Vehicle drive device

Abstract

To restrict busy switching of control modes accompanying setting a limit on an electric pass amount relative to a target electric pass amount.SOLUTION: In the case that an electric pass amount transmitted from a first rotary machine, in an electric path where exchange of power takes place between the first rotary machine and a second rotary machine, is predicted to be smaller relative to a target electric pass amount for making an operation point of an engine reach the target operation point, a second control mode is selected as the control mode. Therefore, when the electric pass amount is easily set to be smaller relative to the target electric pass amount, switching from the second control mode to a first control mode is suppressed. Accordingly, after switching to the first control mode, the occurrence of a need to switch to the second control mode is restricted. Thus, busy switching between the control modes accompanying setting a limit on the electric pass amount relative to the target electric amount is suppressed.SELECTED DRAWING: Figure 12

Description

[Technical Field]

[0001] The present invention relates to a vehicle drive device configured to be able to change an engine operating point by adjusting an electrical path amount between a first rotating machine and a second rotating machine. [Background technology]

[0002] A well-known vehicle drive system includes an engine, an input rotating element to which the engine is power-transmittably connected, an output rotating element to which a drive wheel is power-transmittably connected, and a direct-coupled clutch that couples the input rotating element to the output rotating element, thereby transmitting power from the engine from the input rotating element to the output rotating element via a fluid. The fluid-type power transmission also includes a first rotating machine power-transmittably connected to the input rotating element, and a second rotating machine power-transmittably connected to the drive wheel. For example, a vehicle drive system is described in Patent Document 1. Patent Document 1 discloses a control device for a vehicle drive system that controls an engine operating point by adjusting an electrical path amount, which is the amount of power sent from the first rotating machine in an electrical path through which power is exchanged between the first rotating machine and the second rotating machine. This control device can bring the engine operating point closer to an optimal fuel efficiency point suitable for improving fuel efficiency, thereby improving the vehicle's fuel efficiency. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5700124 Summary of the Invention [Problem to be solved by the invention]

[0004] Depending on the vehicle's driving conditions, the second control mode, in which the direct-coupled clutch is engaged and engine power is transmitted via a fluid-type power transmission with the direct-coupled clutch engaged, may provide better vehicle fuel economy than the first control mode, in which the direct-coupled clutch is disengaged and the first rotating machine is operated to generate electricity so that the electric path amount is the target electric path amount for setting the engine's operating point to the target operating point. Therefore, it is conceivable to select either the first control mode or the second control mode as the control mode that provides better vehicle fuel economy based on the vehicle's driving conditions. However, for example, when the first control mode is selected and switched from a state in which the second control mode is active to the first control mode, if the electric path amount becomes smaller than the target electric path amount, i.e., if the electric path amount is limited relative to the target electric path amount, it becomes difficult to achieve the target electric path amount. As a result, the first control mode cannot be continued, and the vehicle's fuel economy may deteriorate. This may result in the need to switch back to the second control mode, which may result in frequent control mode switching, i.e., a busy state.

[0005] The present invention has been made against the background of the above circumstances, and its purpose is to provide a vehicle drive device that can suppress busy switching of control modes that occurs when the electrical path amount is limited to a target electrical path amount. [Means for solving the problem]

[0006] The gist of a first invention is a vehicle drive device including: (a) an engine; an input side rotating element to which the engine is connected so as to be able to transmit power; an output side rotating element to a drive wheel so as to be able to transmit power; and a fluid-type power transmission device having a direct-coupled clutch that connects the input side rotating element and the output side rotating element, and transmitting power from the engine from the input side rotating element to the output side rotating element via a fluid; a first rotating machine connected so as to be able to transmit power to the input side rotating element; a second rotating machine connected so as to be able to transmit power to the drive wheel; and a control device that controls an operating point of the engine by adjusting an electric path amount, which is the amount of electric power sent from the first rotating machine, in an electric path through which electric power is exchanged between the first rotating machine and the second rotating machine; The control system can selectively establish a first control mode in which the direct-coupled clutch is controlled to a released state and the first rotating machine is operated to generate electricity so that the electric path amount becomes a target electric path amount for making the operating point of the engine a target operating point, and a second control mode in which the direct-coupled clutch is controlled to an engaged state and the power of the engine is transmitted via the fluid-type power transmission device with the direct-coupled clutch in an engaged state, and selects as the control mode from the first control mode and the second control mode the one that improves the fuel efficiency of the vehicle based on the running state of the vehicle; and (c) predicts whether the electric path amount will be reduced relative to the target electric path amount, and selects the second control mode as the control mode if it is predicted that the electric path amount will be reduced relative to the target electric path amount.

[0007] In addition, a second invention is a vehicle drive device described in the first invention, further comprising a first output shaft to which power from the engine is input via the fluid transmission device and which outputs power to one of the front wheels and rear wheels, a second output shaft which outputs power to the other of the front wheels and the rear wheels, and a torque distribution device which distributes a portion of the torque input to the first output shaft to the second output shaft, wherein the torque distribution device comprises the second rotating machine and a differential device having a first rotating element to which the second rotating machine is connected, a second rotating element to which one of the first output shaft and the second output shaft is connected, and a third rotating element to which the other of the first output shaft and the second output shaft is connected, and the control device can control the torque distribution ratio, which is the ratio of the torque distributed to the front wheels and the rear wheels, by controlling the output torque of the second rotating machine, and when the torque distribution ratio is controlled by controlling the output torque of the second rotating machine, it is predicted that the electrical path amount will be smaller than the target electrical path amount.

[0008] Furthermore, a third invention is a vehicle drive device described in the second invention, wherein the torque distribution device further includes an engagement device that selectively connects any two of the first rotating element, the second rotating element, and the third rotating element, and the control device is capable of controlling the torque distribution ratio by controlling the output torque of the second rotating machine when the engagement device is in a disengaged state, and is capable of driving the second rotating machine as a power source when the engagement device is in an engaged state, and predicts that the electrical path amount will not be reduced relative to the target electrical path amount when the engagement device is in an engaged state, and selects the control mode from the first control mode and the second control mode that improves the fuel efficiency of the vehicle.

[0009] Furthermore, a fourth invention is a vehicle drive device according to the third invention, wherein the engagement states of the engagement devices include a slip engagement state in which the engagement devices are engaged with slippage, and a full engagement state in which the engagement devices are fully engaged, and the control device can control the torque distribution ratio by controlling the engagement states of the engagement devices.

[0010] Furthermore, a fifth invention is a vehicle drive device described in any one of the first to fourth inventions, further comprising an electric storage device that supplies and receives electric power to each of the first rotating machine and the second rotating machine, and the control device determines whether the charge amount of the electric storage device is within a predetermined low charge amount range in which charging of the electric path amount is permitted, and when it determines that the charge amount is within the low charge amount range, selects as the control mode between the first control mode and the second control mode the one that improves the fuel efficiency of the vehicle, even if it predicts that the electric path amount will be smaller than the target electric path amount.

[0011] Furthermore, a sixth aspect of the present invention is a vehicle drive device according to any one of the first to fifth aspects of the present invention, wherein the control device predicts that the electrical path amount will be reduced relative to the target electrical path amount when the output of the second rotating machine is limited.

[0012] Furthermore, a seventh invention is a vehicle drive device according to the sixth invention, wherein the control device determines whether the output of the second rotating machine is limited based on whether the temperature of the second rotating machine is within a predetermined high temperature range within which the output of the second rotating machine is limited.

[0013] Furthermore, an eighth aspect of the present invention is a vehicle drive device according to any one of the first to seventh aspects of the present invention, further comprising an electric storage device that supplies and receives electric power to each of the first rotating machine and the second rotating machine, and the control device predicts that the electric path amount will be reduced relative to the target electric path amount when the chargeable power of the electric storage device is within a predetermined low power range in which charging of the electric path amount is limited.

[0014] A ninth aspect of the present invention is that in the vehicle drive device described in the eighth aspect of the present invention, the control device determines whether the chargeable power of the storage device is within the low power range based on whether the charge amount of the storage device is within a predetermined high charge amount range in which charging of the electrical path amount is limited.

[0015] Furthermore, a tenth aspect of the present invention is that in the vehicle drive device described in the eighth or ninth aspect of the present invention, the control device determines whether the chargeable power of the storage device is within a predetermined low temperature range or a predetermined high temperature range in which charging of the electrical path amount is limited, based on whether the temperature of the storage device is within the predetermined low temperature range or high temperature range in which charging of the electrical path amount is limited.

[0016] In addition, an eleventh aspect of the present invention is a vehicle drive device according to any one of the first to tenth aspects of the present invention, wherein the target operating point is a fuel efficiency optimum point that is predetermined as an operating point that is optimal for improving the fuel efficiency of the engine. [Effects of the Invention]

[0017] According to the first aspect of the present invention, when it is predicted that the electrical path amount sent from the first rotating machine in the electrical path through which power is exchanged between the first rotating machine and the second rotating machine will be smaller than the target electrical path amount for setting the engine operating point to the target operating point, the second control mode is selected as the control mode. Therefore, when the electrical path amount is likely to be smaller than the target electrical path amount, switching from the second control mode to the first control mode is suppressed. This prevents the need to switch back to the second control mode after switching to the first control mode. Therefore, it is possible to suppress busy switching of the control mode caused by the electrical path amount being limited to the target electrical path amount.

[0018] According to the second aspect of the present invention, when the torque distribution device controls the output torque of the second rotating machine to control the torque distribution ratio, which is the ratio of torque distributed to the front wheels and the rear wheels, it is predicted that the electrical path amount will be reduced relative to the target electrical path amount, and therefore the second control mode is selected as the control mode when the electrical path amount is constrained by controlling the torque distribution ratio. This avoids switching between the first control mode and the second control mode due to the control of the torque distribution ratio, and makes it possible to maintain the torque distribution between the front wheels and the rear wheels.

[0019] Furthermore, according to the third invention, when the second rotating machine can be driven and operated as a power source, it is predicted that the electrical path amount will not be reduced relative to the target electrical path amount, and the control mode that improves the vehicle's fuel efficiency is selected from the first control mode and the second control mode.Therefore, when the second rotating machine can be driven and operated, the need to switch to the second control mode after switching to the first control mode is suppressed, busy switching of the control mode can be suppressed and the vehicle's fuel efficiency can be improved.

[0020] Furthermore, according to the fourth aspect of the present invention, the second rotating machine can be driven using the second rotating machine as a power source. The engagement states of the engagement device include a slip engagement state and a full engagement state, and the torque distribution ratio is controlled by controlling the engagement state of the engagement device, so that the torque distribution between the front wheels and the rear wheels can be maintained.

[0021] Furthermore, according to the fifth aspect of the present invention, when it is determined that the charge amount of the power storage device that supplies and receives electric power to each of the first rotating machine and the second rotating machine is within a predetermined low charge amount range in which charging of the electric path amount is permitted, even if it is predicted that the electric path amount will be smaller than the target electric path amount, the control mode that improves the fuel efficiency of the vehicle is selected from the first control mode and the second control mode.Therefore, since the amount of electric power that is insufficient for the electric path amount required for the target electric path amount can be charged to the power storage device, when the need to switch to the second control mode after switching to the first control mode is suppressed, busy switching of the control mode can be suppressed and the fuel efficiency of the vehicle can be improved.

[0022] According to the sixth aspect of the present invention, when the output of the second rotating machine is limited, the electrical path amount is predicted to be smaller than the target electrical path amount, and therefore when the electrical path amount is limited by limiting the output of the second rotating machine, the second control mode is selected as the control mode and switching from the second control mode to the first control mode is suppressed. This suppresses the need to switch to the second control mode after switching to the first control mode.

[0023] Furthermore, according to the seventh aspect of the present invention, whether the output of the second rotating machine is limited or not is determined based on whether the temperature of the second rotating machine is within a predetermined high temperature range in which the output of the second rotating machine is limited, so that it is appropriately predicted whether the electrical path amount will be reduced relative to the target electrical path amount.

[0024] According to the eighth aspect of the present invention, when the chargeable power of the power storage device that supplies and receives power to each of the first rotating machine and the second rotating machine is within a predetermined low power range in which charging of the electrical path amount is limited, it is predicted that the electrical path amount will be reduced relative to the target electrical path amount, so when the electrical path amount is limited by the limit on the chargeable power of the power storage device, the second control mode is selected as the control mode and switching from the second control mode to the first control mode is suppressed. This suppresses the need to switch to the second control mode after switching to the first control mode.

[0025] Furthermore, according to the ninth aspect of the present invention, whether the chargeable power of the storage device is within a low power range is determined based on whether the charge amount of the storage device is within a predetermined high charge amount range in which charging of the electrical path amount is limited, so that it is appropriately predicted whether the electrical path amount will be reduced relative to the target electrical path amount.

[0026] Furthermore, according to the tenth aspect of the present invention, whether the chargeable power of the storage device is within a low power range is determined based on whether the temperature of the storage device is within a predetermined low temperature range or a predetermined high temperature range in which charging of the electrical path amount is restricted, so that it is appropriately predicted whether the electrical path amount will be reduced relative to the target electrical path amount.

