Vehicle control system

Abstract

To provide a vehicle control apparatus that can easily secure drive torque while suppressing unnecessary downshift when performing sports run.SOLUTION: When a shift position of an automatic transmission is at a forward travel position, it is determined that sports run is being performed. and if it is determined that a permission condition holds, downshift of the automatic transmission is executed. By so doing, downshift is executed while sports run is being executed, making it easy to secure drive torque. Furthermore, since this is limited to a case where the permission condition holds, downshift is not executed in a state where lateral slip suppression control is in operation, for example. Therefore, in executing sports run, it is possible to easily secure drive torque while suppressing unnecessary downshift. Control of vehicle attitude is facilitated while sports run is being executed. Furthermore, acceleration performance upon a start-up after turning is improved.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a vehicle control device that executes control during sports driving in which a vehicle travels in a sideslip state when turning.

Background Art

[0002] A control device for a vehicle including a power source and an automatic transmission provided in a power transmission path between the power source and driving wheels is well known. For example, the vehicle control device described in Patent Document 1 is such a device. This Patent Document 1 discloses that in a vehicle including an engine and a stepped gear shift mechanism, a downshift is executed when rapid deceleration is requested.

Prior Art Literature

Patent Literature

[0003]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0004] Referring to the technology described in Patent Document 1, it is possible to form a gear step on the lower vehicle speed side by executing a downshift during strong braking before entering a corner. On the other hand, during sports driving in which the vehicle travels in a sideslip state when turning, the vehicle speed and the engine rotation speed may decrease to a low range. In this case, depending on the traveling state during execution of sports driving, the vehicle may not enter the region where a downshift is determined, and there is a possibility that the downshift is not performed. As a result, the driving wheels grip due to insufficient driving torque or the like, and there is a risk that the vehicle attitude, for example, the sideslip state, cannot be properly maintained during the execution of sports driving. Alternatively, after turning, acceleration is performed from a state where driving torque is insufficient, so there is a risk that reacceleration will be delayed.

[0005] The present invention was made against the above circumstances, and its objective is to provide a vehicle control device that can easily secure driving torque while suppressing unnecessary downshifts when performing sporty driving. [Means for solving the problem]

[0006] The gist of the first invention is a control device for a vehicle comprising (a) a power source and an automatic transmission provided in a power transmission path between the power source and the drive wheels, the control device comprising (b) a sports driving determination unit that determines whether or not sports driving is being performed, in which the vehicle is driven in a side-skidding state when turning, (c) a condition fulfillment determination unit that determines whether or not permission conditions are met, such that the vehicle speed is below a predetermined vehicle speed and the operation of the side-skidding suppression control is restricted, and (d) a transmission control unit that performs a downshift of the automatic transmission when it is determined that sports driving is being performed and the permission conditions are met, while the shift position of the automatic transmission is a forward driving position that enables forward driving by executing automatic transmission control. [Effects of the Invention]

[0007] According to the first invention described above, when the shift position of the automatic transmission is in the forward driving position, and it is determined that sporty driving is being performed, and the permitted conditions are met, a downshift of the automatic transmission is performed. This makes it easier to ensure driving torque by performing a downshift during sporty driving. Furthermore, since it is limited to when the permitted conditions are met, a downshift will not be performed, for example, when the yaw control is activated. Therefore, when performing sporty driving, it is possible to easily ensure driving torque while suppressing unnecessary downshifts. It is also easier to control the vehicle's posture during sporty driving. In addition, acceleration performance when coming out of a corner is improved. [Brief explanation of the drawing]

[0008] [Figure 1] This diagram illustrates the schematic configuration of a vehicle to which the present invention is applied, as well as the main parts of the control functions and control systems for various control functions in the vehicle. [Figure 2] This flowchart explains the key aspects of the control operation of an electronic control unit, specifically the control operation designed to facilitate securing drive torque while suppressing unnecessary downshifts during drift driving. [Figure 3] This figure shows an example of a time chart when the control operation shown in the flowchart in Figure 2 is performed. [Modes for carrying out the invention]

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. [Examples]

[0010] Figure 1 is a diagram illustrating the schematic configuration of a vehicle 10 to which the present invention is applied, as well as illustrating the main parts of the control functions and control systems for various controls in the vehicle 10. In Figure 1, the vehicle 10 includes an engine 12 as a power source, drive wheels 14, and a power transmission device 16 provided in the power transmission path between the engine 12 and the drive wheels 14.

