suddenly, switching from the EV mode to the hybrid mode and from the hybrid mode to the EV mode occurs frequently, which may affect fuel efficiency and the driver's riding comfort. However, the hybrid vehicle described in the above Patent Document 1 prioritizes the EV mode only while the EV priority switch is on, so it cannot suppress frequent switching of the driving mode caused by the driver's accelerator operation.

[0005] The present invention has been made in consideration of these problems, and its object is to provide a control device for a hybrid vehicle that can suppress frequent switching between EV mode and hybrid mode. [Means for solving the problem]

[0006] In order to achieve the above object, the control device for a hybrid vehicle of the present invention is a control device for a hybrid vehicle that runs by switching between an EV mode, in which the vehicle runs using an electric motor as a power source, and a hybrid mode, in which the vehicle runs using an internal combustion engine and the electric motor as power sources, depending on whether a transition condition is satisfied.When the transition condition is satisfied while the vehicle is running in the EV mode, the control device switches the driving mode from the EV mode to the hybrid mode after a first judgment time has elapsed, and when the transition condition is satisfied while the vehicle is running in the hybrid mode, the control device switches the driving mode from the hybrid mode to the EV mode after a second judgment time has elapsed, and when the maximum absolute value of the APS change rate, which is the rate of change in accelerator opening, is equal to or greater than a predetermined value between the time when the transition condition was satisfied last time and the time when the transition condition is satisfied this time, a delay time is added to the first judgment time and the second judgment time. Effect of the Invention

[0007] According to the control device for a hybrid vehicle of the present invention, frequent switching between the EV mode and the hybrid mode can be suppressed. [Brief description of the drawings]

[0008] [Figure 1] 1 is a schematic diagram showing a hybrid vehicle equipped with a control device according to an embodiment; [Diagram 2] FIG. 11 is an explanatory diagram showing an example of a map that defines the relationship between the maximum value (absolute value) of the APS change rate and the overall judgment time. [Diagram 3] FIG. 11 is an explanatory diagram showing an example of operation when a vehicle traveling in an EV mode is accelerating slowly. [Figure 4] FIG. 11 is an explanatory diagram showing an example of operation when a vehicle traveling in HV mode slowly decelerates. [Diagram 5] 10A and 10B are explanatory diagrams showing an example of operation when a vehicle traveling in an EV mode accelerates or decelerates. [Figure 6] 10A and 10B are explanatory diagrams showing an example of operation when a vehicle running in EV mode suddenly accelerates and then suddenly decelerates. [Figure 7] FIG. 11 is an explanatory diagram showing an example of operation when a vehicle running in HV mode suddenly decelerates and then suddenly accelerates. [Figure 8] 10 is a flowchart showing an example of setting control of a total judgment time. [Figure 9] 11 is an explanatory diagram showing an example of operation when a vehicle traveling in EV mode accelerates in a case where a high responsiveness mode is set or the available output power of the battery is lower than a predetermined power value. FIG. [Figure 10] 10 is an explanatory diagram showing an example of operation when a vehicle traveling in HV mode decelerates when a high responsiveness mode is set or when the battery's available output power is lower than a predetermined power value. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a schematic diagram showing a hybrid vehicle equipped with a control device of the embodiment. A hybrid vehicle 1 (hereinafter referred to as "vehicle 1") of the embodiment is a plug-in hybrid vehicle having front wheels 3 and rear wheels 5, capable of running by driving the wheels with the output of an engine 2 (internal combustion engine), and equipped with an electric front motor 4 (electric motor) that drives the wheels. Note that a plug-in hybrid vehicle is a vehicle that has external charging, which supplies power from an external power source to a power storage device mounted on the vehicle for charging, and external power supply, which supplies power from a battery to electrical appliances outside the vehicle.

[0010] The engine 2 drives a drive shaft 8 of the front wheels 3 via a front transaxle 7, and also drives a motor generator 9 via the front transaxle 7 to generate electricity. The engine 2 and the front wheels 3 are connected via a clutch 16 arranged in the front transaxle 7. The vehicle 1 is provided with a fuel tank 17 that stores fuel to be supplied to the engine 2. The front motor 4 is driven by high-voltage power supplied from a battery 11 (electricity storage device) and the motor generator 9 mounted on the vehicle 1, and drives the drive shaft 8 of the front wheels 3 via the front transaxle 7. The motor generator 9 can charge the battery 11 with the generated power, and can also supply power to the front motor 4. The battery 11 is formed of a secondary battery such as a lithium-ion battery, and is provided with a charging rate detection unit 11a that detects the charging rate (SOC: State Of Charge). The battery 11 is also provided with a temperature detection unit 11b that detects the temperature of the battery 11.

