Vehicle control device

Abstract

To provide a control device of a vehicle which can suppress blow-up of the input rotational speed during down-shift while suppressing reduction in the responsibility of torque when executing down-shift of a transmission followed by an acceleration operation in a vehicle that uses a motor as a drive source.SOLUTION: In a case where a rotational speed difference ΔNi between an input rotational speed Ni of an automatic transmission 24 during down-shift and a synchronous rotational speed Nsyc calculated on the basis of a transmission ratio γat of the automatic transmission 24 after down-shift is equal to or less than a preset prescribed value K, the increase ratio α of input torque Ti is restricted. With this, in a case where the rotational speed difference ΔNi is equal to or less than the prescribed value K, the time required for the input rotational speed Ni to reach the synchronous rotational speed Nsyc is short, and there is such a risk that blow-up of the input rotational speed Ni occurs during down-shift, the blow-up of the input rotational speed Ni during the down-shift is suppressed due to restriction on the increase ratio α of the input torque Ti.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a control device for a vehicle that uses at least an electric motor as a driving force source. [Background technology]

[0002] Patent Document 1 describes that in a vehicle using an engine and an electric motor as driving power sources, when a power-on downshift of the transmission interposed in the power transmission path between these driving power sources and the drive wheels is performed, the electric motor is used to assist (supplement) the input torque to the transmission. Note that a power-on downshift of the transmission refers to a downshift that is performed in conjunction with accelerator operation by the driver. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-316831 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when torque assist is performed by an electric motor during a power-on downshift of the transmission, if there is a delay in the increase in the torque capacity of the transmission relative to the increase in input torque, there is a risk of the input rotation speed increasing.On the other hand, if the input torque is limited in order to suppress the increase in input rotation speed, the problem of poor torque responsiveness during the downshift occurs.

[0005] The present invention has been made against the background of the above circumstances, and its purpose is to provide a vehicle control device that can suppress a rise in input rotational speed during a downshift of a transmission that involves accelerator operation, while suppressing a decrease in torque responsiveness, at least in a vehicle that uses an electric motor as a driving force source. [Means for solving the problem]

[0006] The gist of the first invention is as follows: (a) The present invention is applied to a vehicle equipped with an electric motor as a driving force source and a transmission interposed in a power transmission path between the electric motor and drive wheels, and when a downshift of the transmission is performed in association with an accelerator operation by a driver, the electric motor torque of the electric motor The downshift a control device for a vehicle configured to control an input torque input to the transmission during First accelerator operation by the driver of the transmission with The downshift In carrying out the above, During the downshift the input rotational speed of the transmission at After the downshift of the transmission The first gear ratio is the gear ratio is calculated based on First synchronous rotation speed If the rotation speed difference between When the rotational speed difference between the input rotational speed and the first synchronous rotational speed is greater than the predetermined value, Limits the rate of increase of input torque (c) when the rate of increase of the input torque is limited during the downshift, if a second accelerator operation by the driver causes the gear ratio of the transmission after the downshift to become a second gear ratio different from the first gear ratio, and a rotational speed difference between the input rotational speed and a second synchronous rotational speed calculated based on the second gear ratio after the downshift becomes larger than the predetermined value, the limit on the rate of increase of the input torque is released. It is characterized by: [Effects of the Invention]

[0007] According to the first invention, (a) During the downshift and the input rotation speed of the transmission at After the downshift of the gearbox The first gear ratio is the gear ratio is calculated based on First synchronous rotation speed If the rotation speed difference between When the rotational speed difference between the input rotational speed and the first synchronous rotational speed is greater than a predetermined value, The rate of increase of the input torque is limited. (b) when the rate of increase of the input torque is limited during the downshift, if the driver operates a second accelerator pedal to change the gear ratio of the transmission after the downshift to a second gear ratio different from the first gear ratio, and the rotational speed difference between the input rotational speed and a second synchronous rotational speed calculated based on the second gear ratio after the downshift becomes larger than a predetermined value, the limit on the rate of increase of the input torque is released.As a result, when the rotational speed difference is equal to or less than a predetermined value, the time it takes for the input rotational speed to reach the synchronous rotational speed is short, and there is a risk of the input rotational speed racing during a downshift, the rate of increase of the input torque is limited, thereby suppressing the input rotational speed racing during the downshift. On the other hand, when the rotational speed difference is greater than a predetermined value, and the transmission has the torque capacity to transmit the input torque before the input rotational speed reaches the synchronous rotational speed, the rate of increase of the input torque is not limited, thereby suppressing a decrease in torque responsiveness. In this way, by limiting the rate of increase of the input torque in accordance with the rotational speed difference calculated during the downshift, it is possible to suppress the input rotational speed racing while suppressing a decrease in torque responsiveness during the downshift.

[0008] Preferably, in the first aspect of the present invention, the limit on the rate of increase of the input torque is implemented from the start of the inertia phase to the end of the torque phase. Before the start of the inertia phase and after the end of the torque phase, the transmission can transmit the input torque, so in these cases the limit on the rate of increase of the input torque is not imposed, thereby preventing a decrease in responsiveness due to unnecessary limiting of the input torque.

[0009] Preferably, in the first aspect of the present invention, the predetermined value is set to a threshold value of the rotational speed difference at which the transmission can transmit the input torque when the input rotational speed of the transmission reaches the synchronous rotational speed. In this way, if the rotational speed difference is greater than the predetermined value, the transmission can transmit the input torque when the input rotational speed of the transmission reaches the synchronous rotational speed, thereby suppressing a sudden increase in the input rotational speed without limiting the rate of increase of the input torque. On the other hand, if the rotational speed difference is equal to or less than the predetermined value, the torque capacity of the transmission may be insufficient for the input torque when the input rotational speed reaches the synchronous rotational speed, potentially causing a sudden increase in the input rotational speed. In such a case, limiting the rate of increase of the input torque suppresses a sudden increase in the input rotational speed during a downshift.