[0011] Engine 12 is a known internal combustion engine. The engine torque Te of engine 12 is controlled by an electronic control device 50, which is provided in the vehicle 10 and includes an electronic throttle valve, fuel injection device, ignition device, etc., and is controlled by an electronic control device 90, which will be described later.

[0012] The power transmission device 16 includes a torque converter 20 connected to the engine 12, an automatic transmission 22 connected to the torque converter 20, etc., housed in a case 18 which is a non-rotating member attached to the vehicle body. The power transmission device 16 also includes a propeller shaft 26 connected to the transmission output shaft 24, a differential gear 28 connected to the propeller shaft 26, a pair of drive shafts 30 connected to the differential gear 28, etc. The transmission output shaft 24 is the output rotating member of the automatic transmission 22. The power transmission device 16 also includes an engine connecting shaft 32 that connects the engine 12 and the torque converter 20.

[0013] The torque converter 20 is a known fluid-type transmission device. The torque converter 20 comprises a pump impeller 20p connected to the engine connecting shaft 32 and a turbine impeller 20t connected to the transmission input shaft 34. The transmission input shaft 34 is the input rotating member of the automatic transmission 22.

[0014] The torque converter 20 is equipped with a LU clutch 36 as a direct-drive clutch that connects the engine connecting shaft 32 and the transmission input shaft 34. The LU clutch 36 is a known lock-up clutch, for example, a hydraulic friction engagement device. The LU clutch 36's operating state, i.e., control state, such as engaged state, slipped state, and released state, is switched by changing the LU torque Tlu, which is the torque capacity of the LU clutch 36, using the LU hydraulic pressure PRlu. The LU hydraulic pressure PRlu is the hydraulic pressure of the regulated oil FLD supplied to the LU clutch 36 from the hydraulic control circuit 52 provided in the vehicle 10. Oil FLD is a hydraulic fluid used for shifting operations of the automatic transmission 22 and switching operations of the LU clutch 36, etc.

[0015] The automatic transmission 22 is a known planetary gear type automatic transmission comprising, for example, one or more sets of planetary gears (not shown) and an engagement device CB. The engagement device CB is a known hydraulic friction engagement device and includes a plurality of engagement devices, such as clutches and brakes. The engagement device CB can switch between control states such as engaged state, slip state, and released state by changing the engagement torque Tcb, which is the torque capacity of the engagement device CB, by the engagement hydraulic pressure PRcb. The engagement hydraulic pressure PRcb is the hydraulic pressure of the regulated oil FLD supplied to the engagement device CB from the hydraulic control circuit 52.

[0016] The automatic transmission 22 is a stepped transmission in which one of several gear stages (also called gear stages GS) with different gear ratios (also called gear ratios) γat (=Ni / No) is formed by the engagement of any of the engagement devices CB. "Ni" is the rotational speed of the transmission input shaft 34, and is the input rotational speed of the automatic transmission 22, i.e., the transmission input rotational speed Ni. "No" is the rotational speed of the transmission output shaft 24, and is the output rotational speed of the automatic transmission 22, i.e., the transmission output rotational speed No.

[0017] The automatic transmission 22 switches the gear stage GS formed by switching the control state of the engagement device CB in accordance with the driver's accelerator operation, vehicle speed V, etc., by the electronic control device 90 described later. In the shifting operation of the automatic transmission 22, a so-called clutch-to-clutch shift is performed, in which the shifting is carried out by releasing the release-side engagement device while engaging the engagement-side engagement device. The release-side engagement device is an engagement device that was in the engaged state before the automatic transmission 22 shifted, and is controlled from the engaged state to the released state during the shifting transient of the automatic transmission 22. The engagement-side engagement device is an engagement device that was in the released state before the automatic transmission 22 shifted, and is controlled from the released state to the engaged state during the shifting transient of the automatic transmission 22.

