Hybrid vehicle control device

Abstract

To provide a control device for a hybrid vehicle, capable of matching actual vehicle acceleration with a sound change when an engine rotation speed increases with accelerator operation, in a hybrid vehicle including a torque converter.SOLUTION: When a rotation speed difference D between an engine rotation speed Ne and a turbine rotation speed Nt during accelerator operation by a driver becomes equal to or greater than a threshold value α, an increase in the engine rotation speed Ne is suppressed by regeneration by an engine-coupled electric motor MG3. In addition, assist torque Tast corresponding to an accelerator opening θacc is generated from a second electric motor MG2, so that it is possible to generate vehicle acceleration G matched with a sound change when the engine rotation speed Ne increases.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a control device for a hybrid vehicle having a first electric motor connected to an engine so as to be capable of power transmission and a torque converter provided on the downstream side of the engine.

Background Art

[0002] A hybrid vehicle having a first electric motor connected to an engine so as to be capable of power transmission and a torque converter provided on the downstream side of the engine has been proposed. Patent Document 1 describes one aspect of a torque converter provided on the downstream side of an engine. Specifically, Patent Document 1 describes a torque converter having a lock-up clutch that directly connects between a pump impeller and a turbine impeller.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In such a hybrid vehicle having a torque converter, when an accelerator operation is performed by a driver during traveling in a state where the lock-up clutch is released, while the engine rotational speed surges greatly, the driving amount transmitted to the drive wheel side is insufficient, and the sound change of the engine sound does not match the actual vehicle acceleration, which may give the driver a sense of discomfort.

[0005] The present invention has been made against the background of the above circumstances, and an object thereof is to provide a control device for a hybrid vehicle capable of matching the sound change at the time of an increase in the engine rotational speed accompanying an accelerator operation with the actual vehicle acceleration in a hybrid vehicle equipped with a torque converter.

Means for Solving the Problem

[0006] The gist of the first invention is a control device for a hybrid vehicle comprising: (a) an engine, a first electric motor connected to the engine so as to be capable of power transmission, a torque converter provided on a power transmission path between the engine and drive wheels, and a second electric motor connected to the power transmission path between the torque converter and the drive wheels so as to be capable of power transmission, wherein (b) when the rotational speed difference between the engine rotational speed of the engine and the turbine rotational speed of the torque converter is equal to or greater than a preset threshold value during an accelerator operation by a driver, the first electric motor performs regeneration to suppress an increase in the engine rotational speed, and the second electric motor generates a driving amount corresponding to the accelerator operation amount.

[0007] The gist of the second invention is that, in the first invention, when an accelerator operation is performed by the driver during traveling in a high vehicle speed region where the vehicle speed is equal to or higher than a preset high vehicle speed threshold value, the first electric motor performs power running to increase the engine rotational speed to a predetermined rotational speed or higher.

Advantages of the Invention

[0008] According to the first invention, when the rotational speed difference between the engine rotational speed and the turbine rotational speed during the driver's accelerator operation becomes equal to or greater than the threshold value, the increase in the engine rotational speed is suppressed by the regeneration of the first electric motor, and further, a driving amount corresponding to the accelerator operation amount is generated from the second electric motor. Therefore, it is possible to generate a vehicle acceleration that matches the sound change during the increase in the engine rotational speed.

[0009] According to the second invention, when an accelerator operation is performed during traveling in the high vehicle speed region, by performing power running of the first electric motor to increase the engine rotational speed to a predetermined rotational speed, the torque responsiveness of the engine can be increased, and a vehicle acceleration corresponding to the accelerator operation amount can be generated.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

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Figure 9

Mode for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following embodiments, the drawings are appropriately simplified or deformed, and the dimensional ratios and shapes of each part are not necessarily accurately drawn.

Embodiment

[0012] FIG. 1 is a diagram for explaining the schematic configuration of a hybrid vehicle 10 to which the present invention is applied, and is also a diagram for explaining the control functions and the main parts of the control system for various controls in the hybrid vehicle 10. In FIG. 1, a hybrid vehicle 10 (hereinafter, vehicle 10) is a hybrid vehicle including an engine 12 and electric motors (first electric motor MG1, second electric motor MG2), which are driving power sources for traveling. The vehicle 10 includes a power transmission device 16 provided in a power transmission path between the engine 12 and the drive wheels 14.

[0013] The engine 12 is a known internal combustion engine such as a gasoline engine or a diesel engine. The engine 12 is controlled by an engine control device 50 including a throttle actuator, a fuel injection device, an ignition device, etc., provided in the vehicle 10 by an electronic control device 100 described later, so that the engine torque Te, which is the output torque of the engine 12, is controlled.

[0014] An engine-connected electric motor MG3 is connected to the engine 12 via a transmission belt 46 so that power can be transmitted. The engine-connected electric motor MG3 generates torque for starting the engine, for example, when starting the engine. Note that the engine-connected electric motor MG3 corresponds to the first electric motor of the present invention.

[0015] The first electric motor MG1, the second electric motor MG2, and the engine-connected electric motor MG3 (hereinafter, these are collectively referred to as each electric motor MG) are rotary electric machines having a function as an engine that generates mechanical power from electric power and a function as a generator that generates electric power from mechanical power, and are so-called motor generators. Each electric motor MG is connected to a battery 54 provided in the vehicle 10 via an inverter 52 provided in the vehicle 10. Each electric motor MG has its output torque, i.e., the MG torque Tm, controlled by controlling the inverter 52 by an electronic control device 100 described later. The MG torque Tm is, for example, in the case of forward rotation where the rotation direction of each electric motor MG is the same as the rotation direction during the operation of the engine 12, the driving torque on the acceleration side is the power running torque, and the negative torque on the deceleration side is the regenerative torque. For example, each electric motor MG generates driving power for traveling by the electric power supplied from the battery 54 via the inverter 52 instead of or in addition to the engine 12. Further, each electric motor MG generates electric power by the power of the engine 12 or the driven power input from the drive wheel 14 side. The electric power generated by the power generation of each electric motor MG is stored in the battery 54 via the inverter 52. The battery 54 is a power storage device that exchanges power with each electric motor MG. The electric power is also the same as electrical energy when not particularly distinguished. The power is also the same as torque or force when not particularly distinguished. Hereinafter, the torque output from the first electric motor MG1 is referred to as MG1 torque Tm1, the torque output from the second electric motor MG2 is referred to as MG2 torque Tm2, and the torque output from the engine-connected electric motor MG3 is referred to as MG3 torque Tm3, respectively.

