Vehicle control device

Abstract

To provide a control device for a vehicle which can reduce transmission of vibration to a vehicle caused by collapse of a mount member supporting an engine, on a vehicle having one wheel driven by power of the engine and the other wheel driven by power of a drive force source separate from the engine.SOLUTION: When a required drive force Fedem of an engine 12 has reached or exceeded a prescribed value Fcri at which characteristics of an engine mount 62 are deteriorated, RrMG-torque TmRr as a required amount of driving of a rear electric motor RrMG is increased and the required drive force Fedem of the engine 12 can be thereby reduced. As a result, collapse of an engine mount 62 supporting the engine 12 is reduced, so engine vibration transmitted to a vehicle body via the engine mount 62 can be reduced.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a control device for a vehicle that can be switched between two-wheel drive running and four-wheel drive running.

Background Art

[0002] Patent Document 1 discloses a four-wheel drive vehicle based on rear-wheel drive, which includes rear wheels power-transmissibly connected to an engine and a rear motor, and front wheels power-transmissibly connected to a front motor. Further, Patent Document 1 discloses a structure in which an engine is supported by a mount member.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in a vehicle that can be switched between two-wheel drive running and four-wheel drive running, in a normal running state, two-wheel drive running in which one of the front and rear wheels is driven by the power of the engine is desirable from the viewpoint of fuel consumption. However, as the required driving force of the engine increases, the insulator (such as rubber) of the engine mount that supports the engine is crushed, and it may become difficult to reduce the vibration from the engine.

[0005] The present invention has been made against the background of the above circumstances, and an object thereof is to provide a vehicle control device that can reduce vibration transmission to a vehicle (vehicle body) due to crushing of a mount member that supports an engine in a vehicle including one wheel driven by the power of the engine and the other wheel driven by the power of a drive power source separate from the engine.

Means for Solving the Problems

[0007] This The gist of the invention is that: (a) an engine provided on a vehicle via a mount member, and a power source provided separately from the engine motor which is and, wherein the engine is connected to one of the front and rear wheels so as to be able to transmit power, and the motor is connected to the other of the front and rear wheels so as to be able to transmit power, a transmission is provided in the power transmission path between the engine and the one wheel, two-wheel drive running in which the one wheel is driven by the engine, and four-wheel drive running in which the one wheel is driven by the engine and the motor the other wheel is driven by the, at least a vehicle control device that can be switched, and (b) the control device During vehicle travel, when the drive demand amount of the engine becomes equal to or greater than a predetermined value based on the characteristics of the mount member, a driving force distribution control unit that executes a driving force distribution control for increasing the drive demand amount of the motor; (c) a determination unit that determines whether or not the driving force distribution control can be performed based on the fact that the torque output from the motor is limited; (d) the by the determination unit, the motor output is limited and is determined that the driving force distribution control cannot be performed in the case, the transmission is shifted so that the rotational speed of the engine is maintained at a predetermined rotational speed or more a shift control unit, and includes characterized by that.

Effect of the Invention

[0012] This According to the invention, motor the output is limited and is determined that the driving force distribution control cannot be performed in the case, since the transmission is shifted so that the rotational speed of the engine is maintained at a predetermined rotational speed or more, the rotational speed of the engine is maintained at a predetermined rotational speed or more, and running can be continued in a state where the transmission sensitivity of the engine vibration to the vehicle is reduced. As a result, the vibration from the engine transmitted via the mount member can be reduced.

Brief Description of the Drawings

[0016]

Figure 1

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Best Mode for Carrying Out the Invention

[0017] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following embodiments, the drawings are appropriately simplified or deformed, and the dimensional ratios and shapes of each part are not necessarily drawn accurately.

Embodiment

[0018] FIG. 1 is a diagram for explaining the schematic configuration of a hybrid vehicle 10 (hereinafter referred to as vehicle 10) to which the present invention is applied, and is also a diagram for explaining the control functions and the main parts of the control system for various controls in vehicle 10. In FIG. 1, vehicle 10 is a four-wheel drive hybrid vehicle based on front-wheel drive, which includes an engine 12 and a front motor FrMG as the driving force sources of the front wheels 14, and a rear motor RrMG as the driving force source of the rear wheels 16. Vehicle 10 includes a front unit 18 provided in the power transmission path between engine 12 and front wheels 14, and a rear unit 20 for driving rear wheels 16.

