JP7704060B2 - Hybrid vehicle control device - Google Patents

Description

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 transmitting power, and a torque converter provided downstream of the engine.

A hybrid vehicle has been proposed that has a first electric motor connected to an engine so as to be capable of transmitting power, and a torque converter provided downstream of the engine. Patent Document 1 describes one embodiment of a torque converter provided downstream of the engine. Specifically, Patent Document 1 describes a torque converter that has a lock-up clutch that directly connects a pump wheel and a turbine wheel.

JP 2005-299715 A

In a hybrid vehicle having such a torque converter, when the driver operates the accelerator while driving with the lock-up clutch released, the engine speed increases significantly, but the amount of drive transmitted to the drive wheels is insufficient, causing a discrepancy between the change in engine sound and the actual vehicle acceleration, which can cause the driver to feel uncomfortable.

The present invention was made against the background of the above circumstances, and its purpose is to provide a control device for a hybrid vehicle equipped with a torque converter that can match the change in sound that occurs when the engine speed increases due to accelerator operation with the actual vehicle acceleration.

The gist of the first invention is a control device for a hybrid vehicle including (a) an engine, a first electric motor connected to the engine so as to be capable of transmitting power, 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 transmitting power, and (b) when the driver operates the accelerator pedal, if 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, the first electric motor is used to regenerate power to suppress an increase in the engine rotational speed, and the second electric motor generates a drive amount according to the accelerator operation amount.

The gist of the second invention is that in the first invention, when the driver operates the accelerator 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, the first electric motor is powered to increase the engine rotation speed to or higher than a preset rotation speed.

According to the first invention, when the difference in rotational speed between the engine rotational speed and the turbine rotational speed during the driver's accelerator operation exceeds a threshold value, the increase in engine rotational speed is suppressed by regeneration of the first electric motor, and furthermore, a driving force corresponding to the accelerator operation amount is generated from the second electric motor, so that vehicle acceleration that matches the sound change when the engine rotational speed increases can be generated.

According to the second invention, when the accelerator is operated while traveling in a high vehicle speed range, the first electric motor is powered to increase the engine rotation speed to a predetermined rotation speed, thereby increasing the torque responsiveness of the engine and generating vehicle acceleration according to the amount of accelerator operation.

1 is a diagram for explaining a schematic configuration of a hybrid vehicle to which the present invention is applied, and is also a diagram for explaining main parts of control functions and a control system for various controls in the hybrid vehicle. 2 is a flowchart for explaining a control operation of the electronic control device of FIG. 1 . 2 is a time chart showing vehicle behavior based on the control operation of the electronic control device of FIG. 1 . FIG. 11 is a functional block diagram for explaining a control function of an electronic control device that controls a hybrid vehicle according to another embodiment of the present invention. 5 is a flowchart for explaining the control operation of the electronic control device of FIG. 4 . 5 is a time chart showing vehicle behavior based on the control operation of the electronic control device of FIG. 4 . FIG. 11 is a functional block diagram illustrating a control function of an electronic control device that controls a hybrid vehicle according to still another embodiment of the present invention. 8 is a flowchart for explaining the control operation of the electronic control device of FIG. 7 . 8 is a time chart showing vehicle behavior based on the control operation of the electronic control device of FIG. 7;

The following describes in detail the embodiments of the present invention with reference to the drawings. Note that in the following embodiments, the drawings have been simplified or modified as appropriate, and the dimensional ratios and shapes of each part are not necessarily drawn accurately.

Figure 1 is a diagram illustrating the schematic configuration of a hybrid vehicle 10 to which the present invention is applied, as well as a diagram illustrating the main parts of the control functions and control system for various controls in the hybrid vehicle 10. In Figure 1, the hybrid vehicle 10 (hereinafter, vehicle 10) is a hybrid vehicle equipped with an engine 12 and electric motors (first electric motor MG1, second electric motor MG2) that are sources of driving power for traveling. The vehicle 10 is equipped with a power transmission device 16 provided in the power transmission path between the engine 12 and the drive wheels 14.

The engine 12 is a known internal combustion engine such as a gasoline engine or a diesel engine. The engine 12 has an engine control device 50, which includes a throttle actuator, a fuel injection device, an ignition device, and the like, provided on the vehicle 10, controlled by an electronic control device 100 (described later), thereby controlling the engine torque Te, which is the output torque of the engine 12.

The engine-connected electric motor MG3 is connected to the engine 12 via a transmission belt 46 so as to be capable of transmitting power. The engine-connected electric motor MG3 generates torque for starting the engine, for example, when starting the engine. The engine-connected electric motor MG3 corresponds to the first electric motor of the present invention.

The first electric motor MG1, the second electric motor MG2, and the engine-connected electric motor MG3 (hereinafter collectively referred to as each electric motor MG) are rotating electric machines that function as a motor that generates mechanical power from electric power and 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. The inverter 52 of each electric motor MG is controlled by an electronic control device 100 described later, and the MG torque Tm, which is the output torque of each electric motor MG, is controlled. For example, when the rotation direction of each electric motor MG is the same as the rotation direction when the engine 12 is operating, the MG torque Tm is a power torque at the positive torque on the acceleration side, and a regenerative torque at the negative torque on the deceleration side. For example, each electric motor MG generates driving power using electric power supplied from the battery 54 via the inverter 52 instead of or in addition to the engine 12. Each electric motor MG generates electricity using the power of the engine 12 or the driven force input from the drive wheels 14. The electric power generated by each electric motor MG is stored in a battery 54 via an inverter 52. The battery 54 is an electric storage device that supplies and receives electric power to each electric motor MG. The electric power is also equivalent to electric energy unless otherwise specified. The power is also equivalent to torque or force unless otherwise specified. 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.