[0016] The power transmission device 16 includes a K0 clutch 20, a torque converter 22, an automatic transmission 24, etc. in 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 first electric motor MG1 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 connected to the torque converter 22 and is interposed in the power transmission path between the torque converter 22 and the drive wheels 14. The torque converter 22 and the automatic transmission 24 each constitute a part of the power transmission path between the engine 12 and the drive wheels 14. The power transmission device 16 includes a propeller shaft 28 connected to the transmission output shaft 26 which is the 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, and the like. Further, the power transmission device 16 includes an engine connecting shaft 34 connecting the engine 12 and the K0 clutch 20, a motor connecting shaft 36 connecting the K0 clutch 20 and the torque converter 22, and the like.

[0018] The first electric motor MG1 is connected in the case 18 to the motor connecting shaft 36 so as to be power-transmittable, and is also connected to the engine 12 via the K0 clutch 20 so as to be power-transmittable. The first electric motor MG1 is connected in a power-transmittable manner to the power transmission path between the engine 12 and the drive wheels 14, particularly to the power transmission path between the K0 clutch 20 and the torque converter 22. That is, the first electric motor MG1 is connected in a power-transmittable manner to the torque converter 22 and the automatic transmission 24 without passing through the K0 clutch 20. In other words, the torque converter 22 and the automatic transmission 24 each constitute a part of the power transmission path between the first electric motor MG1 and the drive wheels 14. The torque converter 22 and the automatic transmission 24 each transmit the driving force from each of the driving force sources of the engine 12 and the first electric motor MG1 to the drive wheels 14.

[0019] The torque converter 22 is provided on the power transmission path between the engine 12 and the drive wheels 14. The torque converter 22 includes a pump impeller 22a connected to the motor connection shaft 36, and a turbine impeller 22b connected to the transmission input shaft 38 which is the input rotating member of the automatic transmission 24. The pump impeller 22a is connected to the engine 12 via the K0 clutch 20 and is directly connected to the first motor MG1. The pump impeller 22a is the input member of the torque converter 22, and the turbine impeller 22b is the output member of the torque converter 22. The motor connection 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 which is integrally formed with the turbine shaft that is rotationally driven by the turbine impeller 22b. The torque converter 22 is a fluid transmission device that transmits the driving force from each of the driving force sources (engine 12, first motor MG1) to the transmission input shaft 38 via a fluid. The torque converter 22 includes a lock-up clutch 40 that connects the pump impeller 22a and the turbine impeller 22b. The lock-up clutch 40 (hereinafter, LU clutch 40) is a known direct connection clutch that disconnects and connects the input and output rotating members of the torque converter 22.

[0020] The LU clutch 40 has its operating state, that is, its control state switched by changing the LU clutch torque Tlu, which is the torque capacity of the LU clutch 40, by the regulated LU hydraulic pressure PRlu supplied from the 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 without slippage.

[0021] The automatic transmission 24 is a known planetary gear type automatic transmission including, for example, one or more sets of planetary gear devices (not shown) and a plurality of engagement devices CB. The engagement device CB is a hydraulic friction engagement device constituted by, for example, a multi-plate or single-plate clutch or brake pressed by a hydraulic actuator, a band brake tightened by a hydraulic actuator, and the like. Each of the engagement devices CB has its control state such as an engaged state or a released state switched by changing the CB torque Tcb, which is the respective torque capacity, by the regulated CB hydraulic pressure PRcb supplied from the hydraulic control circuit 56.

[0022] The automatic transmission 24 is a stepped transmission in which any one of the engagement devices among the engagement devices CB is engaged to form any one of a plurality of gear stages (also referred to as gear steps) having different gear ratios (also referred to as gear ratios) γat (= AT input rotational speed Ni / AT output rotational speed No). The automatic transmission 24 has the gear stage formed according to the accelerator operation of the driver (= driver), the vehicle speed V, etc. switched by the electronic control device 100 described later, that is, a plurality of gear stages are selectively formed. The AT input rotational speed Ni is the rotational speed of the transmission input shaft 38 and is the input rotational speed of the automatic transmission 24. Further, the AT input rotational speed Ni is also the rotational speed of the output rotating member of the torque converter 22 and is the same value as the turbine rotational speed Nt, which is the output rotational speed of the torque converter 22. The AT input rotational speed Ni can be represented by the turbine rotational speed Nt. The AT output rotational speed No is the rotational speed of the transmission output shaft 26 and is the output rotational speed of the automatic transmission 24.

[0023] The K0 clutch 20 is a wet or dry friction engagement device composed of a multi-plate or single-plate clutch pressed by a hydraulic actuator (not shown). The operating state of the hydraulic actuator of the K0 clutch 20 is controlled by an electronic control device 100 described later, whereby the control state such as the engaged state or the released state is switched. In the K0 clutch 20, when the K0 hydraulic pressure PRk0 regulated from the hydraulic control circuit 56 is supplied to the hydraulic actuator, the K0 torque Tk0, which is the torque capacity of the K0 clutch 20, is changed, thereby switching the control state of the K0 clutch 20.

[0024] In the engaged state of the K0 clutch 20, the pump impeller 22a and the engine 12 are integrally rotated via the engine connecting shaft 34. That is, the K0 clutch 20 connects the engine 12 and the drive wheels 14 so that power can be transmitted when engaged. On the other hand, in the released state of the K0 clutch 20, the power transmission between the engine 12 and the pump impeller 22a is interrupted. That is, the K0 clutch 20 disconnects the connection between the engine 12 and the drive wheels 14 when released. Since the first motor MG1 is connected to the pump impeller 22a, the K0 clutch 20 is provided in the power transmission path between the engine 12 and the first motor MG1 and functions as a clutch that disconnects and connects that power transmission path, that is, a clutch that disconnects and connects the engine 12 and the first motor MG1. That is, the K0 clutch 20 is a disconnecting and connecting clutch that connects the engine 12 and the first motor MG1 when engaged and disconnects the connection between the engine 12 and the first motor MG1 when released.

[0025] 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 through the K0 clutch 20, the 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 sequence. Also, the power output from the first motor MG1 is transmitted from the motor connecting shaft 36 to the drive wheels 14 through the torque converter 22, the automatic transmission 24, the propeller shaft 28, the differential gear 30, the drive shaft 32, etc. in sequence regardless of the control state of the K0 clutch 20.