[0019] Engine 12 is a known internal combustion engine such as a gasoline engine or a diesel engine. Engine 12 is controlled by an engine control device 22 including a throttle actuator, a fuel injection device, an ignition device, etc. provided in vehicle 10 by an electronic control device 100 described later, so that the engine torque Te, which is the output torque of engine 12, is controlled.

[0020] Engine 12 is connected to a vehicle member 64 that constitutes the vehicle body via an engine mount 62. In other words, engine 12 is provided in vehicle 10 via engine mount 62. Engine mount 62 is a support member for supporting engine 12, and an insulator such as rubber 66 is inserted so that the vibration of engine 12 is less likely to be transmitted to the vehicle body side. Since engine mount 62 is a known technology, a detailed description thereof is omitted.

[0021] Front motor FrMG and rear motor RrMG are motor generators having a function as an engine that generates mechanical power from electric power, and a function as a generator that generates electric power from mechanical power.

[0022] The front electric motor FrMG is connected to the HEV battery 28 via the front inverter 24 (FrPCU) and the system main relay 26 (SMR). The front electric motor FrMG has its output torque, i.e., the FrMG torque TmFr, controlled by controlling the front inverter 24 with an electronic control unit 100 described later. When the rotational direction of the front electric motor FrMG is the same as that during the operation of the engine 12, i.e., a forward rotation, for example, the positive torque on the acceleration side is the power running torque, and the negative torque on the deceleration side is the regenerative torque.

[0023] The front electric motor FrMG generates driving power for traveling by the electric power supplied from the HEV battery 28 via the front inverter 24 and the system main relay 26, instead of or in addition to the engine 12. Further, the front electric motor FrMG is configured to be able to generate electric power by the power of the engine 12 or the driven power input from the front wheel 14 side. The electric power generated by the front electric motor FrMG is stored in the HEV battery 28 via the front inverter 24 and the system main relay 26. Alternatively, the electric power generated by the front electric motor FrMG is supplied to the rear electric motor RrMG to drive the rear electric motor RrMG. The electric power is also regarded as electrical energy when not particularly distinguished. Further, the driving power is also regarded as torque or force when not particularly distinguished.

[0024] The rear motor RrMG is connected to the HEV battery 28 via the rear inverter 30 (RrPCU) and the system main relay 26 (SMR). The output torque of the rear motor RrMG, i.e., the RrMG torque TmRr, is controlled by controlling the rear inverter 30 by an electronic control unit 100 described later. For example, when the rotational direction of the rear motor RrMG is a positive rotation, which is the same as the rotational direction during forward travel, the positive torque on the acceleration side is the driving torque, and the negative torque on the deceleration side is the regenerative torque. The rear motor RrMG is driven by at least one of the electric power from the HEV battery 28 and the electric power generated by the front motor FrMG.

[0025] The rear motor RrMG functions as a traveling motor that generates a driving force by at least one of the electric power supplied from the HEV battery 28 via the rear inverter 30 and the system main relay 26 and the electric power generated by the front motor FrMG. Also, the rear motor RrMG generates electricity by the driven force input from the rear wheel 16 side. The electric power generated by the power generation of the rear motor RrMG is stored in the HEV battery 28 via the rear inverter 30 and the system main relay 26. The HEV battery 28 is a power storage device that exchanges electric power with the front motor FrMG and the rear motor RrMG. Note that the HEV battery 28 corresponds to the battery of the present invention, and the rear motor RrMG corresponds to a driving power source provided separately from the engine of the present invention.

[0026] The front unit 18 is configured to be able to transmit the power of the engine 12 and the front electric motor FrMG to the front wheels 14. The front unit 18 includes the engine 12, the K0 clutch 34 (K0), the input clutch 36 (WSC), the automatic transmission 38, and the like. The K0 clutch 34 (K0), the input clutch 36 (WSC), and the automatic transmission 38 are housed in a case 32 which is a non-rotating member attached to the vehicle body. The K0 clutch 34 is a clutch provided between the engine 12 and the front electric motor FrMG in the power transmission path between the engine 12 and the front wheels 14. The input clutch 36 is a clutch provided between the K0 clutch 34 and the automatic transmission 38 in the power transmission path between the engine 12, the front electric motor FrMG, and the front wheels 14. Note that the front wheels 14 correspond to one of the wheels of the present invention, and the front electric motor FrMG corresponds to the second electric motor of the present invention.

