Vehicle control device

Abstract

To provide a vehicular control device which properly controls a speed changer and an electric motor so that acceleration performance of a hybrid vehicle is enhanced.SOLUTION: A vehicular control device comprises a control system that controls an electric motor and a speed changer. The control system executes a first speed-change mode or a second speed-change mode as a speed-change mode of the speed changer, on the basis of driving operation by a driver. A speed change ratio in the second speed-change mode is closer to a low side than a speed change ratio in the first speed-change mode, when accelerator operation by the driver is released. The control system executes a first assist mode or a second assist mode that is larger in power running torque than in the first assist mode, as an assist mode in which the electric motor is controlled to a power running state. The control system switches the assist mode to the second assist mode, when operation amounts of an accelerator by the driver exceed a starting threshold, under a situation where the second speed-change mode is executed.SELECTED DRAWING: Figure 16

Description

[Technical Field]

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

[0002] Hybrid vehicles equipped with an engine and an electric motor are equipped with a transmission such as a continuously variable transmission or an automatic transmission (see Patent Documents 1 to 3). When the driver depresses the accelerator pedal to accelerate such a hybrid vehicle, the transmission connected to the engine is controlled to the low side, and the electric motor is controlled to a power running state to assist the engine. This increases the driving force of the hybrid vehicle and improves the vehicle's acceleration performance. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5098338 [Patent Document 2] Patent No. 3685146 [Patent Document 3] Patent No. 4376034 Summary of the Invention [Problem to be solved by the invention]

[0004] Increasing the torque and output of an electric motor is important for improving the acceleration performance of a hybrid vehicle. However, increasing the torque and output of an electric motor not only leads to an increase in the size and cost of the electric motor, but also to an increase in the size and cost of the battery. Therefore, there is a need to improve the acceleration performance of a hybrid vehicle by appropriately controlling the transmission and electric motor of the hybrid vehicle while suppressing the increase in size and cost of the electric motor and battery.

[0005] An object of the present invention is to improve the acceleration performance of a hybrid vehicle by appropriately controlling the transmission and the electric motor. [Means for solving the problem]

[0006] In one embodiment, the vehicle control device is provided in a hybrid vehicle including an electric motor connected to at least one of a first wheel and a second wheel, and an engine connected to at least one of the first wheel and the second wheel via a transmission. The vehicle control device includes a processor and a memory that are communicatively connected to each other, and a control system that controls the electric motor and the transmission. The control system reads the accelerator operation amount detected by the accelerator sensor and calculates the driving intensity at predetermined intervals based on the accelerator operation amount read over a predetermined period or a predetermined mileage. The driving intensity, which is an index showing the degree of gentleness of driving operation, is calculated to be smaller as the accelerator operation amount read over the predetermined period or the predetermined mileage is smaller. As a speed change mode of the transmission, The aforementioned a first speed change mode in which the speed change ratio is controlled based on the accelerator operation amount; The aforementioned and a second speed change mode in which the gear ratio is controlled based on driving intensity. The control system executes the first speed change mode when the driving intensity is below a threshold, and executes the second speed change mode when the driving intensity is above the threshold. The gear ratio of the second speed change mode is lower than the gear ratio of the first speed change mode when the driver releases the accelerator pedal at the same vehicle speed. The control system executes a first assist mode or a second assist mode with a larger power running torque than the first assist mode as an assist mode that controls the electric motor to a power running state. When the second speed change mode is being executed, the control system: The aforementioned When the accelerator operation amount exceeds a start threshold, the assist mode is switched to the second assist mode. [Effects of the Invention]

[0007] In one embodiment, when the second shift mode is being executed and the driver's accelerator operation amount exceeds the start threshold, the vehicle control device switches the assist mode to the second assist mode, thereby appropriately controlling the transmission and the electric motor and improving the acceleration performance of the hybrid vehicle. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram showing an example of the configuration of a hybrid vehicle equipped with a vehicle control device according to an embodiment of the present invention; [Figure 2] FIG. 1 is a diagram illustrating an example of the configuration of a vehicle control device. [Figure 3] FIG. 2 is a diagram simply illustrating the basic structure of each control unit. [Figure 4] FIG. 10 is a diagram showing a shift characteristic map used in a normal shift mode. [Figure 5] FIG. 5 is a diagram showing an example of a fixed gear ratio used in an adaptive gear change mode. [Figure 6] FIG. 4 is a diagram showing an example of a target gear position used in an adaptive shift mode. [Figure 7] FIG. 10 is a diagram illustrating an example of a correction state of a target gear position. [Figure 8] 4 is a timing chart showing an example of a transition of the engine rotation speed in an adaptive shift mode. [Figure 9] FIG. 4 is a diagram illustrating an example of an engine operating point in a normal assist mode. [Figure 10] FIG. 4 is a diagram showing an example of an engine operating point in an acceleration assist mode. [Figure 11] FIG. 10 is a diagram showing an example of a target motor torque set in an acceleration assist mode. [Figure 12] 10 is a flowchart illustrating an example of a procedure for executing assist mode switching control. [Figure 13] FIG. 10 is a diagram illustrating an example of a start threshold value. [Figure 14] FIG. 10 is a diagram illustrating an example of each coefficient used when setting an execution time. [Figure 15] FIG. 10 is a diagram illustrating an example of a stop threshold value. [Figure 16] 6 is a timing chart showing an example of an execution state of assist mode switching control. DETAILED DESCRIPTION OF THE INVENTION

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the accompanying drawings. In the following description, identical or substantially identical configurations and elements are designated by the same reference numerals and will not be described repeatedly.