[0026] The second motor MG2 is connected to the power transmission path between the torque converter 22 and the drive wheels 14 so as to be power-transmittable. Specifically, the second motor MG2 is connected to the transmission output shaft 26 that constitutes the power transmission path between the torque converter 22 and the drive wheels 14 in the case 18 so as to be power-transmittable. Thus, the power output from the second motor MG2 is transmitted to the drive wheels 14 through the transmission output shaft 26, the propeller shaft 28, the differential gear 30, the drive shaft 32, etc. in sequence.

[0027] The vehicle 10 includes a mechanical oil pump 58, an electric oil pump 60, a pump motor 62, etc. The mechanical oil pump 58 is connected to the pump impeller 22a and discharges the hydraulic oil used in the power transmission device 16 by being driven by a driving power source (the engine 12, the first motor MG1). The pump motor 62 is a dedicated motor for driving the electric oil pump 60. The electric oil pump 60 discharges the hydraulic oil by being driven by the pump motor 62. The hydraulic oil discharged by the mechanical oil pump 58 or the electric oil pump 60 is supplied to the hydraulic control circuit 56. The hydraulic control circuit 56 supplies the regulated CB hydraulic pressure PRcb, K0 hydraulic pressure PRk0, LU hydraulic pressure PRlu, etc. based on the hydraulic oil discharged by at least one of the mechanical oil pump 58 and the electric oil pump 60.

[0028] Vehicle 10 further includes an electronic control unit 100 that includes a control unit related to the driving control of vehicle 10 and the like. The electronic control unit 100 is configured to include a so-called microcomputer including, for example, a CPU, a RAM, a ROM, an input / output interface, etc. The CPU performs signal processing according to a program stored in the ROM in advance while using the temporary storage function of the RAM, thereby executing various controls of vehicle 10. The electronic control unit 100 is configured to include respective computers for engine control, motor control, hydraulic control, etc., as necessary.

[0029] Various signals etc. (for example, engine rotation speed Ne which is the rotation speed of engine 12, turbine rotation speed Nt which is the same value as the AT input rotation speed Ni, AT output rotation speed No corresponding to vehicle speed V, MG1 rotation speed Nm1 of the first motor MG1, MG2 rotation speed Nm2 of the second motor MG2, MG3 rotation speed Nm3 of the engine-coupled motor MG3, accelerator opening θacc which is the driver's accelerator operation amount representing the magnitude of the driver's acceleration operation, throttle valve opening θth which is the opening of the electronic throttle valve, brake-on signal Bon which is a signal indicating that the brake pedal for operating the wheel brake is being operated by the driver, battery temperature THbat, battery charge / discharge current Ibat, battery voltage Vbat of battery 54, operating oil temperature THoil which is the temperature of the operating oil OIL in the hydraulic control circuit 56, vehicle acceleration G, etc.) based on the detection values by various sensors etc. (for example, engine rotation speed sensor 70, turbine rotation speed sensor 72, output rotation speed sensor 74, MG1 rotation speed sensor 76, MG2 rotation speed sensor 78, MG3 rotation speed sensor 80, accelerator opening sensor 82, throttle valve opening sensor 84, brake switch 86, battery sensor 88, oil temperature sensor 90, acceleration sensor 92) provided in vehicle 10 are respectively supplied to the electronic control unit 100.

[0030] From the electronic control device 100, various command signals (for example, engine control command signal Se for controlling the engine 12, MG control command signal Sm for controlling each electric motor MG, CB hydraulic pressure control command signal Scb for controlling the engagement device CB, K0 hydraulic pressure control command signal Sko for controlling the K0 clutch 20, LU hydraulic pressure control command signal Slu for controlling the LU clutch 40, electric oil pump control command signal Sop for controlling the electric oil pump 60, etc.) are output to each device (for example, engine control device 50, inverter 52, hydraulic control circuit 56, pump motor 62, etc.) provided in the vehicle 10, respectively.

[0031] The electronic control device 100 includes a hybrid control means, that is, a hybrid control unit 102, a clutch control means, that is, a clutch control unit 104, and a shift control means, that is, a shift control unit 106, in order to realize various controls in the vehicle 10.

[0032] The hybrid control unit 102 includes a function as an engine control means, that is, an engine control unit 102a for controlling the operation of the engine 12, and a function as a motor control means, that is, a motor control unit 102b for controlling the operation of each electric motor MG via the inverter 52, and executes hybrid drive control and the like by the engine 12 and each electric motor MG by these control functions.

[0033] The hybrid control unit 102 calculates the required driving amount for the vehicle 10 by the driver, for example, by applying the accelerator opening θacc and the vehicle speed V to the required driving amount map. The required driving amount map is a relationship obtained experimentally or designed in advance and stored, that is, a predetermined relationship. The required driving amount is, for example, the required driving torque Trdem at the driving wheels 14. The required driving torque Trdem [Nm] is, in other words, the required driving power Prdem [W] at the vehicle speed V at that time. As the required driving amount, the required driving force Frdem [N] at the driving wheels 14, the required AT output torque at the transmission output shaft 26, etc. can also be used. In the calculation of the required driving amount, the AT output rotational speed No or the like may be used instead of the vehicle speed V. Here, the required driving torque Trdem can also be regarded as the total torque of the engine torque Te and the MG torque Tm of each electric motor MG transmitted to the transmission output shaft 26 of the automatic transmission 24. Hereinafter, for convenience, the required driving torque Trdem will be described as the torque transmitted to the transmission output shaft 26.

[0034] The hybrid control unit 102 outputs an engine control command signal Se for controlling the engine 12 and an MG control command signal Sm for controlling each electric motor MG so as to realize the required driving power Prdem in consideration of transmission losses, accessory loads, the gear ratio γat of the automatic transmission 24, the chargeable power Win and the dischargeable power Wout of the battery 54, etc. The engine control command signal Se is, for example, a command value of the engine power Pe, which is the power of the engine 12 that outputs the engine torque Te at the engine rotational speed Ne at that time. The MG control command signal Sm is, for example, a command value of the power consumption Wm (Wm1, Wm2, Wm3) of each electric motor MG that outputs each MG torque Tm (Tm1, Tm2, Tm3) at the MG rotational speed Nm (Nm1, Nm2, Nm3) of each electric motor MG at that time.

[0035] The chargeable power Win of the battery 54 is the maximum input power that can be input, which defines the input power limit of the battery 54 and indicates the input limit of the battery 54. The dischargeable power Wout of the battery 54 is the maximum output power that can be output, which defines the output power limit 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 obtained 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 indicating the state of charge (charge amount, remaining charge) of the battery 54, and is calculated by the electronic control unit 100 based on, for example, the battery charge / discharge current Ibat and the battery voltage Vbat.