[0027] The automatic transmission 38 is provided in the power transmission path between the engine 12, the front electric motor FrMG, and the front wheels 14. Further, the front unit 18 includes a differential device 42 (DIFF) connected to the transmission output shaft 40 of the automatic transmission 38, and a pair of left and right front axles 44 connected to the front wheels 14, and the like. The front unit 18 also includes an engine connecting shaft 46 connecting between the engine 12 and the K0 clutch 34, and a motor connecting shaft 48 connecting between the K0 clutch 34 and the input clutch 36. Note that the automatic transmission 38 corresponds to the transmission of the present invention.

[0028] The front electric motor FrMG is connected to the motor connecting shaft 48 so as to be able to transmit power within the case 32. The front electric motor FrMG is connected to be able to transmit power to the power transmission path between the engine 12 and the front wheels 14, particularly to the power transmission path between the K0 clutch 34 and the input clutch 36. Therefore, the front electric motor FrMG is connected to be able to transmit power to the input clutch 36 and the automatic transmission 38 without passing through the K0 clutch 34.

[0029] The automatic transmission 38 is a known planetary gear type automatic transmission including, for example, one or more sets of planetary gear devices (not shown) and a plurality of engagement devices CB. The engagement device CB is a hydraulic friction engagement device constituted by, for example, a multi-plate or single-plate clutch or brake pressed by a hydraulic actuator, a band brake tightened by a hydraulic actuator, etc. Each engagement device CB has its control state such as an engaged state or a released state switched by changing the CB torque Tcb which is the respective torque capacity by the regulated CB hydraulic pressure PRcb supplied from the hydraulic control circuit 52. Since the power transmission state of the automatic transmission 38 is switched according to the engaged state of the engagement device CB, the engagement device CB is inserted into the power transmission path between the engine 12, the front motor FrMG, and the front wheels 14 and has a function of disconnecting and connecting the power transmission in the power transmission path.

[0030] The automatic transmission 38 is a stepped transmission in which any one of the engagement devices CB is engaged to form any one of a plurality of shift stages (also referred to as gear stages) having different gear ratios (also referred to as gear ratios) γat (= AT input rotational speed Ni / AT output rotational speed No). The automatic transmission 38 of the present embodiment is configured to be shiftable into a gear stage of six forward speeds and one reverse speed. The automatic transmission 38 has the shift stage formed according to the driver's ( = operator's) accelerator operation, vehicle speed V, etc. switched by an electronic control device 100 described later, that is, a plurality of shift stages are selectively formed. The AT input rotational speed Ni is the rotational speed of the transmission input shaft 50 of the automatic transmission 38 and is the input rotational speed of the automatic transmission 38. The AT output rotational speed No is the rotational speed of the transmission output shaft 40 of the automatic transmission 38 and is the output rotational speed of the automatic transmission 38.

[0031] The K0 clutch 34 is a wet or dry friction engagement device composed of, for example, a multi-plate or single-plate clutch. The control state of the K0 clutch 34, such as the engaged state or the released state, is switched by an electronic control device 100 described later. The control state of the K0 clutch 34 is switched by changing the K0 torque Tk0, which is the torque capacity of the K0 clutch 34, by the K0 hydraulic pressure PRk0 supplied from the hydraulic control circuit 52.

[0032] The input clutch 36 is a wet or dry friction engagement device composed of, for example, a multi-plate or single-plate clutch. The control state of the input clutch 36, such as the engaged state or the released state, is switched by an electronic control device 100 described later. The control state of the input clutch 36 is switched by changing the WSC torque Twsc, which is the torque capacity of the input clutch 36, by the WSC hydraulic pressure PRwsc supplied from the hydraulic control circuit 52.

[0033] In the engaged state of the K0 clutch 34, the engine 12 and the front motor FrMG are connected so that power can be transmitted via the engine connection shaft 46 and the motor connection shaft 48. That is, when the K0 clutch 34 is engaged, it connects the engine 12 and the front motor FrMG so that power can be transmitted. On the other hand, in the released state of the K0 clutch 34, the power transmission between the engine 12 and the front motor FrMG is interrupted. That is, when the K0 clutch 34 is released, it disconnects the connection between the engine 12 and the front motor FrMG. That is, the K0 clutch 34 is a make-and-break clutch that connects the engine 12 and the front motor FrMG when engaged and interrupts the connection between the engine 12 and the front motor FrMG when released.