[0010] [Overall configuration of vehicle control device] FIG. 1 is a diagram showing an example of the configuration of a hybrid vehicle 11 equipped with a vehicle control device 10 according to one embodiment of the present invention. As shown in FIG. 1, the hybrid vehicle 11 is equipped with a powertrain 15 including an engine 12, a continuously variable transmission (transmission) 13, and a motor generator (electric motor) 14. Rear wheels (first wheels) 19r are connected to an output shaft 16 of the powertrain 15 via a propeller shaft 17 and a differential mechanism 18. The illustrated powertrain 15 is a rear-wheel drive powertrain 15 that drives the rear wheels 19r, but is not limited to this. For example, the powertrain 15 may be a front-wheel drive powertrain that drives the front wheels (second wheels) 19f, or an all-wheel drive powertrain that drives both the front wheels 19f and the rear wheels 19r.

[0011] Fig. 2 is a diagram showing an example configuration of the vehicle control device 10. As shown in Fig. 2, the powertrain 15 has a continuously variable transmission 13 consisting of a primary pulley 20, a secondary pulley 21, and a drive chain 22. The engine 12 is connected to one side of a primary shaft 23 that supports the primary pulley 20 via a forward / reverse switching mechanism 24 and a torque converter 25. The rotor 14r of the motor generator 14 is connected to the other side of the primary shaft 23 that supports the primary pulley 20. Furthermore, the rear wheels 19r are connected to a secondary shaft 26 that supports the secondary pulley 21 via an output shaft 16, a propeller shaft 17, and a differential mechanism 18.

[0012] In this way, the engine 12 and the rear wheels 19r are connected to each other via a power transmission path 30, which is made up of the torque converter 25, the forward / reverse switching mechanism 24, the continuously variable transmission 13, the propeller shaft 17, the differential mechanism 18, etc. In other words, the rear wheels 19r are connected to the engine 12 via the continuously variable transmission 13. In addition, the motor generator 14 and the rear wheels 19r are connected to each other via a power transmission path 31, which is made up of the continuously variable transmission 13, the propeller shaft 17, the differential mechanism 18, etc. The forward / reverse switching mechanism 24, which switches the rotation direction of the primary pulley 20, is made up of a forward clutch, a reverse brake, a planetary gear train, etc. (not shown).

[0013] Furthermore, in order to control the continuously variable transmission 13, the torque converter 25, the forward / reverse switching mechanism 24, etc., the powertrain 15 is provided with a valve unit 32 consisting of a plurality of electromagnetic valves, oil passages, etc. Furthermore, an oil pump 33 driven by the engine 12, etc. is connected to the valve unit 32. The supply destination, pressure, etc. of the hydraulic oil discharged from the oil pump 33 are controlled by the valve unit 32, and the hydraulic oil is supplied to the continuously variable transmission 13, the torque converter 25, the forward / reverse switching mechanism 24, etc. Furthermore, a shift control unit 34 is connected to the valve unit 32 in order to control the continuously variable transmission 13, etc. via the valve unit 32.

[0014] A throttle valve 41 that adjusts the amount of intake air is provided in an intake manifold 40 of the engine 12. The engine 12 is also provided with an injector 42 that injects fuel into the intake port and cylinder, and an ignition device 43 consisting of an igniter, spark plugs, etc. An engine control unit 44 is connected to the throttle valve 41, injector 42, ignition device 43, etc. to control the engine 12 via the throttle valve 41, etc.

[0015] A battery pack 51 is connected to the stator 14s of the motor generator 14 via an inverter 50. The battery pack 51 is provided with a battery module (electricity storage device) 53 consisting of a plurality of battery cells 52, and a main relay 54 connected to the battery module 53. The battery pack 51 is also provided with a battery control unit 55 that monitors the charging and discharging of the battery module 53, and a battery sensor 56 that detects the charging and discharging current, terminal voltage, etc. The battery control unit 55 has a function of calculating the SOC (State of Charge) of the battery module 53 based on the charging and discharging current, terminal voltage, etc. detected by the battery sensor 56. The SOC of the battery module 53 is a ratio that indicates the remaining amount of electricity in the battery module 53, and is the ratio of the amount of stored electricity to the fully charged capacity of the battery module 53.

[0016] Furthermore, a motor control unit 57 is connected to the inverter 50 to control the motor generator 14 via the inverter 50. The motor control unit 57 controls the inverter 50, which is made up of a plurality of switching elements and the like, thereby controlling the energization state of the stator 14s and controlling the torque and rotation speed of the motor generator 14. When the motor generator 14 is controlled to be in a power running state, power is supplied from the battery module 53 to the stator 14s via the inverter 50. On the other hand, when the motor generator 14 is controlled to be in a power generating state, power is supplied from the stator 14s to the battery module 53 via the inverter 50.