[0036] When the output of each electric motor MG alone can cover the required driving torque Trdem, the hybrid control unit 102 sets the driving mode to the motor driving (= BEV driving) mode. In the BEV driving mode, the hybrid control unit 102 performs BEV driving in which at least one of the first electric motor MG1 and the second electric motor MG2 is used as a driving power source with the K0 clutch 20 disengaged. On the other hand, when the required driving torque Trdem cannot be covered without using at least the output of the engine 12, the hybrid control unit 102 sets the driving mode to the engine driving mode, that is, the hybrid driving (hereinafter, HEV driving) mode. In the hybrid driving mode (hereinafter, HEV driving mode), the hybrid control unit 102 performs engine driving, that is, HEV driving, in which the engine 12 and each electric motor MG are used as driving power sources with the K0 clutch 20 engaged.

[0037] Also, even when the required driving torque Trdem can be covered only by the outputs of the first electric motor MG1 and the second electric motor MG2, the hybrid control unit 102 activates the HEV driving mode when the state of charge value SOC of the battery 54 is less than a predetermined engine start threshold value or when warm-up of the engine 12 etc. is necessary. The engine start threshold value is a predetermined threshold value for determining that it is the state of charge value SOC at which it is necessary to forcibly start the engine 12 to charge the battery 54. Thus, the hybrid control unit 102 automatically stops the engine 12 during HEV driving, restarts the engine 12 after the engine stop, or starts the engine 12 during BEV driving based on the required driving torque Trdem etc., and appropriately switches between the BEV driving mode and the HEV driving mode.

[0038] The clutch control unit 104 controls the K0 clutch 20 according to the driving mode during driving. For example, when it is determined that the vehicle is to be switched to the HEV driving mode during BEV driving with the K0 clutch 20 released, the clutch control unit 104 performs engagement control of the K0 clutch 20 so that the power of the engine 12 is transmitted to the drive wheel 14 side via the K0 clutch 20.

[0039] The shift control unit 106 performs shift determination of the automatic transmission 24 using, for example, a shift map which is a predetermined relationship, and outputs a CB hydraulic pressure control command signal Scb for executing shift control of the automatic transmission 24 to the hydraulic pressure control circuit 56 as necessary. The shift map is a predetermined relationship having a shift line for determining the shift of the automatic transmission 24 on a two-dimensional coordinate with, for example, the vehicle speed V and the accelerator opening θacc as variables. In the shift map, the AT output rotational speed No etc. may be used instead of the vehicle speed V, and the required driving torque Trdem, the required driving force Frdem, the throttle valve opening θth etc. may be used instead of the accelerator opening θacc.

[0040] Incidentally, when the driver deeply depresses the accelerator pedal during HEV driving mode in which the engine 12 is driven and while the LU clutch 40 is disengaged, depending on driving conditions such as vehicle speed V, the surge of the engine rotational speed Ne increases, while the engine torque Te is used for the increase in the engine rotational speed, so that the engine torque Te transmitted to the drive wheel 14 side may be insufficient. At this time, the engine noise associated with the increase in the engine rotational speed Ne does not match the actual vehicle acceleration G (longitudinal acceleration), which may give the driver a sense of discomfort. To prevent such a situation, when the surge of the engine rotational speed Ne becomes large, the electronic control unit 100 performs regeneration with the engine-connected motor MG3 to suppress the increase (specifically, the rate of increase) in the engine rotational speed Ne, and has a control function of generating a drive torque Tr (drive amount) corresponding to the accelerator opening θacc corresponding to the accelerator operation amount from the second motor MG2.

[0041] The electronic control unit 100 functionally includes a lock-up determination unit 108 as a lock-up determination means and a surge amount determination unit 110 as a surge amount determination means for executing the above control.

[0042] When the accelerator pedal is depressed by the driver, the lock-up determination unit 108 determines whether the LU clutch 40 is released. For example, when the rotational speed difference D (=|Ne - Nt|) between the engine rotational speed Ne and the turbine rotational speed Nt is greater than or equal to a predetermined value greater than zero, the lock-up determination unit 108 determines that the LU clutch 40 is released. The predetermined value is set to a threshold value at which it can be determined that the LU clutch 40 is in the released state. Alternatively, the lock-up determination unit 108 can also determine the release of the LU clutch 40 based on whether an LU hydraulic control command signal Slu for releasing the LU clutch 40 is being output. Alternatively, the lock-up determination unit 108 detects the differential pressure (=Pon - Poff) between the hydraulic pressure Pon in the engagement-side oil chamber and the hydraulic pressure Poff in the release-side oil chamber of the LU clutch 40, and when the differential pressure is less than a threshold value near zero at which the LU clutch 40 can be regarded as being in the released state, it can also be determined that the LU clutch 40 is released.

[0043] When it is determined that the LU clutch 40 is released, the blow-up amount determination unit 110 determines whether the blow-up amount K of the engine rotational speed Ne accompanying the depression of the accelerator pedal by the driver is greater than or equal to a preset threshold value α. Here, the blow-up amount K of the engine rotational speed is defined by the rotational speed difference D (=|Ne - Nt|) between the engine rotational speed Ne and the turbine rotational speed Nt. Alternatively, the blow-up amount K of the engine rotational speed Ne can also be defined by the rising rate ΔNe (rising gradient) of the engine rotational speed Ne. Note that the rising rate ΔNe of the engine rotational speed Ne is obtained, for example, by differentiating the engine rotational speed Ne detected at any time with respect to time. The threshold value α is obtained in advance experimentally or by design, and is set, for example, to a threshold value within an allowable range where the actual vehicle acceleration G with respect to the engine noise generated when the engine rotational speed Ne rises does not cause discomfort to the driver.

[0044] Here, when it is determined that the LU clutch 40 is released and the overshoot amount K (rotation speed difference D) of the engine rotation speed Ne is determined to be equal to or greater than the threshold value α, the hybrid control unit 102 executes control to suppress an increase in the engine rotation speed Ne by executing regeneration by the engine-connected motor MG3. The hybrid control unit 102 controls the regeneration amount of the engine-connected motor MG3 so that, for example, the rotation speed difference D (or the increase rate ΔNe of the engine rotation speed Ne) between the engine rotation speed Ne and the turbine rotation speed Nt becomes equal to or less than a predetermined value β smaller than the threshold value α. Thereby, excessive overshoot of the engine rotation speed Ne is suppressed.