[0018] Vehicle 10 is equipped with a mechanical oil pump 38 connected to a pump impeller 20p. The oil pump 38 is rotationally driven by the engine 12 to discharge oil FLD used in the power transmission device 16. The oil FLD discharged from the oil pump 38 is supplied to the hydraulic control circuit 52. The hydraulic control circuit 52 supplies regulated hydraulic pressure PRlu and various engagement hydraulic pressures PRcb based on the oil FLD from the oil pump 38.

[0019] Vehicle 10 is equipped with a wheel brake system 54. The wheel brake system 54 includes a brake master cylinder and cylinder actuator (not shown) that generate brake hydraulic pressure. The wheels WH, including the drive wheels 14 and driven wheels 15, are each equipped with wheel brakes 56. If vehicle 10 is an all-wheel drive vehicle, these driven wheels become drive wheels. The wheel brake system 54 is a braking system that applies a wheel braking torque Tb, which is the braking torque from the wheel brakes 56, to the wheels WH according to a command from the electronic control device 90 (described later). The wheel brake system 54 supplies brake hydraulic pressure to wheel cylinders (not shown) provided on each wheel brake 56 in response to the driver's operation, such as pressing the brake pedal. In the wheel brake system 54, under normal circumstances, master cylinder hydraulic pressure, which is generated from the brake master cylinder and corresponds to the brake operation amount Bra, is supplied to the wheel cylinders as brake hydraulic pressure. The brake operation amount Bra is a signal that represents the magnitude of the driver's brake pedal operation, i.e., the magnitude of the brake operation, corresponding to the force applied to the brake pedal. On the other hand, in the wheel brake system 54, for example, when VSC or automatic brake control is activated, brake hydraulic pressure corresponding to the wheel braking torque Tb required by each control is supplied to the wheel cylinder in order to generate the wheel braking torque Tb.

[0020] VSC (Vehicle Stability Control) is a known sideslip suppression control. In VSC, in order to ensure the stability of the vehicle 10 in the turning direction, the wheel braking torque Tb and the driving torque Td at each of the wheels WH are controlled so as to suppress rear wheel sideslip or front wheel sideslip.

[0021] The vehicle 10 further includes an electronic control unit 90 as a controller including a control device for the vehicle 10 related to control of the engine 12, the automatic transmission 22, and the like. The electronic control unit 90 is configured to include a so-called microcomputer provided with, for example, a CPU, a RAM, a ROM, an input / output interface, and the like. The CPU executes various controls of the vehicle 10 by performing signal processing in accordance with programs stored in advance in the ROM while using, for example, the temporary storage function of the RAM. The electronic control unit 90 is configured to include respective computers for engine control, hydraulic control, brake control, and the like as necessary.

[0022] The electronic control unit 90 is supplied with various signals and the like based on detection values from various sensors and the like provided in the vehicle 10, respectively. The various sensors and the like are, for example, an engine rotational speed sensor 60, an input rotational speed sensor 62, an output rotational speed sensor 64, an accelerator opening sensor 66, a brake sensor 68, an acceleration sensor 70, a yaw rate sensor 72, a steering sensor 74, an operating position sensor 76, an oil temperature sensor 78, and the like. The various signals and the like are, for example, an engine rotational speed Ne, a transmission input rotational speed Ni, a transmission output rotational speed No, an accelerator opening θacc, a brake-on signal Bon, a brake operation amount Bra, a longitudinal acceleration Gx, a lateral acceleration Gy, a yaw rate Ryaw, a steering angle θsw, a steering direction Dsw, an operating position POSop, an oil temperature THfld, and the like.