[0027] Furthermore, according to the eleventh aspect of the present invention, the target operating point is a fuel efficiency optimum point that is predetermined as an operating point that is optimal for improving the fuel efficiency of the engine, so that busy switching of the control mode can be suppressed and the fuel efficiency of the vehicle can be improved. [Brief explanation of the drawings]

[0028] [Figure 1] 1 is a diagram illustrating a schematic configuration of a vehicle drive device 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 drive device. [Figure 2] FIG. 2 is a diagram illustrating a schematic configuration of the hybrid transmission of FIG. 1. [Figure 3]3 is an operation engagement table illustrating the relationship between the shift operation of the automatic transmission of FIG. 2 and the combination of operations of engagement devices used therein. [Figure 4] FIG. 2 is a diagram illustrating a schematic configuration of the transfer case of FIG. [Figure 5] FIG. 5 is a nomographic diagram showing the relative relationship between the rotational speeds of the rotating elements in the transfer case of FIG. 4. [Figure 6] 5 is an operation engagement table illustrating the relationship between each mode established in the transfer case of FIG. 4 and the control state of each engagement device in the transfer case. [Figure 7] 1 is a diagram showing an example of an AT gear stage shift map used for shift control of an automatic transmission and a drive region switching map used for drive mode switching control, and also showing the relationship between them. [Figure 8] FIG. 4 is a diagram showing an example of an input / output limit map used to set basic values ​​of input / output limits of a battery; [Figure 9] FIG. 10 is a diagram showing an example of an input / output limit correction coefficient map used to set a correction coefficient for correcting a basic value of the input / output limit of the battery. [Figure 10] 1 is a diagram illustrating that an engine operating point can be changed in a vehicle drive device in the same manner as in a continuously variable transmission. [Figure 11] FIG. 10 is a diagram showing an example of a predetermined relationship between the power transmission efficiency of electrical transmission and the power transmission efficiency of fluid transmission and the speed ratio of a torque converter. [Figure 12] 10 is a flowchart illustrating the main control operations of the electronic control device, and is a flowchart illustrating the control operations for suppressing busy switching of the control mode due to the electrical path amount being limited to the target electrical path amount. [Figure 13] FIG. 5 is a diagram illustrating a schematic configuration of a transfer case different from that shown in FIG. 4. [Figure 14] FIG. 14 is a nomographic diagram showing the relative relationship of the rotational speeds of the respective rotating elements in the transfer case of FIG. 13. [Figure 15]14 is an operation engagement table illustrating the relationship between each mode established in the transfer case of FIG. 13 and the control state of each engagement device in the transfer case. [Figure 16] FIG. 2 is a diagram illustrating a schematic configuration of a power transmission device different from that shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0029] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. [Example]

[0030] FIG. 1 is a diagram illustrating a schematic configuration of a vehicle drive system 10 provided in a vehicle 8 to which the present invention is applied, and also illustrates key parts of control functions and control systems for various controls in the vehicle drive system 10. In FIG. 1, the vehicle drive system 10 includes an engine 12 (see "ENG" in the diagram), a TM rotary machine MGM, and a TF rotary machine MGF, which function as power sources. The vehicle 8 is a hybrid vehicle. The vehicle drive system 10 also includes a pair of left and right front wheels 14, a pair of left and right rear wheels 16, and a power transmission device 18. The power transmission device 18 is a vehicle power transmission device that transmits power from the engine 12 and the like to the front wheels 14 and the rear wheels 16, respectively. The engine 12, the TM rotary machine MGM, and the TF rotary machine MGF are simply referred to as power source PU when not otherwise distinguished. In particular, the engine 12 and the TM rotary machine MGM, which output power to a torque converter 48 and an automatic transmission 50 (described later), are a first power source PU1. The rotating machine MGM for TM provided in the first power source PU1 is the first rotating machine. The rotating machine MGF for TF provided in a transfer 28 (described later) is the second rotating machine, and is the second power source PU2 used as a power source instead of or in addition to the first power source PU1.

[0031] The vehicle 8 is an all-wheel drive vehicle that can distribute a portion of the torque transmitted to the rear wheels 16 by the vehicle drive system 10 to the front wheels 14. The vehicle drive system 10 can be a rear-wheel drive vehicle that transmits torque only to the rear wheels 16, as well as a front-wheel drive vehicle that transmits torque only to the front wheels 14. The vehicle 8 is a four-wheel drive vehicle because it has two front wheels 14 and two rear wheels 16, for a total of four wheels. In this embodiment, all-wheel drive (=AWD) and four-wheel drive (=4WD) are synonymous. Furthermore, rear-wheel drive and front-wheel drive are each two-wheel drive (=2WD). The front wheels 14 and rear wheels 16 will be simply referred to as drive wheels DW when no particular distinction is made.

[0032] The engine 12 is a known internal combustion engine such as a gasoline engine or a diesel engine. An engine control device 20 including a throttle actuator, a fuel injection device, an ignition device, etc., provided in the vehicle drive system 10 is controlled by an electronic control device 130, which will be described later, to control the engine torque Te, which is the output torque of the engine 12.

[0033] The TM rotating machine MGM and the TF rotating machine MGF 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. The TM rotating machine MGM and the TF rotating machine MGF are each connected to a battery 24 provided in the vehicle drive device 10 via an inverter 22 provided in the vehicle drive device 10. The TM rotating machine MGM and the TF rotating machine MGF each have an inverter 22 controlled by an electronic control device 130 (described later), thereby controlling the MGM torque Tmgm, which is the output torque of the TM rotating machine MGM, and the MGF torque Tmgf, which is the output torque of the TF rotating machine MGF. The MGM torque Tmgm and the MGF torque Tmgf are each power running torque (motor torque) when the rotating machine functions as a motor, and are regenerative torque (power generation torque) when the rotating machine functions as a generator. The battery 24 is an electricity storage device that supplies and receives electric power to each of the TM rotating machine MGM and the TF rotating machine MGF. The term "electric power" also refers to electrical energy unless otherwise specified. The term "power" also refers to driving force, torque, and force unless otherwise specified.

[0034] The power transmission device 18 includes a hybrid transmission 26 (see "HEV T / M" in the figure), a transfer 28 (see "T / F" in the figure), a front propeller shaft 30, a rear propeller shaft 32, a front differential 34 (see "FDiff" in the figure), a rear differential 36 (see "RDiff" in the figure), a pair of left and right front drive shafts 38, and a pair of left and right rear drive shafts 40. In the power transmission device 18, power from the first power source PU1 transmitted via the hybrid transmission 26 is transmitted from the transfer 28 to the rear wheels 16 via the rear propeller shaft 32, the rear differential 36, the rear drive shafts 40, etc. in that order. In addition, in the power transmission device 18, when a portion of the torque from the first power source PU1 transmitted to the transfer 28 is distributed to the front wheels 14, the distributed torque is transmitted to the front wheels 14 sequentially via the front propeller shaft 30, the front differential 34, the front drive shaft 38, etc.

[0035] The hybrid transmission 26 includes a transmission case 42, which is a non-rotating member. The transfer 28 includes a transfer case 44, which is a non-rotating member connected to the transmission case 42. The TM rotating machine MGM is provided within the transmission case 42. The TF rotating machine MGF is provided within the transfer case 44.

[0036] Fig. 2 is a diagram illustrating the schematic configuration of hybrid transmission 26. In Fig. 2, hybrid transmission 26 includes a rotary machine connecting shaft 46, a torque converter 48, and an automatic transmission 50, which are arranged on a common rotational axis CL1 within a transmission case 42. Torque converter 48 and automatic transmission 50 are configured substantially symmetrically with respect to rotational axis CL1, and Fig. 2 omits the lower half of the automatic transmission 50 with respect to rotational axis CL1. Rotational axis CL1 is the axial center of the crankshaft of engine 12, rotary machine connecting shaft 46 connected to the crankshaft, transmission input shaft 52 which is an input rotating member of automatic transmission 50, and transmission output shaft 54 ​​which is an output rotating member of automatic transmission 50.

[0037] The rotary machine connecting shaft 46 is a rotating shaft connecting the engine 12 and the torque converter 48. The torque converter 48 includes a pump wheel 48a connected to the rotary machine connecting shaft 46 and a turbine wheel 48b connected to a transmission input shaft 52. The pump wheel 48a is an input member of the torque converter 48 and is an input-side rotating element to which the first power source PU1 is connected so as to be capable of transmitting power. The turbine wheel 48b is an output member of the torque converter 48 and is an output-side rotating element to which the first power source PU1 is connected so as to be capable of transmitting power. The TM rotary machine MGM is connected to the rotary machine connecting shaft 46 so as to be capable of transmitting power, i.e., is connected to the pump wheel 48a so as to be capable of transmitting power. The rotary machine connecting shaft 46 also serves as an input rotating member of the torque converter 48. The transmission input shaft 52 is also an output rotating member of the torque converter 48 formed integrally with a turbine shaft that is rotationally driven by the turbine wheel 48b. The torque converter 48 is a fluid-type power transmission that transmits power from the first power source PU1 to the transmission input shaft 52 via a fluid, i.e., a fluid-type power transmission that transmits power from the first power source PU1 from the pump wheel 48a to the turbine wheel 48b via a fluid. The torque converter 48 is equipped with a lock-up clutch LU that connects the pump wheel 48a and the turbine wheel 48b. The lock-up clutch LU is a direct-coupled clutch that connects the input and output rotary members of the torque converter 48, i.e., a well-known lock-up clutch.

[0038] The lockup clutch LU switches its operating state, i.e., its control state, by changing the LU torque Tlu, which is the torque capacity of the lockup clutch LU, using the LU oil pressure PRlu, which is a regulated oil pressure supplied from a hydraulic control circuit 60 (see FIG. 1) provided in the vehicle drive system 10. The hydraulic control circuit 60 is controlled by an electronic control device 130, which will be described later. The control states of the lockup clutch LU include a release state (which also refers to a fully release state) in which the lockup clutch LU is fully released, a slip engagement state in which the lockup clutch LU is engaged with slippage, and a fully engaged state in which the lockup clutch LU is fully engaged. The engagement states of the lockup clutch LU include a slip engagement state and a fully engaged state. When the lockup clutch LU is in the release state, the torque converter 48 is in a torque converter state in which torque amplification is achieved. When the lockup clutch LU is in the fully engaged state, the torque converter 48 is in a lockup state in which the pump wheel 48a and the turbine wheel 48b rotate integrally.

[0039] The automatic transmission 50 is interposed in the power transmission path between the torque converter 48 and the transfer case 28. The transmission output shaft 54 ​​is connected to the transfer case 28. The automatic transmission 50 is a mechanical transmission device that transmits power from the first power source PU1 to the transfer case 28. In this manner, the torque converter 48 and the automatic transmission 50 each transmit power from the first power source PU1 to the transfer case 28.

[0040] The automatic transmission 50 is a known planetary gear type automatic transmission that includes multiple sets of planetary gear devices, for example, a first planetary gear device 56 and a second planetary gear device 58, and multiple engagement devices, including a one-way clutch F1, a clutch C1, a clutch C2, a brake B1, and a brake B2. Hereinafter, the clutch C1, the clutch C2, the brake B1, and the brake B2 will be simply referred to as engagement device CB unless otherwise specified.

[0041] The engagement devices CB are known hydraulic friction engagement devices configured with multi-plate or single-plate clutches or brakes pressed by a hydraulic actuator, band brakes tightened by a hydraulic actuator, etc. The engagement devices CB are switched between control states such as an engaged state and a disengaged state by changing the CB torque Tcb, which is their respective torque capacities, using the CB oil pressure PRcb, which is the oil pressure of each engagement device CB adjusted and supplied from the hydraulic control circuit 60.

[0042] In the automatic transmission 50, the rotating elements of the first planetary gear set 56 and the second planetary gear set 58 are partially connected to each other or to the transmission input shaft 52, the transmission case 42, or the transmission output shaft 54, either directly or indirectly via an engagement device CB or a one-way clutch F1. The rotating elements of the first planetary gear set 56 are a sun gear S1, a carrier CA1, and a ring gear R1, and the rotating elements of the second planetary gear set 58 are a sun gear S2, a carrier CA2, and a ring gear R2.

[0043] The automatic transmission 50 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 one of the engagement devices CB. The automatic transmission 50 switches between gear stages established in accordance with the accelerator operation of the driver (=operator), the vehicle speed V, etc., by an electronic control device 130 (described later). In this embodiment, the gear stages established by the automatic transmission 50 are referred to as "AT gear stages." The AT input rotation speed Ni is the rotation speed of the transmission input shaft 52, which is the input rotation speed of the automatic transmission 50, and is equal to the turbine rotation speed Nt, which is the rotation speed of the turbine shaft rotated and driven by the turbine wheel 48b. The AT output rotation speed No is the rotation speed of the transmission output shaft 54, which is the output rotation speed of the automatic transmission 50.

[0044] As shown in the operation and engagement table of FIG. 3, the automatic transmission 50 has four forward AT gears, from an AT 1st gear ("1st" in the figure) to an AT 4th gear ("4th" in the figure), as multiple AT gears. The AT 1st gear has the largest gear ratio γat, and the higher the AT gear, which is closer to the AT 4th gear, which allows high-speed driving, the smaller the gear ratio γat. The operation and engagement table of FIG. 3 summarizes the relationship between each AT gear and each control state of the engagement device CB. In FIG. 3, "◯" indicates engagement, "△" indicates engagement during engine braking or coast downshifting of the automatic transmission 50, and a blank space indicates disengagement. When an AT gear is formed in the automatic transmission 50, the automatic transmission 50 is in a state in which power can be transmitted, i.e., a power transmission enabled state. The neutral state of the automatic transmission 50 ("N" in the drawing) is a state in which the automatic transmission 50 is unable to transmit power, i.e., a power transmission disabled state, which is realized, for example, by disengaging all of the engagement devices CB and interrupting power transmission in the automatic transmission 50. Furthermore, the automatic transmission 50 is in a neutral state ("Rev" in the drawing) when the vehicle 8 is traveling in reverse. When the vehicle 8 is traveling in reverse, power is output, for example, from the TF rotary machine MGF.