The power transmission device 16 includes a K0 clutch 20, a torque converter 22, an automatic transmission 24, and the like, housed 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.

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 a transmission output shaft 26, which is an output rotating member of the automatic transmission 24, a differential gear 30 connected to the propeller shaft 28, a pair of drive shafts 32 connected to the differential gear 30, and the like. The power transmission device 16 also includes an engine connecting shaft 34 that connects the engine 12 and the K0 clutch 20, an electric motor connecting shaft 36 that connects the K0 clutch 20 and the torque converter 22, and the like.

The first electric motor MG1 is connected to the electric motor connecting shaft 36 in the case 18 so as to be capable of transmitting power, and is also connected to the engine 12 via the K0 clutch 20 so as to be capable of transmitting power. The first electric motor MG1 is connected 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 so as to be capable of transmitting power. In other words, the first electric motor MG1 is connected to the torque converter 22 and the automatic transmission 24 so as to be capable of transmitting power 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 drive force from the drive force sources of the engine 12 and the first electric motor MG1 to the drive wheels 14.

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 wheel 22a connected to the motor connecting shaft 36 and a turbine wheel 22b connected to the transmission input shaft 38, which is an input rotating member of the automatic transmission 24. The pump wheel 22a is connected to the engine 12 via the K0 clutch 20 and is directly connected to the first electric motor MG1. The pump wheel 22a is an input member of the torque converter 22, and the turbine wheel 22b is an output member of the torque converter 22. The motor connecting shaft 36 is also an input rotating member of the torque converter 22. The transmission input shaft 38 is also an output rotating member of the torque converter 22, which is formed integrally with the turbine shaft that is rotated by the turbine wheel 22b. The torque converter 22 is a fluid-type transmission device that transmits driving force from each of the driving force sources (engine 12, first electric motor MG1) to the transmission input shaft 38 via a fluid. The torque converter 22 is equipped with 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 connects and disconnects the input and output rotating members of the torque converter 22.

The LU clutch 40 switches its operating state, i.e., its control state, by changing the LU clutch torque Tlu, which is the torque capacity of the LU clutch 40, using 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.

The automatic transmission 24 is a known planetary gear type automatic transmission that includes, for example, one or more planetary gear sets (not shown) and multiple engagement devices CB. The engagement devices CB are hydraulic friction engagement devices that are composed of, for example, multi-plate or single-plate clutches or brakes pressed by a hydraulic actuator, or band brakes tightened by a hydraulic actuator. The engagement devices CB have their respective torque capacities, or CB torques Tcb, changed by the regulated CB hydraulic pressure PRcb supplied from the hydraulic control circuit 56, thereby switching between control states such as an engaged state and a disengaged state.

The automatic transmission 24 is a stepped transmission in which one of a plurality of gear stages (also called gear stages) with different gear ratios (also called gear ratios) γat (=AT input rotation speed Ni/AT output rotation speed No) is formed by engaging one of the engagement devices CB. The automatic transmission 24 selectively forms a plurality of gear stages, that is, the gear stages formed according to the accelerator operation of the driver (=operator) and the vehicle speed V, etc., are switched by the electronic control device 100 described later. The AT input rotation speed Ni is the rotation speed of the transmission input shaft 38 and is the input rotation speed of the automatic transmission 24. The AT input rotation speed Ni is also the rotation speed of the output rotating member of the torque converter 22, and is the same value as the turbine rotation speed Nt, which is the output rotation speed of the torque converter 22. The AT input rotation speed Ni can be expressed as the turbine rotation speed Nt. The AT output rotation speed No is the rotation speed of the transmission output shaft 26, and is the output rotation speed of the automatic transmission 24.

The K0 clutch 20 is a wet or dry friction engagement device consisting of a multi-plate or single-plate clutch pressed by a hydraulic actuator (not shown). The electronic control device 100 (described later) controls the operating state of the hydraulic actuator, thereby switching the control state of the K0 clutch 20 between an engaged state, a released state, and the like. When the K0 hydraulic pressure PRk0 regulated by the hydraulic control circuit 56 is supplied to the hydraulic actuator in the K0 clutch 20, 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.

When the K0 clutch 20 is engaged, the pump impeller 22a and the engine 12 are rotated together via the engine connecting shaft 34. That is, when the K0 clutch 20 is engaged, it connects the engine 12 and the drive wheels 14 so that power can be transmitted. On the other hand, when the K0 clutch 20 is released, the power transmission between the engine 12 and the pump impeller 22a is interrupted. That is, when the K0 clutch 20 is released, it disconnects the engine 12 and the drive wheels 14. Since the first electric 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 electric motor MG1 and functions as a clutch that connects and disconnects the power transmission path, that is, a clutch that connects and disconnects the engine 12 and the first electric motor MG1. In other words, the K0 clutch 20 is a disconnecting clutch that connects the engine 12 and the first electric motor MG1 when engaged, and disconnects the engine 12 and the first electric motor MG1 when released.

In the power transmission device 16, when the K0 clutch 20 is engaged, the power output from the engine 12 is transmitted from the engine connecting shaft 34 to the drive wheels 14 via the K0 clutch 20, the electric motor connecting shaft 36, the torque converter 22, the automatic transmission 24, the propeller shaft 28, the differential gear 30, the drive shaft 32, etc. In addition, the power output from the first electric motor MG1 is transmitted from the electric motor connecting shaft 36 to the drive wheels 14 via the torque converter 22, the automatic transmission 24, the propeller shaft 28, the differential gear 30, the drive shaft 32, etc., regardless of the control state of the K0 clutch 20.

