Vehicle control device

Abstract

To provide a vehicular control apparatus capable of suppressing a feeling of discomfort from giving to a driver in a case where drive control of a motor being a traveling drive source is switched from rotation speed control to torque control.SOLUTION: When a vehicle state is determined to be switched from a stop state to a travel state, in either of cases where (a) feedback torque Tfb that is fed back to motor torque Tmg is a positive value in feedback control in rotation speed control executed in the stop state, with a vehicular speed V exceeding a predetermined vehicular speed threshold V_jdg, and where the feedback torque Tfb is a negative value, with required drive torque Trdem exceeding a predetermined torque threshold Trdem_jdg, the torque control is executed as the drive control for a motor MG. Whereas (b) in the case of neither of the aforementioned cases, feedback torque retention control is executed to control the motor torque Tmg by the feedback torque Tfb.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a vehicle control device that switches between rotational speed control, which causes the rotational speed of an electric motor serving as a driving force source for driving, to converge to a predetermined target rotational speed, and torque control, which controls the motor to achieve a required driving torque, as drive control for the electric motor serving as a driving force source for driving. [Background technology]

[0002] There is known a vehicle control device that switches between rotation speed control, which uses feedback control to converge the rotation speed of the driving power source to a predetermined target rotation speed, and torque control, which controls the output torque of the driving power source to achieve a required driving torque, as drive control for an electric motor that serves as a driving power source for traveling. For example, the device described in Patent Document 1 is such a control device. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2013 / 81121 Summary of the Invention [Problem to be solved by the invention]

[0004] In the vehicle control device described in Patent Document 1, when the vehicle state is switched from a stopped state to a running state and the vehicle starts to run, the drive control of the electric motor is switched from rotational speed control to torque control, which causes fluctuations in the drive force and may cause the driver to feel uncomfortable.

[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 the discomfort felt by the driver when the drive control of the electric motor, which is the driving power source for driving, switches from rotational speed control to torque control. [Means for solving the problem]

[0006] The gist of a first invention is a control device for a vehicle including a driving force source for driving a vehicle including an electric motor, and a torque converter disposed in a power transmission path between the driving force source for driving a vehicle and a driving wheel, the control device (A) switching between rotation speed control for converging the rotation speed of the driving force source for driving a vehicle to a predetermined target rotation speed by feedback control and torque control for controlling the output torque of the driving force source for driving a vehicle so as to realize a required drive amount as drive control of the electric motor, (B) executing the rotation speed control as drive control of the electric motor when the vehicle state is in a stopped state, and when it is determined that the vehicle state has switched from the stopped state to a running state, (b-1) in the feedback control in the rotation speed control executed in the stopped state (b-2) when the feedback torque fed back to the output torque of the electric motor is a positive value and the vehicle speed exceeds a predetermined vehicle speed threshold, or when the feedback torque is a negative value and the required drive amount exceeds a predetermined drive amount threshold, the torque control is executed as drive control of the electric motor; and (b-3) when the feedback torque is a positive value and the vehicle speed exceeds the predetermined vehicle speed threshold, or when the feedback torque is a negative value and the required drive amount exceeds the predetermined drive amount threshold, the feedback torque is held and feedback torque holding control is executed to control the output torque of the driving power source for traveling using the feedback torque. [Effects of the Invention]

[0007] According to the electric motor control device of the first aspect of the present invention, (A) rotational speed control for converging the rotational speed of the driving force source for driving to a predetermined target rotational speed by feedback control and torque control for controlling the output torque of the driving force source for driving to realize a required drive amount are switched and executed as drive control of the electric motor, (B) the rotational speed control is executed as drive control of the electric motor when the vehicle state is in a stopped state, and when it is determined that the vehicle state has switched from the stopped state to a running state, (b-1) a feedback torque that is fed back to the output torque of the electric motor in the feedback control in the rotational speed control executed in the stopped state is executed. (b-1) When the feedback torque is positive and the vehicle speed exceeds a predetermined vehicle speed threshold, or when the feedback torque is negative and the required drive amount exceeds a predetermined drive amount threshold, the torque control is executed as drive control of the electric motor, and (b-2) when the feedback torque is positive and the vehicle speed exceeds the predetermined vehicle speed threshold, or when the feedback torque is negative and the required drive amount does not exceed the predetermined drive amount threshold, the feedback torque is maintained, and feedback torque maintenance control is executed to control the output torque of the driving power source for traveling using the feedback torque. First, when the feedback torque is positive and the vehicle speed exceeds a predetermined vehicle speed threshold, or when the feedback torque is negative and the required drive amount does not exceed the predetermined drive amount threshold, the actual drive torque during creeping of the vehicle is not too large (excessive running), nor is the actual drive torque during creeping too small (excessive running). In such a case, feedback torque maintenance control is performed as drive control of the driving force source for driving, so the driver does not feel uncomfortable due to fluctuations in driving force. On the other hand, when the feedback torque is a positive value and the vehicle speed exceeds a predetermined vehicle speed threshold, the vehicle speed has increased to a certain extent, and the actual driving torque of the vehicle is larger than immediately after the start of driving.In this state, even if the drive control of the electric motor is switched from rotational speed control to torque control and a driving force fluctuation occurs, the impact is relatively small compared to immediately after the start of driving, and the sense of discomfort felt by the driver is suppressed. Furthermore, when the feedback torque is a negative value and the required drive amount exceeds a predetermined drive amount threshold, for example, when the driver operates the accelerator and the required drive amount increases, the drive control of the electric motor is switched from rotational speed control to torque control in conjunction with the driver's accelerator operation. Therefore, even if a driving force fluctuation occurs when the drive control of the electric motor is switched from rotational speed control to torque control, the driving force fluctuation is linked to the driver's accelerator operation, and the sense of discomfort felt by the driver is suppressed. In this way, the sense of discomfort felt by the driver is suppressed when the drive control of the electric motor, which is a driving force source for driving, is switched from rotational speed control to torque control.