[0017] [Control System] As shown in FIG. 2 , the vehicle control device 10 includes a control system 60 made up of multiple electronic control units for controlling the powertrain 15 and other components. The electronic control units constituting the control system 60 include the aforementioned transmission control unit 34, engine control unit 44, battery control unit 55, and motor control unit 57, as well as a vehicle control unit 61 that outputs control signals to these control units 34, 44, 55, and 57. These control units 34, 44, 55, 57, and 61 are communicatively connected to one another via an in-vehicle network 62 such as a CAN or LIN. The vehicle control unit 61 sets operation targets for the engine 12, the continuously variable transmission 13, and other components based on input information from the various control units 34, 44, 55, 57, and 61 and various sensors described below. The vehicle control unit 61 then generates control signals corresponding to the operation targets for the engine 12, the continuously variable transmission 13, and other components, and outputs these control signals to the various control units 34, 44, 55, and 57.

[0018] Sensors connected to the vehicle control unit 61 include a vehicle speed sensor 70 that detects the vehicle speed, which is the traveling speed of the hybrid vehicle 11, an acceleration sensor 71 that detects the longitudinal acceleration acting in the longitudinal direction of the hybrid vehicle 11, an acceleration sensor 72 that detects the lateral acceleration acting in the width direction of the hybrid vehicle 11, and an engine rotation speed sensor 73 that detects the engine rotation speed, which is the rotation speed of the engine 12. Sensors connected to the vehicle control unit 61 also include an accelerator sensor 74 that detects the operation status of the accelerator pedal, a brake sensor 75 that detects the operation status of the brake pedal, and a steering angle sensor 76 that detects the steering angle of the steering wheel. Sensors connected to the vehicle control unit 61 also include a primary rotation speed sensor 77 that detects the rotation speed of the primary pulley 20 and a secondary rotation speed sensor 78 that detects the rotation speed of the secondary pulley 21. A start switch 79 that is operated by the driver to start the control system 60 is also connected to the vehicle control unit 61.

[0019] 3 is a diagram simply illustrating the basic structure of each of the control units 34, 44, 55, 57, and 61. As shown in FIG. 3, each of the control units 34, 44, 55, 57, and 61 has a microcontroller 82 incorporating a processor 80, a memory 81, and the like. A predetermined program is stored in the memory 81, and the processor 80 executes an instruction set of the program. The processor 80 and the memory 81 are connected to each other so that they can communicate with each other. In the illustrated example, one processor 80 and one memory 81 are incorporated in the microcontroller 82, but this is not limiting. Multiple processors 80 may be incorporated in the microcontroller 82, and multiple memories 81 may be incorporated in the microcontroller 82.

[0020] Each control unit 34, 44, 55, 57, 61 is also provided with an input conversion circuit 83, a drive circuit 84, a communication circuit 85, an external memory 86, a power supply circuit 87, and the like. The input conversion circuit 83 converts signals input from various sensors into signals that can be input to the microcontroller 82. The drive circuit 84 generates drive signals for actuators such as the valve unit 32 based on signals output from the microcontroller 82. The communication circuit 85 converts signals output from the microcontroller 82 into communication signals directed to other control units. The communication circuit 85 also converts communication signals received from other control units into signals that can be input to the microcontroller 82. The power supply circuit 87 supplies a stable power supply voltage to the microcontroller 82, the input conversion circuit 83, the drive circuit 84, the communication circuit 85, the external memory 86, and the like. The external memory 86, such as a nonvolatile memory, stores data that should be retained even when power is off.

[0021] [Gear shift control] The shift control executed by the control system 60 will be described. The control system 60 has two shift modes for the continuously variable transmission 13: a normal shift mode (first shift mode) executed during normal driving, and an adaptive shift mode (second shift mode) executed during sporty driving. The control system 60 selects and executes the normal shift mode when the driving intensity of the driver, which will be described later, is below a predetermined threshold D1, and selects and executes the adaptive shift mode when the driving intensity of the driver exceeds the predetermined threshold D1. Here, the driving intensity is an index calculated by the control system 60 based on the driving operation of the driver, and indicates the degree of gentleness of the driving operation by the driver. The control system 60 calculates a low driving intensity when driving operations such as accelerator operation are gentle, and calculates a high driving intensity when driving operations such as accelerator operation are not gentle. The control system 60 calculates and updates the driving intensity at predetermined intervals based on driving operations such as accelerator operation and brake operation over a predetermined period or a predetermined mileage.

[0022] For example, a situation in which the driving intensity is calculated to be high may involve a large accelerator pedal operation amount (hereinafter referred to as accelerator opening) and a fast accelerator pedal operation speed. A situation in which the driving intensity is calculated to be high may involve a large brake pedal operation amount and a fast brake pedal operation speed, a large steering operation amount and a fast steering operation speed. A situation in which the driving intensity is calculated to be high may involve a fast vehicle speed, a large longitudinal acceleration and a large lateral acceleration. On the other hand, a situation in which the driving intensity is calculated to be low may involve a small accelerator opening and a slow accelerator pedal operation speed. A situation in which the driving intensity is calculated to be low may involve a small brake pedal operation amount and a slow brake pedal operation speed, a small steering operation amount and a slow steering operation speed. A situation in which the driving intensity is calculated to be low may involve a slow vehicle speed, a small longitudinal acceleration and a small lateral acceleration.