[0045] Fig. 4 is a diagram illustrating a schematic configuration of the transfer case 28. In Fig. 4, the transfer case 28 includes a TF input shaft 62, a differential 64, a TF clutch CF1, a TF brake BF1, a first output shaft 66, an intermediate shaft 68, a first mesh clutch D1, a second mesh clutch D2, and a drive gear 70, which are arranged on a common rotation axis CL1 within a transfer case 44. The differential 64, the TF clutch CF1, the TF brake BF1, the intermediate shaft 68, the first mesh clutch D1, the second mesh clutch D2, and the drive gear 70 are configured substantially symmetrically with respect to the rotation axis CL1, and the lower half of the transfer case 28 with respect to the rotation axis CL1 is omitted in Fig. 4.

[0046] The transfer 28 also includes a second output shaft 72, a driven gear 74, and other components that are disposed on a common rotational axis CL2 within the transfer case 44. The driven gear 74 is configured substantially symmetrically with respect to the rotational axis CL2, and the upper half of the driven gear 74 with respect to the rotational axis CL2 is omitted in Figure 4. The rotational axis CL2 is the axis of the second output shaft 72, etc.

[0047] The transfer 28 is provided with a TF rotating machine MGF, a rotating machine connecting gear pair 76, and a chain 78 within the transfer case 44. The rotating machine connecting gear pair 76 is made up of a TF rotating machine connecting gear 76a that rotates integrally with the rotor shaft 80 of the TF rotating machine MGF, and a TF counter gear 76b that is constantly meshed with the TF rotating machine connecting gear 76a. The chain 78 is a member that connects the drive gear 70 and the driven gear 74 together.

[0048] The transfer 28 further includes a switching actuator 82 fixed to the transfer case 44 (see FIG. 1). The switching actuator 82 is an actuator for actuating the first mesh clutch D1 and the second mesh clutch D2.

[0049] The TF clutch CF1 and the TF brake BF1 are each a known wet hydraulic friction engagement device configured with a multi-plate or single-plate engagement device pressed by a hydraulic actuator. The TF clutch CF1 has its control state switched by changing the CF1 torque Tcf1, which is the torque capacity of the TF clutch CF1, using the CF1 oil pressure PRcf1, which is the adjusted oil pressure of the TF clutch CF1 supplied from the hydraulic control circuit 60. The control states of the TF clutch CF1 include a released state (also known as a fully released state) in which the TF clutch CF1 is fully released, a slip engagement state in which the TF clutch CF1 is engaged with slippage, and a fully engaged state in which the TF clutch CF1 is fully engaged. The engagement states of the TF clutch CF1 include a slip engagement state and a fully engaged state. Similar to the TF clutch CF1, the TF brake BF1 has its control state switched between the engaged state, the released state, and other states by changing the BF1 torque Tbf1 using the BF1 oil pressure PRbf1 supplied from the hydraulic control circuit 60. The engagement state of the TF brake BF1 is exclusively a fully engaged state. The first mesh clutch D1 and the second mesh clutch D2 are each a known mesh clutch, i.e., a dog clutch. The first mesh clutch D1 and the second mesh clutch D2 each have their meshed states switched as a control state by a switching actuator 82 controlled by an electronic control device 130 (described later).

[0050] The TF input shaft 62 is connected to the transmission output shaft 54 ​​so as to be able to transmit power. The first output shaft 66 is connected to the rear propeller shaft 32 so as to be able to transmit power. The second output shaft 72 is connected to the front propeller shaft 30 so as to be able to transmit power. The driven gear 74 is fixed to the second output shaft 72 so as not to be able to rotate relative to it. The TF counter gear 76b is fixed to the intermediate shaft 68 so as not to be able to rotate relative to it.

[0051] The differential device 64 is configured as a single-pinion planetary gear device and includes a sun gear S, a carrier CA, and a ring gear R. The sun gear S is fixed to an intermediate shaft 68 so as to be non-rotatable relative to the sun gear S. Therefore, the TF rotating machine MGF is connected to the sun gear S via a rotating machine connecting gear pair 76. The carrier CA is connected to a drive gear 70. Therefore, the second output shaft 72 is connected to the carrier CA via the drive gear 70, a chain 78, and a driven gear 74. The ring gear R is selectively connected to the transfer case 44 via a TF brake BF1. The sun gear S and the carrier CA are selectively connected to each other via a TF clutch CF1. The TF clutch CF1 is an engagement device that selectively connects the sun gear S and the carrier CA. The TF brake BF1 is an engagement device that selectively connects the ring gear R to the transfer case 44.

[0052] The first mesh clutch D1 includes first meshing teeth a1, second meshing teeth a2, third meshing teeth a3, and a first sleeve d1s. The first meshing teeth a1 are fixed to the TF input shaft 62 so as to be non-rotatable relative thereto. The second meshing teeth a2 are fixed to the first output shaft 66 so as to be non-rotatable relative thereto. The third meshing teeth a3 are fixed to the intermediate shaft 68 so as to be non-rotatable relative thereto. The first sleeve d1s is provided so as to be movable relative to each of the first meshing teeth a1, second meshing teeth a2, and third meshing teeth a3 in the direction of the rotation axis CL1. The direction of the rotation axis CL1 is parallel to the rotation axis CL1. The first sleeve d1s has internal teeth formed thereon that can mesh with each of the first meshing teeth a1, second meshing teeth a2, and third meshing teeth a3 so as to be non-rotatable relative thereto. The first sleeve d1s is moved in the direction of the rotation axis CL1 by the switching actuator 82, thereby forming or releasing a meshed state with the first meshing teeth a1, the second meshing teeth a2, and the third meshing teeth a3. The first state [1] of the first meshing clutch D1 shows a state in which the first sleeve d1s is meshed with the first meshing teeth a1 and the second meshing teeth a2, respectively, thereby connecting the first meshing teeth a1 and the second meshing teeth a2. The second state [2] of the first meshing clutch D1 shows a state in which the first sleeve d1s is meshed with the first meshing teeth a1 and the third meshing teeth a3, respectively, thereby connecting the first meshing teeth a1 and the third meshing teeth a3. For convenience, FIG. 4 illustrates multiple first sleeves d1s corresponding to each state.

[0053] The second mesh clutch D2 includes fourth meshing teeth a4, fifth meshing teeth a5, sixth meshing teeth a6, and a second sleeve d2s. The fourth meshing teeth a4 are connected to the ring gear R. The fifth meshing teeth a5 are connected to the carrier CA. The sixth meshing teeth a6 are fixed to the first output shaft 66 so as not to rotate relative to the first output shaft 66. The second sleeve d2s is provided so as to be movable relative to each of the fourth meshing teeth a4, fifth meshing teeth a5, and sixth meshing teeth a6 in the direction of the rotation axis CL1. The second sleeve d2s has internal teeth formed thereon that can mesh with each of the fourth meshing teeth a4, fifth meshing teeth a5, and sixth meshing teeth a6 so as not to rotate relative to the fourth meshing teeth a4, fifth meshing teeth a5, and sixth meshing teeth a6. The second sleeve d2s is moved in the direction of the rotation axis CL1 by the switching actuator 82, thereby forming or releasing a meshed state with the fourth meshing teeth a4, the fifth meshing teeth a5, and the sixth meshing teeth a6. The first state [1] of the second meshing clutch D2 indicates a neutral state in which the second sleeve d2s is not meshed with any of the fourth meshing teeth a4, the fifth meshing teeth a5, and the sixth meshing teeth a6, thereby disengaging the fourth meshing teeth a4, the fifth meshing teeth a5, and the sixth meshing teeth a6. The second state [2] of the second meshing clutch D2 indicates a state in which the second sleeve d2s is meshed with the fourth meshing teeth a4 and the sixth meshing teeth a6, thereby engaging the fourth meshing teeth a4 and the sixth meshing teeth a6. The ring gear R is connected to the first output shaft 66 via the second state [2] of the second mesh clutch D2. The third state [3] of the second mesh clutch D2 shows a state in which the second sleeve d2s is engaged with the fifth meshing teeth a5 and the sixth meshing teeth a6, respectively. For convenience, FIG. 4 shows multiple second sleeves d2s corresponding to the respective states.

[0054] Fig. 5 is a nomographic diagram showing the relative relationship between the rotational speeds of the rotating elements in the transfer 28. In Fig. 5, three vertical lines Y1, Y2, and Y3 corresponding to the three rotating elements of the differential device 64 that make up the transfer 28 are axes that, from left to right, represent the rotational speed of the sun gear S corresponding to the first rotating element RE1, the rotational speed of the carrier CA corresponding to the second rotating element RE2, and the rotational speed of the ring gear R corresponding to the third rotating element RE3. The vertical line Y0 shown to the left of the vertical line Y1 is an axis that represents the rotational speed of the first output shaft 66 corresponding to the input / output rotating element REIO.

[0055] 5, in the transfer case 28, the input / output rotary element REIO is selectively connected to the TF input shaft 62 via the first mesh clutch D1 (see the first state [1]) and is also connected to the rear propeller shaft 32. The TF input shaft 62 is connected to the first power source PU1 including the engine 12 via the hybrid transmission 26 so as to be able to transmit power. In the differential device 64, the first rotating element RE1 is connected to the TF rotating machine MGF so as to be able to transmit power and is selectively connected to the TF input shaft 62 via the first dog clutch D1 (see the second state [2]). The second rotating element RE2 is connected to the second output shaft 72, i.e., the front propeller shaft 30, and is selectively connected to the first output shaft 66, i.e., the rear propeller shaft 32, via the second dog clutch D2 (see the third state [3]). The third rotating element RE3 is selectively connected to the first output shaft 66 via the second dog clutch D2 (see the second state [2]) and is selectively connected to the transfer case 44 via the TF brake BF1. The first rotating element RE1 and the second rotating element RE2 are selectively connected to each other via the TF clutch CF1. In the differential device 64, the relationship between the relative rotational speeds of the first rotating element RE1, the second rotating element RE2, and the third rotating element RE3 is indicated by the line Lcd. The first output shaft 66 is an output shaft that receives power from the first power source PU1 via the torque converter 48 and outputs the power to the rear wheels 16. The second output shaft 72 is an output shaft that outputs power to the front wheels 14.

[0056] In the differential device 64, when the TF clutch CF1 is in an engaged state (particularly a fully engaged state) and the TF brake BF1 is in a released state, the first rotating element RE1, the second rotating element RE2, and the third rotating element RE3 are rotated integrally. On the other hand, in the differential device 64, when the TF clutch CF1 is in a released state and the TF brake BF1 is in an engaged state, the rotational speed of the second rotating element RE2 is reduced relative to the rotational speed of the first rotating element RE1. Therefore, the differential device 64 functions as a transmission that selectively establishes a high gear by engaging the TF clutch CF1 and a low gear by engaging the TF brake BF1.

[0057] Furthermore, when both the TF clutch CF1 and the TF brake BF1 are in a disengaged state, the differential device 64 is capable of performing a differential action. Therefore, the differential device 64 functions as a center differential. At this time, when the first mesh clutch D1 is in the first state [1] and the second mesh clutch D2 is in the second state [2] in the transfer 28, the differential device 64 is capable of distributing the torque from the first power source PU1 input to the third rotating element RE3 to the second rotating element RE2 by using the reaction torque of the TF rotating machine MGF connected to the first rotating element RE1. Furthermore, instead of applying the reaction torque of the TF rotating machine MGF, the differential device 64 is capable of distributing the torque from the first power source PU1 input to the third rotating element RE3 to the second rotating element RE2 by limiting the differential action of the differential device 64 by placing the TF clutch CF1 in an engaged state (slip-engaged state or fully engaged state). In this way, the transfer 28 is a torque distribution device that distributes a portion of the torque from the first power source PU1 input to the first output shaft 66 to the second output shaft 72. This enables the transfer 28 to distribute torque to the front wheels 14 and the rear wheels 16. When the second dog clutch D2 in the transfer 28 is in the third state [3], the differential device 64 is in a diff-lock state in which it does not function as a center differential.

[0058] Figure 6 is an operation engagement table that explains the relationship between each mode established in the transfer case 28 and the control state of each engagement device in the transfer case 28. In Figure 6, "○" indicates engagement or connection between meshing teeth, and a blank space indicates release. Note that "(○)" indicates that a blank space is acceptable when it is possible to release the first mesh clutch D1.

[0059] The "EV (FF) High" mode indicated by the number m1 and the "EV (FF) Low" mode indicated by the number m2 are realized by engaging only one of the TF clutch CF1 and the TF brake BF1 (particularly, fully engaged), while the first mesh clutch D1 is in the first state [1] and the second mesh clutch D2 is in the first state [1]. The "EV (FF) High" mode and the "EV (FF) Low" mode are transfer motor modes (TrEV modes) that enable motor running (BEV running) using only the TF rotating machine MGF as a power source. By placing the second mesh clutch D2 in the first state [1], the mutual engagement between the fourth meshing teeth a4, the fifth meshing teeth a5, and the sixth meshing teeth a6 is placed in a neutral state (see "N" in the figure), and therefore the power transmission path between the differential 64 and the rear wheels 16 is cut off. In this state, power from the TF rotary machine MGF is transmitted to the front wheels 14 through the differential 64, which is formed in a high gear by the engagement of the TF clutch CF1 or in a low gear by the engagement of the TF brake BF1. Therefore, BEV driving in this embodiment is achieved through front-wheel drive driving. The TF rotary machine MGF is a second rotary machine connected to the drive wheels DW so as to be able to transmit power. In the TrEV mode, for example, when the first mesh clutch D1 is in the first state [1], the automatic transmission 50 is placed in a neutral state, thereby eliminating drag of the engine 12. Alternatively, if the first mesh clutch D1 can be placed in a released state, in the TrEV mode, for example, the first mesh clutch D1 is placed in a released state, thereby eliminating drag of the automatic transmission 50 or the engine 12, regardless of the state of the automatic transmission 50. Furthermore, in each of the TrEV modes of the "EV (FF) High" mode and the "EV (FF) Low" mode, the automatic transmission 50 is in a power transmission enabled state, making it possible to transmit power from the first power source PU1 to the rear wheels 16, and therefore engine running using at least the engine 12 as a power source, i.e., hybrid running (=HEV running), is possible. In this engine running, for example, AWD running by parallel hybrid running, or rear-wheel drive running using only power from the first power source PU1, is possible.