[0008] According to the electric motor control device of the second aspect of the present invention, when it is determined that the vehicle state has switched from the running state to the stopped state in the first aspect, the rotational speed control is executed as drive control of the electric motor. In this way, when it is determined that the vehicle state has switched from the running state to the stopped state, rotational speed control is executed to converge the rotational speed of the driving power source for driving to a predetermined target rotational speed through feedback control. This prevents the rotational speed of the driving power source for driving from becoming too low. Therefore, when the driver releases the brake operation, creeping travel begins more quickly than when rotational speed control is not executed and the rotational speed of the driving power source for driving becomes too low. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic configuration diagram of a hybrid vehicle equipped with an electronic control device according to an embodiment of the present invention, and is a functional block diagram showing the main parts of control functions for various controls in the hybrid vehicle. [Figure 2] 2 is an example of a flowchart illustrating a control operation of the electronic control device shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] 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]

[0011] FIG. 1 is a schematic diagram of a hybrid vehicle 10 (hereinafter simply referred to as "vehicle 10") equipped with an electronic control device 90 according to an embodiment of the present invention, and is also a functional block diagram showing the main parts of the control functions for various controls in vehicle 10.

[0012] The vehicle 10 includes an engine 12 and an electric motor MG, which are driving power sources PG for traveling, and a power transmission device 16 provided in a power transmission path PT between the engine 12 and drive wheels 14. The vehicle 10 is a hybrid vehicle. The vehicle 10 also includes an inverter 52, a hydraulic control circuit 54, an EOP 56, which is an electric oil pump, a battery 60, and an electronic control device 90. The hybrid vehicle 10 corresponds to the "vehicle" in this invention.

[0013] The engine 12 is a well-known internal combustion engine. An electronic control unit 90 (described later) controls an engine control unit 50 including a throttle actuator, a fuel injection device, an ignition device, and the like provided on the vehicle 10, thereby controlling the engine torque Te [Nm] output from the engine 12. In this specification, unless otherwise specified, the terms torque, driving force, power, and force (power) are synonymous.

[0014] The power transmission device 16 is housed in a case 18, which is a non-rotating member attached to the vehicle body, and includes, in order from the engine 12 side, an engine connecting shaft 20, a clutch K0, an electric motor connecting shaft 22, a torque converter 24, an AT input shaft 26 which is an input rotating member of the automatic transmission 28, and the automatic transmission 28. The power transmission device 16 also includes a differential gear 32 connected to an AT output shaft 30 which is an output rotating member of the automatic transmission 28, a pair of drive shafts 34 connected to the differential gear 32, and the like.

[0015] The engine connecting shaft 20 is a member that connects the engine 12 and the clutch K0, and is, for example, a crankshaft.

[0016] The electric motor MG is a so-called motor generator that has a function as an electric motor that generates mechanical power from electric energy (electric motor function) and a function as a generator that generates electric energy from mechanical power (generator function). The electric motor MG is connected to a battery 60 provided in the vehicle 10 via an inverter 52 described later. The battery 60 is an electricity storage device that supplies and receives electric power to the electric motor MG. The inverter 52 is controlled by an electronic control device 90 described later, thereby controlling the electric motor torque Tmg [Nm], which is the output torque of the electric motor MG. The electric motor MG corresponds to the "electric motor" in the present invention, and the electric motor torque Tmg corresponds to the "output torque of the electric motor" in the present invention. When the vehicle 10 is in a BEV driving mode described later, the electric motor torque Tmg corresponds to the "output torque of the driving power source for driving" in the present invention, and when the vehicle 10 is in an HEV driving mode described later, the sum of the engine torque Te and the electric motor torque Tmg corresponds to the "output torque of the driving power source for driving" in the present invention.

[0017] A clutch K0 is provided between an engine connecting shaft 20 connected to the engine 12 and an electric motor connecting shaft 22 connected to the rotor of the electric motor MG. The clutch K0 is an engagement device that can connect and disconnect power transmission between the engine 12 and the electric motor connecting shaft 22, and is, for example, a wet multi-plate hydraulic friction engagement device. When the clutch K0 is engaged, the clutch K0 enables power transmission between the engine 12 and the electric motor MG. When the clutch K0 is released, the clutch K0 cuts off power transmission between the engine 12 and the electric motor MG. When the clutch K0 is in a half-engaged state, i.e., a slip engagement state, the clutch K0 enables power transmission between the engine 12 and the electric motor MG according to a transmission torque capacity (the engagement force of the clutch K0) based on the slip engagement state.

[0018] The electric motor MG is driven to rotate by the electric power stored in the battery 60 and outputs the driving force for running the hybrid vehicle 10. The electric motor MG also generates electricity using the driving force for running input from the engine 12 via the clutch K0, and generates electricity by converting the driven force input from the drive wheels 14 side into electric power through regeneration. The generated electric power is charged into the battery 60 via the inverter 52.