[0011] The vehicle 1 is equipped with a control unit 20 (hereinafter referred to as "CTU 20") as a control device. The CTU 20 is configured to include an input / output device, a memory device (ROM, RAM, non-volatile RAM, etc.), a central processing unit (CPU), a timer, etc. The CTU 20 controls the APS opening degree α (accelerator opening degree) from the accelerator position sensor 12, the driving mode, the output of the front motor 4, the power generation amount and output of the motor generator 9, the fuel injection amount and fuel injection timing in the engine 2, etc.

[0012] The above-mentioned driving modes include an EV mode and a hybrid mode (hereinafter referred to as "HV mode"). In the EV mode, the engine 2 is stopped, and the front motor 4 is driven by electric power supplied from the battery 11 to drive the vehicle. The HV mode includes a series mode and a parallel mode. In the series mode, the clutch 16 of the front transaxle 7 is disconnected, the engine 2 operates the motor generator 9 to generate electricity, and the front motor 4 is driven by the electric power generated by the motor generator 9 and the electric power supplied from the battery 11 to drive the vehicle. In the parallel mode, the clutch 16 of the front transaxle 7 is connected, and power is mechanically transmitted from the engine 2 and the front motor 4 is driven to drive the front wheels 3. The CTU 20 switches the driving mode according to a number of transition conditions, such as the speed of the vehicle 1, the required output required of the vehicle by the driver, and the charging rate and temperature of the battery 11.

[0013] Furthermore, when a transition condition is satisfied while traveling in EV mode, i.e., when an ENG operation condition is satisfied as a condition for operating the engine 2, the CTU 20 transitions the mode after the overall judgment time ΔT (FIG. 2) has elapsed. Similarly, when a transition condition is satisfied while traveling in HV mode, i.e., when an ENG operation condition is not satisfied, the CTU 20 transitions the mode after the overall judgment time ΔT (FIG. 2) has elapsed. As described above, the ENG operation condition is determined according to the vehicle speed, required output, the charging rate and temperature of the battery 11, etc.

[0014] FIG. 2 is a map showing an example of the total judgment time ΔT. The total judgment time ΔT is set when switching from the EV mode to the HV mode (solid line) and when switching from the HV mode to the EV mode (two-dot chain line). The total judgment time ΔT is set as a value obtained by adding a delay time ΔTb to a first judgment time ΔTa1 and a second judgment time ΔTa2 that are set in advance. The first judgment time ΔTa1 is a judgment time corresponding to switching from the EV mode to the HV mode, and is set as a time required from the establishment of a transition condition from the EV mode to the HV mode until the completion of the process of starting the engine 2 and causing it to completely explode. The second judgment time ΔTa2 is a judgment time corresponding to switching from the HV mode to the EV mode, and is set as a time required from the establishment of a transition condition from the HV mode to the EV mode until the completion of the stop process of the engine 2. Note that FIG. 2 shows an example in which the first judgment time ΔTa1 and the second judgment time ΔTa2 are set to the same value.

[0015] The delay time ΔTb includes a first delay time ΔTb1 corresponding to switching from the EV mode to the HV mode, and a second delay time ΔTb2 corresponding to switching from the HV mode to the EV mode. The delay time ΔTb is set based on the maximum absolute value of the APS change rate X, which is the rate of change of the APS opening α from the time the ENG operating condition was satisfied last time to the time it is satisfied this time. The APS change rate X is calculated by the CTU 20 as the rate of change for a predetermined time based on the APS opening α from the accelerator position sensor 12.

[0016] Specifically, the delay time ΔTb is set to 0 when the maximum absolute value of the APS change rate X is less than a predetermined value Xs. In this case, the overall judgment time ΔT coincides with the first judgment time ΔTa1 and the second judgment time ΔTa2. In contrast, when the maximum absolute value of the APS change rate X is equal to or greater than the predetermined value Xs, the delay time ΔTb is set to be larger as the APS change rate X increases. Now, within the range in which the delay time ΔTb changes, the range from the predetermined value Xs to near the median at the maximum absolute value of the APS change rate X is defined as the "first range ΔX1," the range near the median as the "second range ΔX2," and the range from near the median to the maximum value as the "third range ΔX3." At this time, the delay time ΔTb is set so as to increase most slowly in the first range ΔX1, increase most steeply in the second range ΔX2, and increase more steeply in the third range ΔX3 than in the first range ΔX1 and more slowly than in the second range ΔX2, as the maximum absolute value of the APS change rate X becomes larger, and to converge at predetermined maximum values ​​ΔTb1max, ΔTb2max.