The second electric motor MG2 is connected to the power transmission path between the torque converter 22 and the drive wheels 14 so as to be capable of transmitting power. In detail, the second electric motor MG2 is connected to the transmission output shaft 26, which constitutes the power transmission path between the torque converter 22 and the drive wheels 14, inside the case 18 so as to be capable of transmitting power. As a result, the power output from the second electric motor MG2 is transmitted to the drive wheels 14 via the transmission output shaft 26, the propeller shaft 28, the differential gear 30, the drive shaft 32, etc. in this order.

The vehicle 10 is equipped with 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 is driven by a driving force source (engine 12, first electric motor MG1) to discharge hydraulic oil used in the power transmission device 16. The pump motor 62 is a dedicated motor for driving the electric oil pump 60. The electric oil pump 60 is driven by the pump motor 62 to discharge hydraulic oil. The hydraulic oil discharged by the mechanical oil pump 58 and the electric oil pump 60 is supplied to the hydraulic control circuit 56. The hydraulic control circuit 56 supplies the CB hydraulic pressure PRcb, the K0 hydraulic pressure PRk0, the LU hydraulic pressure PRlu, etc., which are adjusted based on the hydraulic oil discharged by at least one of the mechanical oil pump 58 and the electric oil pump 60.

The vehicle 10 further includes an electronic control device 100 that includes a control device related to driving control of the vehicle 10. The electronic control device 100 includes a so-called microcomputer equipped with, for example, a CPU, RAM, ROM, an input/output interface, etc., and the CPU executes various controls of the vehicle 10 by performing signal processing according to a program previously stored in the ROM while utilizing the temporary storage function of the RAM. The electronic control device 100 includes computers for engine control, electric motor control, hydraulic control, etc. as necessary.

The electronic control device 100 receives various signals based on detection values from various sensors provided in the vehicle 10 (e.g., 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) (e.g., engine rotation speed Ne, which is the rotation speed of the engine 12, turbine rotation speed Nt, which is the same value as the AT input rotation speed Ni, AT output rotation speed No, which corresponds to the vehicle speed V, MG1 of the first electric motor MG1, rotation speed Nm1, MG2 rotation speed Nm2 of the second electric motor MG2, MG3 rotation speed Nm3 of the engine-connected electric motor MG3, accelerator opening θacc which is the driver's accelerator operation amount indicating 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 the state in which the brake pedal for operating the wheel brakes is being operated by the driver, battery temperature THbat, battery charge/discharge current Ibat, battery voltage Vbat of the battery 54, hydraulic oil temperature THoil which is the temperature of the hydraulic oil OIL in the hydraulic control circuit 56, vehicle acceleration G, etc.) are respectively supplied.

The electronic control device 100 outputs various command signals (e.g., engine control command signal Se for controlling the engine 12, MG control command signal Sm for controlling each electric motor MG, CB hydraulic control command signal Scb for controlling the engagement device CB, K0 hydraulic control command signal Sko for controlling the K0 clutch 20, LU hydraulic 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.) to each device (e.g., engine control device 50, inverter 52, hydraulic control circuit 56, pump motor 62, etc.) provided in the vehicle 10.

The electronic control device 100 includes a hybrid control means, i.e., a hybrid control unit 102, a clutch control means, i.e., a clutch control unit 104, and a gear shift control means, i.e., a gear shift control unit 106, in order to realize various controls in the vehicle 10.

The hybrid control unit 102 includes a function as an engine control means, i.e., engine control unit 102a, that controls the operation of the engine 12, and a function as an electric motor control means, i.e., electric motor control unit 102b, that controls the operation of each electric motor MG via the inverter 52, and executes hybrid drive control by the engine 12 and each electric motor MG, etc., using these control functions.

The hybrid control unit 102 calculates the driver's required driving force for the vehicle 10, for example, by applying the accelerator opening θacc and the vehicle speed V to a required driving force map. The required driving force map is a relationship that is experimentally or design-wise obtained and stored in advance, i.e., a predetermined relationship. The required driving force is, for example, the required driving torque Trdem at the driving wheels 14. In other words, the required driving torque Trdem [Nm] is the required driving power Prdem [W] at the vehicle speed V at that time. The required driving force can also be the required driving force Frdem [N] at the driving wheels 14, the required AT output torque at the transmission output shaft 26, etc. In calculating the required driving force, the AT output rotation speed No, etc. can be used instead of the vehicle speed V. Here, the required driving torque Trdem can also be seen as the combined 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. For convenience, the required drive torque Trdem will be described below as the torque transmitted to the transmission output shaft 26.

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, taking into consideration the transmission loss, the auxiliary load, the gear ratio γat of the automatic transmission 24, the chargeable power Win and dischargeable power Wout of the battery 54, etc. The engine control command signal Se is, for example, a command value for the engine power Pe, which is the power of the engine 12 that outputs the engine torque Te at the engine rotation speed Ne at that time. The MG control command signal Sm is, for example, a command value for the power consumption Wm (Wm1, Wm2, Wm3) of each electric motor MG that outputs each MG torque Tm (Tm1, Tm2, Tm3) at the MG rotation speed Nm (Nm1, Nm2, Nm3) of each electric motor MG at that time.