[0019] The inverter 52 is a power supply circuit that is provided between the electric motor MG and the battery 60 and that converts direct current to alternating current and vice versa under the control of the electronic control device 90. For example, the inverter 52 converts direct current supplied from the battery 60 into alternating current and outputs the converted alternating current to the electric motor MG to drive it, or converts alternating current generated by the electric motor MG into direct current and outputs the converted alternating current to the battery 60.

[0020] The battery 60 is a rechargeable secondary battery such as a lithium ion battery or a nickel-metal hydride battery, etc. The battery 60 is mainly used to supply power for driving the electric motor MG and to store the power generated by the electric motor MG through regeneration.

[0021] The torque converter 24 is a well-known torque converter. It includes a pump wheel connected to the electric motor connecting shaft 22, a turbine wheel connected to the automatic transmission input shaft 26, and a lock-up clutch 40 that directly connects the pump wheel and the turbine wheel. The torque converter 24 is disposed in a power transmission path PT between the traveling drive power source PG (engine 12, electric motor MG) and the drive wheels 14, and is a fluid transmission device that can transmit the traveling drive power output from the traveling drive power source PG from the electric motor connecting shaft 22 to the automatic transmission input shaft 26 via a fluid. The vehicle 10 includes a mechanical oil pump MOP 42. The MOP 42 is connected to the pump wheel and is rotationally driven by the traveling drive power source PG (engine 12, electric motor MG) to discharge hydraulic oil OIL used in the power transmission device 16.

[0022] The EOP 56 is a well-known oil pump that can be driven by the rotation of an EOP drive motor 58, independently of the rotation of the engine 12 and electric motor MG, which are the driving power source PG for traveling. The EOP drive motor 58 is a well-known electric motor, and the rotation speed of the EOP drive motor 58 is controlled by an inverter (not shown) being controlled by an electronic control device 90. The EOP 56 is driven to rotate by the EOP drive motor 58, and discharges hydraulic oil OIL used in the power transmission device 16.

[0023] The automatic transmission 28 is a well-known automatic transmission that changes the speed of the driving force input from the driving force source PG (engine 12, electric motor MG) to the AT input shaft 26 and outputs the changed power to the AT output shaft 30. For example, the automatic transmission 28 may be a planetary gear type or a constantly meshing parallel shaft type stepped transmission, or a belt type or power roller type continuously variable transmission. The automatic transmission 28 is controlled by a hydraulic control circuit 54, which is controlled by an electronic control device 90, so that a desired speed ratio (also referred to as a gear ratio) γat (=AT input rotation speed Ni [rpm] / AT output rotation speed No [rpm]) is obtained. In this embodiment, the automatic transmission 28 is a well-known planetary gear type automatic transmission that includes multiple planetary gear devices and multiple shift engagement devices CB. Each of the shift engagement devices CB is switched between an engagement / disengagement state such as a fully engaged state, a half-engaged state, and a disengaged state by adjusting the hydraulic pressure supplied from the hydraulic control circuit 54 to a hydraulic actuator that controls the engagement / disengagement state of the shift engagement devices CB. In the automatic transmission 28, one of a plurality of gear stages (also referred to as gear stages) having different gear ratios γat is formed by engaging one of the engagement devices of the shift engagement devices CB.

[0024] The differential gear 32 is a well-known differential gear that receives the driving force for traveling transmitted from the AT output shaft 30 of the automatic transmission 28 and transmits equal driving torque to a pair of drive shafts 34 while allowing for an appropriate difference in rotational speed.

[0025] The hydraulic control circuit 54 uses the hydraulic pressure of the hydraulic oil OIL discharged from the MOP 42 and the EOP 56 as the source pressure and supplies the necessary hydraulic oil O to each part within the case 18. For example, the hydraulic control circuit 54 generates hydraulic pressure for controlling the engagement and disengagement of the clutch K0, hydraulic pressure for controlling the shifting of the automatic transmission 28, and hydraulic pressure for controlling the engagement and disengagement of the lock-up clutch 40 of the torque converter 24, and supplies these to each hydraulic actuator within the case 18.

[0026] In the power transmission device 16, when the clutch K0 is engaged, the driving force for traveling output from the engine 12 is transmitted from the engine connecting shaft 20 to the driving wheels 14 via the clutch K0, the electric motor connecting shaft 22, the torque converter 24, the automatic transmission 28, the differential gear 32, the drive shaft 34, etc. in this order. The driving force for traveling output from the electric motor MG is transmitted from the electric motor connecting shaft 22 to the driving wheels 14 via the torque converter 24, the automatic transmission 28, the differential gear 32, the drive shaft 34, etc. in this order, regardless of whether the clutch K0 is engaged or disengaged.

[0027] The vehicle 10 can select one of three driving modes: a BEV driving mode, an engine driving mode, and an HEV driving mode. The BEV driving mode is a driving mode in which the engine 12 is stopped and the electric motor MG is powered, thereby performing BEV (Battery Electric Vehicle) driving using only the electric motor MG as a driving force source among the driving force sources PG. The engine driving mode is a driving mode in which the clutch K0 is engaged and only the engine 12 as a driving force source among the driving force sources PG. The HEV driving mode is a driving mode in which the clutch K0 is engaged and both the engine 12 and the electric motor MG as driving force sources among the driving force sources PG are performed HEV (Hybrid Electric Vehicle) driving.

[0028] The driving mode of the vehicle 10 can be switched between the BEV driving mode, the engine driving mode, and the HEV driving mode, for example, using a driving force source switching map. The driving force source switching map is a relationship in which the driving mode is predetermined using two-dimensional coordinates with, for example, vehicle speed V [km / h] and required driving torque Trdem [Nm] as variables. The required driving torque Trdem is the driving torque required for the vehicle 10, for example, the driving torque Tr [Nm] required for the drive wheels 14. A method for calculating the required driving torque Trdem will be described later.