[0034] In the engaged state of the input clutch 36, the motor connection shaft 48 and the transmission input shaft 50 are connected. At this time, the front motor FrMG can be connectively and power-transmittably connected to the front wheels 14 via the motor connection shaft 48, the input clutch 36, the transmission input shaft 50, the transmission output shaft 40, the differential device 42, and the front-wheel axle 44. Also, in the engaged state of the K0 clutch 34 and the input clutch 36, in addition to the front motor FrMG, the engine 12 can be connectively and power-transmittably connected to the front wheels 14 via the motor connection shaft 48, the input clutch 36, the transmission input shaft 50, the transmission output shaft 40, the differential device 42, and the front-wheel axle 44. On the other hand, in the released state of the input clutch 36, the connection between the motor connection shaft 48 and the transmission input shaft 50 is interrupted. That is, the input clutch 36 is a disconnecting and connecting clutch that connects the engine 12 and the front motor FrMG to the front wheels 14 when engaged, and disconnects the engine 12 and the front motor FrMG from the front wheels 14 when released.

[0035] In the front unit 18, when the K0 clutch 34 and the input clutch 36 are engaged, the power output from the engine 12 is transmitted to the front wheels 14 sequentially via the engine connection shaft 46, the motor connection shaft 48, the transmission input shaft 50, the automatic transmission 38, the transmission output shaft 40, the differential device 42, and the front-wheel axle 44. Also, when the input clutch 36 is engaged, the power output from the front motor FrMG is transmitted to the front wheels 14 sequentially via the motor connection shaft 48, the transmission input shaft 50, the automatic transmission 38, the transmission output shaft 40, the differential device 42, and the front-wheel axle 44.

[0036] On the one hand, when the input clutch 36 is disengaged, the power transmission path between the engine 12, the front electric motor FrMG, and the front wheels 14 is interrupted, and the power of the engine 12 and the front electric motor FrMG is not transmitted to the front wheels 14. Also, when the K0 clutch 34 is disengaged while the input clutch 36 is engaged, the power of the front electric motor FrMG is transmitted to the front wheels 14 via the automatic transmission 38 and the like, while the power of the engine 12 is not transmitted to the front wheels 14. Further, when the K0 clutch 34 is engaged while the input clutch 36 is disengaged, although the power of the engine 12 and the front electric motor FrMG is not transmitted to the front wheels 14, the engine 12 and the front electric motor FrMG are connected so as to be power-transmittable. At this time, the front electric motor FrMG can generate electricity by the power of the engine 12.

[0037] The rear unit 20 is configured to be able to transmit the power of the rear electric motor RrMG to the rear wheels 16. The rear unit 20 includes a rear inverter 30 controlled by an electronic control device 100 described later, a rear electric motor RrMG, and a pair of left and right rear axles 54 and the like connected to the left and right rear wheels 16. The rear electric motor RrMG is connected to the pair of left and right rear axles 54 directly or via a speed reducer (not shown). Therefore, the rear electric motor RrMG is connected to the rear wheels 16 so as to be power-transmittable via the rear axle 54 and the like, and the power output from the rear electric motor RrMG is transmitted to the rear wheels 16 via the rear axle 54 and the like. Note that the rear wheels 16 correspond to the other wheels of the present invention, and the rear electric motor RrMG corresponds to the electric motor of the present invention.

[0038] Vehicle 10 is equipped with a mechanical oil pump 58 (MOP) and an electric oil pump 60 (EOP). The mechanical oil pump 58 is connected to the motor coupling shaft 48, for example, through a gear, a belt, a chain, etc. so that power can be transmitted, and is driven by at least one of the engine 12 and the front motor FrMG to discharge the hydraulic oil used in the front unit 18. The electric oil pump 60 is rotationally driven by a pump motor (not shown) to discharge the hydraulic oil. The hydraulic oil discharged by the mechanical oil pump 58 and the electric oil pump 60 is supplied to the hydraulic control circuit 52. The hydraulic control circuit 52 supplies the regulated CB hydraulic pressure PRcb, K0 hydraulic pressure PRk0, WSC hydraulic pressure PRwsc, etc. based on the hydraulic oil discharged by the mechanical oil pump 58 and the electric oil pump 60.

[0039] Vehicle 10 further includes an electronic control unit 100 (control unit) that includes a control device of the vehicle 10 related to driving control, etc. The electronic control unit 100 is configured to include a so-called microcomputer equipped with, for example, a CPU, a RAM, a ROM, an input / output interface, etc. The CPU performs signal processing according to a program stored in the ROM in advance while using the temporary storage function of the RAM to execute various controls of the vehicle 10. The electronic control unit 100 is configured to include each ECU for engine control, motor control, hydraulic control, etc. as necessary.