[0060] The "H4_torque split" mode indicated by the number m3 is realized by disengaging the TF clutch CF1 and the TF brake BF1, setting the first mesh clutch D1 to the first state [1], and setting the second mesh clutch D2 to the second state [2]. The "H4_torque split" mode is a mode in which, for example, with the differential device 64 in a state equivalent to a high gear, torque from the first power source PU1 transmitted from the first output shaft 66 to the differential device 64 is borne by the sun gear S by the reaction torque of the TF rotary machine MGF, thereby distributing torque to the front wheels 14 and the rear wheels 16 at any desired ratio according to the reaction torque of the TF rotary machine MGF. In the "H4_torque split" mode in the transfer case 28, the TF rotary machine MGF is powered.

[0061] The "H4_LSD" mode indicated by number m4 is realized by controlling the TF clutch CF1 to an engaged state (slip engaged state or fully engaged state) while the TF brake BF1 is in a released state, the first mesh clutch D1 is in the first state [1], and the second mesh clutch D2 is in the second state [2]. The "H4_LSD" mode is a mode in which, instead of the action of the reaction torque of the TF rotary machine MGF in the "H4_torque split" mode, torque is distributed to the front wheels 14 and the rear wheels 16 at any desired ratio according to the torque capacity of the TF clutch CF1 by limiting the differential action of the differential device 64 due to the engaged state of the TF clutch CF1. In the "H4_LSD" mode, it is possible to add power from the TF rotary machine MGF to the drive torque Tr.

[0062] The "H4_Lock" mode indicated by number m5 is realized when the TF clutch CF1 and the TF brake BF1 are both released, the first mesh clutch D1 is in the first state [1], and the second mesh clutch D2 is in the third state [3]. The "H4_Lock" mode is a mode in which the differential device 64 is in a differential-lock state, and torque from the first power source PU1 transmitted to the first output shaft 66 is distributed to the front wheels 14 and the rear wheels 16. In the "H4_Lock" mode, for example, by engaging the TF clutch CF1, it is possible to add power from the TF rotary machine MGF to the drive torque Tr.

[0063] The "L4_Lock" mode indicated by number m6 is realized by disengaging the TF clutch CF1, engaging the TF brake BF1, setting the first mesh clutch D1 to the second state [2], and setting the second mesh clutch D2 to the third state [3]. The "L4_Lock" mode is a mode in which the differential device 64 is in a differential lock state and in a low gear, and torque from the first power source PU1 transmitted to the sun gear S of the differential device 64 is distributed to the front wheels 14 and the rear wheels 16. In the "L4_Lock" mode, power from the TF rotary machine MGF can be added to the drive torque Tr.

[0064] Returning to FIG. 1 , the vehicle drive system 10 includes a MOP 84 which is a mechanical oil pump, an EOP 86 which is an electric oil pump, a pump motor 88, etc. The MOP 84 is connected to the rotary machine connecting shaft 46 (see FIG. 2 ), and is rotationally driven by the first power source PU1 to discharge hydraulic oil OIL used in the power transmission device 18. The pump motor 88 is a motor dedicated to the EOP 86 for rotationally driving the EOP 86. The EOP 86 is rotationally driven by the pump motor 88 to discharge hydraulic oil OIL. The hydraulic oil OIL discharged by the MOP 84 and the EOP 86 is supplied to a hydraulic control circuit 60. The hydraulic control circuit 60 supplies the LU hydraulic pressure PRlu, the CB hydraulic pressure PRcb, the CF1 hydraulic pressure PRcf1, the BF1 hydraulic pressure PRbf1, etc., which are each adjusted based on the hydraulic oil OIL discharged by the MOP 84 and / or the EOP 86. The hydraulic oil OIL is oil that operates each of the lockup clutch LU, the engagement device CB, the TF clutch CF1, and the TF brake BF1.

[0065] The vehicle drive system 10 is equipped with an electronic control unit 130 as a controller including a control device that controls the power source PU, the transfer case 28, etc. FIG. 1 is a diagram showing the input / output system of the electronic control unit 130, and is also a functional block diagram explaining the main control functions of the electronic control unit 130. The electronic control unit 130 is configured to include 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 drive system 10 by performing signal processing according to programs stored in the ROM while utilizing the temporary storage function of the RAM. The electronic control unit 130 is configured to include various computers for engine control, gear change control, etc. as necessary.

[0066] The electronic control device 130 includes various sensors provided in the vehicle drive device 10 (for example, an engine rotation speed sensor 90, an MGM rotation speed sensor 92, a turbine rotation speed sensor 94, an AT output rotation speed sensor 96, a vehicle speed sensor 98, an MGF rotation speed sensor 100, an accelerator opening sensor 102, a throttle valve opening sensor 104, a brake pedal sensor 106, a shift position sensor 108, an acceleration sensor 110, a yaw rate sensor 112, a steering sensor 114, a battery sensor 116, an oil temperature sensor 118, an MGF temperature sensor 120, an MGF temperature sensor 122, an MGF rotation speed sensor 124, an MGF rotation speed sensor 126, an MGF rotation speed sensor 128, an MGF rotation speed sensor 128, an MGF rotation speed sensor 129, an MGF rotation speed sensor 130, an MGF rotation speed sensor 131, an MGF rotation speed sensor 132, an MGF rotation speed sensor 133, an MGF rotation speed sensor 134, an MGF rotation speed sensor 135, an MGF rotation speed sensor 136, an MGF rotation speed sensor 137, an MGF rotation speed sensor 138, an MGF rotation speed sensor 139, an MGF rotation speed sensor 140, an MGF rotation speed sensor 141, an MGF rotation speed sensor 142, an MGF rotation speed sensor 143, an MGF rotation speed sensor 144, an MGF rotation speed sensor 145, an MGF rotation speed sensor 146, an MGF rotation speed sensor 147, an MGF rotation speed sensor 148, an MGF rotation speed sensor 149, an MGF rotation speed sensor 150, an MGF rotation speed sensor 151, an MGF rotation speed sensor 152, an MGF rotation speed sensor 153, an MGF rotation speed sensor 15 , differential lock selection switch 122, low gear selection switch 124, etc.), various signals based on detected values ​​(for example, engine rotation speed Ne which is the rotation speed of the engine 12, MGM rotation speed Nmgm which is the rotation speed of the TM rotating machine MGM, turbine rotation speed Nt which is the same value as AT input rotation speed Ni, AT output rotation speed No, TF output rotation speed Nof which is the rotation speed of the first output shaft 66 corresponding to vehicle speed V, MGF rotation speed Nmgf which is the rotation speed of the TF rotating machine MGF, A which is the accelerator operation amount of the driver which indicates the magnitude of the driver's acceleration operation, the throttle opening θacc, the throttle valve opening θth which is the opening of the electronic throttle valve, a brake-on signal Bon which is a signal indicating a state in which the brake pedal for activating the wheel brakes is being operated by the driver, a shift operation position POSsh which indicates the operation position of a shift lever provided in the vehicle 8, a longitudinal acceleration Gx and a lateral acceleration Gy of the vehicle 8, a yaw rate Ryaw which is the rotational angular velocity about the vertical axis of the vehicle 8, a steering angle θsw and a steering direction Dsw of a steering wheel provided in the vehicle 8, a battery temperature THbat which is the temperature of the battery 24, a battery charge / discharge current Ibat which is the input / output current of the battery 24, a battery voltage Vbat which is the voltage of the battery 24, a hydraulic oil temperature THoil which is the temperature of the hydraulic oil OIL, an MGF temperature THmgf which is the temperature of the TF rotating machine MGF, a lock mode on signal LOCKon which is a signal indicating that the “H4_Lock” mode or the “L4_Lock” mode has been selected by the driver, and a low gear on signal LOWon which is a signal indicating that the low gear stage of the differential device 64 has been selected by the driver.

[0067] The differential lock selection switch 122 and the low gear selection switch 124 are provided, for example, near the driver's seat. The differential lock selection switch 122 is a switch that is turned on by the driver when the differential device 64 is to be placed in a differential lock state in the transfer case 28. The low gear selection switch 124 is a switch that is turned on by the driver when the differential device 64 is to be placed in a low gear when the "H4_Lock" mode is established in the transfer case 28.

[0068] The electronic control device 130 transmits various command signals (for example, an engine control command signal Se for controlling the engine 12, an MGM control command signal Smgm for controlling the TM rotating machine MGM, an MGF control command signal Smgf for controlling the TF rotating machine MGF, a hydraulic control command signal Slu for controlling the control state of the lock-up clutch LU, an engagement device C related to the control of the automatic transmission 50, and the like) to various devices (for example, the engine control device 20, the inverter 22, the hydraulic control circuit 60, the switching actuator 82, the pump motor 88, the wheel brake device 126, the information notification device 128, and the like) provided in the vehicle 8. B, a hydraulic control command signal Scbf for controlling the control state of each of the TF clutch CF1 and TF brake BF1 involved in the control of the transfer 28, a transfer control command signal Stf for operating each of the first dog clutch D1 and second dog clutch D2 involved in the control of the transfer 28, an EOP control command signal Seop for controlling the EOP 86, a brake control command signal Sb for controlling the braking force of the wheel brakes, an information notification control command signal Sinf for notifying the driver of various information, etc.

[0069] In order to realize various controls in the vehicle drive system 10, the electronic control device 130 is equipped with a transmission control means, i.e., a transmission control unit 132, a hybrid control means, i.e., a hybrid control unit 134, and a driving state control means, i.e., a driving state control unit 136.

[0070] The transmission control unit 132 determines whether to shift the automatic transmission 50 using an AT gear position shift map such as that shown in FIG. 7, and outputs a hydraulic control command signal Sat to the hydraulic control circuit 60 as necessary to control the shift of the automatic transmission 50. The AT gear position shift map is a relationship that is experimentally or design-based and stored in advance, i.e., a predetermined relationship. The AT gear position shift map is a predetermined relationship having shift lines for determining whether to shift the automatic transmission 50, on a two-dimensional coordinate system using, for example, vehicle speed V and required drive torque Trdem as variables. In the AT gear position shift map, the AT output rotation speed No may be used instead of the vehicle speed V, and the required drive force Frdem, accelerator opening θacc, throttle valve opening θth, etc. may be used instead of the required drive torque Trdem. The shift lines in the AT gear stage shift map are upshift lines indicated by solid lines for determining an upshift, and downshift lines indicated by broken lines for determining a downshift.

[0071] The hybrid control unit 134 includes a function as engine control means, i.e., an engine control unit 134a, that controls the operation of the engine 12, and a function as rotating machine control means, i.e., a rotating machine control unit 134b, that controls the operation of the TM rotating machine MGM and the TF rotating machine MGF via the inverter 22, and executes hybrid drive control using the engine 12, the TM rotating machine MGM, and the TF rotating machine MGF, etc., using these control functions.

[0072] The hybrid control unit 134 calculates the amount of driving demanded by the driver for the vehicle 8 by applying the accelerator opening θacc and the vehicle speed V to, for example, a driving demand map, which has a predetermined relationship. The amount of driving demand is, for example, the required driving torque Trdem [Nm] at the drive wheels DW. The amount of driving demand can also be the required driving force Frdem [N] at the drive wheels DW, the required driving power Prdem [W] at the drive wheels DW, the required AT output torque at the transmission output shaft 54, or the like. In other words, the required driving torque Trdem is the required driving power Prdem at the vehicle speed V at the time of command output. In calculating the amount of driving demand, the TF output rotation speed Nof, or the like, may be used instead of the vehicle speed V.

[0073] The hybrid control unit 134 outputs an engine control command signal Se, an MGM control command signal Smgm, and an MGF control command signal Smgf to realize the required drive power Prdem, taking into consideration factors such as transmission loss, the auxiliary load, the gear ratio γat of the automatic transmission 50, the chargeable power Win and dischargeable power Wout of the battery 24, etc. The engine control command signal Se is, for example, a command value for achieving the required engine power Pedem, which is a required value of the engine power Pe that outputs the engine torque Te at the engine rotation speed Ne when a command is output. The engine power Pe is the output [W] of the engine 12, i.e., power. The MGM control command signal Smgm is, for example, a command value for the consumed power Wcmgm or generated power Wgmgm of the TM rotating machine MGM that outputs the MGM torque Tmgm at the MGM rotation speed Nmgm when a command is output. The MGF control command signal Smgf is, for example, a command value for the consumed power Wcmgf or generated power Wgmgf of the TF rotating machine MGF that outputs the MGF torque Tmgf at the MGF rotation speed Nmgf when a command is output. The chargeable power Win of the battery 24 is the maximum power that can be input, which defines the limit on the input power of the battery 24, and indicates the input limit of the battery 24. The dischargeable power Wout of the battery 24 is the maximum power that can be output, which defines the limit on the output power of the battery 24, and indicates the output limit of the battery 24.