[0017] As a result, the delay time ΔTb and therefore the overall judgment time ΔT are set to draw an approximately S-shaped curve as the maximum value of the absolute value of the APS change rate X increases. In other words, if the driver's accelerator operation is steeper than near the median, the overall judgment time ΔT tends to be longer, and if it is gentler than near the median, the overall judgment time ΔT tends to be shorter, so that the driver's accelerator operation can be more appropriately reflected in the overall judgment time ΔT. In addition, by setting predetermined maximum values ​​ΔTb1max and ΔTb2max, it is possible to prevent the overall judgment time ΔT from becoming excessively long. The maximum values ​​ΔTb1max and ΔTb2max may be determined based on, for example, experiments, analysis, and accumulated experience with actual vehicles, as values ​​that can prevent the overall judgment time ΔT from becoming excessively long and the transition of the driving mode from being unsmooth.

[0018] Next, an operation example when switching the driving mode using the above-mentioned total judgment time ΔT will be described. FIG. 3 is an explanatory diagram showing an operation example when the vehicle 1 running in EV mode accelerates slowly. FIG. 4 is an explanatory diagram showing an operation example when the vehicle 1 running in HV mode decelerates slowly. FIG. 5 is an explanatory diagram showing an operation example when the vehicle 1 running in EV mode accelerates and decelerates quickly. FIG. 6 is an explanatory diagram showing an operation example when the vehicle 1 running in EV mode accelerates and decelerates quickly after suddenly accelerating. FIG. 7 is an explanatory diagram showing an operation example when the vehicle 1 running in HV mode accelerates and decelerates quickly after suddenly decelerating. FIGS. 3 to 7 show the time changes of (a) vehicle speed V, (b) APS opening α, (c) APS change rate X, (d) whether the ENG operation condition is satisfied or not satisfied, (e) a driving mode of a comparative example, and (f) a driving mode of this embodiment. The comparative example (e) represents a driving mode when the first judgment time ΔTa1 or the second judgment time ΔTa2 is set as the total judgment time ΔT without setting the delay time ΔTb.

[0019] As shown in Fig. 3, it is assumed that in a vehicle 1 running in EV mode, the APS opening degree α starts to increase at time t1, the vehicle 1 accelerates slowly, and the ENG operation condition is satisfied at time t2. At this time, since the maximum value Xmax of the APS change rate X on the acceleration side (positive side) is less than the positive predetermined value Xs, the overall judgment time ΔT is set to the first judgment time ΔTa1 in both the comparative example and the embodiment, and after the first judgment time ΔTa1 has elapsed from time t2, the start of the engine 2 is completed and the running mode is switched from the EV mode to the HV mode. Also, as shown in Fig. 4, it is assumed that in a vehicle 1 running in HV mode, the APS opening degree α starts to decrease at time t1, the vehicle 1 decelerates slowly, and the ENG operation condition is not satisfied at time t2. At this time, since the minimum value Xmin of the APS change rate X on the deceleration side (negative side) is greater than the negative predetermined value Xs ("-Xs" in the figure), the overall judgment time ΔT is set to the second judgment time ΔTa2 in both the comparative example and the embodiment, and after the second judgment time ΔTa2 has elapsed from time t4, the engine 2 is stopped and the driving mode is switched from the HV mode to the EV mode.

[0020] In this way, while the vehicle 1 is running in the EV mode (FIG. 3), the CTU 20 monitors the value of the APS change rate X on the acceleration side (positive side) and judges whether the maximum value Xmax is equal to or greater than the positive predetermined value Xs. Also, while the vehicle 1 is running in the HV mode (FIG. 4), the CTU 20 monitors the value of the APS change rate X on the deceleration side (negative side) and judges whether the minimum value Xmin is equal to or less than the negative predetermined value Xs. That is, the maximum value Xmax and the minimum value Xmin are the maximum absolute values ​​of the APS change rate X, and the CTU 20 judges whether the maximum absolute value of the APS change rate X is equal to or greater than the absolute predetermined value Xs. The predetermined value Xs is a threshold value that distinguishes between a case where the APS opening degree α changes slowly so that the transition from the EV mode to the HV mode or the transition from the HV mode to the EV mode is not repeated frequently and a case where the transition is repeated frequently, and is determined based on, for example, experiments, analysis, accumulated experience with actual machines, and the like. Therefore, if the maximum absolute value of the APS change rate X is less than the predetermined value Xs, the driving mode can be switched quickly, as in the comparative example.