The chargeable power Win of the battery 54 is the maximum power that can be input, which specifies the limit on the input power of the battery 54, and indicates the input limit of the battery 54. The dischargeable power Wout of the battery 54 is the maximum power that can be output, which specifies the limit on the output power of the battery 54, and indicates the output limit of the battery 54. The chargeable power Win and dischargeable power Wout of the battery 54 are calculated, for example, based on the battery temperature THbat and the state of charge value SOC [%] of the battery 54. The state of charge value SOC of the battery 54 is a value that indicates the state of charge (charge amount, remaining charge) of the battery 54, and is calculated by the electronic control unit 100, for example, based on the battery charge/discharge current Ibat and the battery voltage Vbat.

When the required drive torque Trdem can be met only by the output of each electric motor MG, the hybrid control unit 102 sets the drive mode to motor drive (=BEV drive) mode. In the BEV drive mode, the hybrid control unit 102 performs BEV drive, in which at least one of the first electric motor MG1 and the second electric motor MG2 is used as a drive source with the K0 clutch 20 in a disengaged state. On the other hand, when the required drive torque Trdem cannot be met without using at least the output of the engine 12, the hybrid control unit 102 sets the drive mode to engine drive mode, i.e., hybrid drive (hereinafter, HEV drive) mode. In the hybrid drive mode (hereinafter, HEV drive mode), the hybrid control unit 102 performs engine drive, i.e., HEV drive, in which the engine 12 and each electric motor MG are used as drive sources with the K0 clutch 20 in an engaged state.

Even if the required drive torque Trdem can be satisfied only by the output of the first electric motor MG1 and the second electric motor MG2, the hybrid control unit 102 establishes the HEV driving mode when the state of charge value SOC of the battery 54 falls below a predetermined engine start threshold value or when warming up of the engine 12 or the like is required. The engine start threshold value is a predetermined threshold value for determining that the state of charge value SOC is such that the engine 12 needs to be forcibly started to charge the battery 54. In this way, the hybrid control unit 102 automatically stops the engine 12 during HEV driving, restarts the engine 12 after the engine is stopped, or starts the engine 12 during BEV driving, based on the required drive torque Trdem, etc., thereby appropriately switching between the BEV driving mode and the HEV driving mode.

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 should be switched to the HEV driving mode during BEV driving with the K0 clutch 20 released, the clutch control unit 104 controls the engagement of the K0 clutch 20 so that the power of the engine 12 is transmitted to the drive wheels 14 via the K0 clutch 20.

The shift control unit 106 judges whether or not the automatic transmission 24 should be shifted using, for example, a shift map, which is a predetermined relationship, and outputs a CB hydraulic control command signal Scb to the hydraulic control circuit 56 to execute shift control of the automatic transmission 24 as necessary. The shift map is a predetermined relationship having a shift line for judging whether or not the automatic transmission 24 should be shifted, on a two-dimensional coordinate system having, for example, vehicle speed V and accelerator opening θacc as variables. In the shift map, the AT output rotation speed No 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.

When the driver depresses the accelerator pedal heavily while driving in the HEV driving mode in which the engine 12 is driven and the LU clutch 40 is released, depending on the driving conditions such as the vehicle speed V, the engine rotation speed Ne may increase, while the engine torque Te is used to increase the engine rotation speed, so that the engine torque Te transmitted to the drive wheels 14 may be insufficient. At this time, the engine sound accompanying the increase in the engine rotation speed Ne may not match the actual vehicle acceleration G (longitudinal acceleration), which may cause the driver to feel uncomfortable. To prevent such a situation, the electronic control unit 100 has a control function that, when the engine rotation speed Ne increases too much, regenerates the engine-connected electric motor MG3 to suppress the increase in the engine rotation speed Ne (specifically, the upward gradient), and generates a drive torque Tr (drive amount) from the second electric motor MG2 according to the accelerator opening θacc, which corresponds to the accelerator operation amount.

The electronic control unit 100 is functionally equipped with a lockup determination unit 108 as a lockup determination means and a speed increase amount determination unit 110 as a speed increase amount determination means for executing the above control.

When the driver depresses the accelerator pedal, the lockup determination unit 108 determines whether the LU clutch 40 is released. For example, when the rotation speed difference D (=|Ne-Nt|) between the engine rotation speed Ne and the turbine rotation speed Nt is equal to or greater than a predetermined value greater than zero, the lockup 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 a released state. Alternatively, the lockup determination unit 108 can determine that the LU clutch 40 is released based on whether an LU hydraulic control command signal Slu for releasing the LU clutch 40 is output. Alternatively, the lockup determination unit 108 can detect the differential pressure (=Pon-Poff) between the hydraulic pressure Pon of the engagement side oil chamber of the LU clutch 40 and the hydraulic pressure Poff of the release side oil chamber, and determine that the LU clutch 40 is released if the differential pressure is less than a threshold value near zero at which the LU clutch 40 can be considered to be in a released state.

When it is determined that the LU clutch 40 is released, the rev-up amount determination unit 110 determines whether the rev-up amount K of the engine rotation speed Ne caused by the driver's depression of the accelerator pedal is equal to or greater than a preset threshold value α. Here, the rev-up amount K of the engine rotation speed is defined as the rotation speed difference D (=|Ne-Nt|) between the engine rotation speed Ne and the turbine rotation speed Nt. Alternatively, the rev-up amount K of the engine rotation speed Ne can be defined as the rate of increase ΔNe (rising gradient) of the engine rotation speed Ne. The rate of increase ΔNe of the engine rotation speed Ne is obtained, for example, by differentiating the engine rotation 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 acceptable range where the actual vehicle acceleration G relative to the engine sound generated when the engine rotation speed Ne increases does not cause the driver to feel uncomfortable.