[0023] Engine rotational speed Ne is the rotational speed of engine 12. Transmission input rotational speed Ni is the same as the turbine rotational speed Nt, which is the rotational speed of turbine blade vehicle 20t. Transmission output rotational speed No is the rotational speed corresponding to vehicle speed V. Accelerator opening θacc is the amount of accelerator operation by the driver, representing the magnitude of the driver's acceleration operation. Brake-on signal Bon is a signal indicating that the brake pedal for activating the wheel brake 56 is being operated by the driver. Yaw rate Ryaw is the rotational angular velocity of vehicle 10 around the vertical axis. Steering angle θsw is the steering angle of the steering wheel (not shown) provided on vehicle 10. Steering direction Dsw is the steering direction of the steering wheel. Oil temperature THfld is the temperature of oil FLD.

[0024] Vehicle 10 is equipped with a shift device 80 having a shift operating member that is operated by the driver to one of a plurality of operating positions POSop. The shift device 80 is a switching device for switching the shift position (also known as shift range Rsh) of the automatic transmission 22. The operating position POSop is a signal that represents the selected state of the power transmission state in the automatic transmission 22, and includes, for example, the P, R, N, and D operating positions. The shift range Rsh represents the power transmission state of the automatic transmission 22, and includes, for example, the P, R, N, and D ranges.

[0025] The P (Parking) operating position represents the selection of the P range of the automatic transmission 22, where the automatic transmission 22 is in neutral and the transmission output shaft 24 is mechanically fixed so as not to rotate. The neutral state of the automatic transmission 22 is a state in which no power transmission is possible as no gear GS is engaged. The R (Reverse) operating position represents the selection of the R range of the automatic transmission 22, which enables reverse driving. The N (Neutral) operating position represents the selection of the N range of the automatic transmission 22, where the automatic transmission 22 is in neutral. The D (Forward) operating position represents the selection of the D range of the automatic transmission 22, which enables forward driving by executing automatic transmission control of the automatic transmission 22. The D range of the automatic transmission 22 is the forward driving position (also known as the forward driving range) of the automatic transmission 22.

[0026] Vehicle 10 is further equipped with a mode selection switch 82. The mode selection switch 82 is a switch operated by the driver to set the drive mode MODEdr of vehicle 10. The drive mode MODEdr includes, for example, normal mode, sport mode (i.e., power mode), and eco mode. Normal mode is a predetermined drive mode for driving in an energy-efficient manner while maximizing power performance. Sport mode is a predetermined drive mode for driving in a manner that prioritizes power performance over energy efficiency compared to normal mode. Eco mode is a predetermined drive mode for driving in a manner that prioritizes energy efficiency over power performance compared to normal mode.

[0027] The mode selection switch 82 includes a sport mode switch 84 and an eco mode switch 86 for switching between drive modes (MODEdr). The sport mode switch 84 is used to set sport mode as the drive mode (MODEdr). The eco mode switch 86 is used to set eco mode as the drive mode (MODEdr). The electronic control unit 90 is supplied with the drive mode (MODEdr) signal detected by the mode selection switch 82. If neither the sport mode switch 84 nor the eco mode switch 86 is operated, normal mode is set as the drive mode (MODEdr).

[0028] Vehicle 10 is further equipped with a VSC deactivation switch 88. The VSC deactivation switch 88 is a switch operated by the driver to limit the operation of the VSC. Modes for limiting the operation of the VSC include, for example, a VSC off mode in which the VSC is basically deactivated during normal driving, and a VSC sport driving mode in which the VSC is basically deactivated during sport driving. For example, each time the VSC deactivation switch 88 is operated, a deactivation operation signal Soff is supplied to the electronic control unit 90. As a result, the VSC mode is switched between the VSC off mode, the VSC sport driving mode, and the VSC on mode in which the VSC is activated, depending on the operation of the VSC deactivation switch 88. Sport driving is a type of driving in which the vehicle 10 is driven in a side-slipping state when turning, and is also called drift driving. Furthermore, "basically" means, for example, except when it is necessary to activate it for safety reasons.