[0010] Preferably, in the first aspect of the present invention, the upper limit guard value for the rate of increase of the input torque, which is set when the rotational speed difference calculated during a downshift is equal to or smaller than a predetermined value, is set to a lower value the smaller the rotational speed difference. In this way, the smaller the rotational speed difference, the shorter the time it takes for the input rotational speed to reach the synchronous rotational speed, and the torque capacity of the transmission becomes insufficient when the input rotational speed reaches the synchronous rotational speed, making it more likely that the input rotational speed will increase too much. However, by setting the upper limit guard value for the rate of increase of the input torque to a lower value the smaller the rotational speed difference, the input torque can be increased more gradually, thereby suppressing the increase in the input rotational speed. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a diagram illustrating a schematic configuration of a vehicle to which the present invention is applied, and is also a diagram illustrating main parts of control functions and control systems for various controls in the vehicle. [Figure 2] 3 is an engagement operation table showing combinations of engagement devices for establishing gear stages of an automatic transmission. [Figure 3] FIG. 10 is a diagram showing one aspect of a relationship map used when setting an upper limit guard value for the rate of increase based on a rotational speed difference. [Figure 4] This is a flowchart for explaining the main control operations of an electronic control device, and is a flowchart for explaining the control operation of setting an upper limit guard value for the rate of increase that suppresses an increase in turbine rotation speed while suppressing a decrease in torque responsiveness during a power-on downshift of an automatic transmission. [Figure 5] 10 is a time chart showing a control state when a rotational speed difference is equal to or less than a predetermined value during a power-on downshift of an automatic transmission. [Figure 6] 10 is a time chart showing a control state when a destination gear is changed to a lower gear during a power-on downshift of an automatic transmission. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that in the following embodiments, the drawings are appropriately simplified or modified, and the dimensional ratios and shapes of the various parts are not necessarily drawn accurately. [Example]

[0013] Fig. 1 is a diagram illustrating the schematic configuration of a vehicle 10 to which the present invention is applied, as well as a diagram illustrating the main parts of the control functions and control systems for various controls in the vehicle 10. In Fig. 1, the vehicle 10 is a hybrid vehicle equipped with an engine 12 and an electric motor MG, which are driving power sources for traveling. The vehicle 10 also has drive wheels 14 and a power transmission device 16 provided in a power transmission path between the engine 12 and the drive wheels 14.

[0014] The engine 12 is a known internal combustion engine such as a gasoline engine, a diesel engine, etc. An electronic control device 90 (described later) controls an engine control device 50 including a throttle actuator, a fuel injection device, an ignition device, etc., provided in the vehicle 10, thereby controlling the engine torque Te, which is the output torque of the engine 12.

[0015] The electric motor MG is a rotating electric machine, a so-called motor generator, that functions as a motor that generates mechanical power from electric power and as a generator that generates electric power from mechanical power. The electric motor MG is connected to a battery 54 provided in the vehicle 10 via an inverter 52 provided in the vehicle 10. The inverter 52 is controlled by an electronic control device 90 (described later), thereby controlling the MG torque Tm, which is the output torque (motor torque) of the electric motor MG. For example, when the rotation direction of the electric motor MG is forward, which is the same as the rotation direction of the engine 12 when it is operating, the MG torque Tm is a powering torque when it is a positive torque on the acceleration side, and a regenerative torque when it is a negative torque on the deceleration side. Specifically, the electric motor MG generates power for traveling using electric power supplied from the battery 54 via the inverter 52 instead of or in addition to the engine 12. The electric motor MG also generates electric power using the power of the engine 12 and the driven force input from the drive wheels 14 side. The electric power generated by the electric motor MG is stored in the battery 54 via the inverter 52. The battery 54 is an electric storage device that supplies and receives electric power to the electric motor MG. The electric power also refers to electrical energy unless otherwise specified. The power also refers to torque or force unless otherwise specified.

[0016] The power transmission device 16 includes a K0 clutch 20, a torque converter 22, an automatic transmission 24, and the like, housed within a case 18, which is a non-rotating member attached to the vehicle body. The K0 clutch 20 is a clutch provided between the engine 12 and the electric motor MG in the power transmission path between the engine 12 and the drive wheels 14. The torque converter 22 is connected to the engine 12 via the K0 clutch 20.

[0017] The automatic transmission 24 is provided in a power transmission path between the engine 12 and electric motor MG and the drive wheels 14. In other words, the automatic transmission 24 constitutes a part of the power transmission path between the engine 12 and electric motor MG and the drive wheels 14. The power transmission device 16 also includes a propeller shaft 28 connected to a transmission output shaft 26, which is an output rotating member of the automatic transmission 24, a differential gear 30 connected to the propeller shaft 28, a pair of drive shafts 32 connected to the differential gear 30, etc. The power transmission device 16 also includes an engine connecting shaft 34 that connects the engine 12 and K0 clutch 20, an electric motor connecting shaft 36 that connects the K0 clutch 20 and the torque converter 22, etc.

[0018] The electric motor MG is connected to the electric motor connecting shaft 36 within the case 18 so as to be able to transmit power. The electric motor MG is connected to a power transmission path between the engine 12 and the drive wheels 14, particularly to a power transmission path between the K0 clutch 20 and the torque converter 22. In other words, the electric motor MG is connected to the torque converter 22 and the automatic transmission 24 so as to be able to transmit power without passing through the K0 clutch 20. In other words, the torque converter 22 and the automatic transmission 24 each constitute part of the power transmission path between the electric motor MG and the drive wheels 14. The torque converter 22 and the automatic transmission 24 transmit the driving power from the driving power sources of the engine 12 and the electric motor MG to the drive wheels 14, respectively.

[0019] The torque converter 22 includes a pump wheel 22a connected to an electric motor connecting shaft 36 and a turbine wheel 22b connected to a transmission input shaft 38, which is an input rotating member of the automatic transmission 24. The pump wheel 22a is connected to the engine 12 via the K0 clutch 20 and is also directly connected to the electric motor MG. The pump wheel 22a is the input member of the torque converter 22, and the turbine wheel 22b is the output member of the torque converter 22. The electric motor connecting shaft 36 is also the input rotating member of the torque converter 22. The transmission input shaft 38 is also the output rotating member of the torque converter 22, formed integrally with a turbine shaft that is rotationally driven by the turbine wheel 22b. The torque converter 22 is a fluid transmission that transmits driving force from each of the driving force sources (engine 12, electric motor MG) to the transmission input shaft 38 via fluid. The torque converter 22 includes a known lock-up clutch 40 (hereinafter referred to as LU clutch 40) that connects and disconnects the pump wheel 22a and the turbine wheel 22b.

[0020] The operating state, i.e., the control state, of the LU clutch 40 is switched by changing the LU clutch torque Tlu, which is the torque capacity of the LU clutch 40, using the regulated LU oil pressure PRlu supplied from a hydraulic control circuit 56 provided in the vehicle 10. The control states of the LU clutch 40 include a fully released state in which the LU clutch 40 is released, a slip state in which the LU clutch 40 is engaged with slippage, and a fully engaged state in which the LU clutch 40 is engaged.

