Hybrid vehicle control device

Abstract

To provide a control device of a hybrid vehicle that can determine whether an engagement device is released with good accuracy during travelling of the vehicle in a travelling mode in which the engagement device inserted between an engine and a first electric motor and a first wheel is released and the vehicle travels by driving a second wheel by power of a second electric motor.SOLUTION: In determining whether an engagement device CB is released during travelling of a vehicle 10 in a series-travelling mode in which the vehicle is made to travel by power of a rear electric motor RrMG while releasing the engagement device CB, the determination is made based on a rotation speed difference ΔNi between an AT input rotation speed Ni and an estimated AT input rotation speed Niest and a rotation state of a front electric motor FrMG, which can accurately determine whether the engagement device CB is released from the rotation state of the front electric motor FrMG, even if the AT input rotation speed Ni happens to match the estimated AT input rotation speed Niest.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a control device for a hybrid vehicle equipped with a first wheel configured to be able to transmit power from an engine and a first electric motor, and a second wheel configured to be able to transmit power from a second electric motor. [Background technology]

[0002] There is known a hybrid vehicle that includes a first wheel configured to be able to transmit power from an engine and a first electric motor, a second wheel configured to transmit power from a second electric motor, and an engagement device interposed in a power transmission path between the engine and the first electric motor and the first wheel, and that can execute a driving mode in which the engagement device is disengaged to interrupt the power transmission path between the engine and the first electric motor and the first wheel, and the second wheel is driven by power from the second electric motor to drive the vehicle. For example, the hybrid vehicle described in Patent Document 1 is such a hybrid vehicle. Patent Document 2 describes that, while traveling in a driving mode in which the second wheel is driven by power from the second electric motor, power generation control is performed to rotate the first electric motor using power from the engine, and the generated power is supplied to the second electric motor, thereby executing series traveling. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-98663 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, while traveling in the above-described traveling mode, it is possible that the engagement device may become engaged if, for example, a mechanical failure of the engagement device occurs. In this case, unintended power may be transmitted to the first wheel. In order to detect engagement of such an engagement device, it is necessary to constantly monitor whether the engagement device is in a disengaged state while traveling in the above-described traveling mode. For example, a conceivable method is to determine whether the engagement device is in a disengaged state based on the difference in rotational speed between the rotating members connected and disconnected by the engagement device. However, because the rotating members connected and disconnected by the engagement device rotate independently of each other, the rotational speeds of the rotating members connected and disconnected by the engagement device may match even when the engagement device is in a disengaged state. In this case, it may be erroneously determined that the engagement device is engaged.

[0005] The present invention has been made against the background of the above circumstances, and its object is to provide a control device for a hybrid vehicle that can execute a driving mode in which an engagement device interposed in a power transmission path between an engine and a first electric motor and a first wheel is released, and the second wheel is driven by power from a second electric motor to drive the vehicle, and that can accurately determine whether the engagement device is released while the vehicle is driving in the driving mode. [Means for solving the problem]

[0006] The gist of a first invention is a control device for a hybrid vehicle that includes: (a) a first wheel configured to be able to transmit power from an engine and a first electric motor; a second wheel configured to be able to transmit power from a second electric motor; and an engagement device that is interposed in a power transmission path between the engine and the first electric motor and the first wheel and that connects and disconnects power transmission in the power transmission path, and that is capable of executing a driving mode in which the engagement device is disengaged and the vehicle is driven by power from the second electric motor; and (b) a control unit that, while the vehicle is traveling in the driving mode, determines whether the engagement device is disengaged based on a rotational speed difference between an input rotating member and an output rotating member that are connected and disconnected by the engagement device, and a rotational state of the engine or a rotational state of the first electric motor. (c) the control unit determines that the engagement device is engaged when a state in which the rotational speed difference is equal to or less than a predetermined first predetermined value continues for a predetermined first predetermined time or more, and a state in which a deviation amount between the rotational speed of the engine or the first electric motor and a target rotational speed of the engine or the first electric motor is equal to or greater than a predetermined second predetermined value continues for a predetermined second predetermined time or more. It is characterized by the following.

[0007] The gist of the second invention is that, in the first invention, a transmission is provided in the power transmission path, the engagement device is a gear-shift engagement device provided in the transmission, and the rotational speed difference of the engagement device is estimated based on the rotational speed difference between the rotational speed of an input shaft of the transmission and an estimated rotational speed of the input shaft calculated from the rotational speed of an output shaft of the transmission and the gear ratio of the transmission.

[0008] The gist of the third invention is that in the first or second invention, when traveling in the traveling mode, power generation control is performed by rotating the first electric motor using the power of the engine, and the power generated by the first electric motor is supplied to the second electric motor to travel, thereby performing series traveling. [Effects of the Invention]

[0010] According to the first invention, when determining whether the engagement device is disengaged while traveling in a driving mode in which the vehicle is driven by the power of the second electric motor with the engagement device disengaged, the determination is made based on the rotational speed difference between the input rotating member and the output rotating member that are connected and disconnected by the engagement device, and the rotational state of the engine or the rotational state of the first electric motor.Therefore, even if the rotational speed of the input rotating member and the rotational speed of the output rotating member of the engagement device happen to match even though the engagement device is disengaged, it is possible to accurately determine whether the engagement device is disengaged by determining whether the engagement device is disengaged from the rotational state of the engine or the rotational state of the first electric motor. In addition, the engagement state of the engagement device can be accurately determined based on whether the state in which the rotational speed difference is less than or equal to a first predetermined value continues for more than a first predetermined time, and whether the state in which the deviation between the rotational speed of the engine or first electric motor and the target rotational speed of the engine or first electric motor is greater than or equal to a second predetermined value continues for more than a second predetermined time.

[0011] According to the second aspect of the present invention, the rotational speed difference between engagement devices provided in a transmission is estimated based on the rotational speed difference between the rotational speed of the input shaft of the transmission and the estimated rotational speed of the input shaft calculated from the rotational speed of the output shaft of the transmission and the gear ratio of the transmission. Therefore, the rotational speed difference between the engagement devices can be estimated using sensors that have already been provided, without adding sensors that detect the rotational speeds of the input rotating member and the output rotating member of the engagement devices.