[0045] On the other hand, since the engine torque Te decreases because the increase in the engine rotation speed Ne is suppressed, the actual vehicle acceleration G becomes smaller than the vehicle acceleration G desired by the driver, which may give the driver a sense of discomfort. In contrast, the hybrid control unit 102 generates an assist torque Tast from the second motor MG2 so as to compensate for the decrease in the engine torque Te accompanying the regeneration of the engine-connected motor MG3. The assist torque Tast is added to the MG2 torque Tm2 currently output from the second motor MG2. The assist torque Tast is calculated as needed based on, for example, the regeneration amount of the engine-connected motor MG3, the characteristics of the torque converter 22, and the gear ratio γat of the automatic transmission 24, and is set to a value that compensates for the difference (=|Trdem - Tr|) between the required drive torque Trdem and the actual drive torque Tr due to the regeneration of the engine-connected motor MG3.

[0046] For example, a relationship map for obtaining an assist torque Tast, which is composed of, for example, the regeneration amount of the engine-connected motor MG3, the accelerator opening θacc, the vehicle speed V, the torque ratio of the torque converter 22, the gear ratio γat of the automatic transmission 24, etc., is obtained and stored in advance. When the regeneration control by the engine-connected motor MG3 is executed, the hybrid control unit 102 calculates the assist torque Tast by applying the actual respective values to the above relationship map. Next, when the hybrid control unit 102 calculates the assist torque Tast, it causes the MG2 torque Tm2 to which the assist torque Tast is added from the second motor MG2 to be output. As a result, the engine noise accompanying the increase in the engine rotation speed Ne and the actual vehicle acceleration G match, and it is possible to realize high-quality acceleration performance that does not give the driver a sense of discomfort.

[0047] FIG. 2 is a flowchart for explaining the control operation of the electronic control device 100, and is a flowchart for explaining the control operation capable of realizing the vehicle acceleration G desired by the driver while suppressing an excessive surge of the engine rotation speed Ne. This flowchart is repeatedly executed every time the accelerator pedal is depressed during traveling in the HEV traveling mode.

[0048] First, in step S10 corresponding to the control function of the lock-up determination unit 108 (hereinafter, steps are omitted), it is determined whether the LU clutch 40 is released. When the determination in S10 is negative, in S40 corresponding to the control function of the hybrid control unit 102, the MG2 torque Tm2 at the time of engagement of the LU clutch 40 is output from the second electric motor MG2. On the other hand, when the determination in S10 is affirmative, in S20 corresponding to the control function of the blow-up amount determination unit 110, it is determined whether the blow-up amount K of the engine rotational speed Ne has become equal to or greater than the threshold value α. When the determination in S20 is negative, in S40, the normal MG2 torque Tm2 is output from the second electric motor MG2. When the determination in S20 is affirmative, in S30 corresponding to the control function of the hybrid control unit 102, regenerative control by the engine-connected electric motor MG3 is executed so as to suppress excessive blow-up of the engine rotational speed Ne. Further, the MG2 torque Tm2 of the second electric motor MG2 is controlled so that the assist torque Tast taking into account the decrease in the engine torque Te generated along with the regeneration of the engine-connected electric motor MG3 is output.

[0049] Figure 3 is a time chart showing vehicle behavior based on the control operation of the electronic control device 100. In Figure 3, the horizontal axis indicates time t [sec], and the vertical axis, in order from the top, shows the accelerator opening θacc [%], the MG2 torque Tm2 [Nm] of the second electric motor MG2, the MG3 torque Tm3 [Nm] of the engine-connected electric motor MG3, the engine rotational speed Ne [rpm] and the turbine rotational speed Nt [rpm], and the vehicle acceleration G [m / s 2 , respectively. Also, in Figure 3, the left side of the paper shows vehicle behavior based on the conventional control operation, and the right side of the paper shows vehicle behavior based on the control operation of this embodiment.

[0050] First, the conventional vehicle behavior shown on the left side of the drawing as a comparison target will be described. At time t1 on the left side of the drawing in FIG. 3, the depression of the accelerator pedal has started. Along with the depression of the accelerator pedal, after time t1, the accelerator opening θacc increases with the passage of time. Also, after time t1, from the second motor MG2, MG2 torque Tm2 (assist torque) corresponding to the accelerator opening θacc is output. Further, after time t1, as the accelerator opening θacc increases, the engine rotational speed Ne increases. Here, while the engine rotational speed Ne shown by the solid line rises rapidly, the turbine rotational speed Nt shown by the broken line rises with a delay, and the rotational speed difference D (=|Ne - Nt|) corresponding to the blow-up amount K of the engine rotational speed Ne increases, and the rotational speed difference D becomes equal to or greater than the threshold value α. At this time, the vehicle acceleration G with respect to the engine sound accompanying the engine rotation becomes smaller than the vehicle acceleration G corresponding to the engine sound shown by the broken line, as shown by the solid line. Therefore, the engine sound and the vehicle acceleration G do not match.

[0051] Next, the vehicle behavior based on the control operation of this embodiment shown on the right side of the paper will be described. At time t1 on the right side of the paper in FIG. 3, the depression of the accelerator pedal has started. Along with the depression of the accelerator pedal, after time t1, the accelerator opening θacc increases with the passage of time. In this embodiment, after time t1, regenerative control of the engine-connected motor MG3 is executed so that the surge amount K of the engine rotational speed Ne becomes equal to or less than a predetermined value β, and MG3 torque Tm3, which is regenerative torque (negative torque), is output from the engine-connected motor MG3. Thereby, the increase in the engine rotational speed Ne is suppressed, and the engine rotational speed Ne linearly increases so as to be proportional to the increase in the accelerator opening θacc. Also, the turbine rotational speed Nt increases so as to follow the increase in the engine rotational speed Ne. On the other hand, MG2 torque Tm2, to which assist torque Tast from the second motor MG2 is added, is output so as to compensate for the decrease in the engine torque Te due to the regenerative control of the engine-connected motor MG3. As a result, the vehicle acceleration G increases in proportion to the increase in the accelerator opening θacc, and the change in the engine sound accompanying the engine rotation and the vehicle acceleration G match each other.

[0052] As described above, according to this embodiment, when the rotational speed difference D between the engine rotational speed Ne and the turbine rotational speed Nt during the driver's accelerator operation becomes equal to or greater than the threshold value α, the increase in the engine rotational speed Ne is suppressed by the regeneration of the engine-connected motor MG3, and further, assist torque Tast corresponding to the accelerator opening θacc is generated from the second motor MG2. Therefore, it is possible to generate a vehicle acceleration G that matches the sound change when the engine rotational speed Ne increases.