[0074] The electronic control unit 130 calculates the chargeable power Win and dischargeable power Wout of the battery 24, i.e., the chargeable and dischargeable powers Win and Wout [W], based on, for example, the battery temperature THbat and the battery charge state SOC [%]. The battery charge state SOC is the charge amount of the battery 24 and is a value indicating the state of charge of the battery 24, i.e., a state of charge value. Specifically, the electronic control unit 130 calculates the battery charge state SOC based on the battery charge / discharge current Ibat and the battery voltage Vbat, etc. The electronic control unit 130 sets basic values ​​of the chargeable and dischargeable powers Win and Wout by applying the battery temperature THbat to an input / output limit map such as that shown in FIG. 8. The input / output limit map shown in FIG. 8 is a diagram illustrating an example of a predetermined relationship between the battery temperature THbat and the basic values ​​of the chargeable and dischargeable powers Win and Wout. As shown in FIG. 8, the basic values ​​of the chargeable and dischargeable powers Win and Wout are reduced as the battery temperature THbat decreases in a low temperature range where the battery temperature THbat is lower than the normal range, and are reduced as the battery temperature THbat increases in a high temperature range where the battery temperature THbat is higher than the normal range. The electronic control unit 130 sets the chargeable power correction coefficient and the dischargeable power correction coefficient by applying the battery charge amount SOC to an input / output limit correction coefficient map such as that shown in FIG. 9. The electronic control unit 130 calculates the chargeable power Win by multiplying a basic value of the chargeable power Win of the battery 24 by the chargeable power correction coefficient, and calculates the dischargeable power Wout by multiplying a basic value of the dischargeable power Wout of the battery 24 by the dischargeable power correction coefficient. The input / output limit correction coefficient map shown in FIG. 9 is a diagram illustrating an example of a predetermined relationship between the battery charge amount SOC and each correction coefficient for each basic value of the chargeable and dischargeable power Win and Wout. Referring to FIG. 9, the chargeable power Win is reduced as the battery charge amount SOC increases in a region where the battery charge amount SOC is high. Furthermore, the dischargeable power Wout is reduced as the battery charge amount SOC decreases in a region where the battery charge amount SOC is low.

[0075] When the required driving power Prdem is in a motor driving region where the required driving power Prdem is less than a predetermined threshold, the hybrid control unit 134 establishes the BEV driving mode as the driving mode for driving the vehicle 8. On the other hand, when the required driving power Prdem is in an engine driving region where the required driving power Prdem is equal to or greater than a predetermined threshold, the hybrid control unit 134 establishes the HEV driving mode as the driving mode. The BEV driving mode is a motor driving mode that enables BEV driving using the TF rotary machine MGF as a power source while the engine 12 is stopped. The HEV driving mode is a hybrid driving mode that enables engine driving using at least the engine 12 as a power source. The dashed-dotted line A in FIG. 7 is the boundary between the engine driving region and the motor driving region. The predetermined relationship having the boundary shown by the dashed-dotted line A in FIG. 7 is an example of a driving region switching map formed by two-dimensional coordinates with the vehicle speed V and the required driving torque Trdem as variables. For convenience, this driving region switching map is shown in FIG. 7 together with an AT gear shift map.

[0076] Even when the required driving power Prdem is in the motor driving range, the hybrid control unit 134 establishes the HEV driving mode when it is necessary to charge the battery 24 or to warm up the engine 12. In other words, when it is necessary to charge the battery 24 or to warm up the engine 12, the motor driving range in the driving range switching map disappears.

[0077] The drive state control unit 136 determines which of the modes (see FIG. 6) of the transfer case 28 should be established based on, for example, the vehicle speed V, accelerator opening θacc, brake-on signal Bon, shift operation position POSsh, longitudinal acceleration Gx and lateral acceleration Gy, yaw rate Ryaw, steering angle θsw and steering direction Dsw, lock mode-on signal LOCKon, low gear-on signal LOWon, etc., and outputs various control command signals for establishing the determined mode. The various control command signals are, for example, a hydraulic control command signal Scbf for the TF clutch CF1 and TF brake BF1, and a transfer control command signal Stf for the first dog clutch D1 and second dog clutch D2.

[0078] In the BEV drive mode, for example, the drive state control unit 136 engages the TF brake BF1 and disengages the TF clutch CF1 to form a low gear in the differential device 64 in a relatively low vehicle speed range, while disengaging the TF brake BF1 and engaging the TF clutch CF1 to form a high gear in the differential device 64 in a relatively high vehicle speed range. That is, in the BEV drive mode, the drive state control unit 136 establishes, for example, an "EV (FF) low" mode in a relatively low vehicle speed range, while establishing an "EV (FF) high" mode in a relatively high vehicle speed range. In the TrEV mode, the hybrid control unit 134 can set the MGF torque Tmgf to the drive torque Tr.

[0079] In the "H4_torque split" mode or the "H4_LSD" mode, the drive state control unit 136 determines the driving state of the vehicle 8 based on various signals from various sensors, such as the vehicle speed sensor 98, the acceleration sensor 110, and the yaw rate sensor 112, and sets a target value for the torque distribution ratio Rx according to the determined driving state. The torque distribution ratio Rx is the ratio of torque from the power source PU that is distributed to the front wheels 14 and the rear wheels 16. The torque distribution ratio Rx can be expressed, for example, as the ratio of torque transmitted to the rear wheels 16 to the total torque transmitted from the power source PU to the rear wheels 16 and the front wheels 14, i.e., the rear-wheel distribution ratio Xr. Alternatively, the torque distribution ratio Rx can be expressed, for example, as the ratio of torque transmitted to the front wheels 14 to the total torque transmitted from the power source PU to the rear wheels 16 and the front wheels 14, i.e., the front-wheel distribution ratio Xf (= 1 - Xr).

[0080] In the "H4_torque split" mode, the driving state control unit 136 outputs an MGF control command signal Smgf for controlling the TF rotating machine MGF so that the rear wheel side distribution rate Xr becomes a target value by adjusting the MGF torque Tmgf that generates a reaction torque by the TF rotating machine MGF. The larger the MGF torque Tmgf, the smaller the rear wheel side distribution rate Xr becomes, that is, the larger the front wheel side distribution rate Xf becomes. When the TF clutch CF1 is in a released state, the driving state control unit 136 can control the torque distribution ratio Rx by controlling the MGF torque Tmgf.

[0081] In the "H4_LSD" mode, the driving state control unit 136 outputs a hydraulic control command signal Scbf for controlling the engagement state (slip engagement state or full engagement state) of the TF clutch CF1 by adjusting the torque capacity of the TF clutch CF1 so that the rear wheel side distribution rate Xr becomes a target value. The larger the torque capacity of the TF clutch CF1, the smaller the rear wheel side distribution rate Xr becomes. The driving state control unit 136 can control the torque distribution ratio Rx by controlling the engagement state of the TF clutch CF1, that is, by controlling the torque capacity of the TF clutch CF1 in the engaged state. In the "H4_LSD" mode, the hybrid control unit 134 can add the MGF torque Tmgf to the driving torque Tr.

[0082] When the driver turns the differential lock selection switch 122 to the on state in the "H4_torque split" mode or the "H4_LSD" mode, the drive state control unit 136 establishes the "H4_Lock" mode. In the "H4_Lock" mode, the hybrid control unit 134 can add the MGF torque Tmgf to the drive torque Tr by engaging the TF clutch CF1.

[0083] The driving state control unit 136 establishes the "L4_Lock" mode when the vehicle 8 is stopped in the "H4_Lock" mode and the driver operates the low gear selection switch 124 to the on state. In the "L4_Lock" mode, the hybrid control unit 134 can add the MGF torque Tmgf to the driving torque Tr.

[0084] The hybrid control unit 134 can drive the TF rotating machine MGF as a power source when the TF clutch CF1 is in an engaged state (see "EV(FF) High" mode, "H4_LSD" mode, and "H4_Lock" mode). Also, the hybrid control unit 134 can drive the TF rotating machine MGF as a power source when the TF brake BF1 is in an engaged state (see "EV(FF) Low" mode and "L4_Lock" mode).

[0085] Here, the fact that the engine operating point PNTeng can be changed in the vehicle drive system 10 in the same way as in a continuously variable transmission will be explained using Figure 10. The engine operating point PNTeng is the operating point, or operating point, of the engine 12, which is expressed by the engine rotation speed Ne and the engine torque Te.

[0086] In FIG. 10 , the constant power line Lpe, indicated by a two-dot chain line, represents an example of the required engine power Pedem required to achieve the required drive power Prdem calculated based on the accelerator opening θacc, etc. The required engine power Pedem is the engine power Pe required by the driver's operation, such as accelerator operation. On the other hand, the dashed line L01 represents, for convenience's sake, an example of the pump torque Tp, which is the torque generated in the pump wheel 48a according to the speed ratio e (=Nt / Np) of the torque converter 48, on a two-dimensional coordinate system using the engine rotation speed Ne and the engine torque Te as variables. The pump rotation speed Np is the rotation speed of the pump wheel 48a and is equal to the engine rotation speed Ne. At a constant turbine rotation speed Nt, the pump torque Tp shows a relationship with the engine rotation speed Ne, which is determined by hardware requirements, as shown by the dashed line L01. When the required engine power Pedem is, for example, the two-dot chain line L02, the engine operating point PNTeng is naturally determined to be the so-called coupling point P01, which is the point where the dashed line L01 and the two-dot chain line L02 overlap.

[0087] For example, by operating the TM rotary machine MGM to generate electricity using a portion of the engine power Pe at the coupling point P01, the engine operating point PNTeng can be changed to, for example, a fuel economy optimal point P02 on the fuel economy optimal line Lfl indicated by the solid line L03, without changing the required engine power Pedem. The fuel economy optimal line Lfl is a predetermined operating curve for the engine 12 that represents the relationship between the engine rotation speed Ne and the engine torque Te at which the fuel economy of the engine 12 is best achieved, and is a series of fuel economy optimal points that are predetermined as the engine operating point PNTeng that is optimal for improving the fuel economy of the engine 12. In the vehicle drive system 10, the MGM torque Tmgm is adjusted so that the sum of the engine torque Te and the MGM torque Tmgm balances with the pump torque Tp, that is, so that the relationship "Tp = Te + Tmgm (Tmgm is a negative value in FIG. 10)" is established, thereby making it possible to arbitrarily change the engine operating point PNTeng without being constrained by the turbine rotation speed Nt. When the MGM torque Tmgm is a negative value, that is, when the TM rotating machine MGM is operated to generate electricity, the electric power generated by the TM rotating machine MGM is basically supplied to the TF rotating machine MGF and converted into mechanical power by the TF rotating machine MGF. The vehicle drive system 10 is equipped with, as power transmission paths for the engine power Pe, an electric path that is an electric path through which power is electrically transmitted by receiving and sending electric power between the TM rotating machine MGM and the TF rotating machine MGF, and a mechanical path that is a mechanical path through which power is mechanically transmitted via the torque converter 48. In the vehicle drive system 10, an electric continuously variable transmission is formed using the TM rotating machine MGM and the TF rotating machine MGF.

[0088] The hybrid control unit 134 controls the engine operating point PNTeng by adjusting the electrical path amount Ppse [W], which is the amount of power in the electrical path through which power is exchanged between the TM rotating machine MGM and the TF rotating machine MGF. The electrical path amount Ppse is particularly the amount of power sent from the TM rotating machine MGM in the electrical path. The electrical path amount Ppse is, for example, the product of the MGM torque Tmgm and the MGM rotation speed Nmgm.

[0089] The hybrid control unit 134 calculates a target electricity path amount Ppsetgt, which is the electricity path amount Ppse for changing the engine operating point PNTeng to the target operating point PNTtgt. The target operating point PNTtgt is, for example, a fuel efficiency optimal point, and is the fuel efficiency optimal point P02 when the required engine power Pedem is the two-dot chain line L02 (see FIG. 10). The target electricity path amount Ppsetgt is the product of the MGM torque Tmgm when the engine operating point PNTeng is changed from the coupling point to the target operating point PNTtgt and the engine rotation speed Ne at the target operating point PNTtgt, i.e., the MGM rotation speed Nmgm. The hybrid control unit 134 controls the MGM torque Tmgm and drives the TF rotating machine MGF so that the electricity path amount Ppse from the TM rotating machine MGM to the TF rotating machine MGF becomes the target electricity path amount Ppsetgt. This improves the combustion efficiency of the engine 12 even with the same engine power Pe, thereby improving the fuel efficiency of the engine 12.

[0090] Here, when the TM rotary machine MGM is operated to generate electricity so that the electrical path amount Ppse becomes the target electrical path amount Ppsetgt, the power of the mechanical path is transmitted through the torque converter 48 with the lockup clutch LU in a disengaged state. On the other hand, when the power of the engine 12 is transmitted through the torque converter 48, the power loss in the torque converter 48 is suppressed when the lockup clutch LU is in an engaged state rather than in a disengaged state. For this reason, the fuel efficiency of the entire vehicle 8 may not necessarily be optimal even if the engine operating point PNTeng is controlled to the target operating point PNTtgt.

[0091] Therefore, the electronic control device 130 compares the fuel efficiency of the vehicle 8 when the TM rotating machine MGM is operated to generate electricity so that the electrical path amount Ppse becomes the target electrical path amount Ppsetgt, and when the lock-up clutch LU is engaged to transmit the power of the engine 12, and controls the drive of the vehicle 8 using the one with the better fuel efficiency.

[0092] A lockup point P03 in Figure 10 indicates an engine operating point PNTeng at which the lockup clutch LU is fully engaged while maintaining the required engine power Pedem relative to the coupling point P01 when using a mechanical path. The engine speed Ne at the lockup point P03 is set to the turbine speed Nt (= γat × No), which is determined based on the speed ratio γat in the AT gear position of the automatic transmission 50 and the AT output speed No. Furthermore, an LU slip engagement point P04 in Figure 10 indicates an engine operating point PNTeng at which the lockup clutch LU is slip-engaged while maintaining the required engine power Pedem relative to the coupling point P01 when using a mechanical path. The engine speed Ne at the LU slip engagement point P04 is set to a speed higher than the engine speed Ne at the lockup point P03 by the slip rotation speed of the lockup clutch LU.