[0021] Next, as shown in FIG. 5, it is assumed that the APS opening degree α increases in the vehicle 1 while the vehicle 1 is running in the EV mode between time t1 and time t2, the vehicle 1 accelerates, and the ENG operation condition is satisfied at time t3. At this time, it is assumed that the maximum value Xmax of the APS change rate X on the acceleration side is equal to or greater than a predetermined value Xs during the period from when the ENG operation condition was satisfied last time (not shown) until when it is satisfied this time at time t3. Therefore, the CTU 20 sets the first delay time ΔTb1 according to this maximum value Xmax. As a result, in the traveling mode of the (f) embodiment, after the total judgment time ΔT obtained by adding the first delay time ΔTb1 to the first judgment time ΔTa1 has elapsed from time t3, the start of the engine 2 is completed and the traveling mode is switched from the EV mode to the HV mode.

[0022] Then, it is assumed that the APS opening degree α is decreased between time t4 and time t5, the vehicle 1 is decelerated, and the ENG operation condition is not satisfied at time t6. At this time, it is assumed that the minimum value Xmin of the APS change rate X on the deceleration side is equal to or less than the negative predetermined value Xs during the period from when the ENG operation condition was satisfied last time at time t3 to when it is not satisfied this time at time t6. Therefore, the CTU 20 sets the second delay time ΔTb2 according to this minimum value Xmin. As a result, in the traveling mode of the (f) embodiment, after the total judgment time ΔT obtained by adding the second delay time ΔTb2 to the second judgment time ΔTa2 has elapsed from time t6, the engine 2 is stopped and the traveling mode is switched from the HV mode to the EV mode.

[0023] 5 shows an example in which the EV mode is switched to the HV mode during acceleration, and the HV mode is switched to the EV mode during deceleration, but the acceleration and deceleration are not so steep, and there is a sufficient time between the switching of the driving mode. Also, since the first delay time ΔTb1 and the second delay time ΔTb2 are set relatively short, the overall determination time ΔT is prevented from becoming long compared to the (e) comparative example.

[0024] Next, as shown in FIG. 6, assume that the APS opening α increases at time t1, decreases once at time t2, increases at time t3, and the vehicle 1 rapidly accelerates, and decreases at time t5, causing the vehicle 1 to rapidly decelerate. Assume also that the ENG operating condition is satisfied at time t4 after the rapid acceleration, and the ENG operating condition is not satisfied at time t6 after the rapid deceleration. In this case, since the delay time ΔTb is not set in the (e) comparative example, it can be seen that the EV mode is switched to the HV mode after the first determination time ΔTa1 has elapsed from time t4, and the HV mode is switched to the EV mode after the second determination time ΔTa2 has elapsed from time t6. In this way, if the vehicle 1 rapidly accelerates and then decelerates, and the ENG operating condition is repeatedly satisfied and not satisfied, the driving mode is frequently switched in a short period of time.

[0025] In contrast, the CTU 20 of the embodiment sets the first delay time ΔTb1 according to the maximum value Xmax of the APS change rate X on the acceleration side during the period from when the ENG operation condition was not satisfied last time (not shown) until it is satisfied this time at time t4 while traveling in the EV mode. Here, although the APS change rates X at times t1 and t3 are both equal to or greater than the predetermined value Xs, the APS change rate X at time t3 is greater than the APS change rate X at time t1, so the first delay time ΔTb1 according to the maximum value Xmax at time t3 is set. As a result, the first delay time ΔTb1 is longer than the value exemplified in FIG. 4. In this way, by monitoring the maximum value Xmax of the APS change rate X during the period from when the ENG operation condition was not satisfied last time until it is satisfied this time, the steepest accelerator operation can be appropriately recognized. And, in the traveling mode of the (f) embodiment, traveling in the EV mode is maintained during the period from when the ENG operation condition is satisfied at time t4 until when the ENG operation condition is not satisfied at time t6. Therefore, frequent switching of the driving mode is suppressed.