[0053] Next, another embodiment of the present invention will be described. In the following description, parts common to the above-described embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

Embodiment

[0054] In the aforementioned First Embodiment, regardless of the vehicle speed range, when the surge amount K of the engine rotational speed Ne becomes equal to or greater than the threshold value α, the above-described control is executed. Incidentally, when the vehicle speed V is in the high vehicle speed range, the background noise becomes high, so even if the engine rotational speed Ne is increased, it becomes difficult for the driver to perceive the change caused thereby. In this embodiment, in consideration of the above, when the accelerator pedal is depressed by the driver, the engine rotational speed Ne is raised to a region where the torque responsiveness of the engine 12 is good, thereby generating an engine torque Te corresponding to an increase in the accelerator opening θacc.

[0055] FIG. 4 is a functional block diagram for explaining the control function of an electronic control unit 200 that controls a hybrid vehicle, corresponding to another embodiment of the present invention. Note that the structure of the hybrid vehicle and the signals input to the electronic control unit 200 are the same as those in the aforementioned First Embodiment, and thus are omitted. Hereinafter, the control function of the electronic control unit 200, which is the main part of this embodiment, will be described.

[0056] The electronic control unit 200 functionally includes a hybrid control unit 202, a clutch control unit 104, a shift control unit 106, a lock-up determination unit 108, and a high vehicle speed range determination unit 210 in order to implement various controls in the vehicle. Note that the clutch control unit 104, the shift control unit 106, and the lock-up determination unit 108 are the same as those in the aforementioned embodiments, and thus are denoted by the same reference numerals and their descriptions are omitted.

[0057] The hybrid control unit 202 includes an engine control unit 202a that controls the operation of the engine 12 and a motor control unit 202b that controls the operation of each electric motor MG. The hybrid control unit 202 executes hybrid drive control and the like by the engine 12 and each electric motor MG by means of these control functions. The control operations of the engine control unit 202a and the motor control unit 202b are basically the same as those of the engine control unit 102a and the motor control unit 102b in the aforementioned First Embodiment, and thus their descriptions are omitted.

[0058] When the accelerator pedal is depressed, the high vehicle speed range determination unit 210 determines whether the current vehicle speed V is equal to or higher than a preset high vehicle speed threshold Vα. The high vehicle speed threshold Vα is determined in advance experimentally or by design and is set as the threshold for the high vehicle speed range where the change in engine noise and vibration associated with the increase in engine rotational speed Ne due to ambient noise during driving becomes difficult for the driver to perceive. Therefore, when the vehicle speed V is equal to or higher than the high vehicle speed threshold Vα, it is determined that the vehicle is running in the high vehicle speed range.

[0059] When the hybrid control unit 202 determines, based on the lock-up determination unit 108, that the LU clutch 40 is released and, based on the high vehicle speed range determination unit 210, that the vehicle is running in the high vehicle speed range, when the driver depresses the accelerator pedal, the engine-connected motor MG3 is forced (driven) to rapidly increase the engine rotational speed Ne to a predetermined rotational speed Ne1 or higher where the torque responsiveness of the engine 12 is good. The predetermined rotational speed Ne1 is determined in advance experimentally or by design based on the characteristics of the engine 12, etc. At this time, although the engine noise increases as the engine rotational speed Ne increases, since the vehicle is running in the high vehicle speed range, the change in engine noise is masked by the ambient noise and the driver hardly perceives the change in engine noise. Also, by increasing the engine rotational speed Ne to the predetermined rotational speed Ne1 or higher, the torque responsiveness of the engine increases, and a vehicle acceleration G corresponding to the accelerator opening θacc can be generated.

[0060] Figure 5 is a flowchart for explaining the control operation of the electronic control device 200 and is a flowchart for explaining the control function capable of realizing a vehicle acceleration G corresponding to the accelerator opening θacc in the high vehicle speed range. This flowchart is repeatedly executed every time the accelerator pedal is depressed while the vehicle is running in the HEV driving mode.

[0061] First, in S100 corresponding to the control function of the lock-up determination unit 108, it is determined whether the LU clutch 40 is released. When the determination in S100 is negative, in S130 corresponding to the control function of the hybrid control unit 202, normal control is executed. When the determination in S100 is positive, in S110 corresponding to the control function of the high vehicle speed range determination unit 210, it is determined whether the vehicle speed V is equal to or higher than the high vehicle speed threshold value Vα. When the determination in S110 is negative, in S130, control is executed where the vehicle speed V is less than the high vehicle speed threshold value Vα. For example, the control of the aforementioned embodiment 1 is executed. When the determination in S110 is positive, in S120 corresponding to the control function of the hybrid control unit 202, the engine rotation speed Ne is quickly increased to a predetermined rotation speed Ne1 by the engine-connected motor MG3. As a result, the torque responsiveness of the engine 12 is increased, and engine torque Te corresponding to the accelerator opening θacc can be generated, and vehicle acceleration G corresponding to the accelerator opening θacc can be generated.

[0062] Figure 6 is a time chart showing vehicle behavior based on the control operation of the electronic control device 200. In Figure 6, the horizontal axis represents time t [sec], and the vertical axis, in order from the top, represents the accelerator opening θacc [%], the MG2 torque Tm2 [Nm] of the second motor MG2, the MG3 torque Tm3 [Nm] of the engine-connected motor MG3, the engine rotation speed Ne [rpm] and the turbine rotation speed Nt [rpm], the engine torque Te [Nm], and the vehicle acceleration G [m / s 2 . Each is shown. Also, in Figure 6, the left side of the paper shows vehicle behavior based on the conventional control operation, and the right side of the paper shows vehicle behavior based on the control operation of this embodiment.

[0063] First, the conventional vehicle behavior shown on the left side of the drawing as a comparison target will be described. At time t1 on the left side of the drawing in FIG. 6, the depression of the accelerator pedal has started. Along with the depression of the accelerator pedal, after time t1, the accelerator opening θacc increases linearly with the passage of time. Also, after time t1, from the second electric motor MG2, MG2 torque Tm2 (assist torque) corresponding to the accelerator opening θacc is output. Further, after time t1, as the accelerator opening θacc increases, the engine rotational speed Ne increases as shown by the solid line, and the turbine rotational speed Nt increases with a delay with respect to the engine rotational speed Ne. Here, when the engine 12 is operating in a region with low torque responsiveness, the engine torque Te shown by the solid line is output with a delay with respect to the engine torque Te in the case of high torque responsiveness shown by the dashed line. Along with this, the vehicle acceleration G is smaller as shown by the solid line compared to the case where the torque responsiveness of the engine 12 shown by the dashed line is high. As a result, the vehicle acceleration G corresponding to the accelerator opening θacc cannot be obtained.