[0021] The automatic transmission 24 is a known planetary gear automatic transmission equipped with, for example, one or more planetary gear sets (not shown) and a plurality of engagement devices CB. The engagement devices CB are hydraulic friction engagement devices, such as multi-plate or single-plate clutches or brakes pressed by hydraulic actuators, or band brakes tightened by hydraulic actuators. The engagement devices CB are switched between control states such as an engaged state and a disengaged state by varying their respective torque capacities Tcb using regulated CB oil pressure PRcb supplied from a hydraulic control circuit 56. In this embodiment, the engagement devices CB are composed of, for example, four clutches C1 to C4 and two brakes B1 and B2.

[0022] The automatic transmission 24 is a stepped automatic transmission in which one of a plurality of gears (also referred to as "gear stages") with different speed ratios (also referred to as "gear ratios") γat (=input rotation speed Ni / output rotation speed No) is established by engaging one of the engagement devices CB. That is, the automatic transmission 24 shifts to a plurality of gears according to combinations of engagement and disengagement of the plurality of engagement devices CB (clutches C1 to C4 and brakes B1 and B2). Specifically, the automatic transmission 24 shifts gears based on an engagement operation table shown in FIG. 2, which shows combinations of the engagement devices CB for establishing the gears of the automatic transmission 24. In FIG. 2, "◯" indicates engagement of an engagement device CB, and "X" indicates disengagement of an engagement device CB. As shown in FIG. 2, the automatic transmission 24 is configured to be able to switch between ten gears, from first gear (1st) to tenth gear (10th), by changing the combinations of engagement and disengagement of the engagement devices CB. The input rotation speed Ni corresponds to the rotation speed of the transmission input shaft 38 of the automatic transmission 24 , and the output rotation speed No corresponds to the rotation speed of the transmission output shaft 26 of the automatic transmission 24 .

[0023] The automatic transmission 24 determines the gear position by an electronic control device 90 (described later) based on the accelerator opening θacc, which is the amount of operation of the accelerator pedal 42 by the driver, and the vehicle speed V. Note that the decision to shift gears may be made not only based on the accelerator opening θacc but also based on a related value of the accelerator opening θacc that is correlated with the accelerator opening θacc, such as the throttle opening θth. Similarly, the decision to shift gears may be made not only based on the vehicle speed V but also based on a related value of the vehicle speed V that is correlated with the vehicle speed V, such as the output rotation speed No. The input rotation speed Ni is the rotation speed of the transmission input shaft 38 and is the input rotation speed of the automatic transmission 24. The input rotation speed Ni is also the rotation speed of the output rotating member of the torque converter 22 and is equivalent to the turbine rotation speed Nt, which is the output rotation speed of the torque converter 22. Therefore, the input rotation speed Ni can be expressed in terms of the turbine rotation speed Nt. The output rotation speed No is the rotation speed of the transmission output shaft 26, and is the output rotation speed of the automatic transmission 24. The automatic transmission 24 corresponds to the transmission of the present invention.

[0024] The K0 clutch 20 is a wet or dry friction engagement device configured with a multi-plate or single-plate clutch pressed by a hydraulic actuator (not shown). The control state of the K0 clutch 20, such as an engaged state or a disengaged state, is switched by an electronic control device 90 (described later) controlling the operating state of the hydraulic actuator. When the K0 clutch 20 receives the K0 oil pressure PRk0 regulated by the hydraulic control circuit 56 and supplied to the hydraulic actuator, the torque capacity Tk0 of the K0 clutch 20 is changed, thereby switching the control state of the K0 clutch 20.

[0025] When the K0 clutch 20 is engaged, the pump wheel 22a and the engine 12 are rotated integrally via the engine connecting shaft 34. That is, when engaged, the K0 clutch 20 connects the engine 12 and the drive wheels 14 so that power can be transmitted between them. On the other hand, when the K0 clutch 20 is disengaged, power transmission between the engine 12 and the pump wheel 22a is interrupted. That is, when disengaged, the K0 clutch 20 disconnects the engine 12 and the drive wheels 14. Because the electric motor MG is connected to the pump wheel 22a, the K0 clutch 20 is provided in the power transmission path between the engine 12 and the electric motor MG and functions as a clutch that connects and disconnects the power transmission path, i.e., a clutch that connects and disconnects the engine 12 and the electric motor MG. That is, the K0 clutch 20 is a connecting / disconnecting clutch that connects the engine 12 and the electric motor MG when engaged and disconnects the connection between the engine 12 and the electric motor MG when disengaged.

[0026] In the power transmission device 16, when the K0 clutch 20 is engaged, the power output from the engine 12 is transmitted from the engine connecting shaft 34 to the drive wheels 14 via the K0 clutch 20, the electric motor connecting shaft 36, the torque converter 22, the automatic transmission 24, the propeller shaft 28, the differential gear 30, the drive shaft 32, etc. in this order. Similarly, the power output from the electric motor MG is transmitted from the electric motor connecting shaft 36 to the drive wheels 14 via the torque converter 22, the automatic transmission 24, the propeller shaft 28, the differential gear 30, the drive shaft 32, etc. in this order, regardless of the control state of the K0 clutch 20.

[0027] The vehicle 10 is equipped with a MOP 58 which is a mechanical oil pump, an EOP 60 which is an electric oil pump, a pump motor 62, etc. The MOP 58 is connected to the pump impeller 22a and is driven to rotate by a driving power source (the engine 12, the electric motor MG) to discharge hydraulic oil used in the power transmission device 16. The pump motor 62 is a motor dedicated to the EOP 60 for driving the EOP 60 to rotate. The EOP 60 is driven to rotate by the pump motor 62 to discharge hydraulic oil. The hydraulic oil discharged by the MOP 58 and the EOP 60 is supplied to a hydraulic control circuit 56. The hydraulic control circuit 56 supplies a CB hydraulic pressure PRcb, a K0 hydraulic pressure PRk0, an LU hydraulic pressure PRlu, etc., each adjusted based on the hydraulic oil discharged by at least one of the MOP 58 and the EOP 60.

[0028] The vehicle 10 further includes an electronic control unit 90 including a control device related to driving control of the vehicle 10. The electronic control unit 90 includes a so-called microcomputer equipped with, for example, a CPU, RAM, ROM, an input / output interface, etc., and the CPU executes various controls of the vehicle 10 by performing signal processing in accordance with programs stored in the ROM in advance while utilizing the temporary storage function of the RAM. The electronic control unit 90 includes computers for engine control, electric motor control, hydraulic control, etc. as necessary.