[0040] The electronic control device 100 is supplied with various signals (for example, the engine rotational speed Ne which is the rotational speed of the engine 12, the AT input rotational speed Ni which is the rotational speed of the transmission input shaft 50 of the automatic transmission 38, the AT output rotational speed No which is the rotational speed of the transmission output shaft 40 of the automatic transmission 38 and corresponds to the vehicle speed V, the FrMG rotational speed NmFr which is the rotational speed of the front motor FrMG, the RrMG rotational speed NmRr which is the rotational speed of the rear motor RrMG, the accelerator opening θacc which is the driver's accelerator operation amount representing the magnitude of the driver's acceleration operation, the throttle valve opening θth which is the opening of the electronic throttle valve, the brake-on signal Bon which is a signal indicating that the brake pedal for operating the wheel brake is being operated by the driver, the battery temperature THbat, the battery charge / discharge current Ibat, and the battery voltage Vbat of the HEV battery 28, and the operating oil temperature THoil which is the temperature of the operating oil in the hydraulic control circuit 52, etc.) based on the detection values from various sensors etc. (for example, the engine rotational speed sensor 70, the input rotational speed sensor 72, the output rotational speed sensor 74, the FrMG rotational speed sensor 76, the RrMG rotational speed sensor 78, the accelerator opening sensor 80, the throttle valve opening sensor 82, the brake switch 84, the battery sensor 86, the oil temperature sensor 88, etc.) provided in the vehicle 10.

[0041] From the electronic control unit 100, various command signals (for example, engine control command signal Se for controlling the engine 12, FrMG control command signal SmFr for controlling the front motor FrMG, RrMG control command signal SmRr for controlling the rear motor RrMG, CB hydraulic pressure control command signal Scb for controlling the engagement device CB, K0 hydraulic pressure control command signal Sk0 for controlling the K0 clutch 34, WSC hydraulic pressure control command signal Swsc for controlling the input clutch 36, relay switching command signal Ssmr for switching the connection / disconnection state of the system main relay 26, etc.) are output to various devices (for example, engine control unit 22, front inverter 24, rear inverter 30, hydraulic control circuit 52, system main relay 26, etc.) provided in the vehicle 10. The system main relay 26 is switched to the connected state by the relay switching command signal Ssmr when, for example, the power switch of the vehicle 10 is switched to the on state, enabling power supply from the HEV battery 28.

[0042] The electronic control unit 100 functionally includes a hybrid control unit 102 that functions as hybrid control means, a clutch control unit 104 that functions as clutch control means, and a shift control unit 106 that functions as shift control means in order to realize various driving controls in the vehicle 10.

[0043] The hybrid control unit 102 functionally includes an engine control unit 102a that functions as engine control means for controlling the operation of the engine 12, an Fr motor control unit 102b that functions as Fr motor control means for controlling the operation of the front motor FrMG via the front inverter 24, and an Rr motor control unit 102c that functions as Rr motor control means for controlling the operation of the rear motor RrMG via the rear inverter 30, and executes hybrid drive control, etc. by the engine 12, the front motor FrMG, and the rear motor RrMG according to their control functions.

[0044] The hybrid control unit 102 calculates the driving demand amount for the vehicle 10 by the driver, for example, by applying the accelerator opening θacc and the vehicle speed V to a driving demand amount map. The driving demand amount map is a relationship obtained experimentally or designedly in advance, that is, a predetermined relationship. The driving demand amount is, for example, the vehicle required driving force Frdem. As the driving demand amount, the required driving torque Trdem, the required AT output torque at the transmission output shaft 40 of the automatic transmission 38, etc. can also be used. Also, in the calculation of the driving demand amount, instead of the vehicle speed V, the AT output rotational speed No or the like can be used.

[0045] The hybrid control unit 102 outputs an engine control command signal Se for controlling the engine 12, an FrMG control command signal SmFr for controlling the front motor FrMG, and an RrMG control command signal SmRr for controlling the rear motor RrMG, so as to realize the required driving power Prdem in consideration of transmission losses, auxiliary load, the gear ratio γat of the automatic transmission 38, the chargeable power Win and the dischargeable power Wout of the HEV battery 28, etc. The engine control command signal Se is, for example, a command value of the engine power Pe which is the power of the engine 12 that outputs the engine torque Te at the engine rotational speed Ne at that time. The FrMG control command signal SmFr is, for example, a command value of the power consumption WmFr of the front motor FrMG that outputs the FrMG torque TmFr at the FrMG rotational speed NmFr at that time. Also, the RrMG control command signal SmRr is, for example, a command value of the power consumption WmRr of the rear motor RrMG that outputs the RrMG torque TmRr at the RrMG rotational speed NmRr at that time.