[0012] According to the third aspect of the present invention, when series running is performed, power from the engine is used to rotate the first electric motor to perform power generation control, and the generated electric power is supplied to the second electric motor to run the vehicle. In this case, even though the engagement device is disengaged, the rotational speed of the input rotating member and the rotational speed of the output rotating member of the engagement device may coincidentally match. Even in such a case, whether the engagement device is disengaged can be determined from the rotational state of the engine or the first electric motor, so it is possible to accurately determine whether the engagement device is disengaged. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a diagram illustrating a schematic configuration of a hybrid vehicle to which the present invention is applied, and is also a diagram illustrating main parts of control functions and control systems for various controls in the vehicle. [Figure 2] 2 is a flowchart for explaining the main control operations of the electronic control device of FIG. 1. [Figure 3] 2 is a time chart showing an example of a control result by the electronic control device of FIG. 1. [Figure 4] FIG. 10 is a diagram illustrating a schematic configuration of a hybrid vehicle according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that in the following embodiments, the drawings are appropriately simplified or modified, and the dimensional ratios and shapes of the various parts are not necessarily drawn accurately. [Example]

[0016] Fig. 1 is a diagram illustrating the schematic configuration of a hybrid vehicle 10 (hereinafter referred to as vehicle 10) to which the present invention is applied, and also illustrates the main parts of the control functions and control systems for various controls in vehicle 10. In Fig. 1, vehicle 10 is a four-wheel drive hybrid vehicle equipped with an engine 12 and a front electric motor FrMG as the driving power source for front wheels 14, and a rear electric motor RrMG as the driving power source for rear wheels 16. Vehicle 10 is equipped with a front unit 18 provided in a power transmission path between engine 12 and front wheels 14, and a rear unit 20 for driving rear wheels 16.

[0017] The engine 12 is a known internal combustion engine such as a gasoline engine or a diesel engine. An electronic control device 100 (described later) controls an engine control device 22, which includes a throttle actuator, a fuel injection device, an ignition device, and the like, provided in the vehicle 10, to control the engine torque Te, which is the output torque of the engine 12.

[0018] The front electric motor FrMG and the rear electric motor RrMG are motor generators that function as an engine that generates mechanical power from electric power, and as a generator that generates electric power from mechanical power.

[0019] The front electric motor FrMG is connected to an HEV battery 28 via a front inverter 24 (FrPCU) and a system main relay 26 (SMR). The front inverter 24 is controlled by an electronic control unit 100 (described later), thereby controlling an FrMG torque TmFr, which is the output torque of the front electric motor FrMG. For example, when the rotation direction of the front electric motor FrMG is forward, which is the same as the rotation direction when the engine 12 is operating, the FrMG torque TmFr is a powering torque on the acceleration side, and a regenerative torque on the deceleration side, which is negative.

[0020] The front electric motor FrMG generates driving power using electric power supplied from the HEV battery 28 via the front inverter 24 and the system main relay 26, instead of or in addition to the engine 12. The front electric motor FrMG also generates electric power using the power of the engine 12 and the driven force input from the front wheels 14. The electric power generated by the front electric motor FrMG is stored in the HEV battery 28 via the front inverter 24 and the system main relay 26. Alternatively, the electric power generated by the front electric motor FrMG is supplied to the rear electric motor RrMG to drive the rear electric motor RrMG. Unless otherwise specified, the term "electric power" also refers to electrical energy. Unless otherwise specified, the term "power" also refers to torque and force.

[0021] The rear electric motor RrMG is connected to an HEV battery 28 via a rear inverter 30 (RrPCU) and a system main relay 26 (SMR). The rear inverter 30 is controlled by an electronic control unit 100 (described later), thereby controlling the RrMG torque TmRr, which is the output torque of the rear electric motor RrMG. For example, when the rotation direction of the rear electric motor RrMG is forward, which is the same as the rotation direction during forward driving, the RrMG torque TmRr is a powering torque on the acceleration side as a positive torque and a regenerative torque on the deceleration side as a negative torque.

[0022] The rear electric motor RrMG generates power for traveling using electric power supplied from the HEV battery 28 via the rear inverter 30 and the system main relay 26, or electric power generated by the front electric motor FrMG. The rear electric motor RrMG also generates electric power using the driven force input from the rear wheels 16. The electric power generated by the rear electric motor RrMG is stored in the HEV battery 28 via the rear inverter 30 and the system main relay 26. The HEV battery 28 is an electric storage device that supplies and receives electric power to the front electric motor FrMG and the rear electric motor RrMG.

[0023] The front unit 18 is configured to be able to transmit power from the engine 12 and the front electric motor FrMG to the front wheels 14. The front unit 18 includes the engine 12, a K0 clutch 34 (K0), an input clutch 36 (WSC), an automatic transmission 38, and the like. The K0 clutch 34 (K0), the input clutch 36 (WSC), and the automatic transmission 38 are each housed in a case 32, which is a non-rotating member attached to the vehicle body. The K0 clutch 34 is a clutch provided between the engine 12 and the front electric motor FrMG in the power transmission path between the engine 12 and the front wheels 14. The input clutch 36 is a clutch provided between the K0 clutch 34 and the automatic transmission 38 in the power transmission path between the engine 12 and the front electric motor FrMG and the front wheels 14. The front wheels 14 correspond to the first wheel of the present invention, and the front electric motor FrMG corresponds to the first electric motor of the present invention.

[0024] The automatic transmission 38 is provided in a power transmission path between the engine 12 and the front electric motor FrMG and the front wheels 14. The front unit 18 also includes a differential device 42 (DIFF) connected to a transmission output shaft 40 of the automatic transmission 38, and a pair of left and right front axles 44 connected to the front wheels 14. The front unit 18 also includes an engine connecting shaft 46 that connects the engine 12 and the K0 clutch 34, and an electric motor connecting shaft 48 that connects the K0 clutch 34 and the input clutch 36. The automatic transmission 38 corresponds to the transmission of the present invention.

[0025] The front electric motor FrMG is connected to an electric motor connecting shaft 48 in the case 32 so as to be able to transmit power. The front electric motor FrMG is connected to a power transmission path between the engine 12 and the front wheels 14, particularly to a power transmission path between the K0 clutch 34 and the input clutch 36. Therefore, the front electric motor FrMG is connected to the input clutch 36 and the automatic transmission 38 so as to be able to transmit power, without passing through the K0 clutch 34.

[0026] The automatic transmission 38 is a known planetary gear automatic transmission equipped with, for example, one or more planetary gear sets (not shown) and multiple engagement devices CB. The engagement devices CB are hydraulic friction engagement devices, such as multi-plate or single-plate clutches or brakes pressed by a hydraulic actuator, or band brakes tightened by a hydraulic actuator. Each engagement device CB switches between an engaged state, a disengaged state, or other control state by varying its torque capacity (CB torque Tcb) using the regulated CB oil pressure PRcb supplied from the hydraulic control circuit 52. Since the automatic transmission 38 switches its power transmission state depending on the engagement state of the engagement devices CB, the engagement devices CB are inserted in the power transmission path between the engine 12 and the front electric motor FrMG and the front wheels 14, and function to connect and disconnect power transmission in the power transmission path. The engagement devices CB correspond to the shift engagement devices provided in the transmission of the present invention.

[0027] The automatic transmission 38 is a stepped transmission in which one of a plurality of gear stages (also referred to as "gear stages") with different speed ratios (also referred to as "gear ratio") γat (=AT input rotation speed Ni / AT output rotation speed No) is established by engaging any of the engagement devices CB. The automatic transmission 38 selectively establishes a plurality of gear stages by switching the established gear stages according to the accelerator operation of the driver (=operator) and the vehicle speed V, etc., using an electronic control device 100 (described later). The AT input rotation speed Ni is the rotation speed of a transmission input shaft 50 of the automatic transmission 38, and is the input rotation speed of the automatic transmission 38. The AT output rotation speed No is the rotation speed of a transmission output shaft 40 of the automatic transmission 38, and is the output rotation speed of the automatic transmission 38. The transmission input shaft 50 corresponds to the input shaft of the transmission in the present invention, and the AT input rotation speed Ni corresponds to the rotation speed of the input shaft in the present invention. Further, the transmission output shaft 40 corresponds to the output shaft of the transmission of the present invention, and the AT output rotation speed No corresponds to the rotation speed of the output shaft of the present invention.