[0029] The electronic control device 90 receives various signals based on detected values ​​from various sensors provided in the vehicle 10 (for example, an engine rotation speed Ne, which is the rotation speed of the engine 12; a turbine rotation speed Nt, which is the same value as the input rotation speed Ni; an output rotation speed No corresponding to the vehicle speed V; an MG rotation speed Nm, which is the rotation speed of the electric motor MG; and a driver's acceleration. The signals supplied include accelerator opening θacc, which is the amount of operation of the accelerator pedal 42 by the driver and indicates the magnitude of the operation; throttle opening θth, which is the opening of the electronic throttle valve; brake-on signal Bon, which is a signal indicating the state in which the brake pedal 44 for activating the wheel brakes is being operated by the driver; battery temperature THbat, battery charge / discharge current Ibat, and battery voltage Vbat of the battery 54; hydraulic oil temperature THoil, which is the temperature of the hydraulic oil in the hydraulic control circuit 56; and shift operation position Psh, which is the operating position of the shift lever 48 of the shift operation device 46 operated by the driver.

[0030] The electronic control device 90 outputs various command signals (e.g., an engine control command signal Se for controlling the engine 12, an MG control command signal Sm for controlling the electric motor MG, a CB hydraulic control command signal Sbc for controlling the engagement device CB, a K0 hydraulic control command signal Sko for controlling the K0 clutch 20, an LU hydraulic control command signal Slu for controlling the LU clutch 40, an EOP control command signal Seop for controlling the EOP 60, etc.) to each device provided in the vehicle 10 (e.g., the engine control device 50, the inverter 52, the hydraulic control circuit 56, the pump motor 62, etc.).

[0031] The electronic control device 90 includes a hybrid control means or hybrid control unit 92, a clutch control means or clutch control unit 94, and a gear shift control means or gear shift control unit 96 in order to realize various controls in the vehicle 10.

[0032] The hybrid control unit 92 has a function as an engine control means, i.e., an engine control unit 92a, that controls the operation of the engine 12, and a function as an electric motor control means, i.e., an electric motor control unit 92b, that controls the operation of the electric motor MG via the inverter 52, and performs hybrid drive control using the engine 12 and the electric motor MG using these control functions.

[0033] The hybrid control unit 92 calculates the drive amount required by the driver for the vehicle 10, for example, by applying the accelerator opening θacc and the vehicle speed V to a required drive amount map. The required drive amount map is a relationship that is experimentally or design-based and stored in advance, i.e., a predetermined relationship. The required drive amount is, for example, the required drive torque Trdem at the drive wheels 14. In other words, the required drive torque Trdem [Nm] is the required drive power Prdem [W] at the current vehicle speed V. The required drive amount can also be the required drive force Frdem [N] at the drive wheels 14, the required AT output torque at the transmission output shaft 26, or the like. In calculating the required drive amount, the output rotation speed No, or the like, can be used instead of the vehicle speed V.

[0034] The hybrid control unit 92 calculates a target engine torque Tedem for the engine 12 and a target MG torque Tmdem for the electric motor MG that realize the required drive torque Trdem, taking into consideration transmission loss, the auxiliary load, the gear ratio γat of the automatic transmission 24, the chargeable power Win and dischargeable power Wout of the battery 54, etc. The hybrid control unit 92 outputs an engine control command signal Se for the engine 12 that outputs the calculated target engine torque Tedem to the engine control device 50. The hybrid control unit 92 also outputs an MG control command signal Sm for the electric motor MG that outputs the calculated target MG torque Tmdem to the inverter 52. The engine control command signal Se is, for example, a command value for engine power Pe, which is the power of the engine 12 that outputs the target engine torque Tedem at a current engine rotation speed Ne. The MG control command signal Sm is, for example, a command value for power consumption Wm of the electric motor MG that outputs the target MG torque Tmdem at a current MG rotation speed Nm.

[0035] The chargeable power Win of the battery 54 is the maximum power that can be input, which defines a limit on the input power of the battery 54, and indicates the input limit of the battery 54. The dischargeable power Wout of the battery 54 is the maximum power that can be output, which defines a limit on the output power of the battery 54, and indicates the output limit of the battery 54. The chargeable power Win and dischargeable power Wout of the battery 54 are calculated by the electronic control device 90 based on, for example, the battery temperature THbat and the state-of-charge value SOC [%] of the battery 54. The state-of-charge value SOC of the battery 54 is a value that indicates the state of charge (charge amount, remaining charge) of the battery 54, and is calculated by the electronic control device 90 based on, for example, the battery charge / discharge current Ibat and the battery voltage Vbat.

[0036] When the required drive torque Trdem can be satisfied only by the output of the electric motor MG, the hybrid control unit 92 sets the drive mode to motor drive (hereinafter referred to as BEV drive) mode. In the BEV drive mode, the hybrid control unit 92 performs BEV drive, in which the vehicle runs using only the electric motor MG as a drive power source with the K0 clutch 20 in a disengaged state. On the other hand, when the required drive torque Trdem cannot be satisfied without using at least the output of the engine 12, the hybrid control unit 92 sets the drive mode to engine drive mode, i.e., hybrid drive (hereinafter referred to as HEV drive) mode.

[0037] In the HEV driving mode, the hybrid control unit 92 performs engine driving, i.e., HEV driving, in which the engine 12 and the electric motor MG are used as driving power sources with the K0 clutch 20 engaged. On the other hand, even if the required driving torque Trdem can be satisfied solely by the output of the electric motor MG, the hybrid control unit 92 establishes the HEV driving mode when the state of charge value SOC of the battery 54 falls below a predetermined engine start threshold or when warming up of the engine 12, etc., is required. The engine start threshold is a predetermined threshold for determining that the state of charge value SOC is such that the engine 12 must be forcibly started to charge the battery 54. In this way, the hybrid control unit 92 automatically stops the engine 12 during HEV driving, restarts the engine 12 after the engine stop, or starts the engine 12 during BEV driving, appropriately switching between the BEV driving mode and the HEV driving mode, based on the required driving torque Trdem, etc.