[0023] <Shift control: normal shift mode> The normal shift mode will now be described. FIG. 4 is a diagram showing a shift characteristic map used in the normal shift mode. The control system 60 references the shift characteristic map based on the accelerator opening and vehicle speed, and sets a target gear ratio to be used in the normal shift mode. As shown in FIG. 4, the shift characteristic map has a characteristic line Low indicating the maximum gear ratio on the low side, and a characteristic line High indicating the minimum gear ratio on the high side. The shift characteristic map also has a plurality of characteristic lines corresponding to the accelerator opening, i.e., the required driving force, as indicated by the dashed lines. The gear ratio is the ratio (Np / Ns) of the rotational speed of the primary pulley 20 (primary rotational speed Np) to the rotational speed of the secondary pulley 21 (secondary rotational speed Ns). Therefore, a larger value of the gear ratio means that the gear ratio is on the low side, and a smaller value of the gear ratio means that the gear ratio is on the high side.

[0024] As shown in Figure 4, the more the accelerator opening increases by depressing the accelerator pedal, i.e., the more the required driving force for the hybrid vehicle 11 increases, the more the characteristic line in the direction of arrow α is selected. On the other hand, the more the accelerator opening decreases by releasing the accelerator pedal, i.e., the more the required driving force for the hybrid vehicle 11 decreases, the more the characteristic line in the direction of arrow β is selected. For example, as shown by arrow γ, when the accelerator pedal is depressed while traveling at vehicle speed V1, the target primary rotation speed is increased from "Npa" to "Npb," and the target gear ratio of the continuously variable transmission 13 is continuously controlled from "Tra" to the lower "Trb." In this way, in the normal shift mode, the target gear ratio is set based on the accelerator opening and the vehicle speed, and the groove widths of the primary pulley 20 and the secondary pulley 21 are controlled to achieve this target gear ratio.

[0025] <Shift control: Adaptive shift mode> The adaptive shift mode will now be described. Fig. 5 is a diagram showing an example of a fixed gear ratio used in the adaptive shift mode, and Fig. 6 is a diagram showing an example of a target gear position used in the adaptive shift mode. As shown in Fig. 5, in the adaptive shift mode, a plurality of fixed gear ratios R1 to R10 are set as the target gear ratio of the shift mode, i.e., the target gear position. Also, as shown in Fig. 6, the control system 60 sets the target gear position of the adaptive shift mode based on the vehicle speed and driving intensity. That is, as the vehicle speed increases, the control system 60 sets the target gear position on the high-speed side (high side), while as the vehicle speed decreases, the control system 60 sets the target gear position on the low-speed side (low side). Also, as the driving intensity increases, the control system 60 sets the target gear position on the high-speed side (high side). low While setting the target gear on the speed side, as the driving intensity decreases, high Set the target gear on the gear side.

[0026] Furthermore, in the adaptive shift mode, the target gear is corrected based on the road surface gradient. Here, FIG. 7 is a diagram showing an example of the correction of the target gear. As shown in FIG. 7, as the upward gradient of the road surface increases, the target gear is corrected to a lower gear, while as the downward gradient of the road surface increases, the target gear is corrected to a higher gear. In other words, when the upward gradient of the road surface is "S1", the target gear set based on FIG. 6 is corrected to a lower gear by one step. On the other hand, when the downward gradient of the road surface is "-S2", the target gear set based on FIG. 6 is corrected to a higher gear by one step. The control system 60 is capable of calculating the gradient of the road surface based on the longitudinal acceleration detected by the acceleration sensor 71.

[0027] Fig. 8 is a timing chart showing an example of changes in engine speed in the adaptive shift mode. Fig. 8 shows a driving situation from entering a corner to exiting the corner. As shown at time t1 in Fig. 8, the driving intensity calculated based on the accelerator operation, etc., exceeds a predetermined threshold D1 (symbol a1), and therefore the adaptive shift mode is executed as the shift mode of the continuously variable transmission 13. Subsequently, as shown at time t2, when the hybrid vehicle 11 enters the corner, the driver releases the accelerator pedal and the accelerator opening decreases (symbol b1).

[0028] In this way, even when the accelerator opening degree decreases, as shown in Fig. 6, the target gear in the adaptive shift mode is set based on the vehicle speed and driving intensity, so the target gear, i.e., the gear ratio of the continuously variable transmission 13, is maintained (symbol c1), and an excessive decrease in engine speed is suppressed (symbol d1). Then, as shown at time t3, when the hybrid vehicle 11 passes through a corner and exits the corner, the accelerator opening degree begins to increase as the driver depresses the accelerator pedal (symbol b2). At this time, the adaptive shift mode keeps the engine speed during cornering high (symbol d2), so the acceleration responsiveness of the hybrid vehicle 11 when exiting the corner can be improved.

[0029] In contrast, as shown by the dashed line in Fig. 8, when the normal driving mode is executed from entering to exiting a corner, the engine speed during cornering drops significantly, making it difficult to improve the acceleration responsiveness of the hybrid vehicle 11 when exiting a corner. That is, as shown at time t1 in Fig. 8, the driving intensity calculated based on the accelerator operation, etc., falls below a predetermined threshold D1 (symbol e1), and the normal speed change mode is executed as the speed change mode of the continuously variable transmission 13. Subsequently, as shown at time t2, when the hybrid vehicle 11 enters a corner, the driver releases the accelerator pedal and the accelerator opening decreases (symbol b1).