[0093] The electronic control unit 130 establishes a first control mode MC1 as a control mode MC for drive control of the vehicle 8. The first control mode MC1 controls the lockup clutch LU to a disengaged state and causes the TM rotary machine MGM to generate electricity so that the electric path amount Ppse becomes the target electric path amount Ppsetgt. The electronic control unit 130 also establishes a second control mode MC2 as a control mode MC. The second control mode MC2 controls the lockup clutch LU to an engaged state and transmits the power of the engine 12 via the torque converter 48 with the lockup clutch LU engaged. The electronic control unit 130 can selectively establish the first control mode MC1 or the second control mode MC2 as the control mode MC. Based on the running state of the vehicle 8, the electronic control unit 130 selects the control mode MC that improves the fuel efficiency of the vehicle 8 from the first control mode MC1 or the second control mode MC2.

[0094] Specifically, the hybrid control unit 134 calculates the fuel efficiency of the vehicle 8 when the control mode MC is set to the first control mode MC1. The hybrid control unit 134 calculates the product of the engine efficiency and the power transmission efficiency when the engine operating point PNTeng is controlled to the target operating point PNTtgt as the fuel efficiency of the vehicle 8 in the first control mode MC1. The engine efficiency in the first control mode MC1 is a predetermined engine efficiency when the engine operating point PNTeng is set to the fuel efficiency optimum point (see the fuel efficiency optimum point P02 in FIG. 10 ). The power transmission efficiency in the first control mode MC1 is, for example, the sum of a value obtained by multiplying the power transmission efficiency in the electric path by the usage rate of the electric path and a value obtained by multiplying the power transmission efficiency in the mechanical path when the lock-up clutch LU is in the released state by the usage rate of the mechanical path. The power transmission efficiency in the electric path is the power transmission efficiency of electricity when power is transmitted via the electric path, and is a predetermined value that changes little with the speed ratio e of the torque converter 48, as shown by the solid line B in FIG. 11 , for example. The power transmission efficiency of the mechanical path when the lock-up clutch LU is disengaged is the power transmission efficiency of fluid transmission when power is transmitted through the torque converter 48 with the lock-up clutch LU disengaged. For example, as shown by the two-dot chain line C in FIG. 11 , this value is predetermined and varies depending on the speed ratio e of the torque converter 48. The power transmission efficiency of fluid transmission shown by the two-dot chain line C in FIG. 11 reaches a maximum value at a predetermined speed ratio e and becomes zero when the speed ratio e is zero. In the coupling region where the speed ratio e is large, the power transmission efficiency increases as the speed ratio e increases. Looking at the torque converter region and the coupling region as a whole, the power transmission efficiency of fluid transmission is highest when the speed ratio e is close to 1. FIG. 11 is a graph showing an example of a predetermined relationship between the power transmission efficiency of electrical transmission and the power transmission efficiency of fluid transmission and the speed ratio e of the torque converter 48.

[0095] The hybrid control unit 134 calculates the fuel efficiency of the vehicle 8 when the control mode MC is set to the second control mode MC2. The hybrid control unit 134 calculates the product of the engine efficiency and the power transmission efficiency when the lockup clutch LU is engaged as the fuel efficiency of the vehicle 8 in the second control mode MC2. The engine efficiency in the second control mode MC2 is a predetermined engine efficiency when the engine operating point PNTeng is set to the lockup point (see lockup point P03 in FIG. 10) or the LU slip engagement point (see LU slip engagement point P04 in FIG. 10). The power transmission efficiency in the second control mode MC2 is, for example, the power transmission efficiency when a mechanical path is used when the lockup clutch LU is engaged. The power transmission efficiency when this mechanical path is used is a predetermined power transmission efficiency when power is transmitted via the torque converter 48 with the lockup clutch LU engaged, and is, for example, 100% excluding losses in the power transmission path.

[0096] The hybrid control unit 134 determines whether the fuel economy of the vehicle 8 in the first control mode MC1 is better than the fuel economy of the vehicle 8 in the second control mode MC2. If the hybrid control unit 134 determines that the fuel economy of the vehicle 8 in the first control mode MC1 is better than the fuel economy of the vehicle 8 in the second control mode MC2, it selects the first control mode MC1 as the control mode MC. If the hybrid control unit 134 determines that the fuel economy of the vehicle 8 in the second control mode MC2 is better than the fuel economy of the vehicle 8 in the first control mode MC1, it selects the second control mode MC2 as the control mode MC.

[0097] However, for example, when switching from the second control mode MC2 to the first control mode MC1, if the electrical path amount Ppse is made smaller than the target electrical path amount Ppsetgt, that is, if the electrical path amount Ppse is limited relative to the target electrical path amount Ppsetgt, it becomes difficult to achieve the target electrical path amount Ppsetgt. As a result, the first control mode MC1 cannot be continued, and the fuel efficiency of the vehicle 8 may deteriorate. This may result in a need to switch back to the second control mode MC2, which may cause busy switching of the control mode MC.

[0098] Therefore, the hybrid control unit 134 predicts whether the electricity path amount Ppse will be reduced relative to the target electricity path amount Ppsetgt, that is, whether the electricity path amount Ppse will be limited relative to the target electricity path amount Ppsetgt. If the hybrid control unit 134 predicts that the electricity path amount Ppse will not be reduced relative to the target electricity path amount Ppsetgt, that is, if the hybrid control unit 134 predicts that the electricity path amount Ppse will not be limited relative to the target electricity path amount Ppsetgt, the hybrid control unit 134 selects, as the control mode MC, one of the first control mode MC1 and the second control mode MC2, which improves the fuel efficiency of the vehicle 8. If the hybrid control unit 134 predicts that the electricity path amount Ppse will be limited relative to the target electricity path amount Ppsetgt, the hybrid control unit 134 selects, as the control mode MC, the second control mode MC2, regardless of whether the second control mode MC2 improves the fuel efficiency of the vehicle 8.

[0099] In the "H4_torque split" mode, the powering operation of the TF rotating machine MGF is controlled so that the torque distribution ratio Rx becomes a target value. Therefore, when an electric path is used, the required electric path amount Ppse is the MGF discharge amount Pmgf [W], which is the electric power during the powering operation of the TF rotating machine MGF that is required to control the torque distribution ratio Rx to the target value. The MGF discharge amount Pmgf is, for example, the product of the MGF torque Tmgf and the MGF rotation speed Nmgf when controlling the torque distribution ratio Rx to become the target value. Because the MGF discharge amount Pmgf is constrained by the target value of the torque distribution ratio Rx, the electric path amount Ppse is limited to the target electric path amount Ppsetgt, and there is a risk that the first control mode MC1 cannot be continued. Alternatively, because the MGF discharge amount Pmgf changes according to the target value of the torque distribution ratio Rx, the required electrical path amount Ppse increases or decreases due to control of the torque distribution ratio Rx, which may result in switching between the first control mode MC1 and the second control mode MC2 each time. Therefore, the hybrid control unit 134 selects the second control mode MC2 as the control mode MC in the "H4_torque split" mode. In other words, while the "H4_torque split" mode is being executed, that is, when the torque distribution ratio Rx is being controlled by controlling the MGF torque Tmgf, the hybrid control unit 134 predicts that the electrical path amount Ppse will be limited to the target electrical path amount Ppsetgt.

[0100] On the other hand, when the TF clutch CF1 is in an engaged state (see "EV(FF) High" mode, "H4_LSD" mode, and "H4_Lock" mode), or when the TF brake BF1 is in an engaged state (see "EV(FF) Low" mode and "L4_Lock" mode), the hybrid control unit 134 can drive the TF rotating machine MGF as a power source using the electric path amount Ppse equal to the target electric path amount Ppsetgt. Therefore, when the TF rotating machine MGF can be driven as a power source, the hybrid control unit 134 predicts that the electric path amount Ppse will not be limited with respect to the target electric path amount Ppsetgt, and selects, as the control mode MC, the first control mode MC1 or the second control mode MC2, whichever improves the fuel efficiency of the vehicle 8. In other words, when the TF clutch CF1 is in an engaged state or when the TF brake BF1 is in an engaged state, the hybrid control unit 134 predicts that the electrical path amount Ppse will not be limited to the target electrical path amount Ppsetgt, and selects as the control mode MC the first control mode MC1 or the second control mode MC2 that improves the fuel efficiency of the vehicle 8.

[0101] A load factor limit may be imposed on the TF rotating machine MGF, limiting the MGF discharge amount Pmgf during powering operation of the TF rotating machine MGF. The load factor limit on a rotating machine is a numerical value that indicates the allowable load when the rated power of the rotating machine is 100%. In other words, the output of the TF rotating machine MGF may be limited relative to the rated output. In this case, the limited MGF discharge amount Pmgf is set as the upper limit value of the electrical path amount Ppse. When a load factor limit is imposed on the TF rotating machine MGF, the hybrid control unit 134 predicts that the electrical path amount Ppse will be limited relative to the target electrical path amount Ppsetgt. A typical example of a load factor limit on the TF rotating machine MGF is when the TF rotating machine MGF becomes hot. The load factor limit on the TF rotating machine MGF is gradually reduced from a maximum of 100% as the temperature increases, for example, in a high-temperature region. The hybrid control unit 134 determines whether a load factor limit is applied to the TF rotating machine MGF based on whether the MGF temperature THmgf is within a predetermined high temperature range in which the output of the TF rotating machine MGF is limited relative to the rated output. Note that a load factor limit may also be applied to the TM rotating machine MGM, in which case the upper limit of the electrical path amount Ppse is the limited power generation of the TM rotating machine MGM. When a load factor limit is applied to the TM rotating machine MGM, the hybrid control unit 134 may predict that the electrical path amount Ppse will be limited relative to the target electrical path amount Ppsetgt.

[0102] Even if the electricity path amount Ppse is predicted to be limited relative to the target electricity path amount Ppsetgt, as long as the battery 24 can be charged with power that is insufficient for the electricity path amount Ppse required for the target electricity path amount Ppsetgt, the first control mode MC1 or the second control mode MC2, whichever improves the fuel efficiency of the vehicle 8, may be selected as the control mode MC. The hybrid control unit 134 determines whether the battery charge amount SOC is within a predetermined low charge amount range in which charging of the electricity path amount Ppse controlled to the target electricity path amount Ppsetgt is permitted. For example, the hybrid control unit 134 determines whether the battery charge amount SOC is within the low charge amount range based on whether the battery charge amount SOC is lower than 40%. When the hybrid control unit 134 determines that the battery charge amount SOC is within the low charge amount range, it selects the control mode MC that improves the fuel efficiency of the vehicle 8 from the first control mode MC1 and the second control mode MC2, even if it predicts that the electric path amount Ppse will be limited to the target electric path amount Ppsetgt.

[0103] From another perspective, if the chargeable power Win of the battery 24 is limited and reduced relative to its maximum value, there is a possibility that the power that is insufficient for the required electric path amount Ppse relative to the target electric path amount Ppsetgt cannot be charged to the battery 24. In this case, the electric path amount Ppse may be considered to be limited relative to the target electric path amount Ppsetgt. If the chargeable power Win is within a predetermined low power range in which charging of the electric path amount Ppse controlled to be the target electric path amount Ppsetgt is limited, the hybrid control unit 134 predicts that the electric path amount Ppse will be limited relative to the target electric path amount Ppsetgt. The hybrid control unit 134 determines whether the chargeable power Win is within the low power range based on whether the battery state of charge SOC is within a predetermined high charge amount range in which charging of the electric path amount Ppse controlled to be the target electric path amount Ppsetgt is limited (see "high charge amount range" in FIG. 9). The hybrid control unit 134 determines whether the chargeable power Win is within a low power range based on whether the battery temperature THbat is within a predetermined low temperature range or high temperature range in which charging of the electric path amount Ppse, which is controlled so that the battery temperature THbat becomes the target electric path amount Ppsetgt, is restricted (see "low temperature range" and "high temperature range" in Figure 8).

[0104] Figure 12 is a flowchart explaining the main parts of the control operation of the electronic control unit 130, and is a flowchart explaining the control operation for suppressing busy switching of the control mode MC due to the electrical path amount Ppse being limited to the target electrical path amount Ppsetgt, and is executed, for example, repeatedly.

[0105] 12, each step of the flowchart corresponds to a function of the hybrid control unit 134. First, in step (hereinafter, "step" will be omitted) S10, it is predicted whether or not the electric path amount Ppse is limited to the target electric path amount Ppsetgt. If the determination in S10 is affirmative, it is determined in S20 whether or not the battery charge amount SOC is within a low charge amount range based on whether or not the battery charge amount SOC is lower than 40%. If the determination in S10 is negative, or if the determination in S20 is affirmative, the fuel economy of the vehicle 8 in the first control mode MC1 is calculated in S30. Next, the fuel economy of the vehicle 8 in the second control mode MC2 is calculated in S40. Next, it is determined in S50 whether or not the fuel economy of the vehicle 8 in the first control mode MC1 is better than the fuel economy of the vehicle 8 in the second control mode MC2. If the determination in S50 is affirmative, the first control mode MC1 is selected as the control mode MC in S60. If the determination in S20 above is negative, or if the determination in S50 above is negative, the second control mode MC2 is selected as the control mode MC in S70.

[0106] As described above, according to this embodiment, when it is predicted that the electrical path amount Ppse will be limited relative to the target electrical path amount Ppsetgt, the second control mode MC2 is selected as the control mode MC. Therefore, when the electrical path amount Ppse is likely to be limited relative to the target electrical path amount Ppsetgt, switching from the second control mode MC2 to the first control mode MC1 is suppressed. This suppresses the need to switch to the second control mode MC2 after switching to the first control mode MC1. Therefore, it is possible to suppress busy switching of the control mode MC that occurs when the electrical path amount Ppse is limited relative to the target electrical path amount Ppsetgt.