[0028] The K0 clutch 34 is a wet or dry friction engagement device, for example, configured with a multi-plate or single-plate clutch. The control state of the K0 clutch 34, such as an engaged state or a disengaged state, is switched by an electronic control device 100, which will be described later. The control state of the K0 clutch 34 is switched by changing the K0 torque Tk0, which is the torque capacity of the K0 clutch 34, using the K0 oil pressure PRk0 supplied from the hydraulic control circuit 52.

[0029] The input clutch 36 is a wet or dry friction engagement device, for example, configured with a multi-plate or single-plate clutch. The control state of the input clutch 36, such as an engaged state or a released state, is switched by an electronic control device 100, which will be described later. The control state of the input clutch 36 is switched by changing the WSC torque Twsc, which is the torque capacity of the input clutch 36, using the WSC oil pressure PRwsc supplied from the hydraulic control circuit 52.

[0030] When the K0 clutch 34 is in an engaged state, the engine 12 and the front electric motor FrMG are connected to each other so that power can be transmitted via the engine connecting shaft 46 and the electric motor connecting shaft 48. That is, when the K0 clutch 34 is engaged, it connects the engine 12 and the front electric motor FrMG to each other so that power can be transmitted. On the other hand, when the K0 clutch 34 is in a disengaged state, it cuts off the transmission of power between the engine 12 and the front electric motor FrMG. That is, when the K0 clutch 34 is released, it cuts off the connection between the engine 12 and the front electric motor FrMG. In other words, the K0 clutch 34 is a connect / disconnect clutch that connects the engine 12 and the front electric motor FrMG to each other when engaged, and disconnects the engine 12 and the front electric motor FrMG to each other when released.

[0031] When the input clutch 36 is engaged, the electric motor connecting shaft 48 and the transmission input shaft 50 are connected to each other. At this time, the front electric motor FrMG is connected to the front wheels 14 via the electric motor connecting shaft 48, input clutch 36, transmission input shaft 50, transmission output shaft 40, differential 42, and front axle 44 so as to be able to transmit power. Furthermore, when the K0 clutch 34 and the input clutch 36 are engaged, in addition to the front electric motor FrMG, the engine 12 is connected to the front wheels 14 via the electric motor connecting shaft 48, input clutch 36, transmission input shaft 50, transmission output shaft 40, differential 42, and front axle 44 so as to be able to transmit power. On the other hand, when the input clutch 36 is disengaged, the electric motor connecting shaft 48 and the transmission input shaft 50 are disconnected from each other. In other words, the input clutch 36 is an engaging / disengaging clutch that connects the engine 12 and the front electric motor FrMG to the front wheels 14 when engaged, and disconnects the engine 12 and the front electric motor FrMG from the front wheels 14 when released.

[0032] In the front unit 18, when the K0 clutch 34 and the input clutch 36 are engaged, the power output from the engine 12 is transmitted to the front wheels 14 via the engine connecting shaft 46, the electric motor connecting shaft 48, the transmission input shaft 50, the automatic transmission 38, the transmission output shaft 40, the differential 42, and the front axle 44 in that order. Also, when the input clutch 36 is engaged, the power output from the front electric motor FrMG is transmitted to the front wheels 14 via the electric motor connecting shaft 48, the transmission input shaft 50, the automatic transmission 38, the transmission output shaft 40, the differential 42, and the front axle 44 in that order.

[0033] On the other hand, when the input clutch 36 is disengaged, the power transmission path between the engine 12 and front electric motor FrMG and the front wheels 14 is interrupted, and the power of the engine 12 and front electric motor FrMG is not transmitted to the front wheels 14. Furthermore, when the K0 clutch 34 is disengaged but the input clutch 36 is engaged, the power of the front electric motor FrMG is transmitted to the front wheels 14 via the automatic transmission 38 or the like, but the power of the engine 12 is not transmitted to the front wheels 14. Furthermore, when the K0 clutch 34 is engaged but the input clutch 36 is disengaged, the power of the engine 12 and front electric motor FrMG is not transmitted to the front wheels 14, but the engine 12 and the front electric motor FrMG are connected to each other so that power can be transmitted. At this time, the front electric motor FrMG can generate power using the power of the engine 12.

[0034] The rear unit 20 is configured to be able to transmit power from the rear electric motor RrMG to the rear wheels 16. The rear unit 20 includes a rear inverter 30 controlled by an electronic control device 100 (described later), the rear electric motor RrMG, and a pair of left and right rear axles 54 connected to the left and right rear wheels 16. The rear electric motor RrMG is connected to the pair of left and right rear axles 54 directly or via a speed reducer (not shown). Therefore, the rear electric motor RrMG is connected to the rear wheels 16 via the rear axles 54 etc. so that power can be transmitted to them, and power output from the rear electric motor RrMG is transmitted to the rear wheels 16 via the rear axles 54 etc. The rear wheels 16 correspond to the second wheel of the present invention, and the rear electric motor RrMG corresponds to the second electric motor of the present invention.

[0035] The vehicle 10 is equipped with a mechanical oil pump 58 (MOP) and an electric oil pump 60 (EOP). The mechanical oil pump 58 is connected to the electric motor connecting shaft 48 via gears, a belt, a chain, or the like so as to be capable of transmitting power, and is driven by at least one of the engine 12 and the front electric motor FrMG to discharge hydraulic oil used in the front unit 18. The electric oil pump 60 is rotationally driven by a pump motor (not shown) 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 52. The hydraulic control circuit 52 supplies the CB hydraulic pressure PRcb, the K0 hydraulic pressure PRk0, the WSC hydraulic pressure PRwsc, and the like, which are adjusted based on the hydraulic oil discharged by the mechanical oil pump 58 and the electric oil pump 60, respectively.

[0036] The vehicle 10 further includes an electronic control unit 100 (control unit) including a control unit of the vehicle 10 related to driving control, etc. The electronic control unit 100 includes a so-called microcomputer equipped with, for example, a CPU, RAM, ROM, an input / output interface, etc. The CPU executes various controls of the vehicle 10 by performing signal processing in accordance with programs stored in the ROM in advance while utilizing the temporary storage function of the RAM. The electronic control unit 100 includes ECUs for engine control, electric motor control, hydraulic control, etc. as necessary.