[0046] The chargeable power Win of the HEV battery 28 is the maximum input power that can be input, which defines the input power limit of the HEV battery 28 and indicates the input limit of the HEV battery 28. The dischargeable power Wout of the HEV battery 28 is the maximum output power that can be output, which defines the output power limit of the HEV battery 28 and indicates the output limit of the HEV battery 28. The chargeable power Win and the dischargeable power Wout of the HEV battery 28 are calculated by the electronic control unit 100 based on, for example, the battery temperature THbat and the state of charge value SOC [%] of the HEV battery 28. The state of charge value SOC of the HEV battery 28 is a value indicating the state of charge of the HEV battery 28 and is calculated by the electronic control unit 100 based on, for example, the battery charge / discharge current Ibat and the battery voltage Vbat.

[0047] When the hybrid control unit 102 can supply the required drive torque Trdem with only the output of at least one of the front motor FrMG and the rear motor RrMG, the driving mode is set to the motor driving (= BEV driving) mode. In the BEV driving mode, the hybrid control unit 102 performs BEV (Battery Electric Vehicle) driving in which at least one of the front motor FrMG and the rear motor RrMG is used as a driving power source in the released state of the K0 clutch 34 and the engaged state of the input clutch 36.

[0048] On the other hand, when the required drive torque Trdem cannot be satisfied without using at least the output of the engine 12, the hybrid control unit 102 sets the driving mode to the engine driving mode, that is, the hybrid driving (= HEV driving) mode. In the HEV driving mode, the hybrid control unit 102 performs engine driving, that is, HEV (Hybrid Electric Vehicle) driving, with at least the engine 12 as a driving power source in the engaged states of the K0 clutch 34 and the input clutch 36. Further, even when the required drive torque Trdem can be satisfied by the output of at least one of the front motor FrMG and the rear motor RrMG, the hybrid control unit 102 activates the HEV driving mode when the state of charge value SOC of the HEV battery 28 is less than a predetermined engine start threshold value or when the engine 12 needs to be warmed up. The engine start threshold value is a predetermined threshold value for determining that it is the state of charge value SOC at which it is necessary to forcibly start the engine 12 to charge the HEV battery 28. Thus, the hybrid control unit 102 automatically stops the engine 12 during HEV driving, restarts the engine 12 after the engine stop, or starts the engine 12 during BEV driving based on the required drive torque Trdem, the required drive power Prdem, etc., and switches between the BEV driving mode and the HEV driving mode.

[0049] Also, during driving in the HEV driving mode, the power of the engine 12 is transmitted as a driving force to the front wheels 14, and by transmitting a part of the power of the engine 12 to the front motor FrMG, power generation by the front motor FrMG becomes possible. Further, by supplying the generated power WgFr generated by the front motor FrMG to the rear motor RrMG, the rear motor RrMG can be driven to drive the vehicle 10 in four-wheel drive. Therefore, the vehicle 10 is configured to be switchable between two-wheel drive in which only the front wheels 14 are driven by the power of the engine 12 and four-wheel drive in which the front wheels 14 are driven by the power of the engine 12 and the rear wheels 16 are driven by the power of the rear motor RrMG.

[0050] The hybrid control unit 102 functionally includes a driving force distribution control unit 102d as driving force distribution control means that controls the driving forces of the front and rear wheels (front wheels 14 and rear wheels 16) as appropriate according to the driving state of the vehicle 10 so as to obtain appropriate driving performance. The driving force distribution control unit 102d calculates an appropriate driving force distribution ratio R of the front and rear wheels based on the driving state of the vehicle 10. Further, the driving force distribution control unit 102d calculates the outputs of the engine 12, the front motor FrMG, and the rear motor RrMG such that the calculated driving force distribution ratio R is achieved. The hybrid control unit 102 controls the engine 12, the front motor FrMG, and the rear motor RrMG so that the calculated outputs of the engine 12, the front motor FrMG, and the rear motor RrMG are realized. As a result, the outputs of the engine 12, the front motor FrMG, and the rear motor RrMG are controlled so as to achieve the calculated driving force distribution ratio R, thereby performing the driving force distribution between the front and rear wheels. Thus, the vehicle 10 is configured to be able to adjust the driving force distribution between the front and rear wheels. In this embodiment, the driving force distribution ratio R is defined as the ratio of the driving force transmitted to the rear wheels 16 among the vehicle required driving force Frdem. For example, when the driving force distribution ratio R is zero, it becomes two-wheel drive running in which only the front wheels 14 are driven. Also, when the driving force distribution ratio R is 0.2, it becomes four-wheel drive running in which the ratio of the driving forces of the front wheels 14 and the rear wheels 16 is 80:20.