[0029] Generally, the BEV driving mode is selected in a low vehicle speed region where the vehicle speed V is relatively low and the required drive torque Trdem is relatively low (= a region where the accelerator pedal opening θacc [%] is relatively low), where engine efficiency decreases. On the other hand, the engine driving mode or the HEV driving mode is selected in a high vehicle speed region where the vehicle speed V is relatively high or in a high load region where the required drive torque Trdem is relatively high (= a region where the accelerator pedal opening θacc is relatively high). The BEV driving mode is applied when the state of charge value SOC [%] of the battery 60 (the ratio of the amount of charge actually stored to a predetermined full charge capacity) is equal to or greater than a predetermined engine start threshold. In other words, when the state of charge value SOC of the battery 60 is less than the predetermined engine start threshold, there is no region in the driving force source switching map where the BEV driving mode is selected, and the engine driving mode or the HEV driving mode is selected in all regions. In the engine driving mode or the HEV driving mode, the motor rotation speed Nmg [rpm], which is the rotation speed of the electric motor MG, is equal to the engine rotation speed Ne [rpm], which is the rotation speed of the engine 12. The predetermined engine start threshold is a threshold set in advance for determining that the state of charge value SOC is at a value at which the engine 12 needs to be forcibly started and the battery 60 needs to be charged.

[0030] The electronic control unit 90 includes a so-called microcomputer equipped with, for example, a CPU, RAM, ROM, an input / output interface, etc. The CPU executes various controls of the vehicle 10 by performing signal processing in accordance with programs stored in the ROM 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 needed. The electronic control unit 90 corresponds to the "control unit" in this invention.

[0031] The electronic control unit 90 receives various signals (for example, an engine rotation speed Ne [rpm] which is the rotation speed of the engine 12, a turbine rotation speed Nt [rpm] which is the same value as the AT input rotation speed Ni [rpm], a vehicle speed V the AT output rotation speed No [rpm] corresponding to the vehicle speed, the electric motor rotation speed Nmg [rpm] which is the rotation speed of the electric motor MG, the accelerator opening θacc [%] which is the amount of accelerator operation by the driver which indicates the magnitude of the driver's acceleration operation, the driver's brake operation θbrk [%] which indicates the magnitude of the driver's deceleration operation, the throttle valve opening θth [%] which is the opening of the electronic throttle valve, the battery temperature THbat [°C] of the battery 60, the battery charge / discharge current Ibat [A], the battery voltage Vbat [V], etc.) are input.

[0032] The electronic control device 90 outputs various command signals (e.g., an engine control signal Se for controlling the engine 12, an electric motor control signal Smg for controlling the electric motor MG, a shift control signal Sat for controlling the shift engagement device CB, a K0 control signal Sk0 for controlling the clutch K0, an LU control signal Slu for controlling the lock-up clutch 40, an EOP control signal Seop for controlling the EOP 56, etc.) to each device provided in the vehicle 10 (e.g., an engine control device 50, an inverter 52, a hydraulic control circuit 54, an EOP drive motor 58, etc.).

[0033] The electronic control unit 90 functionally comprises a hybrid control unit 92, a clutch control unit 94, a gear change control unit 96, a vehicle stop state determination unit 98, a running start determination unit 100, a running state determination unit 102, and a running end determination unit 104.

[0034] The hybrid control unit 92 functionally comprises an engine control unit 92a that controls the operation of the engine 12, and 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, etc., using these control functions.

[0035] The hybrid control unit 92 calculates the drive amount (e.g., required drive torque Trdem) required by the driver for the vehicle 10, for example, by applying the actual accelerator opening θacc and vehicle speed V to a required drive amount map. The required drive amount map is a map in which the relationship between the accelerator opening θacc, vehicle speed V, and the required drive amount is determined in advance through experimentation or design and stored. The required drive amount is the drive amount required for the vehicle 10, for example, the required drive torque Trdem. In other words, the required drive torque Trdem 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 output torque at the AT output shaft 30, or the like. In calculating the required drive amount, the AT output rotation speed No, or the like, can be used instead of the vehicle speed V. In this way, the required drive torque Trdem, the required drive power Prdem, the required drive force Frdem, and the required output torque at the AT output shaft 30 are all the same in that they are the required drive amounts of the vehicle 10.

[0036] The hybrid control unit 92 outputs an engine control signal Se for controlling the engine 12 and an electric motor control signal Smg for controlling the electric motor MG so as to realize the required driving power Prdem, taking into consideration factors such as transmission loss, the auxiliary load, the gear ratio γat of the automatic transmission 28, and the chargeable power Win [W] and dischargeable power Wout [W] of the battery 60. The engine control signal Se is, for example, a command value for engine power Pe [W], which is the power of the engine 12 that outputs engine torque Te at a current engine rotation speed Ne. The electric motor control signal Smg is, for example, a command value for power consumption Wm [W] of the electric motor MG that outputs electric motor torque Tmg at a current electric motor rotation speed Nmg.

[0037] The chargeable power Win of the battery 60 is the maximum power that can be input, which defines the limit on the input power of the battery 60, and indicates the input limit of the battery 60. The dischargeable power Wout of the battery 60 is the maximum power that can be output, which defines the limit on the output power of the battery 60, and indicates the output limit of the battery 60. The chargeable power Win and dischargeable power Wout of the battery 60 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 60.