[0029] The electronic control unit 90 outputs various command signals to each device installed in the vehicle 10. These devices include, for example, the engine control unit 50, the hydraulic control circuit 52, and the wheel brake device 54. The various command signals include, for example, the engine control command signal Se, the engagement hydraulic control command signal Scrb, the LU hydraulic control command signal Slu, and the brake control command signal Sbra. The engine control command signal Se is a command signal for controlling the engine 12. The engagement hydraulic control command signal Scrb is a command signal for controlling the engagement device CB and is the instruction hydraulic pressure for the engagement hydraulic pressure PRcb. The LU hydraulic control command signal Slu is a command signal for controlling the LU clutch 36 and is the instruction hydraulic pressure for the LU hydraulic pressure PRlu. The brake control command signal Sbra is a command signal for controlling the wheel braking torque Tb.

[0030] The electronic control unit 90 includes a driving control unit 92 and a brake control unit 94 in order to implement various controls in the vehicle 10.

[0031] The driving control unit 92 includes an engine control unit 92a that controls the engine 12 and a transmission control unit 92b that controls the shifting of the automatic transmission 22.

[0032] The engine control unit 92a calculates the amount of drive requested by the driver to the vehicle 10 by applying the accelerator opening θacc and vehicle speed V to a predetermined drive request map, which has been experimentally or design-determined in advance. The amount of drive requested is, for example, the required drive torque Tddem at the drive wheels 14. The engine control unit 92a outputs an engine control command signal Se to control the engine 12 so that the required engine torque Tedem is obtained to realize the required drive torque Tddem, which has been calculated considering transmission losses, auxiliary loads, gear ratio γat, etc. When VSC is activated, the engine control unit 92a outputs an engine control command signal Se to control the engine 12 so that the required engine torque Tedem is obtained to realize the required drive torque Tddem required for each control.

[0033] The transmission control unit 92b makes a shift decision for the automatic transmission 22 using, for example, a predetermined shift map, and outputs an engagement hydraulic control command signal Sb to the hydraulic control circuit 52 to execute shift control of the automatic transmission 22 according to the result of that shift decision.

[0034] The brake control unit 94 controls the wheel brake device 54. The brake control unit 94 outputs a brake control command signal Sbra to generate a wheel braking torque Tb corresponding to the brake operation amount Bra. When VSC or automatic brake control is activated, the brake control unit 94 outputs a brake control command signal Sbra to generate the wheel braking torque Tb required for each control.

[0035] Incidentally, if the vehicle speed V or engine speed Ne drops to a low level while drifting in D range, the shift map may not determine that the automatic transmission 22 should downshift, and a downshift may not occur. In that case, during drifting, where the accelerator is repeatedly turned on and off, the drive wheels 14 may lose grip due to insufficient drive torque Td caused by the decrease in engine speed Ne, making it difficult to maintain the vehicle's posture during drifting. Alternatively, after cornering, acceleration may be sluggish because the vehicle accelerates from a state where the engine speed Ne has decreased. When drifting in D range, it is desirable to maintain the low-speed gear GS in order to corner smoothly and ensure responsive acceleration out of corners. The low-speed gear GS is the low gear GSlow, where the gear ratio γat is a relatively large value.

[0036] Therefore, when the electronic control unit 90 detects a decrease in vehicle speed V during drift driving in D range, it performs a downshift of the automatic transmission 22. The electronic control unit 90 prevents a decrease in driving performance by maintaining the engine rotation speed Ne at a high range while turning. In this case, for example, when VSC is activated while driving on a slippery road surface such as a snowy road, it is undesirable to perform a downshift. By limiting the operation of VSC to a state in which the operation of the electronic control unit 90 is restricted, it is possible to achieve compatibility with driving other than motorsports. For this reason, the electronic control unit 90 further includes a sports driving determination unit 96 and a condition fulfillment determination unit 98.

[0037] The sports driving determination unit 96 determines whether or not sports driving, that is, drift driving, is in progress. The sports driving determination unit 96 functions as a drift driving determination unit. The sports driving determination unit 96 determines whether or not drift driving is in progress based on whether or not the vehicle is in one of the following states: oversteer, understeer, countersteer, or vehicle counter. The drift driving determined by the sports driving determination unit 96 is a broad definition of drift driving, including oversteer, understeer, countersteer, and vehicle counter. The countersteer state is a state in which the steering wheel is operated in the opposite direction to the left or right of the turning direction of the vehicle 10, and is a state of drift driving in the narrow sense. The vehicle counter state is a state in which the vehicle 10 is sliding sideways when it is returned from the countersteer state to the straight-ahead state of the vehicle 10. The sports driving determination unit 96 determines whether the vehicle is in one of the following states: oversteer, understeer, countersteer, or vehicle counter-steering, based on, for example, the left-right acceleration Gy, yaw rate Ryaw, steering angle θsw, steering direction Dsw, etc.