[0030] In this way, when the accelerator opening decreases, as shown in Figure 4, the target gear ratio in the normal shift mode is set based on the accelerator opening, i.e., the required driving force, so the target gear ratio is upshifted to the higher side (symbol f1), and the engine speed drops significantly (symbol g1). Then, as shown at time t3, when the hybrid vehicle 11 passes through a corner and exits the corner, the accelerator opening begins to increase as the driver depresses the accelerator pedal (symbol b2). At this time, the engine speed during cornering drops significantly (symbol g2) due to the normal shift mode, so the acceleration responsiveness of the hybrid vehicle 11 when exiting the corner drops.

[0031] As explained above, when the accelerator pedal is released, upshifts are suppressed in the adaptive shift mode, whereas upshifts are actively performed in the normal shift mode. In other words, the gear ratio in the adaptive shift mode is lower than the gear ratio in the normal shift mode when the driver releases the accelerator pedal. As a result, by executing the adaptive shift mode as the shift mode, even when the accelerator pedal is released when entering a corner, upshifts can be suppressed and the engine speed can be kept high, thereby improving acceleration responsiveness when exiting the corner.

[0032] [Assist control] The assist control executed by the control system 60 will now be described. In order to improve acceleration response in the adaptive shift mode, the control system 60 executes assist control that controls the motor generator 14 to a powering state during acceleration driving. Assist modes used in this assist control include a normal assist mode (first assist mode) in which the target motor torque is set small, and an acceleration assist mode (second assist mode) in which the target motor torque is set large. That is, when the required driving force for the hybrid vehicle 11 is the same, that is, when the accelerator opening is the same, the powering torque of the motor generator 14 when the acceleration assist mode is executed is controlled to be larger than the powering torque of the motor generator 14 when the normal assist mode is executed. The powering torque of the motor generator 14 is the motor torque output from the motor generator 14 controlled to a powering state.

[0033] <Assist control: Normal assist mode> The normal assist mode will now be described. FIG. 9 is a diagram showing an example of engine operating points in the normal assist mode, and FIG. 9 shows an example of the target engine torque and target motor torque that are set when the normal assist mode is executed. The dashed-dotted line in FIG. 9 is a line connecting points with equal engine thermal efficiency. That is, as indicated by arrow α in FIG. 9, the thermal efficiency of the engine 12 increases toward dashed-dotted line La, while as indicated by arrow β, the thermal efficiency of the engine 12 decreases toward dashed-dotted line Lb. Also, in FIG. 9, the solid line Ma1 indicates the maximum torque of the engine 12, and the dashed line Ma2 indicates the maximum torque of the combined power source of the engine 12 and the motor-generator 14.

[0034] As shown in FIG. 9 , when the normal assist mode is executed, the control system 60 sets a required driving force for the drive wheels, i.e., the rear wheels 19r, based on the accelerator pedal position of the driver, and then sets a target operating point Pt of the combined power source, which is the engine 12 and the motor generator 14, based on this required driving force. Next, the control system 60 sets a target operating point Pe for the engine 12 to enhance thermal efficiency, and sets a target engine torque Te1 for the engine 12. The control system 60 then sets a target motor torque Tm1 for the motor generator 14 so that the combined power source, which is the engine 12 and the motor generator 14, operates at the target operating point Pt when the engine 12 is controlled toward the target engine torque Te1. In this way, when the normal assist mode is executed, the target engine torque Te1 is set to enhance thermal efficiency, and then the target motor torque Tm1 is set to obtain the desired required driving force. This allows the engine 12 to operate in a range with high thermal efficiency even during acceleration, thereby improving the fuel economy of the hybrid vehicle 11.

[0035] <Assist control: Acceleration assist mode> The acceleration assist mode will now be described. Fig. 10 is a diagram showing an example of an engine operating point in the acceleration assist mode, and Fig. 10 shows an example of a target engine torque and a target motor torque that are set when the acceleration assist mode is executed. Fig. 11 is a diagram showing an example of a target motor torque that is set in the acceleration assist mode. Note that Figs. 9 and 10 show a situation when the vehicle speed and required driving force are the same.

[0036] As shown in FIG. 10, when executing the acceleration assist mode, the control system 60 sets a required driving force for the drive wheels based on the accelerator pedal position of the driver, and then sets a target operating point Pt of the combined power source of the engine 12 and the motor generator 14 based on this required driving force. Next, the control system 60 references the torque map of FIG. 11 and sets a target motor torque Tm2 based on the accelerator pedal position. As shown in FIG. 11, the target motor torque Tm2 is set to increase as the accelerator pedal position increases and to decrease as the accelerator pedal position decreases. The control system 60 then sets a target engine torque Te2 for the engine 12 so that the combined power source of the engine 12 and the motor generator 14 operates at the target operating point Pt when the control system 60 controls the motor generator 14 toward the target motor torque Tm2. In this way, when executing the acceleration assist mode, the target motor torque Tm2 is set based on the accelerator pedal position, and then the target engine torque Te2 is set so as to obtain the desired required driving force. This allows the motor generator 14 to be actively used, thereby improving the acceleration responsiveness of the hybrid vehicle 11. In the illustrated acceleration assist mode, the operating point of the engine 12 is "Pe2."

[0037] [Assist mode switching control (flowchart)] As described above, in the acceleration assist mode, the motor generator 14 is used more actively than in the normal assist mode, thereby improving the acceleration responsiveness of the hybrid vehicle 11. For this reason, it is desirable to actively execute the acceleration assist mode during sporty driving in which the adaptive shift mode is executed. However, because executing the acceleration assist mode causes a significant decrease in the SOC of the battery module 53, it is necessary to execute the acceleration assist mode at an appropriate timing that contributes to improving the acceleration responsiveness. Therefore, the control system 60 executes the assist mode switching control, which will be described later, to execute the acceleration assist mode at an appropriate timing that contributes to improving the acceleration responsiveness.