[0037] The electronic control device 100 receives various signals (e.g., engine rotation speed Ne, which is the rotation speed of the engine 12; AT input rotation speed Ni, which is the rotation speed of the transmission input shaft 50 of the automatic transmission 38; AT output rotation speed No, which is the rotation speed of the transmission output shaft 40 of the automatic transmission 38 and corresponds to the vehicle speed V; The following are supplied to the control circuit 53: an FrMG rotation speed NmFr which is the rotation speed of the front electric motor FrMG; an RrMG rotation speed NmRr which is the rotation speed of the rear electric motor RrMG; an accelerator opening θacc which is the amount of accelerator operation by the driver which indicates the magnitude of the driver's acceleration operation; a throttle valve opening θth which is the opening of the electronic throttle valve; a 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; a battery temperature THbat, a battery charge / discharge current Ibat, and a battery voltage Vbat of the HEV battery 28; and a hydraulic oil temperature THoil which is the temperature of the hydraulic oil in the hydraulic control circuit 52.

[0038] The electronic control unit 100 outputs various command signals (e.g., an engine control command signal Se for controlling the engine 12, an FrMG control command signal SmFr for controlling the front electric motor FrMG, an RrMG control command signal SmRr for controlling the rear electric motor RrMG, a CB hydraulic control command signal Scb for controlling the engagement device CB, a K0 hydraulic control command signal Sk0 for controlling the K0 clutch 34, a WSC hydraulic control command signal Swsc for controlling the input clutch 36, and a relay switching command signal Ssmr for switching the connection / disconnection state of the system main relay 26) to various devices (e.g., an engine control unit 22, a front inverter 24, a rear inverter 30, a hydraulic control circuit 52, a system main relay 26, etc.) provided in the vehicle 10. For example, when a power switch of the vehicle 10 is switched to an on state, the system main relay 26 is switched to a connection state by the relay switching command signal Ssmr, enabling power supply from the HEV battery 28.

[0039] The electronic control unit 100 includes a hybrid control unit 102 that functions as hybrid control means, a clutch control unit 104 that functions as clutch control means, a gear change control unit 106 that functions as gear change control means, and a clutch release determination unit 108 that functions as clutch disengagement determination means, in order to realize various driving controls in the vehicle 10. The clutch release determination unit 108 corresponds to the control unit of the present invention.

[0040] The hybrid control unit 102 functionally includes an engine control unit 102a that functions as engine control means for controlling the operation of the engine 12, an Fr electric motor control unit 102b that functions as Fr electric motor control means for controlling the operation of the front electric motor FrMG via the front inverter 24, and an Rr electric motor control unit 102c that functions as Rr electric motor control means for controlling the operation of the rear electric motor RrMG via the rear inverter 30, and these control functions are used to perform hybrid drive control using the engine 12, the front electric motor FrMG, and the rear electric motor RrMG.

[0041] The hybrid control unit 102 calculates the amount of driving demanded by the driver for the vehicle 10, for example, by applying the accelerator opening θacc and the vehicle speed V to a driving demand map. The driving demand map is a relationship that is experimentally or design-based and stored in advance, i.e., a predetermined relationship. The driving demand is, for example, the required driving torque Trdem at the front wheels 14 and the rear wheels 16. The required driving torque Trdem [Nm] can be viewed as the required driving power Prdem [W] at the current vehicle speed V. The driving demand may also be the required driving force Frdem [N], the required AT output torque at the transmission output shaft 40 of the automatic transmission 38, or the like. In calculating the driving demand, the AT output rotation speed No, or the like, may be used instead of the vehicle speed V.

[0042] The hybrid control unit 102 outputs an engine control command signal Se for controlling the engine 12, an FrMG control command signal SmFr for controlling the front electric motor FrMG, and an RrMG control command signal SmRr for controlling the rear electric motor RrMG so as to realize the required driving power Prdem, taking into consideration factors such as transmission loss, auxiliary load, the gear ratio γat of the automatic transmission 38, and the chargeable power Win and dischargeable power Wout of the HEV battery 28. The engine control command signal Se is, for example, a command value for engine power Pe, which is the power of the engine 12 that outputs engine torque Te at a current engine rotation speed Ne. The FrMG control command signal SmFr is, for example, a command value for power consumption WmFr of the front electric motor FrMG that outputs FrMG torque TmFr at a current FrMG rotation speed NmFr. The RrMG control command signal SmRr is, for example, a command value for power consumption WmRr of the rear electric motor RrMG that outputs an RrMG torque TmRr at an RrMG rotation speed NmRr at that time.

[0043] The chargeable power Win of the HEV battery 28 is the maximum power that can be input, which defines the limit on the input power of the HEV battery 28, and indicates the input limit of the HEV battery 28. The dischargeable power Wout of the HEV battery 28 is the maximum power that can be output, which defines the limit on the output power of the HEV battery 28, and indicates the output limit of the HEV battery 28. The chargeable power Win and dischargeable power Wout of the HEV battery 28 are calculated by the electronic control unit 100 based on, for example, the battery temperature THbat and the state-of-charge value SOC [%] of the HEV battery 28. The state-of-charge value SOC of the HEV battery 28 is a value that indicates the state of charge of the HEV battery 28, and is calculated by the electronic control unit 100 based on, for example, the battery charge / discharge current Ibat and the battery voltage Vbat.

[0044] When the required drive torque Trdem can be satisfied by the output of at least one of the front electric motor FrMG and the rear electric motor RrMG, the hybrid control unit 102 sets the drive mode to the motor drive (=BEV drive) mode. In the BEV drive mode, the hybrid control unit 102 performs BEV (Battery Electric Vehicle) drive, in which the vehicle runs using at least one of the front electric motor FrMG and the rear electric motor RrMG as a drive power source, with the K0 clutch 34 in a released state and the input clutch 36 in an engaged state.

[0045] On the other hand, when the required drive torque Trdem cannot be satisfied without using at least the output of the engine 12, the hybrid control unit 102 sets the drive mode to engine drive mode, i.e., hybrid drive (=HEV drive) mode. In the HEV drive mode, the hybrid control unit 102 performs engine drive, i.e., HEV (Hybrid Electric Vehicle) drive, using at least the engine 12 as a drive power source, with the K0 clutch 34 and the input clutch 36 engaged. Even when the required drive torque Trdem can be satisfied with the output of at least one of the front electric motor FrMG and the rear electric motor RrMG, the hybrid control unit 102 establishes the HEV drive mode when the state of charge value SOC of the HEV battery 28 falls below a predetermined engine start threshold or when the engine 12 needs to be warmed up. The engine start threshold is a predetermined threshold for determining that the state of charge value SOC is at a value at which the engine 12 needs to be forcibly started and the HEV battery 28 needs to be charged. In this way, the hybrid control unit 102 switches between the BEV driving mode and the HEV driving mode by automatically stopping the engine 12 during HEV driving, restarting the engine 12 after the engine has stopped, or starting the engine 12 during BEV driving, based on the required driving torque Trdem, the required driving power Prdem, etc.