[0038] The condition fulfillment determination unit 98 determines whether the permission condition Cp is met. The permission condition Cp is a prerequisite for allowing downshifting of the automatic transmission 22 while performing drift driving in D range. The permission condition Cp includes the condition that the vehicle speed V is less than a predetermined vehicle speed Vf and that the operation of VSC is restricted.

[0039] The predetermined vehicle speed Vf is a predetermined lower limit of the vehicle speed V at which the engine torque Te capable of generating the drive torque Td required for, for example, drift driving can be achieved. The engine 12 has a torque band, which is a range of engine rotational speed Ne at which engine torque Te is easily produced. The predetermined vehicle speed Vf is the vehicle speed V corresponding to the lower limit of the range of engine rotational speed Ne within this torque band. Vehicle speed V being less than the predetermined vehicle speed Vf is equivalent to transmission output rotational speed No being less than the predetermined output rotational speed Nof. The predetermined output rotational speed Nof is a predetermined threshold corresponding to the predetermined vehicle speed Vf. The predetermined vehicle speed Vf and predetermined output rotational speed Nof are also values ​​used, for example, to ensure that the engine rotational speed Ne does not exceed the allowable rotational speed after downshifting by the automatic transmission 22.

[0040] The state in which the VSC operation is restricted is when the VSC mode is set to VSC off mode or VSC sport driving mode by operating the VSC release switch 88.

[0041] The transmission control unit 92b determines whether the shift range Rsh of the automatic transmission 22 is in the D range. When the transmission control unit 92b determines that the shift range Rsh is in the D range, and the sports driving determination unit 96 determines that drift driving is in progress, and the condition fulfillment determination unit 98 determines that the permission condition Cp is fulfilled, the transmission control unit 92b performs a downshift of the automatic transmission 22. In this way, the driving control unit 92 determines a downshift of the automatic transmission 22 not only using the shift map, but also based on the engine rotation speed Ne (vehicle speed V, transmission output rotation speed No is also synonymous).

[0042] The transmission control unit 92b performs downshifts of the automatic transmission 22 during drift driving using blipping downshifts rather than clutch-to-clutch shifting. A blipping downshift is a downshift in which the engine torque Te increases the transmission input rotational speed Ni towards the synchronous rotational speed after downshifting (=γata×No) with the release-side engaging device released, and then the engaging-side engaging device is engaged. "γata" is the gear ratio γat in gear stage GS after downshifting. Compared to clutch-to-clutch shifting, blipping downshifts have a shorter gear transition time.

[0043] Blip-down shifting may not be properly performed in the low oil temperature THfld range. Alternatively, blipping downshifting is a control method that increases the transmission input rotational speed Ni, which cannot be increased automatically in the neutral state with the release-side engagement device released, by using engine torque Te. In other words, blipping downshifting is performed by increasing the engine torque Te, which is in a relatively small range, regardless of the accelerator opening θacc. Conversely, in blipping downshifting, if the engine torque Te is originally large, it may not be possible to properly increase the transmission input rotational speed Ni towards the synchronous rotational speed after downshifting. For this reason, the permission condition Cp may further include at least one of the following: the oil temperature THfld is greater than or equal to the lower limit oil temperature THfldf, and the accelerator opening θacc is less than or equal to the upper limit accelerator opening θaccf. The lower limit oil temperature THfldf is, for example, a predetermined threshold that makes blipping downshifting possible. The upper limit of accelerator opening θaccf is a predetermined upper limit of accelerator operation that enables transient control of, for example, blipping downshifts.