Here, if it is determined that the LU clutch 40 is released and the amount of increase K of the engine rotation speed Ne (rotation speed difference D) is 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 using the engine-connected electric motor MG3. For example, the hybrid control unit 102 controls the amount of regeneration of the engine-connected electric motor MG3 so that the rotation speed difference D between the engine rotation speed Ne and the turbine rotation speed Nt (or the rate of increase ΔNe of the engine rotation speed Ne) is equal to or less than a predetermined value β that is smaller than the threshold value α. This suppresses excessive increase in the engine rotation speed Ne.

On the other hand, since the increase in engine speed Ne is suppressed, the engine torque Te decreases, and the actual vehicle acceleration G becomes smaller than the vehicle acceleration G desired by the driver, which may cause the driver to feel uncomfortable. In response to this, the hybrid control unit 102 generates an assist torque Tast from the second electric motor MG2 to compensate for the decrease in engine torque Te caused by the regeneration of the engine-connected electric motor MG3. The assist torque Tast is added to the MG2 torque Tm2 currently output from the second electric motor MG2. The assist torque Tast is calculated as needed based on, for example, the amount of regeneration of the engine-connected electric 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 electric motor MG3.

For example, a relationship map for calculating the assist torque Tast, which is composed of the regeneration amount of the engine-connected electric 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 calculated and stored in advance. When regeneration control by the engine-connected electric motor MG3 is executed, the hybrid control unit 102 calculates the assist torque Tast by applying the actual values to the relationship map. Next, when the hybrid control unit 102 calculates the assist torque Tast, it causes the second electric motor MG2 to output the MG2 torque Tm2 to which the assist torque Tast has been added. As a result, the engine sound accompanying the increase in engine speed Ne matches the actual vehicle acceleration G, and high-quality acceleration performance that does not cause the driver to feel uncomfortable can be achieved.

Figure 2 is a flowchart for explaining the control operation of the electronic control unit 100, which is capable of realizing the vehicle acceleration G desired by the driver while suppressing excessive increase in the engine speed Ne. This flowchart is executed repeatedly each time the accelerator pedal is depressed while driving in the HEV driving mode.

First, in step S10 (hereinafter, steps are omitted) corresponding to the control function of the lockup determination unit 108, it is determined whether the LU clutch 40 is released. If the determination in S10 is negative, in S40 corresponding to the control function of the hybrid control unit 102, the MG2 torque Tm2 when the LU clutch 40 is engaged is output from the second electric motor MG2. On the other hand, if the determination in S10 is positive, in S20 corresponding to the control function of the rev-up amount determination unit 110, it is determined whether the rev-up amount K of the engine rotation speed Ne has become equal to or greater than the threshold value α. If the determination in S20 is negative, in S40, the MG2 torque Tm2 in normal operation is output from the second electric motor MG2. If the determination in S20 is positive, in S30 corresponding to the control function of the hybrid control unit 102, regenerative control is performed by the engine-coupled electric motor MG3 so that excessive rev-up of the engine rotation speed Ne is suppressed. Furthermore, the MG2 torque Tm2 of the second motor MG2 is controlled so that the assist torque Tast is output, taking into account the decrease in engine torque Te that occurs as the engine-connected motor MG3 regenerates.

Fig. 3 is a time chart showing vehicle behavior based on the control operation of the electronic control device 100. In Fig. 3, the horizontal axis shows time t [sec], and the vertical axis shows, from top to bottom, accelerator opening θacc [%], MG2 torque Tm2 [Nm] of the second electric motor MG2, MG3 torque Tm3 [Nm] of the engine-connected electric motor MG3, engine rotation speed Ne [rpm], turbine rotation speed Nt [rpm], and vehicle acceleration G [m/ ^s2 ]. In Fig. 3, the left side of the page shows vehicle behavior based on the conventional control operation, and the right side of the page shows vehicle behavior based on the control operation of this embodiment.

First, the conventional vehicle behavior shown on the left side of the page as a comparison target will be described. At time t1 on the left side of the page in FIG. 3, the accelerator pedal is started to be depressed. As the accelerator pedal is depressed, the accelerator opening θacc increases over time from time t1 onwards. Also, from time t1 onwards, the MG2 torque Tm2 (assist torque) corresponding to the accelerator opening θacc is output from the second electric motor MG2. Furthermore, from time t1 onwards, the engine speed Ne increases with the increase in the accelerator opening θacc. Here, the engine speed Ne shown by the solid line increases quickly, while the turbine speed Nt shown by the dashed line increases with a delay, and the rotation speed difference D (=|Ne-Nt|) corresponding to the amount of revving up K of the engine speed Ne increases, and the rotation 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 dashed line, as shown by the solid line. Therefore, the engine sound and vehicle acceleration G do not match.

Next, the vehicle behavior based on the control operation of this embodiment shown on the right side of the page will be described. At time t1 on the right side of the page in FIG. 3, the accelerator pedal is started to be depressed. As the accelerator pedal is depressed, the accelerator opening θacc increases over time from time t1 onwards. In this embodiment, regenerative control of the engine-connected motor MG3 is executed from time t1 onwards so that the amount of increase K in the engine speed Ne is equal to or less than a predetermined value β, and the MG3 torque Tm3, which is a regenerative torque (negative torque), is output from the engine-connected motor MG3. This suppresses the increase in the engine speed Ne, and the engine speed Ne increases linearly in proportion to the increase in the accelerator opening θacc. The turbine speed Nt also increases so as to follow the increase in the engine speed Ne. On the other hand, to compensate for the decrease in engine torque Te due to the regenerative control of the engine-connected electric motor MG3, the second electric motor MG2 outputs the MG2 torque Tm2 to which the assist torque Tast has been added. As a result, the vehicle acceleration G increases in proportion to the increase in the accelerator opening θacc, and the change in engine sound accompanying the engine rotation coincides with the vehicle acceleration G.