[0064] Next, the vehicle behavior based on the control operation of this embodiment shown on the right side of the drawing will be described. At time t1 on the right side of the drawing in FIG. 6, the depression of the accelerator pedal has started. Along with the depression of the accelerator pedal, after time t1, the accelerator opening θacc increases with the passage of time. Also, after time t1, from the second electric motor MG2, MG2 torque Tm2 (assist torque) corresponding to the accelerator opening θacc is output.

[0065] In this embodiment, after time t1, MG3 torque Tm3 for increasing the engine rotation speed is output from the engine-connected motor MG3 so that the engine rotation speed Ne quickly rises to a predetermined rotation speed Ne1. Accordingly, as shown by the solid line, the engine rotation speed Ne is controlled to a higher rotation speed (i.e., the predetermined rotation speed Ne1) compared to the case where the MG3 torque Tm3 shown by the broken line is not output. As a result, the torque responsiveness of the engine 12 is increased, and the engine torque Te shown by the solid line increases so as to follow the accelerator opening θacc from time t1. In relation to this, the vehicle acceleration G also rises so as to follow the accelerator opening θacc from time t1. As a result, since the vehicle acceleration G quickly increases in response to an increase in the accelerator opening θacc, a vehicle acceleration G corresponding to the accelerator opening θacc can be generated, and high-quality acceleration performance can be realized.

[0066] As described above, according to this embodiment, when an accelerator operation is performed while traveling in a high vehicle speed range, by causing the engine-connected motor MG3 to perform power running and increasing the engine rotation speed Ne to the predetermined rotation speed Ne1, the torque responsiveness of the engine 12 can be increased, and a vehicle acceleration G corresponding to the accelerator opening θacc can be generated.

Embodiment

[0067] In a region where the engine rotation speed Ne is low and the engine 12 is under high load, when the LU clutch 40 is engaged, low-frequency booming noise is likely to occur in the drive system. On the other hand, when the LU clutch 40 is disengaged, the booming noise is suppressed, but when the accelerator pedal is depressed, since torque is used for increasing the engine rotation speed Ne, it becomes difficult to realize a vehicle acceleration G corresponding to the accelerator opening θacc. Alternatively, it is also conceivable to take measures to reduce the booming noise in the LU clutch 40, but the lock-up damper and friction plate of the LU clutch 40 become expensive, and the manufacturing cost increases. In this embodiment, in a region where the engine 12 is rotating at a low speed and under high load, by executing the control described later, the acceleration performance when the accelerator pedal is depressed is ensured.

[0068] FIG. 7 is a functional block diagram for explaining the control function of an electronic control unit 300 that controls a hybrid vehicle, corresponding to still another embodiment of the present invention. Note that the structure of the hybrid vehicle and signals input to the electronic control unit 300 are the same as those in the aforementioned first embodiment, and thus are omitted. Hereinafter, the control function of the electronic control unit 300, which is a main part of this embodiment, will be described.

[0069] The electronic control unit 300 functionally includes a hybrid control unit 302, a clutch control unit 104, a shift control unit 106, a lock-up determination unit 108, and a heatstroke sound region determination unit 310 in order to execute various controls in the vehicle. Note that the clutch control unit 104, the shift control unit 106, and the lock-up determination unit 108 are the same as those in the aforementioned embodiment, and thus are denoted by the same reference numerals and their descriptions are omitted.

[0070] The hybrid control unit 302 includes an engine control unit 302a that controls the operation of the engine 12 and a motor control unit 302b that controls the operation of each electric motor MG, and executes hybrid drive control and the like by the engine 12 and each electric motor MG according to their control functions. The control operations of the engine control unit 302a and the motor control unit 302b are basically the same as those of the engine control unit 102a and the motor control unit 102b in the first embodiment described above, and thus their descriptions are omitted.

[0071] The hibernation noise region determination unit 310 determines whether the operating region of the engine 12 is in a region where hibernation noise is likely to occur in the engaged state of the LU clutch 40. The region where hibernation noise is likely to occur is obtained experimentally or design-wise in advance and is stored, for example, as a relationship map defined by the engine rotational speed Ne and the accelerator opening θacc. The hibernation noise region determination unit 310 determines that it is in a region where hibernation noise is likely to occur when the engine rotational speed Ne is within the rotational speed range defined by the relationship map and the accelerator opening θacc is within the range defined by the relationship map. Note that the region where hibernation noise is likely to occur is generally a region where the engine rotational speed Ne is low and the load on the engine 12 is high (i.e., the accelerator opening θacc is large).

[0072] When the hybrid control unit 302 determines, based on the hibernation noise region determination unit 310, that the operating region of the engine 12 is in a region where hibernation noise is likely to occur and, based on the lock-up determination unit 108, that the LU clutch 40 is in the released state, the hybrid control unit 302 controls the MG3 torque Tm3 of the engine-connected motor MG3 so that an assist torque taking into account the inertia of the engine 12 is output. Specifically, the hybrid control unit 302 causes the engine-connected motor MG3 to output, as the assist torque, the torque required for increasing the engine rotational speed Ne. By outputting the torque required for increasing the engine rotational speed Ne from the engine-connected motor MG3, the torque required for increasing the rotational speed of the engine 12 is not consumed from the engine torque Te, so that a vehicle acceleration G corresponding to the accelerator opening θacc can be generated.

[0073] FIG. 8 is a flowchart for explaining the control operation of the electronic control device 300 and is a flowchart for explaining a control function capable of generating a vehicle acceleration G corresponding to the accelerator opening θacc even in a region where hibernation noise is likely to occur. This flowchart is repeatedly executed every time the accelerator pedal is depressed during traveling in the HEV traveling mode.

[0074] First, in S200 corresponding to the control function of the hibernation sound region determination unit 310, it is determined whether the operating region of the engine 12 is within the range of the low rotation high load region where hibernation sound is likely to occur. If the determination in S200 is negative, normal control is performed in S230 corresponding to the control function of the hybrid control unit 302. If the determination in S200 is positive, in S210 corresponding to the control function of the lock-up determination unit 108, it is determined whether the LU clutch 40 is released. If the determination in S210 is negative, normal control is performed in S230. If the determination in S210 is positive, in S220 corresponding to the control function of the hybrid control unit 302, assist by the engine-connected motor MG3 considering the inertia of the engine 12 is executed. Specifically, the assist torque is output from the engine-connected motor MG3 as much as the torque required to increase the engine rotation speed Ne.