[0038] The assist mode switching control executed by the control system 60 will be described below. Fig. 12 is a flowchart showing an example of the execution procedure of the assist mode switching control, and Fig. 13 is a diagram showing an example of the start threshold value Xa1. Fig. 14 is a diagram showing an example of each of the coefficients k1 to k4 used when setting the execution time Xt, and Fig. 15 is a diagram showing an example of the stop threshold value Xa2. Each step shown in the flowchart in Fig. 12 represents processing executed by one or more processors 80 constituting the control system 60. The assist mode switching control shown in Fig. 12 is control that is executed by the control system 60 at predetermined intervals after the driver operates the start switch 79 and the control system 60, which is composed of the vehicle control unit 61 and the like, is started up.

[0039] As shown in FIG. 12, in step S10, it is determined whether or not the adaptive shift mode is being executed. If it is determined in step S10 that the adaptive shift mode is being executed, the process proceeds to step S11, where the normal assist mode is selected as the assist mode. In other words, when the hybrid vehicle 11 is accelerated by depressing the accelerator pedal, the normal assist mode is executed as the assist mode. Next, in step S12, a start threshold Xa1 is set based on the vehicle speed and the road gradient, and in step S13, it is determined whether or not the accelerator opening (accelerator operation amount) Acp exceeds the start threshold Xa1. Here, as shown in FIG. 13, the start threshold Xa1 is set to be larger as the vehicle speed increases and as the uphill gradient of the road surface increases. In other words, the start threshold Xa1 is set to be larger as the running resistance increases.

[0040] 12, if it is determined in step S13 that the accelerator pedal depression Acp is equal to or less than the start threshold Xa1, i.e., if it is determined that the driver has not requested strong acceleration, the process returns to step S11, and the selection of the normal assist mode continues. On the other hand, if it is determined in step S13 that the accelerator pedal depression Acp exceeds the start threshold Xa1, i.e., if it is determined that the driver has requested strong acceleration, the process proceeds to step S14, and the acceleration assist mode is executed. In this way, if the accelerator pedal depression Acp exceeds the start threshold Xa1 while the adaptive shift mode is being executed, the normal assist mode is switched to the acceleration assist mode. As a result, when accelerating the hybrid vehicle 11, for example, when exiting a corner, the motor generator 14 can be actively driven, thereby further improving the acceleration responsiveness in the adaptive shift mode.

[0041] In the next step S15, a predetermined reference time Tb is multiplied by each of the coefficients k1 to k4 to set an execution time Xt, which is the duration of the acceleration assist mode. Here, as shown in FIG. 14, coefficient k1 is set based on the vehicle speed, and the coefficient k1 is set to increase as the vehicle speed decreases. Coefficient k2 is set based on the road gradient, and the coefficient k2 is set to increase as the downhill gradient increases. Coefficient k3 is set based on the accelerator pedal position, and the coefficient k3 is set to increase as the accelerator pedal position increases. Coefficient k4 is set based on the SOC, and the coefficient k4 is set to increase as the SOC increases. In other words, when the vehicle speed is low, the downhill gradient is large, the accelerator pedal position is large, or the SOC is high, the execution time Xt is set to be long. On the other hand, when the vehicle speed is high, the uphill gradient is large, the accelerator pedal position is small, or the SOC is low, the execution time Xt is set to be short.

[0042] As described above, once the execution time Xt is set based on the accelerator opening, etc., the process proceeds to step S16, where it is determined whether the elapsed time Tacc since the acceleration assist mode was started exceeds the execution time Xt. If it is determined in step S16 that the elapsed time Tacc exceeds the execution time Xt, that is, if the acceleration assist mode has been executed for the predetermined execution time Xt, the process proceeds to step S17, where the acceleration assist mode is stopped, and then to step S18, where it is determined whether the adaptive shifting mode is stopped. If it is determined in step S18 that the adaptive shifting mode is to be stopped, the process exits the routine. However, if it is determined that the adaptive shifting mode is to be continued, the process returns to step S11, where the normal assist mode is selected. In other words, if the adaptive shifting mode is to be continued, the assist mode is switched from the acceleration assist mode to the normal assist mode.

[0043] On the other hand, if it is determined in step S16 that the elapsed time Tacc is equal to or less than the execution time Xt, that is, if the acceleration assist mode has not been executed for the predetermined execution time Xt, the process proceeds to step S19. Then, in step S19, a stop threshold Xa2 is set based on the vehicle speed and the road surface gradient, and in the following step S20, it is determined whether the accelerator opening Acp is below the stop threshold Xa2. Here, as shown in FIG. 15, the stop threshold Xa2 is set to be larger as the vehicle speed increases and as the uphill gradient of the road surface increases. In other words, the stop threshold Xa2 is set to be larger as the running resistance increases. Furthermore, the stop threshold Xa2 is set to a value smaller than the start threshold Xa1 described above.