[0046] Furthermore, the hybrid control unit 102 distributes driving force between the front wheels 14 and the rear wheels 16 according to the driving conditions of the vehicle 10, and controls the distribution so as to obtain appropriate driving performance. For example, when the vehicle starts, accelerates, or is driving on a slippery, low-μ road, the hybrid control unit 102 drives the rear wheels 16 in addition to the front wheels 14 to drive the vehicle 10, thereby performing four-wheel drive driving. At this time, the hybrid control unit 102 calculates an appropriate driving force distribution ratio between the front and rear wheels based on the driving conditions of the vehicle 10, and controls the outputs of the engine 12, the front electric motor FrMG, and the rear electric motor RrMG so that the driving force distribution between the front and rear wheels matches the calculated driving force distribution ratio. For example, when driving in HEV driving mode, the power of the engine 12 is transmitted to the front wheels 14 as driving force, and a portion of the power of the engine 12 is transmitted to the front electric motor FrMG, thereby enabling the front electric motor FrMG to generate electricity. Furthermore, the generated electric power WgFr generated by the front electric motor FrMG is supplied to the rear electric motor RrMG, thereby driving the rear electric motor RrMG and causing the vehicle 10 to travel.

[0047] Furthermore, in low vehicle speeds and low loads, the hybrid control unit 102 performs power generation control by using the power of the engine 12 to rotate the front electric motor FrMG while the K0 clutch 34 is engaged and power transmission in the automatic transmission 38 is interrupted (i.e., the engagement device CB is disengaged), and the front electric motor FrMG is supplied with generated power WgFr to drive the rear electric motor RrMG, thereby performing series running. In this case, because power transmission in the automatic transmission 38 is interrupted, power from the engine 12 and the front electric motor FrMG is not transmitted to the front wheels 14. The above-described running mode, in which the power of the engine 12 is exclusively used to generate power for the front electric motor FrMG and the generated power WgFr is supplied to the rear electric motor RrMG to run the vehicle 10 using the power of the rear electric motor RrMG, is referred to as series running mode. The series running mode is also executed, for example, during evacuation running when an abnormality is detected in the vehicle 10.

[0048] During series running, hybrid control unit 102 determines a required generation power WgFr* from the state of charge value SOC of HEV battery 28, etc., and determines a target engine rotation speed Ne* and target engine torque Te* of engine 12, and a target FrMG rotation speed NmFr* and target FrMG torque TmFr* (regenerative torque) of front electric motor FrMG based on the determined required generation power WgFr*. Hybrid control unit 102 controls the output of engine 12 so that engine 12 operates at the determined target engine rotation speed Ne* and target engine torque Te*, and also controls the output of front electric motor FrMG so that front electric motor FrMG operates at the determined target FrMG rotation speed NmFr* and target FrMG torque TmFr*. For example, the Fr electric motor control unit 102b executes feedback control (F / B control) using the difference (=NmFr*-NmFr) between the target FrMG rotation speed NmFr* of the front electric motor FrMG and the actual FrMG rotation speed NmFr as the deviation. By executing the F / B control, the FrMG rotation speed NmFr of the front electric motor FrMG follows the target FrMG rotation speed NmFr*. Note that the FrMG rotation speed NmFr corresponds to the rotation speed of the first electric motor of the present invention, and the target FrMG rotation speed NmFr* corresponds to the target rotation speed of the first electric motor of the present invention.

[0049] During at least HEV driving using the engine 12 as a driving force source, the clutch control unit 104 engages the K0 clutch 34 and the input clutch 36 to switch to a state in which power from the engine 12 can be transmitted to the front wheels 14. During motor driving, the clutch control unit 104 disengages the K0 clutch 34 and engages the input clutch 36 to switch to a state in which driving is possible using the front electric motor FrMG and the rear electric motor RrMG. During deceleration driving, the clutch control unit 104 engages the input clutch 36 to switch to a state in which power can be transmitted between the front electric motor FrMG and the front wheels 14 so that regeneration by the front electric motor FrMG is possible. During series driving mode, the clutch control unit 104 engages the K0 clutch 34 and the input clutch 36. In this embodiment, during driving in the series driving mode, the automatic transmission 38 is controlled to a neutral state, thereby interrupting the power transmission path between the engine 12 and the front electric motor FrMG and the front wheels 14.

[0050] The shift control unit 106 determines whether to shift the automatic transmission 38 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 52 as needed to execute shift control of the automatic transmission 38. The shift map is a predetermined relationship having shift lines for determining whether to shift the automatic transmission 38 on a two-dimensional coordinate system using, for example, vehicle speed V and required drive torque Trdem as variables. In the shift map, the AT output rotation speed No or the like may be used instead of the vehicle speed V, and the required drive force Frdem, accelerator opening θacc, throttle valve opening θth or the like may be used instead of the required drive torque Trdem.

[0051] When a predetermined abnormality is detected while the vehicle 10 is traveling, the vehicle switches to series traveling as an evacuation mode. At this time, the automatic transmission 38 is switched to a neutral state by disengaging the engagement device CB of the automatic transmission 38. However, if a solenoid valve that controls the engagement state of the engagement device CB becomes stuck, the engagement device CB cannot be controlled to be disengaged. In this case, there is a risk that part of the engine torque Te of the engine 12, which outputs power for generating electricity during series traveling, will be transmitted to the front wheels 14 via the automatic transmission 38.

[0052] In order to avoid the driving state described above, when series driving begins, the clutch release determination unit 108 constantly determines whether the automatic transmission 38 is in a neutral state (power transmission cut-off state), in other words, whether the engagement device CB provided in the automatic transmission 38 is released.

[0053] When series running begins, the clutch release determination unit 108 calculates the rotational speed difference ΔNi (=|Ni-Niest|) between the AT input rotational speed Ni of the automatic transmission 38 and an estimate of the AT input rotational speed Ni (hereinafter referred to as the estimated AT input rotational speed Niest) calculated based on the AT output rotational speed No of the automatic transmission 38 and the gear ratio γat of the automatic transmission 38, and determines whether the rotational speed difference ΔNi is equal to or less than a first predetermined value α1. The first predetermined value α1 is determined experimentally or by design, and is set to a threshold value at which it can be determined that the AT input rotational speed Ni matches or approximately matches the estimated AT input rotational speed Niest. The estimated AT input rotational speed Niest corresponds to the estimated rotational speed of the input shaft in this invention.

[0054] Here, the gear ratio γat of the automatic transmission 38 changes depending on the gear position of the automatic transmission 38, and there is a possibility that the automatic transmission 38 will be shifted to any gear position depending on the engagement state of the engagement device CB. Therefore, the estimated AT input rotation speed Niest is calculated for each gear ratio γat of each gear position, and for each of the calculated estimated AT input rotation speeds Niest, it is determined whether the rotation speed difference ΔNi between the AT input rotation speed Ni and the estimated AT input rotation speed Ni is equal to or smaller than a first predetermined value α1.