[0044] From a drivability perspective, a situation in which ensuring acceleration responsiveness is preferable is, for example, when the drive mode MODEdr of the vehicle 10 is set to sport mode by the mode selection switch 82. Therefore, the permission condition Cp may further include the condition that the drive mode MODEdr set in the vehicle 10 is sport mode.

[0045] Figure 2 is a flowchart illustrating the main part of the control operation of the electronic control device 90, and is a flowchart illustrating the control operation that makes it easier to secure drive torque Td while suppressing unnecessary downshifts when performing drift driving, and is, for example, executed repeatedly.

[0046] In Figure 2, first, in step S10, which corresponds to the function of the transmission control unit 92b (the step is omitted hereafter), it is determined whether the shift range Rsh is in the D range. If the determination in S10 is negative, this routine is terminated. If the determination in S10 is positive, in S20, which corresponds to the function of the sports driving determination unit 96, it is determined whether drift driving is in progress. If the determination in S20 is positive, in S30, which corresponds to the function of the condition fulfillment determination unit 98, it is determined whether the permission condition Cp is fulfilled. If the determination in S30 is positive, in S40, which corresponds to the function of the transmission control unit 92b, a downshift of the automatic transmission 22 is performed. If the determination in S20 is negative, or if the determination in S30 is negative, in S50, which corresponds to the function of the transmission control unit 92b, a downshift of the automatic transmission 22 is not performed.

[0047] Figure 3 shows an example of a time chart when the control operation shown in the flowchart of Figure 2 is performed. Figure 3 shows an example when driving in D range in VSC off mode or VSC sport driving mode. In Figure 3, time t1 indicates the time when the determination that drift driving is performed begins. If the vehicle speed V falls below a predetermined vehicle speed Vf during drift driving, the automatic transmission 22 performs a downshift (see time t2). In the comparative example shown by the dashed line, since no downshift is performed during drift driving, the engine torque Te is in a low range (see from time t2 onwards), and the vehicle attitude during drift driving is not properly maintained (see yaw rate Ryaw or lateral acceleration Gy). In addition, the acceleration response after turning is not good. On the other hand, in this embodiment shown by the solid line, the engine torque Te is maintained in a high range by downshifting (see from time t2 onwards), and the vehicle attitude during drift driving is properly maintained (see yaw rate Ryaw or lateral acceleration Gy). In addition, the acceleration response after turning is improved.

[0048] As described above, according to this embodiment, when the shift range Rsh is in the D range, if it is determined that drift driving is in progress and the permission condition Cp is met, a downshift of the automatic transmission 22 is performed. This allows for a downshift during drift driving, keeping the engine speed Ne at a high range and making it easier to secure the drive torque Td. Furthermore, since it is limited to when the permission condition Cp is met, for example, a downshift will not be performed when the VSC is activated. In other words, by limiting the operation of the VSC, unnecessary downshifts are not performed during slips other than drift driving (including when the VSC is activated), making it easier to maintain compatibility with normal driving. Therefore, when performing drift driving, it is possible to easily secure the drive torque Td while suppressing unnecessary downshifts. During drift driving, the engine speed Ne is kept at a high range, making it easier to control the vehicle's attitude. In addition, acceleration performance when coming out of a turn is improved.

[0049] Furthermore, according to this embodiment, the predetermined vehicle speed Vf is a predetermined lower limit of the vehicle speed V at which the engine torque Te capable of generating the drive torque Td required for drift driving can be generated. As a result, downshifting is performed during drift driving, the engine rotation speed Ne is kept in the high range, and the drive torque Td is more easily secured.

[0050] Furthermore, according to this embodiment, the downshift of the automatic transmission 22 during drift driving is a blipping downshift. This shortens the transition time compared to clutch-to-clutch shifting, and the engine speed Ne is quickly maintained at a high range.

[0051] Furthermore, according to this embodiment, the permission condition Cp may also include at least one of the following: the oil temperature THfld is equal to or greater than the lower limit oil temperature THfldf, and the accelerator opening θacc is equal to or less than the upper limit accelerator opening θaccf. This ensures that the blipping downshift of the automatic transmission 22 is properly performed during drift driving.