[0038] During coasting with the accelerator pedal 42 released, the hybrid control unit 92 executes regenerative control to generate electricity by rotating the electric motor MG using the driven torque transmitted from the drive wheels 14. The electric power generated by regeneration is charged into the battery 54 via the inverter 52. When braking by depressing the brake pedal 44, the braking force distribution between the braking force by the hydraulic brakes provided on each wheel and the braking force by the regeneration of the electric motor MG is appropriately adjusted so that a braking force corresponding to the amount of operation of the brake pedal 44 is obtained.

[0039] The clutch control unit 94 controls the K0 clutch 20 in accordance with the driving mode during driving. For example, when it is determined that the driving mode is to be switched to the HEV driving mode during BEV driving, the clutch control unit 94 controls the engagement of the K0 clutch 20 so as to execute start control of the engine 12. For example, when it is determined that there is a request to start the engine 12 based on the driving state, the clutch control unit 94 controls the engagement of the K0 clutch 20 to transmit to the engine 12 the torque required for cranking the engine 12, which is the torque that increases the engine rotation speed Ne. Torque capacity Tk0 The hydraulic control circuit 56 outputs a K0 hydraulic control command signal Sko to control the K0 clutch 20 from the released state toward the engaged state so that the above equation is obtained.

[0040] The shift control unit 96 determines whether to shift the automatic transmission 24 based on, for example, a shift map in which predetermined shift conditions are defined, and outputs a CB hydraulic control command signal Scb to the hydraulic control circuit 56 as necessary to execute shift control of the automatic transmission 24. During a shift transition period, the CB1 hydraulic pressure PRcb1 supplied to the engagement device that is engaged during the shift (hereinafter referred to as the engagement side engagement device CB1) is increased, and the CB2 hydraulic pressure PRcb2 supplied to the engagement device that is released during the engagement (hereinafter referred to as the release side engagement device CB2) is reduced.

[0041] The shift map is a predetermined relationship on a two-dimensional coordinate system using, for example, vehicle speed V and accelerator opening θacc as variables, with shift lines for determining whether to shift gears in the automatic transmission 24. For example, when the vehicle speed V or accelerator opening θacc changes while traveling and the traveling state crosses a shift line defined on the relationship map, it is determined that a shift condition is satisfied and the gear is changed. In the shift map, the output rotation speed No or the like may be used as a value related to the vehicle speed V instead of the vehicle speed V, and the required drive torque Trdem, the required drive force Frdem, the throttle opening θth or the like may be used as a value related to the accelerator opening θacc instead of the accelerator opening θacc.

[0042] When the automatic transmission 24 is downshifted in response to the driver's depression of the accelerator pedal 42 (i.e., a power-on downshift), the shift control unit 96 outputs a command to the electric motor control unit 92b to control the input torque Ti to the automatic transmission 24 during the downshift using the MG torque Tm of the electric motor MG. The electric motor control unit 92b calculates the target input torque Titgt based on the accelerator pedal opening θacc, the vehicle speed V, and the like, and then controls the MG torque Tm so that the input torque Ti increases, for example, at an increase rate α corresponding to the accelerator pedal opening θacc, with the calculated target input torque Titgt as the target. Here, the MG torque Tm of the electric motor MG has higher responsiveness than the engine torque Te of the engine 12. Therefore, during a power-on downshift of the automatic transmission 24, the input torque Ti is controlled solely by the MG torque Tm.

[0043] During a power-on downshift of the automatic transmission 24, it is preferable that the input torque Ti input to the automatic transmission 24 be approximately equal to the torque capacity (hereinafter, torque capacity Tat) that the automatic transmission 24 can transmit. However, at the beginning of the downshift, the responsiveness of the torque capacity Tat of the automatic transmission 24 is poor compared to the responsiveness of the MG torque Tm of the electric motor MG. This means that the torque capacity Tat cannot keep up with the MG torque Tm, and when the input rotation speed Ni of the automatic transmission 24 reaches the synchronous rotation speed Nsyc, there is a risk of the input rotation speed Ni racing up. One way to suppress this racing up of the input rotation speed Ni is to limit the input torque Ti, but this has the tradeoff of reducing torque responsiveness. In this embodiment, the input rotation speed Ni is the same rotation speed as the turbine rotation speed Nt, so in the following, the input rotation speed Ni may be read as the turbine rotation speed Nt.

[0044] In response to this, when executing a power-on downshift, if the rotational speed difference ΔNi (=|Nsyc-Ni|) between the input rotational speed Ni and the synchronous rotational speed Nsyc calculated based on the gear ratio γat of the automatic transmission 24 after the downshift is equal to or less than a predetermined value K, the shift control unit 96 sets an upper limit guard value αgd for the increase rate α of the input torque Ti to limit the increase rate α of the input torque Ti. Here, the increase rate α corresponds to the amount of increase in the input torque Ti per unit time. Therefore, when the increase rate α is high, the increase gradient of the input torque Ti becomes steep, and when the increase rate α is low, the increase gradient of the input torque Ti becomes gentle. The synchronous rotational speed Nsyc can be calculated by multiplying the output rotational speed No by the gear ratio γat of the automatic transmission 24 at the gear stage after the downshift (=No×γat).

[0045] In a power-on downshift, after the disengagement side engagement device CB2, which is disengaged after the downshift, is disengaged, Input torque Ti The inertia phase is initiated by increasing the input rotation speed Ni by the torque phase control signal. Next, engagement of the on-coming engagement device CB1 is initiated in accordance with the increase in the input rotation speed Ni, and when the input rotation speed Ni reaches the synchronous rotation speed Nsyc or approaches the synchronous rotation speed Nsyc, a torque phase is initiated in which the CB1 oil pressure PRcb1 of the on-coming engagement device CB1 is increased until the torque capacity Tat of the automatic transmission 24 becomes sufficient to transmit the input torque Ti. Then, when it is determined that the torque capacity Tat of the automatic transmission 24 has increased to the sufficient capacity, the torque phase ends and the downshift is completed.

[0046] The shift control unit 96 determines the start of the inertia phase based on, for example, whether the amount of increase in the input rotation speed Ni has reached a predetermined value β1. The predetermined value β1 is determined in advance through experimentation or design and is set to a value that allows the start of the inertia phase to be determined.

[0047] Furthermore, the shift control unit 96 determines the end of the inertia phase, in other words, the start of the torque phase, based on whether the rotational speed difference ΔNi between the input rotational speed Ni and the synchronous rotational speed Nsyc is equal to or less than a predetermined value β2. The predetermined value β2 is determined in advance experimentally or by design, and is set to a value at which it can be determined that the input rotational speed Ni has reached the synchronous rotational speed Nsyc.