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 electric motor MG3, and further, the assist torque Tast corresponding to the accelerator opening θacc is generated from the second electric motor MG2, so that a vehicle acceleration G that matches the sound change when the engine rotational speed Ne increases can be generated.

Next, another embodiment of the present invention will be described. In the following description, parts common to the previous embodiment will be given the same reference numerals and will not be described.

In the above-mentioned first embodiment, the above-mentioned control is executed when the amount of revving up of the engine rotation speed Ne becomes equal to or exceeds the threshold value α, regardless of the vehicle speed range. However, when the vehicle speed V reaches a high vehicle speed range, background noise increases, so even if the engine rotation speed Ne is increased, the driver is less likely to detect the resulting change. In this embodiment, taking the above into consideration, when the driver depresses the accelerator pedal, the engine rotation speed Ne is raised to a range where the engine 12 has good torque response, thereby generating an engine torque Te that corresponds to an increase in the accelerator opening θacc.

Figure 4 is a functional block diagram for explaining the control functions of an electronic control unit 200 that controls a hybrid vehicle, which corresponds 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 omitted because they are the same as those in the first embodiment described above. The control functions of the electronic control unit 200, which is the main part of this embodiment, are explained below.

The electronic control unit 200 functionally comprises a hybrid control unit 202, a clutch control unit 104, a gear shift control unit 106, a lock-up determination unit 108, and a high vehicle speed range determination unit 210 to realize various controls in the vehicle. Note that the clutch control unit 104, the gear shift control unit 106, and the lock-up determination unit 108 are the same as in the previous embodiment, so they are denoted by the same reference numerals and their description is omitted.

The hybrid control unit 202 includes an engine control unit 202a that controls the operation of the engine 12, and an electric motor control unit 202b that controls the operation of each electric motor MG. The hybrid control unit 202 executes hybrid drive control by the engine 12 and each electric motor MG using these control functions. The control operation of the engine control unit 202a and the electric motor control unit 202b is basically the same as the engine control unit 102a and the electric motor control unit 102b in the first embodiment described above, so a description thereof will be omitted.

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 greater than a preset high vehicle speed threshold Vα. The high vehicle speed threshold Vα is determined in advance by experiment or design, and is set as a threshold for the high vehicle speed range where the change in engine sound and vibrations caused by an increase in engine rotation speed Ne are less likely to be transmitted to the driver due to background noise while driving. Therefore, if the vehicle speed V is equal to or greater than the high vehicle speed threshold Vα, it is determined that the vehicle is driving in a high vehicle speed range.

When the hybrid control unit 202 determines that the LU clutch 40 is released based on the lock-up determination unit 108 and that the vehicle is traveling in a high vehicle speed range based on the high vehicle speed range determination unit 210, when the driver depresses the accelerator pedal, the hybrid control unit 202 powers (drives) the engine-coupled electric motor MG3 and quickly increases the engine rotation speed Ne to a predetermined rotation speed Ne1 or higher that provides good torque response of the engine 12. The predetermined rotation speed Ne1 is determined in advance experimentally or by design and is determined based on the characteristics of the engine 12. At this time, the engine sound increases with the increase in engine rotation speed Ne, but since the vehicle is traveling in a high vehicle speed range, the change in engine sound is drowned out by background noise and the driver hardly feels the change in engine sound. In addition, when the engine rotation speed Ne increases to the predetermined rotation speed Ne1 or higher, the engine torque response increases, and vehicle acceleration G corresponding to the accelerator opening θacc can be generated.

Figure 5 is a flowchart for explaining the control operation of the electronic control unit 200, and is a flowchart for explaining the control function that can realize the vehicle acceleration G according to the accelerator opening θacc in the high vehicle speed range. This flowchart is executed repeatedly each time the accelerator pedal is depressed while driving in the HEV driving mode.

First, in S100, which corresponds 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 S100 is negative, normal control is executed in S130, which corresponds to the control function of the hybrid control unit 202. If the determination in S100 is positive, it is determined in S110, which corresponds to the control function of the high vehicle speed range determination unit 210, whether the vehicle speed V is equal to or higher than the high vehicle speed threshold value Vα. If the determination in S110 is negative, control is executed in S130 when the vehicle speed V is less than the high vehicle speed threshold value Vα. For example, the control of the first embodiment described above is executed. If the determination in S110 is positive, in S120, which corresponds 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-coupled electric motor MG3. As a result, the torque responsiveness of the engine 12 is improved, and an engine torque Te corresponding to the accelerator opening θacc is generated, making it possible to generate a vehicle acceleration G corresponding to the accelerator opening θacc.

Fig. 6 is a time chart showing vehicle behavior based on the control operation of the electronic control device 200. In Fig. 6, the horizontal axis shows time t [sec], and the vertical axis shows, from top to bottom, accelerator opening θacc [%], MG2 torque Tm2 [Nm] of the second electric motor MG2, MG3 torque Tm3 [Nm] of the engine-connected electric motor MG3, engine rotation speed Ne [rpm] and turbine rotation speed Nt [rpm], engine torque Te [Nm], and vehicle acceleration G [m/ ^s2 ]. In Fig. 6, the left side of the page shows vehicle behavior based on the conventional control operation, and the right side of the page shows vehicle behavior based on the control operation of this embodiment.