[0051] The driving force distribution control unit 102d sets the driving force distribution ratio R to zero, for example, at low vehicle speeds when the load during running is small. That is, the driving force distribution control unit 102d stops the rear motor RrMG and executes two-wheel drive running in which only the front wheels 14 are driven by the power of the engine 12 at low vehicle speeds when the load during running is small. Also, the driving force distribution control unit 102d sets the driving force distribution ratio R to a value greater than zero, for example, at the time of vehicle start, acceleration, or running on a low-μ road where skidding is likely, and executes four-wheel drive running in which the rear wheels 16 are driven in addition to the front wheels 14.

[0052] Incidentally, when the generated power WgFr generated by the front motor FrMG is supplied to the rear motor RrMG, the power of the engine 12 is converted into electric energy and transmitted to the rear motor RrMG, and then reconverted into driving force by the rear motor RrMG. Therefore, the energy efficiency deteriorates. Accordingly, from the viewpoint of fuel efficiency, it is desirable to drive the front wheels 14 using only the power of the engine 12. On the other hand, when the vehicle 10 is driven by the driving force of the engine 12, the displacement amount of the rubber 66 constituting the engine mount 62 (i.e., the amount of compression of the rubber 66) increases due to the reaction force against the driving force of the engine 12. At this time, since the rubber 66 becomes hard, the vibration of the engine 12 (engine vibration) is likely to be transmitted to the vehicle body side (vehicle side) via the engine mount 62. Note that the engine mount 62 corresponds to the mount member of the present invention.

[0053] FIG. 2 shows the relationship between the mount displacement L [mm] during the driving of the engine 12 and the engine mount load Fmt [N]. The mount displacement L corresponds to the deformation amount (i.e., the amount of compression) of the rubber 66 constituting the engine mount 62. The engine mount load Fmt is the load applied to the engine mount 62 during engine driving and corresponds to the reaction force against the driving force of the engine 12. The engine mount load Fmt increases in proportion to the driving force of the engine 12. As shown in FIG. 2, as the mount displacement L increases, the inclination of the increase in the engine mount load Fmt becomes steeper. From this, it can be seen that the harder the rubber 66 becomes as the engine mount load Fmt increases, and the more difficult it is for the rubber 66 to deform, so the transmission sensitivity of engine vibration increases. That is, the larger the engine mount load Fmt, the easier it is for the engine vibration to be transmitted to the vehicle body side via the engine mount 62.

[0054] On the other hand, during vehicle travel, when the required driving force Fedem of the engine becomes equal to or greater than a predetermined value Fcri set in advance, the driving force distribution control unit 102d increases the driving force distribution ratio R to be greater than the current value. That is, during vehicle travel, when the required driving force Fedem, which is the driving requirement amount of the engine 12, becomes equal to or greater than a predetermined value Fcri set in advance, the RrMG torque TmRr, which is the driving requirement amount of the rear motor RrMG, is increased.

[0055] Here, the predetermined value Fcri of the engine 12 is obtained in advance experimentally or by design and is set based on the characteristics of the engine mount 62. FIG. 3 shows the relationship between the engine mount load Fmt and the slope M of the mount displacement L. As shown in FIG. 3, in the region where the engine mount load Fmt is small, the slope M of the mount displacement L becomes a constant value M1. However, when the engine mount load Fmt exceeds a predetermined value, the slope M of the mount displacement L decreases as the engine mount load Fmt increases. That is, when the engine mount load Fmt exceeds a predetermined value, the rubber 66 of the engine mount 62 hardens, and the function of suppressing the transmission sensitivity of engine vibration due to the elastic deformation of the rubber 66 decreases.