[0038] The hybrid control unit 92 controls the vehicle 10 in a driving mode (BEV driving mode, engine driving mode, HEV driving mode) according to the state of the vehicle 10. For example, the driving mode according to the state of the vehicle 10 is selected by the driving power source switching map described above.

[0039] The engine control unit 92a controls the engine torque Te to realize the required drive amount for the vehicle 10. The electric motor control unit 92b executes torque control to control the electric motor torque Tmg to realize the required drive amount for the vehicle 10 while the vehicle is traveling in an accelerator-on state. The accelerator-on state is a vehicle state in which the driver operates the accelerator (for example, the driver depresses the accelerator pedal Acc) and the accelerator opening θacc is greater than zero. The torque control is control to make the electric motor torque Tmg equal to a predetermined target torque so as to realize the required drive amount for the vehicle 10. Specifically, when traveling in the BEV traveling mode, the electric motor control unit 92b controls the electric motor torque Tmg to realize the required drive torque Trdem. When traveling in the engine traveling mode, the engine control unit 92a controls the engine torque Te to realize the entire required drive torque Trdem, and when there is a surplus of the engine torque Te relative to the required drive torque Trdem, the electric motor control unit 92b controls the electric motor torque Tmg to generate electricity using the surplus. When driving in HEV driving mode, the engine control unit 92a controls the engine torque Te to achieve part of the required drive torque Trdem, and the electric motor control unit 92b controls the electric motor torque Tmg to compensate for the torque that is insufficient in the engine torque Te relative to the required drive torque Trdem.

[0040] The hybrid control unit 92 and the clutch control unit 94 execute engine start control by cranking the engine 12 using the electric motor MG as necessary. Specifically, the electric motor control unit 92b controls the electric motor MG to output a cranking torque Tcr [Nm] until cranking ends in accordance with the clutch control unit 94 switching the clutch K0 from a released state to an engaged state. Furthermore, the engine control unit 92a controls the supply of fuel to the engine 12, ignition, and the like in conjunction with the cranking of the engine 12 by the clutch K0 and the electric motor MG.

[0041] The shift control unit 96 determines whether to shift the automatic transmission 28 using a shift map, for example, and outputs a shift control signal Sat to the hydraulic control circuit 54 to execute shift control as necessary. The shift map is a predetermined relationship having shift lines for determining whether to shift the automatic transmission 28 on a two-dimensional coordinate system using, for example, vehicle speed V and required drive torque Trdem as variables. In the shift map, the AT output rotation speed No or the like may be used in place of the vehicle speed V, and the required drive force Frdem, accelerator opening θacc, throttle valve opening θth or the like may be used in place of the required drive torque Trdem.

[0042] Here, a case will be described in which the vehicle state is switched from a stopped state to a traveling state by drive control of the electric motor MG in response to release of the brake operation by the driver (for example, depression of the brake pedal Brk by the driver).

[0043] The vehicle stop state determination unit 98 determines whether the vehicle is stopped, specifically, whether the vehicle speed V is equal to or less than a predetermined vehicle stop speed V_stp and the driver is braking. The predetermined vehicle stop speed V_stp is, for example, a predetermined near-zero determination value for determining whether the vehicle is stopped.

[0044] When the vehicle stop state determination unit 98 determines that the vehicle state is a stopped state, the electric motor control unit 92b executes rotation speed control using a feedback torque Tfb [Nm] to converge the electric motor rotation speed Nmg to the idle rotation speed Nmg_idl. The idle rotation speed Nmg_idl is the rotation speed at which the engine 12 idles when the vehicle state is stopped in the HEV driving mode. The electric motor rotation speed Nmg and the idle rotation speed Nmg_idl correspond to the "rotation speed of the driving power source for traveling" and the "predetermined target rotation speed," respectively, in the present invention. For example, the drag torque (=load torque) in the transmission path after the torque converter 24 in the power transmission path PT changes depending on the temperature of the hydraulic oil OIL. In the rotation speed control, the electric motor torque Tmg is feedback-controlled so that the drag torque is canceled out and the electric motor rotation speed Nmg becomes the idle rotation speed Nmg_idl. In the rotation speed control, the torque fed back to the electric motor torque Tmg is the feedback torque Tfb.

[0045] If the stopped state determination unit 98 determines that the vehicle state is not stopped, the running start determination unit 100 determines whether the vehicle state has switched from a stopped state to a running state, i.e., whether running has started. For example, if the vehicle speed V switches from a state where it is equal to or less than a predetermined stopped vehicle speed value V_stp to a state where it exceeds the predetermined stopped vehicle speed value V_stp, it is determined that running has started.

[0046] When the traveling start determination unit 100 determines that traveling has started, the motor control unit 92b stores the feedback torque Tfb in the rotational speed control, and the traveling state determination unit 102 determines whether the started traveling state satisfies predetermined traveling conditions. The feedback torque Tfb is the feedback torque Tfb at that time in the rotational speed control being executed by the motor control unit 92b. The predetermined traveling conditions are that the actual drive torque Tr during creep traveling in a state in which the motor torque Tmg is controlled by the feedback torque Tfb is not too large, resulting in excessive traveling, and that the actual drive torque Tr during creep traveling is not too small, resulting in insufficient traveling. Creep traveling refers to traveling in which the vehicle 10 equipped with the automatic transmission 28 moves slowly, like a crawl, without the driver operating the accelerator, when the vehicle 10 is in a range in which the vehicle 10 can travel, such as a forward traveling range (D range) or a reverse traveling range (R range).