[0075] FIG. 9 is a time chart showing vehicle behavior based on the control operation of the electronic control device 300. In FIG. 9, the horizontal axis represents time t [sec], and the vertical axis, in order from the top, represents the accelerator opening θacc [%], the MG3 torque Tm3 [Nm] of the engine-connected motor MG3, the engine rotation speed Ne [rpm], and the vehicle acceleration G [m / s 2 . Also, in FIG. 9, the left side of the paper shows the vehicle behavior based on the conventional control operation, and the right side of the paper shows the vehicle behavior based on the control operation of this embodiment.

[0076] First, the conventional vehicle behavior shown on the left side of the drawing sheet as the comparison target will be described. At time t1 on the left side of the drawing sheet in FIG. 9, the depression of the accelerator pedal has started. Along with this, after time t1, the accelerator opening θacc increases linearly with the passage of time. Also, after time t1, in response to the increase in the accelerator opening θacc, the MG3 torque Tm3 of the engine-connected motor MG3 increases linearly. Further, after time t1, in response to the increase in the accelerator opening θacc, the engine rotational speed Ne increases. At this time, since the engine torque Te is used for the increase in the engine rotational speed Ne, the engine torque Te transmitted to the drive wheel 14 side decreases. As a result, with respect to the increase in the accelerator opening θacc, the vehicle acceleration G shown by the solid line becomes smaller than the vehicle acceleration G when the engine torque Te shown by the broken line does not decrease.

[0077] Next, the vehicle behavior based on the control operation of this embodiment shown on the right side of the drawing sheet will be described. At time t1 on the right side of the drawing sheet in FIG. 9, the depression of the accelerator pedal has started. Along with this, after time t1, the accelerator opening θacc increases linearly with the passage of time. Also, after time t1, in response to the increase in the accelerator opening, the engine rotational speed Ne increases. Here, in this embodiment, after time t1, the torque required for the increase in the engine rotational speed Ne is added to the MG3 torque Tm3 of the engine-connected motor MG3. As a result, since a part of the engine torque Te is not used for the increase in the engine rotational speed Ne, as shown by the solid line, a vehicle acceleration G corresponding to the accelerator opening θacc is generated from time t1. Note that the vehicle acceleration G shown by the broken line indicates the conventional vehicle behavior.

[0078] As described above, according to this embodiment, when the accelerator pedal is depressed in the low rotational speed high load region of the engine 12 where the stuffy sound is likely to occur, the torque required for the increase in the engine rotational speed Ne is output as the assist torque from the engine-connected motor MG3, so that the vehicle acceleration G corresponding to the accelerator opening θacc can be generated.

[0079] As described above, the embodiments of the present invention have been described in detail with reference to the drawings, but the present invention can also be applied in other aspects.

[0080] For example, although the above-described Embodiments 1 to 3 were each independently implemented, it is not necessarily required to implement each of Embodiments 1 to 3 independently, and it may be possible to implement them by appropriately combining Embodiments 1 to 3.

[0081] Also, in the above-described embodiments, regenerative control was performed by the engine-connected motor MG3 so as to suppress the surge of the engine rotational speed Ne, but instead of the engine-connected motor MG3, regenerative control by the first motor MG1 may be performed.

[0082] Also, in the above-described embodiments, the engine-connected motor MG3 was connected to the engine 12 via the transmission belt 46 so that power could be transmitted, but the present invention is not necessarily limited to this. For example, the engine-connected motor MG3 may be provided between the engine 12 and the K0 clutch 20. In short, any motor that can be connected to the engine 12 so as to be able to transmit power can be applied to the present invention. Also, the transmission belt 46 that connects between the engine 12 and the engine-connected motor MG3 is not necessarily limited to this, and for example, it can be appropriately changed to a gear, a chain, or the like.

[0083] Also, in the above-described embodiments, the second motor MG2 was connected to the transmission output shaft 26 so that power could be transmitted, but the present invention is not necessarily limited to the above configuration. For example, a configuration in which motors are respectively connected to a pair of drive shafts 32 connected to a pair of drive wheels 14 may be used. Alternatively, a configuration in which an in-wheel motor housed in the drive wheel 14 is used as the second motor may be used. In short, any motor that can apply assist torque to the left and right drive wheels 14 can be applied to the present invention.

[0084] In addition, in the foregoing embodiments, the automatic transmission 24 was a known planetary gear type automatic transmission including one or more sets of planetary gear devices and a plurality of engagement devices CB, but the present invention is not necessarily limited to this configuration. For example, the automatic transmission may be a known DCT (Dual Clutch Transmission), or a known belt type continuously variable transmission, etc.

[0085] In addition, in the foregoing embodiments, the torque converter 22 was used as the fluid transmission device, but it is not necessarily limited to this mode. For example, as the fluid transmission device, instead of the torque converter 22, other fluid transmission devices such as a fluid coupling without torque amplification effect may be used.

[0086] In addition, in each of the foregoing embodiments 1 to 3, the order of each step in each flowchart may be appropriately changed within a non - contradictory range.

[0087] Note that the above - described is merely one embodiment, and the present invention can be implemented in various modified and improved forms based on the knowledge of those skilled in the art.

Explanation of Reference Numerals

[0088] 10: Hybrid vehicle 12: Engine 14: Driving wheels 22: Torque converter 100, 200, 300: Electronic control unit (control unit) MG2: Second motor MG3: Engine - connected motor (first motor) D: Rotational speed difference α: Threshold value Vα: High vehicle speed threshold value Ne1: Predetermined rotational speed

Claims

1. A control device for a hybrid vehicle comprising: an engine; a first electric motor connected to the engine so as to be capable of power transmission; a torque converter provided on a power transmission path between the engine and drive wheels; and a second electric motor connected to the power transmission path between the torque converter and the drive wheels so as to be capable of power transmission, wherein when a rotational speed difference between the engine rotational speed of the engine and the turbine rotational speed of the torque converter during an accelerator operation by a driver is equal to or greater than a preset threshold value, the first electric motor performs regeneration to suppress an increase in the engine rotational speed, and the second electric motor generates a driving amount corresponding to the accelerator operation amount A control device for a hybrid vehicle, characterized by the above.

2. When an accelerator operation is performed by a driver while the vehicle is traveling in a high vehicle speed range where the vehicle speed is equal to or higher than a preset high vehicle speed threshold value, the first electric motor is caused to perform power running to increase the engine rotational speed to be equal to or higher than a preset predetermined rotational speed A control device for a hybrid vehicle according to Claim 1, characterized by the above.

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