[0107] Furthermore, according to this embodiment, since it is predicted that the electrical path amount Ppse will be limited relative to the target electrical path amount Ppsetgt while the "H4_torque split" mode is being executed, when the electrical path amount Ppse is constrained by control of the torque distribution ratio Rx, the second control mode MC2 is selected as the control mode MC. This avoids switching between the first control mode MC1 and the second control mode MC2 that accompanies control of the torque distribution ratio Rx, and makes it possible to maintain torque distribution between the front wheels 14 and the rear wheels 16.

[0108] Furthermore, according to this embodiment, when the TF rotating machine MGF can be driven and operated as a power source, it is predicted that the electrical path amount Ppse will not be limited to the target electrical path amount Ppsetgt, and the control mode MC that improves the fuel efficiency of the vehicle 8 is selected from the first control mode MC1 and the second control mode MC2.Therefore, when the need to switch to the second control mode MC2 after switching to the first control mode MC1 is suppressed by being able to drive and operate the TF rotating machine MGF, busy switching of the control mode MC can be suppressed and the fuel efficiency of the vehicle 8 can be improved.

[0109] Furthermore, according to this embodiment, the TF rotating machine MGF can be used as a power source for driving operation. The engagement states of the TF clutch CF1 include a slip engagement state and a full engagement state, and the torque distribution ratio Rx is controlled by controlling the engagement state of the TF clutch CF1, so that the torque distribution between the front wheels 14 and the rear wheels 16 can be maintained.

[0110] Furthermore, according to this embodiment, when it is determined that the battery charge amount SOC is within the low charge amount range, even if it is predicted that the electric path amount Ppse will be limited relative to the target electric path amount Ppsetgt, the first control mode MC1 or the second control mode MC2, whichever improves the fuel efficiency of the vehicle 8, is selected as the control mode MC. Therefore, since the amount of power that is insufficient for the electric path amount Ppse required for the target electric path amount Ppsetgt can be charged to the battery 24, when the need to switch to the second control mode MC2 after switching to the first control mode MC1 is suppressed, busy switching of the control mode MC can be suppressed and the fuel efficiency of the vehicle 8 can be improved.

[0111] Furthermore, according to this embodiment, when the output of the TF rotating machine MGF is limited, it is predicted that the electrical path amount Ppse will be limited relative to the target electrical path amount Ppsetgt, and therefore when the electrical path amount Ppse is limited by limiting the output of the TF rotating machine MGF, the second control mode MC2 is selected as the control mode MC, and switching from the second control mode MC2 to the first control mode MC1 is suppressed. This suppresses the need to switch to the second control mode MC2 after switching to the first control mode MC1.

[0112] Furthermore, according to this embodiment, whether the output of the TF rotating machine MGF is limited is determined based on whether the MGF temperature THmgf is within the high temperature range, so that it is appropriately predicted whether the electrical path amount Ppse is limited relative to the target electrical path amount Ppsetgt.

[0113] Furthermore, according to this embodiment, when the chargeable power Win is within the low power range, it is predicted that the electrical path amount Ppse will be limited relative to the target electrical path amount Ppsetgt. Therefore, when the electrical path amount Ppse is limited due to the limitation on the chargeable power Win, the second control mode MC2 is selected as the control mode MC, and switching from the second control mode MC2 to the first control mode MC1 is suppressed. This suppresses the need to switch to the second control mode MC2 after switching to the first control mode MC1.

[0114] Furthermore, according to this embodiment, whether the chargeable power Win is within the low power range is determined based on whether the battery charge amount SOC is within the high charge amount range, so that it is appropriately predicted whether the electrical path amount Ppse is limited to the target electrical path amount Ppsetgt.

[0115] Furthermore, according to this embodiment, whether the chargeable power Win is within the low power range is determined based on whether the battery temperature THbat is within the low temperature range or the high temperature range, so that it is appropriately predicted whether the electrical path amount Ppse is limited to the target electrical path amount Ppsetgt.

[0116] Furthermore, according to this embodiment, the target operating point PNTtgt is the optimum fuel economy point, so busy switching of the control mode MC can be suppressed and the fuel economy of the vehicle 8 can be improved.

[0117] Next, another embodiment of the present invention will be described. In the following description, parts common to the embodiments will be given the same reference numerals and the description thereof will be omitted. [Example]

[0118] FIG. 13 is a diagram illustrating the schematic configuration of a transfer 200 different from the transfer 28 of FIG. 4. The transfer 200 is a torque distribution device similar to the transfer 28 and replaces the transfer 28 in the vehicle drive system 10. In FIG. 13, the transfer 200 includes a TF input shaft 204, a differential 206, a TF clutch CF1, a TF brake BF1, a first output shaft 208, an intermediate shaft 210, a first mesh clutch D1, a second mesh clutch D2, and a drive gear 212, which are arranged on a common rotation axis CL1 within a transfer case 202, which is a non-rotating member. The differential 206, the TF clutch CF1, the TF brake BF1, the intermediate shaft 210, the first mesh clutch D1, the second mesh clutch D2, and the drive gear 212 are configured substantially symmetrically with respect to the rotation axis CL1, and the lower half of the components with respect to the rotation axis CL1 is omitted in FIG. 13.

[0119] The transfer 200 also includes a second output shaft 214, a driven gear 216, and other components disposed on a common rotational axis CL2 within the transfer case 202. The driven gear 216 is configured substantially symmetrically with respect to the rotational axis CL2, and the upper half of the driven gear 216 with respect to the rotational axis CL2 is omitted in Figure 13. In the transfer 200, the rotational axis CL2 is the axis of the second output shaft 214, etc.

[0120] The transfer 200 is provided with a TF rotating machine MGF, a rotating machine connecting gear pair 218, and a chain 220 within a transfer case 202. The rotating machine connecting gear pair 218 is made up of a TF rotating machine connecting gear 218a that rotates integrally with a rotor shaft 222 of the TF rotating machine MGF, and a TF counter gear 218b that is constantly meshed with the TF rotating machine connecting gear 218a. The chain 220 is a member that connects the drive gear 212 and the driven gear 216.

[0121] 4, the transfer 200 is provided with a switching actuator (not shown) fixed to the transfer case 202 for actuating the first dog clutch D1 and the second dog clutch D2. The first sleeve d1s of the first dog clutch D1 is moved in the direction of the rotation axis CL1 by the switching actuator. The second sleeve d2s of the second dog clutch D2 is moved in the direction of the rotation axis CL1 by the switching actuator.

[0122] The TF input shaft 204 is connected to the transmission output shaft 54 ​​so as to be able to transmit power. The first output shaft 208 is connected to the rear propeller shaft 32 so as to be able to transmit power. The second output shaft 214 is connected to the front propeller shaft 30 so as to be able to transmit power. The driven gear 216 is fixed to the second output shaft 214 so as not to be able to rotate relative to it. The TF counter gear 218b is fixed to the intermediate shaft 210 so as not to be able to rotate relative to it.

[0123] The differential device 206 is configured as a single-pinion planetary gear device and includes a sun gear S, a carrier CA, and a ring gear R. The sun gear S is fixed to the intermediate shaft 210 so as to be non-rotatable relative to the intermediate shaft 210. Therefore, the TF rotating machine MGF is connected to the sun gear S via a rotating machine connecting gear pair 218. The carrier CA is fixed to the first output shaft 208 so as to be non-rotatable relative to the intermediate shaft 210. The ring gear R is selectively connected to the transfer case 202 via a TF brake BF1. The sun gear S and the carrier CA are selectively connected to each other via a TF clutch CF1.

[0124] The first meshing teeth a1 of the first mesh clutch D1 are fixed to the TF input shaft 204 so as to be non-rotatable relative to the TF input shaft 204. The second meshing teeth a2 of the first mesh clutch D1 are fixed to the first output shaft 208 so as to be non-rotatable relative to the TF input shaft 204. The third meshing teeth a3 of the first mesh clutch D1 are fixed to the intermediate shaft 210 so as to be non-rotatable relative to the TF input shaft 204. For convenience, FIG. 13 illustrates a plurality of first sleeves d1s of the first mesh clutch D1, one for each of the first state [1] and the second state [2].

[0125] The fourth meshing tooth a4 of the second mesh clutch D2 is connected to the ring gear R. The fifth meshing tooth a5 of the second mesh clutch D2 is fixed to the first output shaft 208 so as to be unable to rotate relative to the first output shaft 208. The sixth meshing tooth a6 of the second mesh clutch D2 is connected to the drive gear 212. For convenience, FIG. 13 illustrates a plurality of second sleeves d2s of the second mesh clutch D2, one for each of the first state [1], the second state [2], and the third state [3].

[0126] Fig. 14 is a nomographic diagram showing the relative relationship between the rotational speeds of the rotating elements in transfer 200. In Fig. 14, three vertical lines Y1, Y2, and Y3 corresponding to the three rotating elements of differential device 206 that make up transfer 200 are axes that, from left to right, represent the rotational speed of sun gear S corresponding to first rotating element RE1, the rotational speed of carrier CA corresponding to second rotating element RE2, and the rotational speed of ring gear R corresponding to third rotating element RE3. Vertical line Y0, shown to the left of vertical line Y1, is an axis that represents the rotational speed of first output shaft 208 corresponding to input / output rotating element REIO.

[0127] 14, in the transfer 200, the input / output rotary element REIO is selectively connected to the TF input shaft 204 via the first mesh clutch D1 (see the first state [1]) and is also connected to the rear propeller shaft 32. The TF input shaft 204 is connected to the first power source PU1 including the engine 12 via the hybrid transmission 26 so as to be able to transmit power. In the differential device 206, the first rotating element RE1 is connected to the TF rotating machine MGF so as to be able to transmit power and is selectively connected to the TF input shaft 204 via the first dog clutch D1 (see the second state [2]), the second rotating element RE2 is connected to the first output shaft 208, i.e., the rear propeller shaft 32, and is selectively connected to the second output shaft 214, i.e., the front propeller shaft 30, via the second dog clutch D2 (see the third state [3]), and the third rotating element RE3 is selectively connected to the second output shaft 214 via the second dog clutch D2 (see the second state [2]) and is selectively connected to the transfer case 202 via the TF brake BF1. The first rotating element RE1 and the second rotating element RE2 are selectively connected to each other via the TF clutch CF1. In the differential device 206, the relationship between the rotational speeds of the first rotating element RE1, the second rotating element RE2, and the third rotating element RE3 is indicated by the line Lcd. The first output shaft 208 is an output shaft to which power from the first power source PU1 is input via the torque converter 48 and which outputs the power to the rear wheels 16. The second output shaft 214 is an output shaft which outputs the power to the front wheels 14.

[0128] The differential device 206 functions as a transmission that selectively establishes a high gear stage by engaging the TF clutch CF1 and a low gear stage by engaging the TF brake BF1.

[0129] The differential device 206 also functions as a center differential. In this case, when the first mesh clutch D1 is in the first state [1] and the second mesh clutch D2 is in the second state [2] in the transfer 200, the differential device 206 can distribute the torque from the first power source PU1 input to the second rotating element RE2 to the third rotating element RE3 by using the reaction torque of the TF rotating machine MGF connected to the first rotating element RE1. Instead of using the reaction torque of the TF rotating machine MGF, the differential device 206 can distribute the torque from the first power source PU1 input to the second rotating element RE2 to the third rotating element RE3 by limiting the differential action of the differential device 206 with the TF clutch CF1 in an engaged state (slip-engaged state or fully engaged state). In this way, the transfer 200 is a torque distribution device that distributes a portion of the torque from the first power source PU1 input to the first output shaft 208 to the second output shaft 214. This allows the transfer 200 to distribute torque to the front wheels 14 and the rear wheels 16. When the second mesh clutch D2 of the transfer 200 is in the third state [3], the differential 206 is in a diff-lock state in which it does not function as a center differential.

[0130] FIG. 15 is an operation engagement table that explains the relationship between each mode established in transfer case 200 and the control state of each engagement device in transfer case 200. In FIG. 15, "○" indicates engagement or connection between meshing teeth, and a blank space indicates release. "(○)" indicates that a blank space is acceptable when first mesh clutch D1 can be released. FIG. 15 differs from the operation engagement table of FIG. 6 mainly in that the "EV (FF) High" mode indicated by number m1 becomes the "EV (FR) High" mode, and the "EV (FF) Low" mode indicated by number m2 becomes the "EV (FR) Low" mode. The differences between FIG. 15 and FIG. 6 will be explained below.

[0131] The "EV (FR) High" mode numbered m1 and the "EV (FR) Low" mode numbered m2 are both TrEV modes. In the "EV (FR) High" mode and the "EV (FR) Low" mode, the second mesh clutch D2 is set to the first state [1], which places the fourth meshing tooth a4, the fifth meshing tooth a5, and the sixth meshing tooth a6 in a neutral state (see "N" in the figure), thereby cutting off the power transmission path between the differential device 206 and the front wheels 14. In this state, power from the TF rotary machine MGF is transmitted to the rear wheels 16 in the differential device 206, which is set to a high gear by the engagement of the TF clutch CF1 or a low gear by the engagement of the TF brake BF1. Therefore, BEV driving in this embodiment is achieved by rear-wheel drive driving. In the TrEV mode, for example, when the first mesh clutch D1 is in the first state [1], the automatic transmission 50 is placed in a neutral state, thereby eliminating drag of the engine 12. Alternatively, if the first mesh clutch D1 can be placed in a disengaged state, in the TrEV mode, for example, the first mesh clutch D1 is placed in a disengaged state, thereby eliminating drag of the automatic transmission 50 and the engine 12 regardless of the state of the automatic transmission 50. Furthermore, in each of the TrEV modes in the "EV (FR) High" mode and the "EV (FR) Low" mode, the automatic transmission 50 is placed in a power transmission enabled state, thereby enabling power from the first power source PU1 to be transmitted to the rear wheels 16, thereby enabling engine running, i.e., HEV running. In this engine running, for example, rear-wheel drive running using parallel hybrid running or rear-wheel drive running using only power from the first power source PU1 is possible.