[0047] Specifically, when the feedback torque Tfb is a positive value and the vehicle speed V exceeds a predetermined vehicle speed threshold V_jdg, the vehicle is traveling too fast and does not satisfy a predetermined driving condition. The predetermined vehicle speed threshold V_jdg is a vehicle speed value determined in advance by design or experimentation, such that even if drive control of the electric motor MG is switched from rotational speed control to torque control and driving force fluctuations occur, the discomfort felt by the driver is within an acceptable range. When the feedback torque Tfb is a negative value and the required drive torque Trdem exceeds a predetermined torque threshold Trdem_jdg, the vehicle is traveling too slowly and does not satisfy a predetermined driving condition. The predetermined torque threshold Trdem_jdg is a torque value determined in advance by design or experimentation, such that even if drive control of the electric motor MG is switched from rotational speed control to torque control and driving force fluctuations occur, the discomfort felt by the driver due to the driving force fluctuations being linked to the driver's accelerator operation is within an acceptable range. The required drive torque Trdem and the predetermined torque threshold Trdem_jdg correspond to the "required drive amount" and the "predetermined drive amount threshold" in the present invention, respectively.

[0048] Therefore, the case where the specified driving conditions are met is neither the case where the feedback torque Tfb is a positive value and the vehicle speed V exceeds a specified vehicle speed threshold V_jdg, nor the case where the feedback torque Tfb is a negative value and the required driving torque Trdem exceeds a specified torque threshold Trdem_jdg.

[0049] When the running state determination unit 102 determines that the started running state satisfies predetermined running conditions, the electric motor control unit 92b executes feedback torque holding control to hold the feedback torque Tfb and control the electric motor torque Tmg using the feedback torque Tfb.

[0050] If the traveling state determination unit 102 determines that the started traveling state does not satisfy the predetermined traveling conditions, the motor control unit 92b switches the drive control of the electric motor MG from rotational speed control to torque control. In this case, the electric motor control unit 92b sets a target torque of the electric motor torque Tmg so as to realize the required driving torque Trdem. For example, when the driver is not operating the accelerator or brake and creeping is being performed, the electric motor torque Tmg that realizes the required driving torque Trdem, i.e., the target torque of the electric motor torque Tmg, is set to a predetermined creep torque for running the vehicle 10 in creeping mode. For example, when the driver is operating the accelerator, the target torque of the electric motor torque Tmg is set using the required driving amount map described above.

[0051] When it is determined that the feedback torque Tfb is a positive value and the vehicle speed V exceeds a predetermined vehicle speed threshold V_jdg and thus does not satisfy a predetermined driving condition, overtraveling in the started driving state is corrected by executing torque control. In this case, the vehicle speed V is relatively high, and the actual drive torque Tr at the drive wheels 14 is larger than immediately after the start of driving. In this state, even if the drive control of the electric motor MG is switched from rotational speed control to torque control and a driving force fluctuation occurs, the effect is relatively small compared to immediately after the start of driving, and the sense of discomfort felt by the driver is suppressed.

[0052] When it is determined that the feedback torque Tfb is a negative value and the required drive torque Trdem exceeds a predetermined torque threshold Trdem_jdg and thus the predetermined driving condition is not satisfied, the excessively slow driving in the started driving state is corrected by executing torque control. This case corresponds to, for example, a case in which the required drive torque Trdem increases due to an accelerator operation by the driver, and the drive control of the electric motor MG is switched from rotational speed control to torque control in conjunction with the accelerator operation by the driver. Therefore, even if the drive control of the electric motor MG is switched from rotational speed control to torque control and a driving force fluctuation occurs, the driving force fluctuation is linked to the accelerator operation by the driver, so that the discomfort felt by the driver is suppressed.

[0053] When the stopped state determination unit 98 determines that the vehicle state is not a stopped state and the running start determination unit 100 determines that running has not started, the running end determination unit 104 determines whether the vehicle state has switched from a running state to a stopped state, that is, whether the vehicle has stopped. For example, when the vehicle speed V switches from a state in which it exceeds a predetermined stopped vehicle speed value V_stp to a state in which it is equal to or less than the predetermined stopped vehicle speed value V_stp, it is determined that the vehicle has stopped.

[0054] When the traveling end determination unit 104 determines that the vehicle has stopped, the motor control unit 92b immediately switches the drive control of the electric motor MG from torque control to rotational speed control. That is, rotational speed control is executed using a feedback torque Tfb that converges the electric motor rotational speed Nmg to the idle rotational speed Nmg_idl, and the electric motor rotational speed Nmg is maintained at the idle rotational speed Nmg_idl. Note that when the vehicle is stopped, the driver applies a brake, so even if the drive control of the electric motor MG is switched from torque control to rotational speed control and a driving force fluctuation occurs, the sense of discomfort felt by the driver is suppressed. When the driver releases the brake while the vehicle is stopped and rotational speed control is being executed as the drive control of the electric motor MG, creeping travel begins more quickly than when rotational speed control is not executed and the electric motor rotational speed Nmg becomes lower than the idle rotational speed Nmg_idl. In addition, when the vehicle is stopped in HEV driving mode (= when the vehicle 10 starts to stop), the engine rotation speed Ne, which is equal to the motor rotation speed Nmg, is prevented from becoming too low, thereby preventing the engine 12 from stalling, i.e., stopping.