[0026] Next, as shown in FIG. 7, in the vehicle 1 traveling in HV mode, the APS opening α decreases at time t1, increases once at time t2, decreases at time t3, the vehicle 1 suddenly decelerates, and increases at time t5, causing the vehicle 1 to suddenly accelerate. Also, assume that the ENG operation condition is not satisfied at time t4 after the sudden deceleration, and the ENG operation condition is satisfied at time t6 after the sudden acceleration. In this case, since the delay time ΔTb is not set in the (e) comparative example, it can be seen that the HV mode is switched to the EV mode after the second judgment time ΔTa2 has elapsed from time t4, and the EV mode is switched to the HV mode after the first judgment time ΔTa1 has elapsed from time t6. In this way, even if the vehicle 1 suddenly decelerates and then accelerates, and the ENG operation condition is repeatedly not satisfied and satisfied, frequent switching of the traveling mode occurs in a short time.

[0027] In contrast, the CTU 20 of the embodiment sets the second delay time ΔTb2 according to the minimum value Xmin of the APS change rate X on the deceleration side during the period from when the ENG operation condition was satisfied last time (not shown) to when the ENG operation condition is not satisfied this time at time t4 while traveling in the HV mode. Here, although the APS change rates X at times t1 and t3 are both equal to or less than the negative predetermined value Xs, the APS change rate X at time t3 is smaller than the APS change rate X at time t1, so the second delay time ΔTb2 according to the minimum value Xmin at time t3 is set. As a result, the second delay time ΔTb2 is longer than the value exemplified in FIG. 5. In this way, by monitoring the minimum value Xmin of the APS change rate X during the period from when the ENG operation condition was satisfied last time to when it is not satisfied this time, the steepest accelerator operation can be appropriately recognized. And, in the traveling mode of the (f) embodiment, traveling in the HV mode is maintained during the period from when the ENG operation condition is not satisfied at time t4 to when the ENG operation condition is satisfied at time t6. Therefore, frequent switching of the driving mode is suppressed.

[0028] Next, an example of the process of setting and controlling the overall judgment time ΔT will be described with reference to Fig. 8. Fig. 8 is a flowchart showing an example of the process of setting and controlling the overall judgment time ΔT. The process shown in Fig. 8 is repeatedly executed by the CTU 20 for each unit time while the vehicle 1 is traveling. If a transition condition is satisfied while the process shown in Fig. 8 is being executed, the traveling mode is switched after the overall judgment time ΔT has elapsed. The initial values ​​of the maximum value Xmax and the minimum value Xmin of the APS change rate X are set to 0.

[0029] First, the CTU20 judges whether the driving mode is the EV mode or the HV mode (step St1). When the CTU20 judges that the driving mode is the EV mode (Yes in step St1), it acquires the current APS change rate X and monitors the value on the acceleration side (positive side) (step St2). Next, the CTU20 judges whether the monitored current APS change rate X (absolute value) is greater than the stored maximum value Xmax (step St3). When the current APS change rate X is equal to or less than the stored maximum value Xmax (No in step St3), the CTU20 maintains the maximum value Xmax without updating it. On the other hand, when the current APS change rate X is greater than the stored maximum value Xmax (Yes in step St3), the CTU20 updates the maximum value Xmax to the current APS change rate X (step St4). As a result, during driving in the EV mode, the maximum value Xmax of the APS change rate X is updated to the largest value at any time.

[0030] Next, the CTU 20 judges whether the ENG operating condition is satisfied (step St5). When the CTU 20 judges that the ENG operating condition is not satisfied (No in step St5), the CTU 20 executes this routine from the beginning because there is no need to switch the driving mode from the EV mode to the HV mode. On the other hand, when the CTU 20 judges that the ENG operating condition is satisfied (Yes in step St5), the CTU 20 sets the first delay time ΔTb1 according to the maximum value Xmax (step St6). The CTU 20 adds the first delay time ΔTb1 to the first judgment time ΔTa1 to set the total judgment time ΔT (step St7). As a result, the total judgment time ΔT during the driving in the EV mode illustrated in FIG. 3, FIG. 5, and FIG. 6 is set. Then, since the CTU 20 judges that the ENG operating condition is satisfied this time in step St5, the CTU 20 sets the maximum value Xmax to a value of 0 (step St8) and executes this routine again from the beginning. As a result, if the EV mode is continued after the ENG operating condition is satisfied, the processing from step St2 onwards is executed again after step St1. On the other hand, if the EV mode is switched to the HV mode after the ENG operating condition is satisfied, the process proceeds from step St1 to step St9.