[0055] When the rotational speed difference ΔNi between the AT input rotational speed Ni and the estimated AT input rotational speed Niest is equal to or less than the first predetermined value α1, one of the gears is established in the automatic transmission 38, and therefore the rotational speed difference ΔNcb between the input rotating member 90 and the output rotating member 92, which are connected and disconnected by one of the engagement devices CB of the automatic transmission 38, becomes a very small value that allows it to be determined that the engagement device CB is engaged. Therefore, the rotational speed difference ΔNcb between the input rotating member 90 and the output rotating member 92, which are connected and disconnected by the engagement device CB, is estimated based on the rotational speed difference ΔNi between the AT input rotational speed Ni and the estimated AT input rotational speed Niest.

[0056] When the clutch release determination unit 108 determines that the rotational speed difference ΔNi has become equal to or less than the first predetermined value α1, it begins measuring the elapsed time t from the time of the determination and determines whether the rotational speed difference ΔNi has remained equal to or less than the first predetermined value α1 for a first predetermined time β1 or longer. The first predetermined time β1 is determined in advance experimentally or by design and is set to a value that excludes cases where the AT input rotational speed Ni temporarily matches the estimated AT input rotational speed Niest. Therefore, if the state in which the rotational speed difference ΔNi is equal to or less than the first predetermined value α1 does not reach the first predetermined time β1, it is determined that the match between the AT input rotational speed Ni and the estimated AT input rotational speed Niest is temporary and within the margin of error. The clutch release determination unit 108 determines that the engagement device CB of the automatic transmission 38 is disengaged if the rotational speed difference ΔNi has not become equal to or less than the first predetermined value α1 and if the state in which the rotational speed difference ΔNi is equal to or less than the first predetermined value α1 does not reach the first predetermined time β1.

[0057] On the other hand, if the state in which the rotational speed difference ΔNi is equal to or less than the first predetermined value α1 continues for at least the first predetermined time β1, the clutch release determination unit 108 determines that the AT input rotation speed Ni matches or approximately matches the estimated AT input rotation speed Niest. Here, if the AT input rotation speed Ni matches or approximately matches the estimated AT input rotation speed Niest, it is presumed that the engagement device CB of the automatic transmission 38 is engaged. However, in the vehicle 10, because the front wheels 14 and the rear wheels 16 are driven independently, it is possible that the AT input rotation speed Ni coincidentally matches or approximately matches the estimated AT input rotation speed Niest even when the engagement device CB is not engaged.

[0058] Therefore, when it is determined that the AT input rotation speed Ni matches or approximately matches the estimated AT input rotation speed Niest during series running, the clutch release determination unit 108 further determines whether the engagement device CB is disengaged based on the rotation state of the front electric motor FrMG. When it is determined that the AT input rotation speed Ni matches or approximately matches the estimated AT input rotation speed Niest, the clutch release determination unit 108 determines whether the FrMG rotation speed NmFr of the front electric motor FrMG deviates from the target FrMG rotation speed NmFr*. Note that the target FrMG rotation speed NmFr* of the front electric motor FrMG is a value that is calculated as needed based on the required power generation WgFr* by the front electric motor FrMG, etc.

[0059] In determining whether the FrMG rotation speed NmFr of the front electric motor FrMG deviates from the target FrMG rotation speed NmFr*, first, the clutch release determination unit 108 calculates the amount of deviation ΔNmFr (=|NmFr-NmFr*|) between the FrMG rotation speed NmFr of the front electric motor FrMG and the target FrMG rotation speed NmFr*, and determines whether the calculated amount of deviation ΔNmFr is equal to or greater than a second predetermined value α2. The second predetermined value α2 is determined in advance experimentally or by design, and is set to a value at which it can be determined that the FrMG rotation speed NmFr has deviated from the target FrMG rotation speed NmFr*.

[0060] When it is determined that the deviation ΔNmFr is equal to or greater than the second predetermined value α2, the clutch release determination unit 108 begins measuring the elapsed time t from the time point at which the determination was made, and determines whether the deviation ΔNmFr remains equal to or greater than the second predetermined value α2 for a second predetermined time β2 or longer. The second predetermined time β2 is determined in advance experimentally or by design, and is set to a value that eliminates cases in which the FrMG rotation speed NmFr temporarily deviates from the target FrMG rotation speed NmFr*. Therefore, if the state in which the deviation ΔNmFr is equal to or greater than the second predetermined value α2 does not last for the second predetermined time β2, the deviation of the FrMG rotation speed NmFr from the target FrMG rotation speed NmFr* is determined to be temporary and within the range of error. If the deviation amount ΔNmFr does not become equal to or greater than the second predetermined value α2, and if the state in which the deviation amount ΔNmFr is equal to or greater than the second predetermined value α2 does not reach the second predetermined time β2, the clutch release determination unit 108 determines that the FrMG rotation speed NmFr does not deviate from the target FrMG rotation speed NmFr*.If the FrMG rotation speed NmFr does not deviate from the target FrMG rotation speed NmFr*, it is determined that the fact that the AT input rotation speed Ni matches or approximately matches the estimated AT input rotation speed Niest is a coincidence, and that the engagement device CB is disengaged.

[0061] On the other hand, the clutch release determination unit 108 determines that the engagement device CB is engaged when the rotational speed difference ΔNi remains equal to or smaller than the first predetermined value α1 for at least the first predetermined time β1 and the deviation ΔNmFr between the FrMG rotation speed NmFr and the target FrMG rotation speed NmFr* remains equal to or larger than the second predetermined value α2 for at least the second predetermined time β2. During series traveling, the F / B control described above is executed, causing the FrMG rotation speed NmFr of the front electric motor FrMG to follow the target FrMG rotation speed NmFr*. However, if the engagement device CB of the automatic transmission 38 is engaged at this time, the power of the engine 12 is transmitted to the front wheels 14 via the automatic transmission 38. At this time, the FrMG rotation speed NmFr becomes less responsive, and the FrMG rotation speed NmFr deviates from the target FrMG rotation speed NmFr*. Therefore, when it is determined that the FrMG rotation speed NmFr deviates from the target FrMG rotation speed NmFr*, it is determined that the engagement device CB is engaged.

[0062] When the clutch release determination unit 108 determines that the engagement device CB is engaged, the hybrid control unit 102 stops series running and performs rear motor running using the rear electric motor RrMG. In rear motor running, the engine 12 is stopped and power generation by the front electric motor FrMG is stopped. In other words, the power output from the front unit 18 is set to zero, and running is performed using the rear electric motor RrMG using power from the HEV battery 28. In this way, when the engagement device CB is engaged in the automatic transmission 38, switching from series running to rear motor running using power from the HEV battery 28 ensures safe running.

[0063] 2 is a flowchart for explaining the main control operations of the electronic control unit 100, and is a flowchart for explaining the control operations for determining whether the engagement device CB of the automatic transmission 38 is in a disengaged state during series running. This flowchart is repeatedly executed during series running.