First, the conventional vehicle behavior shown on the left side of the page as a comparison target will be described. At time t1 on the left side of the page in FIG. 6, the accelerator pedal is started to be depressed. As the accelerator pedal is depressed, the accelerator opening θacc increases linearly over time from time t1 onward. In addition, from time t1 onward, the second electric motor MG2 outputs the MG2 torque Tm2 (assist torque) according to the accelerator opening θacc. Furthermore, from time t1 onward, the engine rotation speed Ne increases as shown by the solid line with the increase in the accelerator opening θacc, and the turbine rotation speed Nt increases with a delay relative to the engine rotation speed Ne. Here, when the engine 12 is operated in a region with low torque responsiveness, the engine torque Te shown by the solid line is output with a delay relative to the engine torque Te when the torque responsiveness is high shown by the dashed line. Accordingly, the vehicle acceleration G is smaller as shown by the solid line than when the torque responsiveness of the engine 12 is high shown by the dashed line. As a result, the vehicle acceleration G corresponding to the accelerator opening θacc cannot be obtained.

Next, the vehicle behavior based on the control operation of this embodiment, shown on the right side of the page, will be described. At time t1 on the right side of the page in FIG. 6, depression of the accelerator pedal begins. As the accelerator pedal is depressed, from time t1 onwards, the accelerator opening θacc increases over time. Also, from time t1 onwards, the second electric motor MG2 outputs an MG2 torque Tm2 (assist torque) that corresponds to the accelerator opening θacc.

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

As described above, according to this embodiment, when the accelerator is operated while traveling in the high vehicle speed range, the engine-connected electric motor MG3 is powered to increase the engine rotation speed Ne to a predetermined rotation speed Ne1, thereby increasing the torque responsiveness of the engine 12 and generating a vehicle acceleration G according to the accelerator opening θacc.

When the engine speed Ne is low and the engine 12 is in a high load range, low-frequency booming noise is likely to occur in the drive system when the LU clutch 40 is engaged. In contrast, when the LU clutch 40 is released, the booming noise is suppressed, but when the accelerator pedal is depressed, torque is used to increase the engine speed Ne, making it difficult to achieve the vehicle acceleration G corresponding to the accelerator opening θacc. Alternatively, measures to reduce the booming noise could be applied to the LU clutch 40, but the lock-up damper and friction plate of the LU clutch 40 would be expensive, resulting in high manufacturing costs. In this embodiment, in the low rotation and high load range of the engine 12, the control described below is executed to ensure acceleration performance when the accelerator pedal is depressed.

Figure 7 is a functional block diagram illustrating the control functions of an electronic control device 300 that controls a hybrid vehicle, which corresponds to yet another embodiment of the present invention. Note that the structure of the hybrid vehicle and the signals input to the electronic control device 300 are omitted because they are the same as those in the first embodiment described above. The control functions of the electronic control device 300, which is the main part of this embodiment, are described below.

The electronic control unit 300 functionally comprises a hybrid control unit 302, a clutch control unit 104, a gear shift control unit 106, a lock-up determination unit 108, and a booming noise area determination unit 310 in order to execute various controls in the vehicle. Note that the clutch control unit 104, the gear shift control unit 106, and the lock-up determination unit 108 are the same as in the previous embodiment, so they are given the same reference numerals and their description is omitted.

The hybrid control unit 302 includes an engine control unit 302a that controls the operation of the engine 12 and an electric motor control unit 302b that controls the operation of each electric motor MG, and executes hybrid drive control by the engine 12 and each electric motor MG through these control functions. The control operation of the engine control unit 302a and the electric motor control unit 302b is basically the same as that of the engine control unit 102a and the electric motor control unit 102b in the first embodiment described above, so a description thereof will be omitted.

The muffled sound area determination unit 310 determines whether the operating area of the engine 12 is in an area where muffled sound is likely to occur when the LU clutch 40 is engaged. The area where muffled sound is likely to occur is determined in advance by experiment or design, and is stored as a relationship map defined by, for example, the engine speed Ne and the accelerator opening θacc. The muffled sound area determination unit 310 determines that the area where muffled sound is likely to occur is in a case where the engine speed Ne is in the rotation speed range defined by the relationship map, and the accelerator opening θacc is in the range defined by the relationship map. Note that the area where muffled sound is likely to occur is generally considered to be an area where the engine speed Ne is low and the load on the engine 12 is high (i.e., the accelerator opening θacc is large).

When the muffled sound area determination unit 310 determines that the operating area of the engine 12 is in an area where muffled sound is likely to occur and the lock-up determination unit 108 determines that the LU clutch 40 is in a disengaged state, the hybrid control unit 302 controls the MG3 torque Tm3 of the engine-connected electric 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 electric motor MG3 to output the torque required to increase the engine rotation speed Ne as an assist torque. By outputting the torque required to increase the engine rotation speed Ne from the engine-connected electric motor MG3, the torque required to increase the rotation 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.

Figure 8 is a flowchart for explaining the control operation of the electronic control unit 300, and is a flowchart for explaining the control function that can generate vehicle acceleration G according to the accelerator opening θacc even in an area where muffled noise is likely to occur. This flowchart is executed repeatedly each time the accelerator pedal is depressed while driving in the HEV driving mode.

First, in S200, which corresponds to the control function of the booming sound area determination unit 310, it is determined whether the operating area of the engine 12 is in the low rotation/high load area where booming sound is likely to occur. If the determination in S200 is negative, normal control is implemented in S230, which corresponds to the control function of the hybrid control unit 302. If the determination in S200 is positive, it is determined in S210, which corresponds to the control function of the lockup determination unit 108, whether the LU clutch 40 is released. If the determination in S210 is negative, normal control is implemented in S230. If the determination in S210 is positive, assistance is performed by the engine-connected electric motor MG3 taking into account the inertia of the engine 12 in S220, which corresponds to the control function of the hybrid control unit 302. Specifically, the torque required to increase the engine rotation speed Ne is output as an assist torque from the engine-connected electric motor MG3.