[0048] The shift control unit 96 determines the end of the torque phase based on whether a predetermined time β3 has elapsed since the start of the torque phase. The predetermined time β3 is determined in advance through experimentation or design, and is set to a value that allows it to be determined that the torque capacity Tat of the automatic transmission 24 has become large enough to transmit the input torque Ti.

[0049] When the shift control unit 96 determines that the inertia phase has started, it calculates the synchronous rotation speed Nsyc and determines whether the rotation speed difference ΔNi between the synchronous rotation speed Nsyc and the input rotation speed Ni is equal to or less than a predetermined value K. The predetermined value K is determined in advance experimentally or by design, and is set to a threshold value of the rotation speed difference ΔNi at which the torque capacity Tat of the automatic transmission 24 becomes a capacity capable of transmitting the input torque Ti (target input torque Titgt) when the input rotation speed Ni reaches the synchronous rotation speed Nsyc.

[0050] For example, when the rotational speed difference ΔNi is large, such as at high vehicle speeds, it takes a long time for the input rotational speed Ni to reach the synchronous rotational speed Nsyc. Therefore, by the time the input rotational speed Ni reaches the synchronous rotational speed Nsyc, the CB oil pressure PRcb (actual pressure) of the engagement device CB can be made to follow the command pressure, so that the torque capacity Tat of the automatic transmission 24 can be made to be a capacity capable of transmitting the input torque Ti. In this case, the increase in the input rotational speed Ni is suppressed without limiting the increase rate α of the input torque Ti. Thus, the predetermined value K can be considered a threshold value of the rotational speed difference ΔNi at which the increase in the input rotational speed Ni does not occur, even when the increase rate α of the input torque Ti is not limited. Note that the predetermined value K does not necessarily have to be a constant value and can be changed as appropriate depending on the vehicle speed V, the shift pattern, the accelerator opening θacc, etc.

[0051] When the rotational speed difference ΔNi is greater than the predetermined value K, the shift control unit 96 does not set an upper limit guard value αgd for the input torque Ti because the input rotational speed Ni will not increase even if the input torque Ti is not limited. As a result, the responsiveness of the input torque Ti does not decrease during a power-on downshift, and the input rotational speed Ni does not increase.

[0052] On the other hand, when the rotational speed difference ΔNi is equal to or smaller than a predetermined value K, the shift control unit 96 sets an upper limit guard value αgd for the increase rate α of the input torque Ti. The upper limit guard value αgd is determined in advance experimentally or by design, and is set to a value that suppresses the input rotational speed Ni from racing up when the input rotational speed Ni reaches the synchronous rotational speed Nsyc during a power-on downshift. The upper limit guard value αgd is also changed according to the rotational speed difference ΔNi.

[0053] Fig. 3 shows one aspect of a relationship map used when setting the upper limit guard value αgd of the rate of increase α based on the rotational speed difference ΔNi. In Fig. 3, the horizontal axis represents the rotational speed difference ΔNi, and the vertical axis represents the upper limit guard value αgd of the rate of increase α. As shown in Fig. 3, the upper limit guard value αgd is defined in a region where the rotational speed difference ΔNi is equal to or less than a predetermined value K. Also, as shown in Fig. 3, the smaller the rotational speed difference ΔNi, the lower the upper limit guard value αgd of the rate of increase α.

[0054] As the rotational speed difference ΔNi decreases, the time required for the input rotational speed Ni to reach the synchronous rotational speed Nsyc decreases. As a result, the CB oil pressure PRcb (actual pressure) of the engagement device CB cannot follow the command pressure, and the torque capacity Tat of the automatic transmission 24 cannot reach a capacity capable of transmitting the input torque Ti before the input rotational speed Ni reaches the synchronous rotational speed. This insufficient torque capacity Tat causes the input rotational speed Ni to overshoot. Taking this into consideration, the upper limit guard value αgd in FIG. 3 is changed according to the rotational speed difference ΔNi. Specifically, the upper limit guard value αgd for each rotational speed difference ΔNi shown in FIG. 3 is determined in advance experimentally or by design and set to a threshold value of the input torque Ti that prevents the input rotational speed Ni from overshooting when the input rotational speed Ni reaches the synchronous rotational speed Nsyc. In other words, the upper limit guard value αgd is set to a value that minimizes the decrease in the rate of increase α of the input torque Ti while suppressing the overshoot of the input rotational speed Ni.

[0055] When the rate of increase α of the input torque Ti is limited by the upper guard value αgd, the change in the input torque Ti becomes more gradual than when the rate of increase α is not limited by the upper guard value αgd. In connection with this, the increase gradient of the input rotation speed Ni also becomes more gradual, and the time it takes for the input rotation speed Ni to reach the synchronous rotation speed Nsyc is delayed. As a result, the torque capacity Tat of the automatic transmission 24 can be increased to a capacity capable of transmitting the input torque Ti by the time the input rotation speed Ni reaches the synchronous rotation speed Nsyc, thereby suppressing the increase in the input rotation speed Ni.

[0056] The relationship map shown in Fig. 3 is defined separately for each gear shift pattern during a power-on downshift (such as a downshift from third gear 3rd to second gear 2nd), or for each type of engagement device CB (clutch C1) that is engaged or disengaged during a power-on downshift. This is because the responsiveness of the torque capacity Tcb of the engagement device CB differs depending on the gear shift pattern and engagement device CB, even if the rotational speed difference ΔNi is the same.

[0057] After calculating the rotational speed difference ΔNi, the gear shift control unit 96 determines an appropriate upper limit guard value αgd by applying the rotational speed difference ΔNi to the relationship map shown in Figure 3. Once the gear shift control unit 96 has determined the upper limit guard value αgd, it issues a command to the hybrid control unit 92 to limit the rate of increase α of the input torque Ti to equal to or less than the upper limit guard value αgd. In response to this command, the hybrid control unit 92 controls the input torque Ti so that the rate of increase α of the input torque Ti is equal to or less than the upper limit guard value αgd.

[0058] For example, the shift control unit 96 determines the upper limit guard value αgd based on the rotational speed difference ΔNi initially calculated when the start of the inertia phase is determined, and then maintains the upper limit guard value αgd at that value until the end of the torque phase is determined. Alternatively, the shift control unit 96 calculates the rotational speed difference ΔNi as needed from the time the start of the inertia phase is determined until the end of the torque phase is determined, and changes the upper limit guard value αgd as needed based on the calculated rotational speed difference ΔNi.