[0055] If the driving end determination unit 104 determines that the vehicle 10 is not stopped, i.e., if it determines that the vehicle 10 is driving, the motor control unit 92b drives and controls the electric motor MG by torque control so that the electric motor torque Tmg realizes the required driving torque Trdem of the vehicle 10.

[0056] Fig. 2 is an example of a flowchart illustrating the control operation of the electronic control device 90 shown in Fig. 1. The flowchart in Fig. 2 is repeatedly executed.

[0057] First, in step S10 (hereinafter, "step" will be omitted) corresponding to the function of the vehicle stop state determination unit 98, it is determined whether the vehicle state is a stopped state.

[0058] If the determination in S10 is positive, in S80, which corresponds to the function of the electric motor control unit 92b, rotation speed control is executed using the feedback torque Tfb to converge the electric motor rotation speed Nmg to the idle rotation speed Nmg_idl. Then, the process returns.

[0059] If the determination in S10 is negative, it is determined whether or not traveling has started in S20, which corresponds to the function of the traveling start determination unit 100. If the determination in S20 is positive, the feedback torque Tfb in the rotation speed control is stored in S30, which corresponds to the function of the electric motor control unit 92b, and it is determined in S40, which corresponds to the function of the traveling state determination unit 102, whether or not the feedback torque Tfb is a positive value and the vehicle speed V exceeds a predetermined vehicle speed threshold V_jdg.

[0060] If the determination in S40 is negative, in S50 corresponding to the function of the running state determination unit 102, it is determined whether or not the feedback torque Tfb is a negative value and the required driving torque Trdem exceeds a predetermined torque threshold value Trdem_jdg.

[0061] If the determination in S40 is positive or if the determination in S50 is positive, in S60, which corresponds to the function of the motor control unit 92b, the drive control of the electric motor MG is switched from rotational speed control to torque control. With this switch to torque control, the feedback torque Tfb is cleared, that is, the feedback torque Tfb is no longer fed back to the electric motor torque Tmg. After execution of S60, the process returns.

[0062] If the determination in S50 is negative, in S70, which corresponds to the function of the electric motor control unit 92b, feedback torque holding control is executed as drive control of the electric motor MG. After execution of S70, the process returns.

[0063] If the determination in S20 is negative, in S90 corresponding to the function of the traveling end determination unit 104, it is determined whether the vehicle state has switched from a traveling state to a stopped state.

[0064] If the determination in S90 is positive, in S100, which corresponds to the function of the motor control unit 92b, the drive control of the electric motor MG is immediately switched from torque control to rotational speed control. In this case, the rotational speed control is performed by feeding back the feedback torque Tfb, which causes the electric motor rotational speed Nmg to converge to the idle rotational speed Nmg_idl, to the electric motor torque Tmg. After execution of S100, the process returns.

[0065] If the determination in S90 is negative, in S110, which corresponds to the function of the motor control unit 92b, torque control is executed as drive control of the electric motor MG. In this torque control, the electric motor MG is controlled to drive so that the electric motor torque Tmg achieves the required drive torque Trdem. After execution of S110, the process returns.

[0066] According to this embodiment, (A) the rotation speed control for converging the electric motor rotation speed Nmg to the idle rotation speed Nmg_idl by feedback control and the torque control for controlling the output torque of the driving power source PG for driving so as to realize the required driving torque Trdem are switched and executed as the drive control of the electric motor MG, (B) the rotation speed control is executed as the drive control of the electric motor MG when the vehicle state is in a stopped state, and when it is determined that the vehicle state has switched from the stopped state to the running state, (b-1) in the feedback control in the rotation speed control executed in the stopped state, the feedback torque Tfb fed back to the electric motor torque Tmg is a positive value and the vehicle speed V is equal to or greater than a predetermined vehicle speed threshold V (b-1) When the feedback torque Tfb is a positive value and the vehicle speed V exceeds the predetermined vehicle speed threshold V_jdg, or when the feedback torque Tfb is a negative value and the required drive torque Trdem exceeds the predetermined torque threshold Trdem_jdg, torque control is executed as drive control of the electric motor MG, and (b-2) when the feedback torque Tfb is a positive value and the vehicle speed V exceeds the predetermined vehicle speed threshold V_jdg, or when the feedback torque Tfb is a negative value and the required drive torque Trdem exceeds the predetermined torque threshold Trdem_jdg, feedback torque hold control is executed to control the electric motor torque Tmg using the feedback torque Tfb. First, when the feedback torque Tfb is a positive value and the vehicle speed V exceeds the predetermined vehicle speed threshold V_jdg, or when the feedback torque Tfb is a negative value and the required drive torque Trdem exceeds the predetermined torque threshold Trdem_jdg, the vehicle 10 is neither overrunning nor underrunning during creeping. In such a case, feedback torque holding control is executed as drive control for the electric motor MG, so the driver does not feel uncomfortable due to fluctuations in driving force. On the other hand, when the feedback torque Tfb is a positive value and the vehicle speed V exceeds a predetermined vehicle speed threshold V_jdg, the vehicle speed V is relatively high, and the actual drive torque Tr at the drive wheels 14 is large compared to immediately after the start of driving.In this state, even if the drive control of the electric motor MG is switched from rotational speed control to torque control and a driving force fluctuation occurs, the impact is relatively small compared to immediately after the start of driving, and the sense of discomfort felt by the driver is suppressed. Furthermore, when the feedback torque Tfb is a negative value and the required drive torque Trdem exceeds a predetermined torque threshold Trdem_jdg, for example, when the driver operates the accelerator and the required drive torque Trdem increases, the drive control of the electric motor MG is switched from rotational speed control to torque control in conjunction with the driver's accelerator operation. Therefore, even if a driving force fluctuation occurs when the drive control of the electric motor MG is switched from rotational speed control to torque control, the driving force fluctuation is linked to the driver's accelerator operation, and the sense of discomfort felt by the driver is suppressed. In this way, the sense of discomfort felt by the driver is suppressed when the drive control of the electric motor MG, which is the driving force source PG for driving, is switched from rotational speed control to torque control.