[0064] First, in step S10 (hereinafter, the term "step" will be omitted) corresponding to the control function of the clutch release determination unit 108, control is started to monitor whether the engagement device CB of the automatic transmission 38 is in a disengaged state when the mode is switched to series running. Next, in step S20 corresponding to the control function of the clutch release determination unit 108, it is determined whether any gear has been established in the automatic transmission 38. Specifically, it is determined whether a state in which the AT input rotation speed Ni matches or approximately matches the estimated AT input rotation speed Niest (=No×γat), i.e., a state in which the rotation speed difference ΔNi between the AT input rotation speed Ni and the estimated AT input rotation speed Niest is equal to or less than a first predetermined value α1, has continued for a first predetermined time β1 or more. If the determination in S20 is negative, the process returns to S20, and it is again determined whether any gear has been established in the automatic transmission 38. If the determination in S20 is affirmative, then in S30, which corresponds to the control function of the clutch release determination unit 108, it is determined whether or not a state in which the FrMG rotation speed NmFr of the front electric motor FrMG deviates from the target FrMG rotation speed NmFr*, i.e., a state in which the deviation amount ΔNmFr between the FrMG rotation speed NmFr and the target FrMG rotation speed NmFr* is equal to or greater than a second predetermined value α2, has continued for a second predetermined time β2 or longer. If the determination in S30 is negative, then the process returns to S20, where it is repeatedly determined whether or not a gear has been established in the automatic transmission 38. If the determination in S30 is affirmative, then it is determined that a gear has been established in the automatic transmission 38, i.e., that the engagement device CB of the automatic transmission 38 is engaged. At this time, in S40, which corresponds to the control function of the hybrid control unit 102, series running is interrupted, and the system is switched to rear motor running by the rear electric motor RrMG using electric power from the HEV battery 28. In this way, during series driving, whether or not the engagement device CB is disengaged is determined based on the rotational speed difference ΔNi between the AT input rotational speed Ni and the estimated AT input rotational speed Niest, and the deviation ΔNmFr between the FrMG rotational speed NmFr and the target FrMG rotational speed NmFr*, thereby accurately determining whether or not the engagement device CB is disengaged.

[0065] Fig. 3 is a time chart showing one example of the control results by the electronic control unit 100. Specifically, the time chart shown in Fig. 3 shows the example when the engagement device CB of the automatic transmission 38 is engaged during series running. In this embodiment, since the input clutch 36 is engaged during series running, the AT input rotation speed Ni and the FrMG rotation speed NmFr shown in Fig. 3 become the same rotation speed.

[0066] In the time chart of FIG. 3, series running has been performed since before time t1. Also, as shown in FIG. 3, the AT input rotation speed Ni continues to match the estimated AT input rotation speed Niest from before time t1, and the elapsed time t until the AT input rotation speed Ni matches the estimated AT input rotation speed Niest is measured. In connection with this, the XXth gear establishment counter, which indicates an increase in the elapsed time t, is incremented. When, at time t1, the elapsed time t until the AT input rotation speed Ni matches the estimated AT input rotation speed Niest reaches a first predetermined time β1, it is determined that a predetermined gear has been established in the automatic transmission 38, and the gear establishment determination shown in FIG. 3 is switched from OFF to ON. Next, a determination is started as to whether the FrMG rotation speed NmFr of the front electric motor FrMG has deviated from the target FrMG rotation speed NmFr*. In FIG. 3, the FrMG rotation speed NmFr deviates from the target FrMG rotation speed NmFr* at time t2. At this time, measurement of elapsed time t is started based on time t2. In connection with this, the MG rotation deviation counter, which indicates the increase in elapsed time t, is incremented. At time t3, when the elapsed time t from time t2 reaches the second predetermined time β2, it is determined that the FrMG rotation speed NmFr has deviated from the target FrMG rotation speed NmFr*. At this time, series traveling is interrupted, and the evacuation traveling pattern is switched from series traveling to rear motor traveling. In this way, even when the AT input rotation speed Ni matches the estimated AT input rotation speed Niest, it is further determined whether the FrMG rotation speed NmFr of the front electric motor FrMG has deviated from the target FrMG rotation speed NmFr*, making it possible to accurately determine whether the engagement device CB has been disengaged.

[0067] As described above, according to this embodiment, when driving in a series driving mode in which the vehicle 10 is driven by the power of the rear electric motor RrMG with the engagement device CB disengaged, whether the engagement device CB is disengaged is determined based on the rotational speed difference ΔNi between the AT input rotational speed Ni and the estimated AT input rotational speed Niest and the rotational state of the front electric motor FrMG.Therefore, even if the AT input rotational speed Ni and the estimated AT input rotational speed Niest happen to match even though the engagement device CB is disengaged, it is possible to accurately determine whether the engagement device CB is disengaged by determining whether the engagement device CB is disengaged from the rotational state of the front electric motor FrMG.

[0068] Furthermore, according to this embodiment, the rotational speed difference ΔNcb between the input rotating member 90 and the output rotating member 92 of the engagement device CB provided in the automatic transmission 38 is estimated based on the rotational speed difference ΔNcb between the AT input rotational speed N i of the automatic transmission 38 and the estimated AT input rotational speed N i est calculated from the AT output rotational speed N o and the gear ratio γat of the automatic transmission 38. Therefore, the rotational speed difference ΔNcb of the engagement device CB can be estimated using sensors that have been previously provided, without adding sensors that detect the rotational speeds of the input rotating member 90 and the output rotating member 92 of the engagement device CB. Furthermore, when series traveling is performed, the front electric motor FrMG is rotated by the power output from the engine 12, which may cause the AT input rotational speed N i and the estimated AT input rotational speed N i est to coincide with each other even though the engagement device CB is disengaged. Even in such a case, whether the engagement device CB is disengaged can be accurately determined because the rotational state of the front electric motor FrMG can also be determined.

[0069] Next, another embodiment of the present invention will be described. In the following description, parts common to the above embodiment will be designated by the same reference numerals and description thereof will be omitted. [Example]

[0070] FIG. 4 is a diagram illustrating a schematic configuration of a hybrid vehicle 120 (hereinafter, vehicle 120) according to another embodiment of the present invention. The vehicle 120 is provided with a speed reducer 122 having a fixed gear ratio, instead of the automatic transmission 38 provided in the vehicle 10 of the previously described embodiment. In the vehicle 120, a speed reducer input shaft 124 of the speed reducer 122 is connected to the input clutch 36. Furthermore, a speed reducer output shaft 126 of the speed reducer 122 is connected to the differential 42. Other structural features of the vehicle 120 are the same as those of the vehicle 10 of the previously described embodiment, and therefore, further description thereof will be omitted. Furthermore, an electronic control device 130 that performs driving control and the like for the vehicle 120 is basically the same, except that it does not functionally include the gear shift control unit 106 of the previously described embodiment. The speed reducer input shaft 124 corresponds to the input rotating member of the present invention, and the speed reducer output shaft 126 corresponds to the output rotating member of the present invention.

[0071] In the vehicle 120, during series running, the input clutch 36 is disengaged, thereby interrupting power transmission between the engine 12 and the front electric motor FrMG and the front wheels 14. In connection with this, the clutch release determination unit 108 determines whether the input clutch 36 is disengaged during series running based on the difference in rotational speed between the reduction gear input shaft 124 and the reduction gear output shaft 126. Furthermore, when it is determined that the rotational speed of the reduction gear input shaft 124 and the rotational speed of the reduction gear output shaft 126 match or approximately match, the clutch release determination unit 108 determines whether the input clutch 36 is disengaged based on the rotational state of the front electric motor FrMG. Even when controlled as described above, it is possible to accurately determine whether the input clutch 36 is disengaged during series running, thereby achieving the same effects as the above-described embodiment.