[0059] Furthermore, for example, if the gear to which the automatic transmission 24 is shifted is changed during a power-on downshift, the shift control unit 96 recalculates the synchronous rotation speed Nsyc based on the gear ratio γat of the new gear, and calculates the rotation speed difference ΔNi from the calculated synchronous rotation speed Nsyc. Next, as described above, the shift control unit 96 determines whether the rotation speed difference ΔNi is equal to or smaller than the predetermined value K, and cancels the upper limit guard value αgd if the rotation speed difference ΔNi is greater than the predetermined value K, and resets the upper limit guard value αgd of the increase rate α based on the rotation speed difference ΔNi if the rotation speed difference ΔNi is equal to or smaller than the predetermined value K.

[0060] Furthermore, when the shift control unit 96 determines that the torque phase has ended, it cancels the setting of the upper limit guard value αgd. This is because, at the end of the torque phase, the torque capacity Tat of the automatic transmission 24 is sufficient to transmit the input torque Ti, so there is no impact even if the upper limit guard value αgd is canceled. Furthermore, before the inertia phase begins, the automatic transmission 24 can transmit the input torque Ti through the disengagement engagement device CB2, so there is no impact even if the upper limit guard value αgd is not set before the inertia phase begins. Therefore, by not setting the upper limit guard value αgd before the inertia phase begins and after the torque phase ends, a decrease in the responsiveness of the input torque Ti due to the setting of the upper limit guard value αgd is suppressed. In other words, by limiting the rate of increase α of the input torque Ti by the upper limit guard value αgd from the start of the inertia phase to the end of the torque phase, the rate of increase α of the input torque Ti is efficiently limited.

[0061] 4 is a flowchart illustrating the main control operations of the electronic control unit 90, specifically, the control operations for setting an upper limit guard value αgd for the rate of increase α that suppresses an increase in the input rotation speed Ni while suppressing a decrease in the responsiveness of the input torque Ti during a power-on downshift of the automatic transmission 24 accompanied by depression of the accelerator pedal 42. This flowchart is repeatedly executed while the vehicle is traveling.

[0062] First, in step S10 (hereinafter, the term "step" will be omitted) corresponding to the control function of the shift control unit 96, it is determined whether a power-on downshift of the automatic transmission 24 is being executed in association with the driver's depression of the accelerator pedal 42. If the determination in S10 is negative, the routine is terminated. If the determination in S10 is positive, then in step S20, corresponding to the control function of the shift control unit 96, it is determined whether the downshift is occurring between the start of the inertia phase (I phase) and the end of the torque phase (T phase). If the determination in S20 is negative, the routine is terminated. If the determination in S20 is positive, then in step S30, corresponding to the control function of the shift control unit 96, it is determined whether the rotational speed difference ΔNi between the synchronous rotational speed Nsyc and the input rotational speed Ni is equal to or less than a predetermined value K. If the rotational speed difference ΔNi is greater than the predetermined value K, the determination in S30 is negative, and the routine is terminated. If the determination in S30 is positive, in S40, which corresponds to the control function of the shift control unit 96, an upper limit guard value αgd is set based on the rotational speed difference ΔNi. Note that once the upper limit guard value αgd is set, if that upper limit guard value αgd is maintained until the downshift is completed, once the upper limit guard value αgd is set in S40, the step of S40 is passed through without being executed until the downshift is completed. On the other hand, if the upper limit guard value αgd is changed as needed from the start of the inertia phase to the end of the torque phase, the upper limit guard value αgd is repeatedly set (updated) in S40.

[0063] 5 and 6 are time charts showing the control state during a power-on downshift of the automatic transmission 24. Fig. 5 is a time chart showing the control state when the rotational speed difference ΔNi during a power-on downshift is equal to or less than a predetermined value K. Fig. 6 is a time chart showing the control state when the shift destination is changed to an even lower gear during a power-on downshift of the automatic transmission 24.

[0064] First, a case where the rotational speed difference ΔNi is equal to or less than the predetermined value K during a power-on downshift of the automatic transmission 24, as shown in FIG. 5, will be described.

[0065] At time t1 in Figure 5, a downshift of the automatic transmission 24 (power-on downshift) is determined in response to depression of the accelerator pedal 42, thereby starting a downshift of the automatic transmission 24. At time t2, when it is determined that the inertia phase has started, the rotational speed difference ΔNi is calculated, and it is determined whether the rotational speed difference ΔNi is equal to or less than a predetermined value K. If it is determined that the rotational speed difference ΔNi is equal to or less than the predetermined value K, the rotational speed difference ΔNi is applied to a relationship map such as that shown in Figure 3, which defines the relationship between the rotational speed difference ΔNi and the upper limit guard value αgd, thereby setting the upper limit guard value αgd.

[0066] After time t2, the upper limit guard value αgd is set, and the input torque Ti becomes the post-guard input torque Tigd shown by the solid line. As shown in FIG. 5, the increase rate α of the post-guard input torque Tigd is limited to the upper limit guard value αgd after time t2. Here, the dashed line shows the input torque Ti when the upper limit guard value αgd is not set. When the upper limit guard value αgd is not set, the input torque Ti increases at the increase rate α before the inertia phase begins. As a result, the post-guard input torque Tigd increases more slowly than the input torque Ti when the upper limit guard value αgd is not set. Furthermore, the input rotation speed Ni shown by the solid line also increases more slowly than when the increase rate α shown by the dashed line is not limited.

[0067] At time t3, the input rotation speed Ni reaches the synchronous rotation speed Nsyc. At this time, the input torque Ti is limited by the upper limit guard value αgd, thereby suppressing the input rotation speed Ni from racing up. On the other hand, if the upper limit guard value αgd indicated by the dashed line is not set, the input rotation speed Ni reaches the synchronous rotation speed Nsyc earlier than time t3, as indicated by the dashed line. Furthermore, at the time when the input rotation speed Ni reaches the synchronous rotation speed Nsyc, the torque capacity Tat of the automatic transmission 24 is not sufficient to transmit the input torque Ti, causing the input rotation speed Ni to race up. At time t4, the end of the torque phase is determined, and the upper limit guard value αgd is released. In connection with this, the rate of increase α of the input torque Ti increases after time t4, and the input torque Titgt corresponding to the accelerator opening θacc is quickly reached.

[0068] Next, a case will be described in which, as shown in FIG. 6, the accelerator pedal 42 is depressed further during a power-on downshift of the automatic transmission 24, and the gear shift destination is changed to a lower gear.