[0031] When the CTU 20 determines that the driving mode is the HV mode (No in step St1), it acquires the current APS change rate X and monitors the deceleration side (negative side) value (step St9). Next, the CTU 20 determines whether the monitored current APS change rate X is smaller than the stored minimum value Xmin (step St10). When the current APS change rate X is equal to or greater than the stored minimum value Xmin (No in step St10), the CTU 20 maintains the minimum value Xmin without updating it. On the other hand, when the current APS change rate X is smaller than the stored minimum value Xmin (Yes in step St10), the CTU 20 updates the minimum value Xmin to the current APS change rate X (step St11). As a result, the minimum value Xmin of the APS change rate X is updated to the smallest value as needed while driving in the HV mode.

[0032] Next, the CTU 20 judges whether the ENG operating condition is not satisfied (step St12). When the CTU 20 judges that the ENG operating condition is not satisfied (No in step St12), there is no need to switch the driving mode, and therefore the routine is executed from the beginning. On the other hand, when the CTU 20 judges that the ENG operating condition is not satisfied (Yes in step St12), the CTU 20 sets the second delay time ΔTb2 according to the minimum value Xmin (step St13), and sets the total judgment time ΔT by adding the second delay time ΔTb2 to the second judgment time ΔTa2 (step St14). This sets the total judgment time ΔT during the driving in the HV mode exemplified in FIG. 4, FIG. 5, and FIG. 7. Then, since the CTU 20 judges that the ENG operating condition is not satisfied this time in step St13, the CTU 20 sets the maximum value Xmax to the value 0 (step St15), and executes the routine again from the beginning. If the HV mode continues after the ENG operating condition is not satisfied, the process of step St9 and subsequent steps is executed again after step St1. On the other hand, if the HV mode is switched to the EV mode after the ENG operating condition is not satisfied, the process proceeds from step St1 to step St2.

[0033] As described above, the CTU20 (control device) of the embodiment switches the driving mode from the EV mode to the HV mode (hybrid mode) by operating the engine 2 after the first judgment time ΔTa1 has elapsed when the transition condition is satisfied while the vehicle 1 is running in the EV mode, and switches the driving mode from the HV mode to the EV mode by stopping the engine 2 after the second judgment time ΔTa2 has elapsed when the transition condition is satisfied while the vehicle 1 is running in the HV mode. When the maximum value (maximum value Xmax or minimum value Xmin) of the absolute value of the APS change rate X is equal to or greater than the predetermined value Xs during the period from when the transition condition was satisfied last time until when it is satisfied this time, the CTU20 adds a delay time ΔTb to the first judgment time ΔTa1 and the second judgment time ΔTa2. As described above, "the period from when the transition condition was satisfied last time until when it is satisfied this time" means the period from when the ENG operating condition was satisfied last time until when it is not satisfied this time, and the period from when the ENG operating condition was not satisfied last time until when it is satisfied this time.

[0034] With this configuration, when the maximum absolute value of the APS change rate X is equal to or greater than a predetermined value Xs and it is considered that the driver has performed an abrupt accelerator operation, the switching from the EV mode to the HV mode and the switching from the HV mode to the EV mode can be delayed by the delay time ΔTb. As a result, as shown in Figs. 6 and 7, for example, even if the transition condition is repeatedly satisfied in a short period of time when the vehicle 1 decelerates after abrupt acceleration or accelerates after abrupt deceleration, the driving mode can be prevented from being switched continuously. Therefore, according to the CTU 20 of the vehicle 1 of the embodiment, it is possible to suppress frequent switching between the EV mode and the hybrid mode. As a result, it is possible to improve fuel efficiency and operability by using the EV mode for a long time, and to improve operability by using the HV mode for a long time.

[0035] Moreover, the delay time ΔTb is set according to the maximum absolute value of the APS change rate X. With this configuration, the steepness of the accelerator operation by the driver can be reflected in the delay time ΔTb. More specifically, the delay time ΔTb is set longer as the maximum absolute value of the APS change rate X is larger, and shorter as the maximum absolute value is smaller. With this configuration, the steepness of the accelerator operation can be more appropriately reflected in the delay time ΔTb.

[0036] The delay time ΔTb includes a first delay time ΔTb1 corresponding to switching from the EV mode to the HV mode and a second delay time ΔTb2 corresponding to switching from the HV mode to the EV mode, and the first delay time ΔTb1 is longer than the second delay time ΔTb2 for the maximum absolute value of the APS change rate X of the same magnitude. With this configuration, the overall judgment time ΔT when switching from the EV mode to the HV mode is likely to be longer than the overall judgment time ΔT when switching from the HV mode to the EV mode. Therefore, the EV mode tends to continue for a longer period of time, and the fuel efficiency of the vehicle 1 can be improved.