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 shows time t [sec], and the vertical axis shows, from top to bottom, accelerator opening θacc [%], MG3 torque Tm3 [Nm] of the engine-connected electric motor MG3, engine rotation speed Ne [rpm], and vehicle acceleration G [m/ ^s2 ]. In Fig. 9, the left side of the page shows vehicle behavior based on the conventional control operation, and the right side of the page shows vehicle behavior based on the control operation of this embodiment.

First, the conventional vehicle behavior shown on the left side of the page as a comparison example will be described. At time t1 on the left side of the page in FIG. 9, the accelerator pedal is started to be depressed. Accordingly, from time t1 onwards, the accelerator opening θacc increases linearly over time. Also, from time t1 onwards, the MG3 torque Tm3 of the engine-linked electric motor MG3 increases linearly in response to the increase in the accelerator opening θacc. Furthermore, from time t1 onwards, the engine speed Ne increases in response to the increase in the accelerator opening θacc. At this time, the engine torque Te is used to increase the engine speed Ne, so that the engine torque Te transmitted to the drive wheels 14 decreases. As a result, the vehicle acceleration G shown by the solid line becomes smaller in response to the increase in the accelerator opening θacc than the vehicle acceleration G shown by the dashed line when the engine torque Te does not decrease.

Next, the vehicle behavior based on the control operation of this embodiment shown on the right side of the page will be described. At time t1 on the right side of the page in FIG. 9, the accelerator pedal is started to be depressed. Accordingly, from time t1 onwards, the accelerator opening θacc increases linearly over time. Furthermore, from time t1 onwards, the engine speed Ne increases in response to the increase in the accelerator opening. Here, in this embodiment, from time t1 onwards, the torque required to increase the engine speed Ne is added to the MG3 torque Tm3 of the engine-linked electric motor MG3. As a result, a portion of the engine torque Te is no longer used to increase the engine speed Ne, and 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 dashed line indicates the conventional vehicle behavior.

As described above, according to this embodiment, when the accelerator pedal is depressed in the low-speed, high-load region of the engine 12 where muffled noise is likely to occur, the torque required to increase the engine speed Ne is output as an assist torque from the engine-connected electric motor MG3, thereby generating a vehicle acceleration G according to the accelerator opening θacc.

The above describes an embodiment of the present invention in detail with reference to the drawings, but the present invention can also be applied in other aspects.

For example, although the above-mentioned Examples 1 to 3 were implemented independently, it is not necessary to implement Examples 1 to 3 independently, and Examples 1 to 3 may be implemented in appropriate combination.

In addition, in the above-described embodiment, regenerative control is performed by the engine-connected electric motor MG3 to suppress the engine speed Ne from increasing too much. However, regenerative control may be performed by the first electric motor MG1 instead of the engine-connected electric motor MG3.

In addition, in the above-described embodiment, the engine-connected electric motor MG3 is connected to the engine 12 via the transmission belt 46 so that power can be transmitted, but the present invention is not necessarily limited to this. For example, the engine-connected electric motor MG3 may be provided between the engine 12 and the K0 clutch 20. In short, any electric motor that is connected to the engine 12 so that power can be transmitted can be applied to the present invention. Furthermore, the transmission belt 46 that connects the engine 12 and the engine-connected electric motor MG3 is not necessarily limited to this, and can be changed as appropriate, for example, to a gear or a chain.

In addition, in the above-described embodiment, the second electric motor MG2 is connected to the transmission output shaft 26 so as to be capable of transmitting power, but the present invention is not necessarily limited to the above configuration. For example, a configuration in which an electric motor is connected to each of a pair of drive shafts 32 connected to a pair of drive wheels 14 may also be used. Alternatively, a configuration in which an in-wheel motor housed within the drive wheels 14 is used as the second electric motor may also be used. In short, any electric motor that can apply assist torque to the left and right drive wheels 14 can be applied to the present invention.

In addition, in the above-described embodiment, the automatic transmission 24 is a known planetary gear type automatic transmission equipped with one or more planetary gear devices and multiple 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.

In addition, in the above-described embodiment, a torque converter 22 is used as the fluid-type transmission device, but this is not necessarily limited to this embodiment. For example, instead of the torque converter 22, other fluid-type transmission devices that do not have a torque amplification effect, such as a fluid coupling, may be used as the fluid-type transmission device.

In addition, in each of the above-mentioned embodiments 1 to 3, the order of each step in each flowchart may be changed as appropriate to the extent that no inconsistencies are present.

Note that the above is merely one embodiment, and the present invention can be implemented in various forms with various modifications and improvements based on the knowledge of those skilled in the art.

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

Claims (2)

A control device for a hybrid vehicle including an engine, a first electric motor connected to the engine so as to be capable of transmitting power, 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 transmitting power,
a control device for a hybrid vehicle, characterized in that, when a rotational speed difference between an engine rotational speed of the engine and a 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 is used to regenerate power to suppress an increase in the engine rotational speed, and the second electric motor is used to generate a driving force corresponding to an accelerator operation amount. 2. The control device for a hybrid vehicle according to claim 1, wherein, when an accelerator pedal 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, the first electric motor is powered to increase the engine rotation speed to a predetermined rotation speed or higher.

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