[0067] According to this embodiment, when it is determined that the vehicle state has switched from a traveling state to a stopped state, rotational speed control is executed as drive control of the electric motor MG. In this way, when it is determined that the vehicle state has switched from a traveling state to a stopped state, rotational speed control is executed to converge the electric motor rotational speed Nmg to the idle rotational speed Nmg_idl by feedback control. This prevents the electric motor rotational speed Nmg from becoming too low. Therefore, when the driver releases the brake operation, creep running begins more quickly than when rotational speed control is not executed and the electric motor rotational speed Nmg becomes too low. Furthermore, when the vehicle is stopped in the HEV traveling mode, engine stalling is suppressed by preventing the engine rotational speed Ne, which is equal to the electric motor rotational speed Nmg, from becoming too low.

[0068] 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.

[0069] In the above-described embodiment, the vehicle 10 is a hybrid vehicle equipped with an engine 12 and an electric motor MG as a driving force source PG for running, but the present invention is not limited to this. For example, the present invention is also applicable to an electric vehicle that does not have an engine 12 as a driving force source PG but only has an electric motor MG. Note that when the vehicle 10 is an electric vehicle, the electric motor torque Tmg corresponds to the "output torque of the driving force source for running" in the present invention.

[0070] In the above-described embodiment, when it is determined that the vehicle state is in a stopped state, the motor control unit 92b performs rotational speed control using a feedback torque Tfb to converge the motor rotational speed Nmg to the idle rotational speed Nmg_idl. However, for example, in the HEV driving mode, the engine control unit 92a may perform rotational speed control to converge the engine rotational speed Ne (= motor rotational speed Nmg) to the idle rotational speed Nmg_idl, and the motor control unit 92b may perform rotational speed control using a feedback torque Tfb to converge the motor rotational speed Nmg to the idle rotational speed Nmg_idl.

[0071] In the above-described embodiment, the "predetermined target rotation speed" to which the electric motor rotation speed Nmg is converged in the rotation speed control is the idle rotation speed Nmg_idl, but the present invention is not limited to this. For example, in the embodiment, when the vehicle state is stopped in the BEV driving mode or when the vehicle 10 is an electric vehicle without an engine 12, the "predetermined target rotation speed" may be set to a rotation speed at which creep driving is possible.

[0072] In the above-described embodiment, the feedback torque Tfb is no longer fed back to the motor torque Tmg as the drive control of the electric motor MG is switched from rotational speed control to torque control at S60 in the flowchart of FIG. 2 . However, the present invention is not limited to this. For example, the feedback torque Tfb may be fed back to the electric motor torque Tmg, but the magnitude (absolute value) of the feedback torque Tfb may be reduced once and then gradually reduced to zero.

[0073] In the above-described embodiment, the battery 60 is a secondary battery, but this is not limiting. For example, a capacitor such as an electric double layer that does not use a chemical reaction may be used instead of a secondary battery as long as it can store electrical energy.

[0074] It should be noted that the above is merely an example of the present invention, and the present invention can be embodied in various forms with various modifications and improvements based on the knowledge of those skilled in the art, without departing from the spirit of the present invention. [Explanation of symbols]

[0075] 10: Hybrid vehicle (vehicle) 14: Drive wheel 24: Torque converter 90: Electronic control device (control device) MG: Electric motor Nmg: Motor rotation speed (rotation speed of the driving power source for running) Nmg_idl: Idle speed (predetermined target speed) PG: Driving power source PT: Power transmission path Tfb: Feedback torque Tmg: Motor torque (motor output torque) Trdem: Required driving torque (required driving amount) Trdem_jdg: Predetermined torque threshold (predetermined driving amount threshold) V:Vehicle speed V_jdg: Predetermined vehicle speed threshold

Claims

[Claim 1] A control device for a vehicle including a driving power source for running including an electric motor, and a torque converter disposed in a power transmission path between the driving power source for running and a drive wheel, a rotation speed control for causing the rotation speed of the driving power source for driving to converge to a predetermined target rotation speed by feedback control, and a torque control for controlling an output torque of the driving power source for driving to realize a required drive amount, and the control is switched between these two control as a drive control of the electric motor; When the rotation speed control is executed as the drive control of the electric motor while the vehicle state is in a stopped state, and it is determined that the vehicle state has switched from the stopped state to a running state, executes the torque control as a drive control of the electric motor when a feedback torque fed back to an output torque of the electric motor in the feedback control in the rotation speed control executed in the stopped state is a positive value and the vehicle speed exceeds a predetermined vehicle speed threshold value, or when the feedback torque is a negative value and the required drive amount exceeds a predetermined drive amount threshold value; When the feedback torque is a positive value and the vehicle speed exceeds the predetermined vehicle speed threshold, and when the feedback torque is a negative value and the required drive amount exceeds the predetermined drive amount threshold, the feedback torque is held and a feedback torque holding control is executed to control the output torque of the driving force source for traveling by the feedback torque. A vehicle control device comprising:

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