[0037] Although the description of the embodiment is finished above, the aspect of the present invention is not limited to this embodiment. For example, in this embodiment, the first judgment time ΔTa1 corresponding to the switch from the EV mode to the HV mode and the second judgment time ΔTa2 corresponding to the switch from the HV mode to the EV mode are set to be the same length. However, the first judgment time ΔTa1 may be set longer than the second judgment time ΔTa2 for the maximum value of the absolute value of the APS change rate X of the same magnitude. This makes it easier to continue the EV mode for a longer period of time, and further improves the fuel efficiency of the vehicle 1.

[0038] In this embodiment, the first delay time ΔTb1 and the second delay time ΔTb2 are set to different values ​​that change according to the maximum absolute value of the APS change rate X. However, the first delay time ΔTb1 and the second delay time ΔTb2 may be set to the same value for the maximum absolute value of the APS change rate X. Also, the first delay time ΔTb1 and the second delay time ΔTb2 may be set to different constant values ​​or the same constant value.

[0039] In addition, in the present embodiment, an example in which the delay time ΔTb is set in consideration of the APS change rate X has been described, but the delay time ΔTb may be set in consideration of other conditions of the vehicle 1. For example, the CTU 20 may change the delay time ΔTb when the vehicle 1 is set to a high responsiveness mode in which the acceleration responsiveness is increased more than normal, or when the outputtable power of the battery 11 is lower than a predetermined power value. The high responsiveness mode includes, for example, a power mode for performing powerful and highly responsive driving during straight acceleration by increasing the response of the front motor 4, and a tarmac mode for improving turning performance by increasing the distribution of driving force to the rear wheels. The high responsiveness mode may be set by the driver operating a mode selection switch 14 provided in the vehicle cabin, as shown in FIG. 1. In addition, a case in which the outputtable power of the battery 11 is lower than a predetermined power value refers to a case in which the charging rate of the battery 11 is lower than a predetermined charging rate, or a case in which the power that can be output from the battery 11 is limited to a standard value, such as a case in which the temperature of the battery 11 is extremely low or extremely high.

[0040] FIG. 9 is an explanatory diagram showing an example of operation when the vehicle 1 traveling in the EV mode accelerates when the high-response mode is set or when the outputtable power of the battery 11 is lower than a predetermined power value. As shown in the figure, it is assumed that the APS opening degree α increases in the vehicle 1 traveling in the EV mode between time t1 and time t2, the vehicle 1 accelerates, and the ENG operation condition is satisfied at time t3. Also, it is assumed that the maximum value Xmax of the APS change rate X on the acceleration side is equal to or greater than the predetermined value Xs between the time when the ENG operation condition was satisfied last time (not shown) and the time when the ENG operation condition is satisfied this time at time t3. In this case, in the above-mentioned example, the first delay time ΔTb1 is set according to the maximum value Xmax as shown by the dashed line in the figure. However, when the high-response mode is set or when the outputtable power of the battery 11 is lower than the predetermined power value, it is considered that the HV mode should be executed preferentially over the EV mode as much as possible. Therefore, the CTU 20 sets the first delay time ΔTb1 to be shorter than the example shown in FIG. 2, for example, to a value of 0 (i.e., the first delay time ΔTb1 is not set). This allows the vehicle to be quickly switched from the EV mode to the HV mode after the first determination time ΔTa1 has elapsed from time t3, as shown in the figure.

[0041] FIG. 10 is an explanatory diagram showing an example of operation when the vehicle 1 running in HV mode decelerates when the high-response mode is set or when the outputtable power of the battery 11 is lower than a predetermined power value. As shown in the figure, it is assumed that the APS opening degree α decreases between time t1 and time t2 in the vehicle 1 running in HV mode, the vehicle 1 decelerates, the ENG operation condition is not satisfied at time t3, the vehicle accelerates again at time t4, and the ENG operation condition is satisfied at time t5. Also, it is assumed that the minimum value Xmin of the APS change rate X on the deceleration side is greater than the negative predetermined value Xs between the time when the ENG operation condition was satisfied last time (not shown) and the time when it is not satisfied this time at time t3. In this case, in the above-mentioned example, as shown by the dashed line in the figure, the second delay time ΔTb2 is not set and the vehicle 1 switches from the HV mode to the EV mode after the second judgment time ΔTa2 has elapsed from time t3. However, when the high-response mode is set as described above or when the outputtable power of the battery 11 is lower than the predetermined power value, it is desired to execute the HV mode as preferentially as possible over the EV mode. Therefore, the CTU 20 sets the second delay time ΔTb2 to, for example, a maximum value ΔTb2max, longer than the example shown in Fig. 2. As a result, as shown in the figure, the vehicle does not transition to the EV mode until the first determination time ΔTa1 and the second delay time ΔTb2 have elapsed from time t3, and the HV mode can be continued even after time t4.