[0132] The "H4_torque split" mode numbered m3 is a mode in which, for example, with the differential device 206 in a state equivalent to a high gear, torque from the first power source PU1 transmitted from the first output shaft 208 to the differential device 206 is borne by the sun gear S by the reaction torque of the TF rotation machine MGF, thereby distributing torque to the front wheels 14 and the rear wheels 16 at any desired ratio according to the reaction torque of the TF rotation machine MGF. In the "H4_torque split" mode in the transfer 200, the TF rotation machine MGF is regenerated. The electric power generated by the regeneration of the TF rotation machine MGF is charged to the battery 24, for example.

[0133] The "H4_LSD" mode numbered m4 is a mode in which, instead of the action of the reaction torque of the TF rotary machine MGF in the "H4_torque split" mode, torque is distributed to the front wheels 14 and the rear wheels 16 at any desired ratio according to the torque capacity of the TF clutch CF1 by limiting the differential action of the differential device 206 depending on the engagement state (slip engagement state or full engagement state) of the TF clutch CF1. In the "H4_LSD" mode, it is possible to add power from the TF rotary machine MGF to the drive torque Tr.

[0134] The "H4_Lock" mode numbered m5 is a mode in which, with the differential device 206 in a differential lock state, torque from the first power source PU1 transmitted to the first output shaft 208 is distributed to the front wheels 14 and the rear wheels 16. In the "H4_Lock" mode, for example, by engaging the TF clutch CF1, it is possible to add power from the TF rotary machine MGF to the drive torque Tr.

[0135] The "L4_Lock" mode numbered m6 is a mode in which, with the differential device 206 in a differential-locked state and in a low gear position, torque from the first power source PU1 transmitted to the sun gear S of the differential device 206 is distributed to the front wheels 14 and the rear wheels 16. In the "L4_Lock" mode, it is possible to add power from the TF rotary machine MGF to the drive torque Tr.

[0136] In the transfer case 200 of this embodiment, the TF rotating machine MGF is operated in regenerative mode, so the electric path amount Ppse is not required in the H4 torque split mode. Therefore, the hybrid control unit 134 predicts that the electric path amount Ppse will be limited to the target electric path amount Ppsetgt while the H4 torque split mode is being executed. However, if the battery 24 can be charged with electric power generated by regeneration of the TF rotating machine MGF and the electric path amount Ppse controlled to be the target electric path amount Ppsetgt in the H4 torque split mode, the first control mode MC1 or the second control mode MC2, whichever improves the fuel efficiency of the vehicle 8, may be selected as the control mode MC. [Example]

[0137] Figure 16 is a diagram illustrating the schematic configuration of a power transmission device 300 that is different from the power transmission device 18 in Figure 1. In Figure 16, the power transmission device 300 differs from the power transmission device 18 mainly in that it includes an engine connecting / disconnecting clutch K0 and a rotating machine connecting / disconnecting clutch K2.

[0138] Specifically, the power transmission device 300 includes an engine connecting / disconnecting clutch K0 and a rotating machine connecting / disconnecting clutch K2 in the transmission case 42. The engine connecting / disconnecting clutch K0 is a clutch that disconnects the connecting between the rotating machine connecting shaft 46 and the engine 12. The rotating machine connecting / disconnecting clutch K2 is a clutch that disconnects the connecting between the rotating machine connecting shaft 46 and the TM rotating machine MGM.

[0139] In each TrEV mode in the "EV (FF) High" mode and "EV (FF) Low" mode shown in FIG. 6, or in each TrEV mode in the "EV (FR) High" mode and "EV (FR) Low" mode shown in FIG. 15, when the first mesh clutch D1 is in the first state [1], for example, the engine disconnecting clutch K0 is released, thereby eliminating drag of the engine 12. In this case, if the TM rotary machine MGM is powered without being allowed to idle, BEV running using power from the two rotary machines, the TM rotary machine MGM and the TF rotary machine MGF, is possible. Furthermore, in the TrEV mode, the rotary machine disconnecting clutch K2 is released, thereby eliminating drag of the TM rotary machine MGM without controlling the TM rotary machine MGM to idle.

[0140] 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.

[0141] 12 , the required engine power Pedem that realizes the required drive power Prdem based on the accelerator pedal position θacc and the vehicle speed V is calculated, and the fuel-efficiency-optimum point P02 and the lock-up point P03 or the LU slip engagement point P04 are determined as the engine operating point PNTeng that realizes the required engine power Pedem. The fuel economy of the vehicle 8 in the control mode MC that realizes each engine operating point PNTeng is calculated, and the control mode MC that improves the fuel economy of the vehicle 8 is selected. However, the present invention is not limited to this. For example, the fuel economy at the fuel-efficiency-optimum point P02 and the lock-up point P03 or the LU slip engagement point P04 that realize the required engine power Pedem may be calculated in advance, and the selection result of the control mode MC may be set in advance on a two-dimensional map of the accelerator pedal position θacc and the vehicle speed V. Then, the first control mode MC1 or the second control mode MC2 that improves the fuel economy of the vehicle 8 may be selected as the control mode MC. In this case, hysteresis may be provided in the switching between the first control mode MC1 and the second control mode MC2.

[0142] In the first and second embodiments, the transfer 28, 200 may be provided with at least the TF clutch CF1 of the TF clutch CF1 and the TF brake BF1.

[0143] In the first and second embodiments, the differential devices 64 and 206 may function as a transmission with three or more speeds, or may function as a continuously variable transmission.

[0144] Furthermore, in the above-described first and second embodiments, the TF clutch CF1 may be a clutch that selectively connects the first rotating element RE1 and the third rotating element RE3 of the differential device 64, 206, or may be a clutch that selectively connects the second rotating element RE2 and the third rotating element RE3 of the differential device 64, 206. In short, the TF clutch CF1 may be a clutch that selectively connects any two of the first rotating element RE1, the second rotating element RE2, and the third rotating element RE3.

[0145] Furthermore, in the above-described first and second embodiments, the vehicle drive device may be configured such that the first output shaft 66, 208 is an output shaft that outputs power from the first power source PU1 input via the torque converter 48 to the front wheels, and the second output shaft 72, 214 is an output shaft that outputs power to the rear wheels.

[0146] In addition, in the third embodiment described above, the power transmission device 300 is provided with the engine connecting / disconnecting clutch K0 and the rotating machine connecting / disconnecting clutch K2, but is not limited to this. For example, from the viewpoint that it is sufficient if the engine 12 can be disconnected from the driveline, the power transmission device 300 may be provided with the engine connecting / disconnecting clutch K0 without the rotating machine connecting / disconnecting clutch K2.

[0147] In the above-described embodiment, the automatic transmission 50 may be a synchronous mesh parallel two-shaft automatic transmission including a known DCT (Dual Clutch Transmission), a known belt-type continuously variable transmission, or the like.

[0148] In the above-described embodiment, the torque converter 48 is used as the fluid transmission device, but the present invention is not limited to this. For example, instead of the torque converter 48, other fluid transmission devices such as a fluid coupling that does not have a torque amplification function may be used as the fluid transmission device.

[0149] It should be noted that the above is merely one embodiment, and the present invention can be embodied in various forms with various modifications and improvements based on the knowledge of those skilled in the art. [Explanation of symbols]

[0150] 8: Vehicle 10: Vehicle drive unit 12: Engine 14: Front wheel 16: Rear wheel 24: Battery (power storage device) 28: Transfer (torque distribution device) 48: Torque converter (fluid transmission) 48a: Pump impeller (input side rotating element) 48b: Turbine impeller (output rotating element) 64: Differential device 66: 1st output shaft 72: Second output shaft 130: Electronic control device (control device) 200: Transfer (torque distribution device) 206: Differential device 208: 1st output shaft 214: Second output shaft CF1: TF clutch (engagement device) DW: Drive wheel LU: Lock-up clutch (direct-coupled clutch) MGM: TM rotating machine (first rotating machine) MGF: TF rotating machine (second rotating machine) RE1: First rotation element RE2: Second rotation element RE3: Third rotation element

Claims

1. A vehicle drive device comprising: an engine; an input side rotating element to which the engine is connected so as to be capable of transmitting power; an output side rotating element connected to a drive wheel so as to be capable of transmitting power; and a direct-coupled clutch that connects the input side rotating element and the output side rotating element, and which transmits power from the engine from the input side rotating element to the output side rotating element via a fluid; a first rotating machine connected to the input side rotating element so as to be capable of transmitting power; a second rotating machine connected to the drive wheel so as to be capable of transmitting power; and a control device that controls an operating point of the engine by adjusting an electric path amount, which is the magnitude of electric power sent from the first rotating machine in an electric path through which electric power is exchanged between the first rotating machine and the second rotating machine, The control device includes: As a control mode for driving and controlling the vehicle, a first control mode in which the direct-coupled clutch is controlled to a released state and the first rotating machine is operated to generate electricity so that the electric path amount becomes a target electric path amount for making the operating point of the engine a target operating point, and a second control mode in which the direct-coupled clutch is controlled to an engaged state and the power of the engine is transmitted via the fluid type power transmission device with the direct-coupled clutch in an engaged state can be selectively established, and the control mode that improves the fuel efficiency of the vehicle is selected from the first control mode and the second control mode based on the running state of the vehicle, A vehicle drive device characterized in that it predicts whether the electrical path amount will be made smaller than the target electrical path amount, and if it is predicted that the electrical path amount will be made smaller than the target electrical path amount, it selects the second control mode as the control mode.

2. the vehicle further includes a first output shaft receiving power from the engine via the fluid transmission device and outputting the power to one of front wheels and rear wheels, a second output shaft outputting the power to the other of the front wheels and the rear wheels, and a torque distribution device distributing a portion of the torque input to the first output shaft to the second output shaft, the torque distribution device includes the second rotating machine; and a differential device including a first rotating element to which the second rotating machine is connected, a second rotating element to which one of the first output shaft and the second output shaft is connected, and a third rotating element to which the other of the first output shaft and the second output shaft is connected, The control device includes: a torque distribution ratio, which is a ratio of torque distributed to the front wheels and the rear wheels, can be controlled by controlling an output torque of the second rotating machine, 2. The vehicle drive device according to claim 1, wherein when the torque distribution ratio is controlled by controlling the output torque of the second rotating machine, it is predicted that the electrical path amount will be made smaller than the target electrical path amount.

3. The torque distribution device further includes an engagement device that selectively connects any two of the first rotation element, the second rotation element, and the third rotation element, The control device includes: When the engagement device is in a disengaged state, the torque distribution ratio can be controlled by controlling the output torque of the second rotating machine, and when the engagement device is in an engaged state, the second rotating machine can be driven as a power source, 3. A vehicle drive device as described in claim 2, characterized in that when the engagement device is in an engaged state, it is predicted that the electrical path amount will not be made smaller than the target electrical path amount, and one of the first control mode and the second control mode, which improves the fuel efficiency of the vehicle, is selected as the control mode.

4. The engagement state of the engagement device includes a slip engagement state in which the engagement device is engaged with slippage, and a full engagement state in which the engagement device is fully engaged, 4. The vehicle drive system according to claim 3, wherein the control device is capable of controlling the torque distribution ratio by controlling an engagement state of the engagement device.

5. The power generating device further includes an electric storage device that supplies electric power to and receives electric power from each of the first rotating machine and the second rotating machine, The vehicle drive device according to any one of claims 1 to 4, characterized in that the control device determines whether the charge amount of the storage device is within a predetermined low charge amount range in which charging of the electrical path amount is permitted, and when it determines that the charge amount is within the low charge amount range, selects as the control mode between the first control mode and the second control mode, the one that improves the fuel efficiency of the vehicle, even if it predicts that the electrical path amount will be made smaller than the target electrical path amount.

6. The vehicle drive device according to any one of claims 1 to 5, characterized in that, when the output of the second rotating machine is limited, the control device predicts that the electrical path amount will be made smaller than the target electrical path amount.

7. 7. The vehicle drive device according to claim 6, wherein the control device determines whether or not the output of the second rotating machine is limited based on whether or not the temperature of the second rotating machine is within a predetermined high temperature range in which the output of the second rotating machine is limited.

8. The power generating device further includes an electric storage device that supplies electric power to and receives electric power from each of the first rotating machine and the second rotating machine, 8. The vehicle drive device according to claim 1, wherein the control device predicts that the electrical path amount will be reduced relative to the target electrical path amount when the chargeable power of the storage device is within a predetermined low power range in which charging of the electrical path amount is limited.

9. 9. The vehicle drive device according to claim 8, wherein the control device determines whether the chargeable power of the power storage device is within the low power range based on whether the charge amount of the power storage device is within a predetermined high charge amount range in which charging of the electric path amount is limited.

10. 10. The vehicle drive device according to claim 8 or 9, characterized in that the control device determines whether the chargeable power of the power storage device is within a low power range based on whether the temperature of the power storage device is within a predetermined low temperature range or a predetermined high temperature range in which charging of the electric path amount is limited.

11. 11. The vehicle drive system according to claim 1, wherein the target operating point is a fuel efficiency optimum point that is determined in advance as an optimum operating point for improving fuel efficiency of the engine.

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