[0044] 12, if it is determined in the following step S20 that the accelerator opening Acp is equal to or greater than the stop threshold Xa2, that is, if it is determined that the driver is continuing to request acceleration, the process returns to step S14, and the acceleration assist mode continues to be executed. On the other hand, if it is determined in step S20 that the accelerator opening Acp is below the stop threshold Xa2, that is, if it is determined that the driver is not requesting strong acceleration, the process proceeds to step S17, where the acceleration assist mode is stopped, and also to step S18, where it is determined whether or not the adaptive shift mode is to be stopped.

[0045] As explained above, when the accelerator pedal position Acp exceeds the start threshold Xa1 while the adaptive shift mode is being executed, the mode is switched from the normal assist mode to the acceleration assist mode. This allows the motor generator 14 to be actively driven at an appropriate timing, thereby further improving acceleration responsiveness in the adaptive shift mode. Then, when the acceleration assist mode continues for a predetermined execution time Xt, the mode is switched from the acceleration assist mode to the normal assist mode. Furthermore, when the acceleration assist mode is being executed, if it is determined that the accelerator pedal position Acp falls below the stop threshold Xa2, which is smaller than the start threshold Xa1, the mode is switched from the acceleration assist mode to the normal assist mode. This allows the acceleration assist mode to be ended at an appropriate time, allowing efficient use of the electrical energy of the battery module 53.

[0046] Furthermore, the start threshold Xa1 that determines the start timing of the acceleration assist mode and the stop threshold Xa2 that determines the stop timing of the acceleration assist mode are set to larger values ​​as the running resistance increases. This allows the acceleration assist mode, which contributes to acceleration responsiveness, to be executed at an appropriate timing. Note that in the examples shown in FIGS. 13 and 15, the start threshold Xa1 and the stop threshold Xa2 are set based on the vehicle speed and the road surface gradient, but this is not limitative, and the start threshold Xa1 and the stop threshold Xa2 may be set based only on the vehicle speed, or may be set based only on the road surface gradient.

[0047] Furthermore, the execution time Xt, which determines the duration of the acceleration assist mode, is set to be long when the vehicle speed is low or the downhill gradient is steep. As a result, in situations where the acceleration assist mode contributes to improving acceleration responsiveness, the acceleration assist mode can be continued for a long period of time, thereby improving the acceleration responsiveness of the adaptive shift mode. Furthermore, the execution time Xt, which determines the duration of the acceleration assist mode, is set to be long when the accelerator opening is large or the SOC is high. As a result, when the driver requests strong acceleration or when sufficient electrical energy has been stored in the battery module 53, the acceleration assist mode can be continued for a long period of time, thereby improving the acceleration responsiveness of the adaptive shift mode.

[0048] As shown in FIG. 14, the coefficient k1 is set to be larger as the vehicle speed decreases and the coefficient k2 is set to be larger as the downhill gradient increases, but this is not limited to this. For example, as shown by the dashed lines in FIG. 14, the coefficient k1 may be set to be larger as the vehicle speed increases, and the coefficient k2 may be set to be larger as the uphill gradient increases. In other words, the execution time Xt, which determines the duration of the acceleration assist mode, may be set to be longer when the vehicle speed is high or the uphill gradient is steep. For example, when the power storage capacity of the battery module 53 is large, it is possible to actively expand the power running range of the motor generator 14. In such a hybrid vehicle, the acceleration responsiveness of the adaptive shift mode can be improved by continuing the acceleration assist mode for a long period of time when the vehicle speed is high or the uphill gradient is steep.

[0049] In the above description, the execution time Xt, which determines the duration of the acceleration assist mode, is set based on the vehicle speed, road gradient, accelerator opening, and SOC, but this is not limited to this. For example, the execution time Xt may be set based only on the vehicle speed, the road gradient, the accelerator opening, or the SOC. In other words, the execution time Xt may be set based on at least one of the vehicle speed, road gradient, accelerator opening, and SOC.

[0050] [Assist mode switching control (timing chart)] Next, the above-mentioned assist mode switching control will be described with reference to a timing chart. Fig. 16 is a timing chart showing an example of the execution status of the assist mode switching control. As shown at time t1 in Fig. 16, the driver's driving intensity exceeds threshold value D1 (symbol a1), and the adaptive shift mode is executed as the shift mode (symbol b1). Furthermore, because the accelerator opening falls below stop threshold value Xa2 (symbol c1), the normal assist mode is executed during acceleration driving (symbol d1). Thereafter, as shown at time t2, when the accelerator opening exceeds start threshold value Xa1 due to depression of the accelerator pedal (symbol c2), the assist mode is switched to acceleration assist mode (symbol d2). Then, as shown at time t3, when the duration of acceleration assist mode exceeds execution time Xt, the assist mode is switched to normal assist mode (symbol d3). Furthermore, as shown by the dashed line and time t3a in Figure 16, when the adaptive shift mode is being executed and the acceleration assist mode is being executed, if the accelerator pedal is released and the accelerator opening falls below the stop threshold value Xa2 (symbol e1), the assist mode is switched to the normal assist mode (symbol f1).

[0051] In this way, when the accelerator opening degree exceeds the start threshold Xa1 while the adaptive shift mode is being executed, the mode is switched from the normal assist mode to the acceleration assist mode. This allows the motor generator 14 to be actively driven at an appropriate timing, thereby further improving acceleration responsiveness in the adaptive shift mode. Then, when the acceleration assist mode continues for a predetermined execution time Xt, the mode is switched from the acceleration assist mode to the normal assist mode. Furthermore, when the acceleration assist mode is being executed, if it is determined that the accelerator opening degree Acp falls below the stop threshold Xa2, which is smaller than the start threshold Xa1, the mode is switched from the acceleration assist mode to the normal assist mode. This allows the acceleration assist mode to be ended at an appropriate time, allowing efficient use of the electrical energy of the battery module 53.