[0069] At time t1 in FIG. 6, a downshift of the automatic transmission 24 (power-on downshift) is determined in response to depression of the accelerator pedal 42, and a downshift of the automatic transmission 24 is initiated. When a start of the inertia phase is determined at time t2, the rotational speed difference ΔNi is calculated, and it is determined whether the rotational speed difference ΔNi is equal to or less than a predetermined value K. At this time, if it is determined that the rotational speed difference ΔNi is equal to or less than the predetermined value K, an upper limit guard value αgd is set. Therefore, from time t2 onwards, the rate of increase α of the input torque Ti is limited to the upper limit guard value αgd, and the increase in the input torque Ti becomes gradual. At time t3, the driver further depresses the accelerator pedal 42, and the automatic transmission 24 shifts to an even lower gear. At this time, the synchronous rotation speed Nsyc is recalculated based on the speed ratio γat of the changed gear, and the rotation speed difference ΔNi is calculated based on the recalculated synchronous rotation speed Nsyc, and it is determined whether the rotation speed difference ΔNi is equal to or less than a predetermined value K. At time t3 in FIG. 6, it is determined that the rotation speed difference ΔNi is greater than the predetermined value K, and the upper limit guard value αgd is therefore released. As a result, from time t3 onwards, the input torque Ti increases at the increase rate α that would be achieved if the upper limit guard value αgd were not set. At time t4, the input rotation speed Ni reaches the synchronous rotation speed Nsyc, but at this time, the torque capacity Tat of the automatic transmission 24 has increased to a capacity that can transmit the input torque Ti, thereby suppressing the input rotation speed Ni from racing up.

[0070] As described above, according to this embodiment, when the rotational speed difference ΔNi between the input rotational speed Ni of the automatic transmission 24 during a downshift and the synchronous rotational speed Nsyc calculated based on the gear ratio γat of the automatic transmission 24 after the downshift is equal to or less than a predetermined value K, the increase rate α of the input torque Ti is limited. Thus, when the rotational speed difference ΔNi is equal to or less than the predetermined value K, the time it takes for the input rotational speed Ni to reach the synchronous rotational speed Nsyc is short, and there is a risk of the input rotational speed Ni racing up during the downshift, the increase rate α of the input torque Ti is limited, thereby suppressing the increase in the input rotational speed Ni during the downshift. On the other hand, when the rotational speed difference ΔNi is greater than the predetermined value K, and the automatic transmission 24 has a torque capacity Tat capable of transmitting the input torque Ti before the input rotational speed Ni reaches the synchronous rotational speed Nsyc, the increase rate α of the input torque Ti is not limited, thereby suppressing a decrease in torque responsiveness. In this way, by limiting the rate of increase α of the input torque Ti in accordance with the rotational speed difference ΔNi calculated during the downshift, it is possible to suppress a decrease in torque responsiveness during the downshift while suppressing a rise in the input rotational speed Ni.

[0071] Although the embodiments of the present invention have been described in detail above with reference to the drawings, the present invention can also be applied to other embodiments.

[0072] For example, in the above-described embodiment, once it is determined that the inertia phase has started, it is determined whether or not to set the upper limit guard value αgd, but it may also be determined immediately before the inertia phase starts. For example, the time immediately before the inertia phase starts, relative to the time when it is determined that a downshift has started, is determined in advance experimentally or by design, and once this time has elapsed from the time when it is determined that a downshift has started, it is determined whether or not to set the upper limit guard value αgd.

[0073] Furthermore, in the above-described embodiment, the upper limit guard value αgd is released when the end of the torque phase is determined, but the upper limit guard value αgd may be maintained until the downshift is completed.

[0074] In the above-described embodiment, the automatic transmission 24 is a planetary gear type stepped transmission including one or more planetary gear devices and multiple engagement devices CB, but the present invention is not necessarily limited to this. For example, the present invention can be applied to a known DCT (Dual Clutch Transmission) type transmission including a first clutch that establishes odd-numbered gears and a second clutch that establishes even-numbered gears.

[0075] In the above-described embodiment, the vehicle 10 is a single-motor hybrid vehicle including the engine 12 and electric motor MG as driving force sources, the automatic transmission 24, and the K0 clutch 20 interposed between the engine 12 and the electric motor MG, but the present invention is not necessarily limited to this. For example, the hybrid vehicle may be configured to include a planetary gear set operating as a power split device, an engine connected to a first rotating element of the planetary gear set, a first electric motor connected to a second rotating element of the planetary gear set, and a second electric motor and transmission connected to a third rotating element of the planetary gear set.

[0076] Furthermore, in the above-described embodiment, the accelerator opening θacc increases in response to depression of the accelerator pedal 42, but the present invention is not limited to depression of the accelerator pedal 42, and may be configured so that the accelerator opening θacc is increased by manual operation by the driver.

[0077] It should be noted that the above is merely one embodiment, and the present invention can be implemented in various forms with various modifications and improvements based on the knowledge of those skilled in the art. [Explanation of symbols]

[0078] 10: Vehicle 14: Drive wheel 24: Automatic transmission (transmission) 90: Electronic control device (control device) MG: Electric motor Ni: Input rotation speed (input rotation speed of the transmission) Nsyc: Synchronous rotation speed ΔNi :Rotational speed difference Ti: Input torque Tm: MG torque (motor torque) K: predetermined value α: Rate of increase γat: gear ratio

Claims

[Claim 1] A vehicle control device is applied to a vehicle including an electric motor as a driving force source and a transmission interposed in a power transmission path between the electric motor and drive wheels, and is configured to control an input torque input to the transmission during a downshift of the transmission accompanied by an accelerator operation by a driver, using electric motor torque of the electric motor, When performing the downshift of the transmission accompanied by a first accelerator operation by the driver, if a rotational speed difference between an input rotational speed of the transmission during the downshift and a first synchronous rotational speed calculated based on a first gear ratio that is the gear ratio of the transmission after the downshift is equal to or less than a predetermined value, a rate of increase of the input torque input to the transmission is limited compared to when the rotational speed difference between the input rotational speed and the first synchronous rotational speed is greater than the predetermined value; When the rate of increase of the input torque is limited during the downshift, if the speed ratio of the transmission after the downshift becomes a second speed ratio different from the first speed ratio due to a second accelerator operation by the driver, and the rotational speed difference between the input rotational speed and a second synchronous rotational speed calculated based on the second speed ratio after the downshift becomes larger than the predetermined value that is set in advance, the limit on the rate of increase of the input torque is released. A vehicle control device comprising:

Images