[0042] In addition, the CTU 20 may obtain a map of the area around the current location of the vehicle 1 from an information terminal such as a navigation system mounted on the vehicle 1, and when there is a downhill slope in the traveling direction of the vehicle 1 while traveling in the EV mode, the first delay time ΔTb1 may be set to a longer time than the example shown in FIG. 2, for example, a maximum value ΔTb1max. This allows the EV mode to be continued as long as possible when traveling at low power due to the downhill slope. Also, when there is an uphill slope in the traveling direction of the vehicle 1 while traveling in the EV mode, the CTU 20 may set the first delay time ΔTb1 to a shorter time than the example shown in FIG. 2, for example, a value of 0. This allows the traveling mode to be quickly switched to the HV mode when traveling at high power due to the uphill slope.

[0043] In addition, the CTU 20 may obtain a map of the area around the current location of the vehicle 1, and when there is an uphill slope in the traveling direction of the vehicle 1 while traveling in HV mode, the second delay time ΔTb2 may be set longer than the example shown in FIG. 2, for example to a maximum value ΔTb2max. This allows the HV mode to be continued as long as possible when traveling at high power due to an uphill slope. In addition, the CTU 20 may set the second delay time ΔTb2 shorter than the example shown in FIG. 2, for example to a value of 0, when there is a downhill slope in the traveling direction of the vehicle 1 while traveling in HV mode. This allows the traveling mode to be quickly switched to EV mode when traveling at low power due to a downhill slope. [Explanation of symbols]

[0044] 1 vehicle (hybrid vehicle) 2 Engine 4 Front motor (electric motor) 11 Battery (energy storage device) 20 Control unit (control device) X APS change rate Xmax Maximum APS change rate Xmin Minimum APS rate of change Xs Predetermined value α APS opening (accelerator opening) ΔT Total judgment time ΔTa1 First judgment time ΔTa2 Second judgment time ΔTb Delay time ΔTb1 First delay time ΔTb1max Maximum value of the first delay time ΔTb2 Second delay time ΔTb2max Maximum value of second delay time

Claims

1. A control device for a hybrid vehicle that runs by switching between an EV mode in which the vehicle runs using an electric motor as a power source and a hybrid mode in which the vehicle runs using an internal combustion engine and the electric motor as a power source in response to establishment of a transition condition, when the transition condition is satisfied while the vehicle is traveling in the EV mode, the traveling mode is switched from the EV mode to the hybrid mode after a first determination time has elapsed; When the transition condition is satisfied while the vehicle is traveling in the hybrid mode, the traveling mode is switched from the hybrid mode to the EV mode after a second determination time has elapsed; A control device for a hybrid vehicle that adds a delay time to the first determination time and the second determination time when the maximum absolute value of the APS change rate, which is the rate of change of the accelerator opening, is equal to or greater than a predetermined value between the time when the transition condition is satisfied last time and the time when the transition condition is satisfied this time.

2. 2. The control device for a hybrid vehicle according to claim 1, wherein the delay time is set in accordance with a maximum absolute value of the APS rate of change.

3. 3. The control device for a hybrid vehicle according to claim 2, wherein the delay time is set longer as the maximum absolute value of the APS rate of change is larger, and set shorter as the maximum absolute value is smaller.

4. The control device for a hybrid vehicle according to claim 1 , wherein the first determination time is longer than the second determination time.

5. the delay time includes a first delay time corresponding to switching from the EV mode to the hybrid mode and a second delay time corresponding to switching from the hybrid mode to the EV mode, The first delay time is longer than the second delay time for a maximum absolute value of the APS change rate of the same magnitude. The control device for a hybrid vehicle according to any one of claims 1 to 4.

6. 5. The control device for a hybrid vehicle according to claim 1, wherein the delay time corresponding to switching from the EV mode to the hybrid mode is not set when at least one of a high response mode in which acceleration response is improved compared to normal is selected and a power storage device that supplies power to the electric motor has an output capacity lower than a predetermined power value.

7. 5. The control device for a hybrid vehicle according to claim 1, wherein the delay time corresponding to switching from the hybrid mode to the EV mode is set to a maximum value when at least one of a high response mode in which acceleration response is improved compared to normal is selected and a power storage device that supplies power to the electric motor has an output capacity lower than a predetermined power value.

Images