[0052] Furthermore, according to this embodiment, the permission condition Cp may also include the drive mode MODEdr set in the vehicle 10 being in sport mode. This improves drivability by improving acceleration response.

[0053] Although embodiments of the present invention have been described in detail above with reference to the drawings, the present invention is also applicable to other embodiments.

[0054] For example, in the above-described embodiment, an engine 12 was used as an example of a power source, but the embodiment is not limited to this. For example, an electric motor may be used as a power source in addition to or instead of the engine 12.

[0055] Furthermore, in the above-described embodiment, the downshift of the automatic transmission 22 during drift driving does not have to be a blipping downshift; it may also be a clutch-to-clutch downshift. Even in this case, certain effects of the present invention can be obtained.

[0056] Furthermore, although a planetary gear type stepped transmission was exemplified as the automatic transmission 22 in the above-described embodiment, the embodiment is not limited to this. For example, except for the control related to blipping downshift, the automatic transmission 22 may be a synchronous meshing type parallel two-axis automatic transmission including a known DCT (Dual Clutch Transmission), a known continuously variable transmission such as a belt type, or a known electric continuously variable transmission. In the case of a continuously variable transmission, for example, stepped gear stages may be formed.

[0057] Furthermore, in the above-described embodiment, the drive mode MODEdr may include a predetermined drive mode, such as a drift mode, which allows the vehicle 10 to be driven in a state where it is easy to slide sideways during turns. This drift mode is a drive mode suitable for drift driving, which is driving in a state where the vehicle 10 slides sideways during turns. The permission condition Cp may further include the fact that the drive mode MODEdr set for the vehicle 10 is the drift mode. This improves drivability by allowing the vehicle's posture during drift driving to be properly maintained.

[0058] It should be noted that the above-described embodiment is merely one example, and the present invention can be implemented in various modified and improved forms based on the knowledge of those skilled in the art. [Explanation of symbols]

[0059] 10: Vehicle 12: Engine (power source) 14: Drive wheels 22: Automatic transmission 90: Electronic control unit (control device) 92b: Transmission control unit 96: Sport driving determination unit 98: Condition fulfillment determination unit CB: Engagement device FLD: Oil (hydraulic fluid)

Claims

1. A control device for a vehicle comprising a power source and an automatic transmission provided in the power transmission path between the power source and the drive wheels, A sports driving determination unit that determines whether or not the vehicle is in the process of performing sports driving, which involves driving the vehicle in a side-slip state when turning, A condition fulfillment determination unit that determines whether the permission conditions are met, namely that the vehicle speed is below a predetermined speed and the operation of the yaw suppression control is restricted, When the shift position of the automatic transmission is a forward driving position that enables forward driving by executing automatic shift control, and it is determined that the sport driving is being performed and the permission conditions are met, the transmission control unit executes a downshift of the automatic transmission. A vehicle control device characterized by including [a specific feature].

2. The vehicle control device according to claim 1, characterized in that the predetermined vehicle speed is a predetermined lower limit of the vehicle speed at which the power source can generate the torque necessary to perform the sports driving.

3. The aforementioned automatic transmission is a stepped transmission in which one of the multiple gear stages is formed by the engagement of one of the multiple engagement devices. The vehicle control device according to claim 1 or 2, characterized in that the downshift is a blipping downshift in which the engagement device on the engagement side is engaged after the torque of the power source has increased the input rotational speed of the stepped transmission toward the synchronous rotational speed after the downshift while the engagement device on the release side is released.

4. The vehicle control device according to claim 3, characterized in that the permission conditions further include at least one of the following: the temperature of the hydraulic fluid used for shifting the automatic transmission is above a predetermined lower limit oil temperature that enables the blipping downshift; and the accelerator operation amount is below a predetermined upper limit accelerator operation amount that enables transient control of the blipping downshift.

5. The vehicle control device according to claim 1 or 2, characterized in that the aforementioned permission conditions further include a sport mode in which the vehicle is driven in a manner that prioritizes power performance over energy efficiency.

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