[0072] Although the embodiments of the present invention have been described in detail above with reference to the drawings, the present invention can also be applied to other embodiments.

[0073] For example, in the above-described embodiment, it was determined whether the engagement device CB was disengaged based on the deviation ΔNmFr between the FrMG rotation speed NmFr of the front electric motor FrMG and the target FrMG rotation speed NmFr*, but instead it may be determined whether the engagement device CB was disengaged based on the deviation between the engine rotation speed Ne of the engine 12 and the target engine rotation speed Ne*.

[0074] Furthermore, in the above-described embodiment, when the engagement device CB of the automatic transmission 38 or the input clutch 36 is disengaged, power generation control is performed by rotating the front electric motor FrMG using the power of the engine 12, but this power generation control does not have to be performed.

[0075] Furthermore, in the second embodiment described above, the vehicle 120 is configured to include the reduction gear 122 between the engine 12 and the front electric motor FrMG and the front wheels 14, but the reduction gear 122 is not necessarily required, and the vehicle may not include the reduction gear 122. Alternatively, the vehicle may include a speed increaser instead of the reduction gear 122.

[0076] Furthermore, in the above-described embodiment, the vehicle 10 is configured such that the engine 12 and the front electric motor FrMG are connected to the front wheels 14 so as to be able to transmit power, and the rear electric motor RrMG is connected to the rear wheels 16 so as to be able to transmit power. However, the vehicle may be configured such that the front electric motor FrMG is connected to the front wheels 14 so as to be able to transmit power, and the engine 12 and the rear electric motor RrMG are connected to the rear wheels 16 so as to be able to transmit power. In this case, during series running, power generation control is performed by driving the rear electric motor RrMG with power from the engine 12, and series running is performed by supplying electric power generated by the rear electric motor RrMG to the front electric motor FrMG. Furthermore, an automatic transmission 38 or a predetermined engagement device is interposed in the power transmission path between the engine 12 and the rear electric motor RrMG and the rear wheels 16, and during series running, the engagement device CB or the predetermined engagement device of the automatic transmission 38 is disengaged.

[0077] Furthermore, in the above-described embodiment, the automatic transmission 38 is a stepped transmission including one or more planetary gear sets and multiple engagement devices CB. However, the present invention is not necessarily limited to the above-described configuration of the automatic transmission 38. For example, the automatic transmission may be a transmission including a forward / reverse switching device and a belt-type continuously variable transmission. In this case, power transmission between the engine 12 and the front electric motor FrMG and the front wheels 14 is interrupted by disengaging the engagement devices provided in the forward / reverse switching device during series running. In short, the present invention can be applied to any transmission that is inserted in the power transmission path between the engine 12 and the front electric motor FrMG and the front wheels 14 and that can interrupt power transmission in the power transmission path during series running.

[0078] Furthermore, in the above-described embodiment, the power transmission between the engine 12 and the front electric motor FrMG and the front wheels 14 is interrupted by interrupting the power transmission of the automatic transmission 38 during series running, but the power transmission between the engine 12 and the front electric motor FrMG and the front wheels 14 may also be interrupted by disengaging the input clutch 36. In this case, whether or not the input clutch 36 is disengaged is determined during series running based on the rotational speed difference between the rotational speed of the electric motor connecting shaft 48 (i.e., FrMG rotational speed NmFr) and the rotational speed of the transmission input shaft 50 (i.e., AT input rotational speed Ni).

[0079] Furthermore, in the above-described embodiment, the input clutch 36 (WSC) was interposed between the front electric motor FrMG and the automatic transmission 38, but the input clutch 36 is not necessarily required, and the input clutch 36 may be omitted.

[0080] It should be noted that the above is merely one embodiment, and the present invention can be implemented in various forms with various modifications and improvements based on the knowledge of those skilled in the art. [Explanation of symbols]

[0081] 10, 120: Hybrid vehicles 12: Engine 14: Front wheel (1st wheel) 16: Rear wheel (2nd wheel) 38: Automatic transmission (transmission) 40: Transmission output shaft (output shaft) 50: Transmission input shaft (input shaft) 90: Input rotating member 92: Output rotating member 100: Electronic control device (control device) 108: Clutch release determination unit (control unit) 124: Reducer input shaft (input rotating member) 126: Reducer output shaft (output rotating member) FrMG: Front electric motor (first electric motor) RrMG: Rear electric motor (second electric motor) CB: Engagement device (gear shift engagement device) Ni: AT input rotation speed (input shaft rotation speed) Niest: Estimated AT input rotation speed (estimated rotation speed of input shaft) No:AT output rotation speed (rotation speed of output shaft) NmFr: FrMG rotation speed (rotation speed of the first motor) NmFr*: Target FrMG rotation speed NmFr (target rotation speed of the first motor) ΔNi: Rotational speed difference (=|Ni-Niest|) ΔNmFr: Deviation (=|NmFr-NmFr*|) α1: First predetermined value α2: Second predetermined value β1: First predetermined time β2: Second predetermined time

Claims

1. A control device for a hybrid vehicle including first wheels configured to be able to transmit power from an engine and a first electric motor, second wheels configured to be able to transmit power from a second electric motor, and an engagement device interposed in a power transmission path between the engine and the first electric motor and the first wheels to connect and disconnect power transmission in the power transmission path, the control device being capable of operating a driving mode in which the engagement device is released and the vehicle is driven by power from the second electric motor, a control unit that determines whether the engagement device is disengaged while the vehicle is traveling in the traveling mode based on a rotational speed difference between an input rotary member and an output rotary member that are connected and disconnected by the engagement device, and a rotational state of the engine or a rotational state of the first electric motor, The control unit determines that the engagement device is engaged when a state in which the rotational speed difference is equal to or less than a predetermined first predetermined value continues for a predetermined first predetermined time or more, and a state in which a deviation amount between the rotational speed of the engine or the first electric motor and a target rotational speed of the engine or the first electric motor is equal to or greater than a predetermined second predetermined value continues for a predetermined second predetermined time or more. A control device for a hybrid vehicle.

2. A transmission is provided in the power transmission path, the engagement device is a gear shift engagement device provided in the transmission, The rotational speed difference of the engagement device is estimated based on the rotational speed difference between the rotational speed of the input shaft of the transmission and the estimated rotational speed of the input shaft calculated from the rotational speed of the output shaft of the transmission and the gear ratio of the transmission.

2. The control device for a hybrid vehicle according to claim 1.

3. During running in the running mode, power generation control is performed by rotating the first electric motor using power from the engine, and electric power generated by the first electric motor is supplied to the second electric motor to run the vehicle, thereby performing series running.

3. The control device for a hybrid vehicle according to claim 1 or 2.

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