[0052] The present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit and scope of the present invention. In the above description, the control system 60 is configured using multiple control units 34, 44, 55, 57, and 61. However, this is not limiting. For example, the control system 60 may be configured using a single control unit. In the example shown in FIG. 2, the motor generator 14 is connected to the input side of the continuously variable transmission 13. However, this is not limiting. The motor generator 14 may be connected to the output side of the continuously variable transmission 13. In the example shown in FIG. 2, both the engine 12 and the motor generator 14 are connected to the rear wheels 19r. However, this is not limiting. Both the engine 12 and the motor generator 14 may be connected to the front wheels 19f. Alternatively, the engine 12 may be connected to the front wheels 19f while the motor generator 14 is connected to the rear wheels 19r. Alternatively, the engine 12 may be connected to the rear wheels 19r while the motor generator 14 is connected to the front wheels 19f. Furthermore, the engine 12 may be connected to both the front wheels 19f and the rear wheels 19r, and the motor generator 14 may be connected to both the front wheels 19f and the rear wheels 19r. In the above description, the rear wheels 19r are the first wheels and the front wheels 19f are the second wheels, but this is not limitative, and the front wheels 19f may be the first wheels and the rear wheels 19r may be the second wheels.

[0053] In the examples shown in FIGS. 12 and 14, when setting the execution time Xt of the acceleration assist mode, the coefficients k1 to k4 are set based on the vehicle speed, accelerator pedal position, etc., and the basic time Tb is multiplied by each of the coefficients k1 to k4. However, this is not a limitation. For example, multiple execution times may be set based on the vehicle speed, road gradient, accelerator pedal position, and SOC, and these execution times may be added together to set the execution time Xt. In addition, in the example shown in FIG. 2, the continuously variable transmission 13 is used as the transmission, but this is not a limitation. A planetary gear or parallel shaft automatic transmission may also be used as the transmission. In addition, in the above description, the gear ratio is continuously changed in the normal shift mode. However, this is not a limitation. The gear ratio may also be changed in steps. In addition, in the above description, the gear ratio is continuously changed in the adaptive shift mode. However, this is not a limitation. The gear ratio may also be changed continuously. [Explanation of symbols]

[0054] 10 Vehicle control device 11 Hybrid vehicles 12 Engine 13 Continuously variable transmission (transmission) 14 Motor generator (electric motor) 19r rear wheel (first wheel) 19f Front wheel (2nd wheel) 53 Battery module (energy storage device) 60 Control System Acp Accelerator opening (accelerator operation amount) Xa1 starting threshold Xa2 Stop Threshold Xt Execution Time

Claims

1. A vehicle control device provided in a hybrid vehicle including an electric motor connected to at least one of a first wheel and a second wheel, and an engine connected to at least one of the first wheel and the second wheel via a transmission, a control system including a processor and a memory communicatively connected to each other, the control system controlling the electric motor and the transmission; The control system reads an accelerator operation amount detected by an accelerator sensor, and calculates a driving intensity at predetermined intervals based on the accelerator operation amount read over a predetermined period or a predetermined mileage, The driving intensity, which is an index showing the degree of gentleness of driving operation, is calculated to be smaller as the accelerator operation amount read over a predetermined period or a predetermined mileage is smaller, The speed change modes of the transmission include a first speed change mode in which a speed change ratio is controlled based on the accelerator operation amount, and a second speed change mode in which a speed change ratio is controlled based on the driving intensity, the control system executes the first speed change mode when the driving intensity is below a threshold, and executes the second speed change mode when the driving intensity is above the threshold; the gear ratio of the second speed change mode is lower than the gear ratio of the first speed change mode when the driver releases the accelerator pedal operation at the same vehicle speed, the control system executes a first assist mode or a second assist mode in which a powering torque is greater than that in the first assist mode as an assist mode in which the electric motor is controlled to a powering state; the control system switches the assist mode to the second assist mode when the accelerator operation amount exceeds a start threshold while the second shift mode is being executed. Vehicle control device.

2. 2. The vehicle control device according to claim 1, The control system includes: Under the condition that the second speed change mode is being executed, When the accelerator operation amount exceeds the start threshold, the assist mode is switched to the second assist mode. When an execution time has elapsed since the accelerator operation amount exceeded the start threshold, the assist mode is switched to the first assist mode. Vehicle control device.

3. 2. The vehicle control device according to claim 1, The control system includes: Under the condition that the second speed change mode is being executed, When the accelerator operation amount exceeds the start threshold, the assist mode is switched to the second assist mode. When the accelerator operation amount falls below a stop threshold that is smaller than the start threshold, the assist mode is switched to the first assist mode. Vehicle control device.

4. The vehicle control device according to any one of claims 1 to 3, The start threshold is set to increase as the running resistance increases. Vehicle control device.

5. 3. The vehicle control device according to claim 2, an electric storage device connected to the electric motor; The execution time is set based on at least one of a vehicle speed, an accelerator operation amount, a road gradient, and an SOC of the power storage device. Vehicle control device.

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