[0056] From this, the predetermined value Fcri of the engine 12 is set to a value corresponding to the load Fα of the engine mount load Fmt at which the slope M of the mount displacement L becomes a slope Mα smaller than the constant value M1. This load Fα is set to a threshold value at which the engine vibration transmitted to the vehicle body side through the engine mount 62 is within an allowable range. Further, since there is a one-to-one relationship between the driving force of the engine 12 and the engine mount load Fmt, when the engine mount load Fmt is determined, the corresponding driving force of the engine 12 is uniquely determined.

[0057] When the driving force of the engine 12 reaches the predetermined value Fcri, the driving force distribution control unit 102d determines the driving force distribution between the front and rear wheels (that is, the driving force distribution ratio R) based on a relationship map as shown in FIG. 4.

[0058] FIG. 4 shows an example of a relationship map between the vehicle required driving force Frdem [N] and the driving force distribution to the rear wheels 16, that is, the driving force distribution ratio R. In FIG. 4, a relationship map applied during two-wheel drive running is shown as an example. During two-wheel drive running, the vehicle required driving force Frdem is equivalent to the required driving force Fedem of the engine 12. As shown in FIG. 4, when the vehicle required driving force Frdem (that is, the required driving force Fedem of the engine 12) is less than a predetermined value Fcri, the driving force distribution ratio R is set to zero and two-wheel drive running is permitted. On the other hand, during two-wheel drive running, when the vehicle required driving force Frdem (that is, the required driving force Fedem of the engine 12) becomes equal to or greater than the predetermined value Fcri, the driving force distribution ratio R increases as the vehicle required driving force Frdem increases. The driving force distribution ratio R with respect to the vehicle required driving force Frdem in the region where the vehicle required driving force Frdem is equal to or greater than the predetermined value Fcri is set in consideration of the characteristics of the engine mount 62, so that the required driving force Fedem of the engine 12 does not exceed the predetermined value Fcri even if the vehicle required driving force Frdem increases. Thus, as shown in FIG. 4, the driving force distribution ratio R changes curvilinearly according to the vehicle required driving force Frdem, or the driving force distribution ratio R changes linearly according to the vehicle required driving force Frdem.

[0059] Also, although FIG. 4 is a relationship map applied during two-wheel drive running, the driving force distribution ratio R may be determined using the relationship map of FIG. 4 even during four-wheel drive running. For example, a new driving force distribution ratio R can be determined by adding the driving force distribution ratio R obtained from the relationship map of FIG. 4 to the currently set driving force distribution ratio R. Alternatively, a relationship map of the driving force distribution ratio R with respect to the vehicle required driving force Frdem considering the current driving force distribution ratio R may be obtained, and during four-wheel drive running, the driving force distribution ratio R may be set based on that relationship map.

[0060] FIG. 5 is a flowchart for explaining the main part of the control function of the electronic control unit 100, and is a flowchart for explaining control operations that can effectively reduce engine vibrations transmitted to the vehicle body side (vehicle side) via the engine mount 62. This flowchart is repeatedly executed while the vehicle is running.

[0061] First, in step S10 corresponding to the control function of the driving force distribution control unit 102d (hereinafter, steps are omitted), the required driving force Fedem of the engine 12 is calculated. For example, based on the running state of the vehicle 10 (such as uphill running or turning), the driving force distribution ratio R is determined. Further, based on the determined driving force distribution ratio R, the vehicle required driving force Frdem obtained from the accelerator opening θacc, etc., the required driving force Fedem of the engine 12 that realizes the obtained driving force distribution ratio R is calculated. Next, in S20 corresponding to the control function of the driving force distribution control unit 102d, it is determined whether or not the required driving force Fedem of the engine 12 calculated in S10 is less than a preset value Fcri. If the determination in S20 is affirmed, this routine is terminated.

[0062] On the other hand, if the determination in S20 is negative, the required driving force Fedem of the engine 12 becomes equal to or greater than the predetermined value Fcri. At this time, in S30 corresponding to the control function of the driving force distribution control unit 102d, based on the relationship map shown in FIG. 4, the driving force distribution ratio R is increased. Therefore, while the driving force distribution to the rear wheels 16 increases, the driving force distribution to the front wheels 14 decreases, so the required driving force Fedem of the engine 12 decreases and the required driving force Fedem becomes less than the predetermined value Fcri. As a result, since the engine mount load Fmt applied to the engine mount 62 becomes smaller than the load Fα, the state of the engine mount 62 improves, and the engine vibrations transmitted to the vehicle body side via the engine mount 62 are within an allowable range. In connection with this, the deterioration of NV characteristics such as stuffy noise and mount vibrations caused by engine vibrations is suppressed.

[0063] FIG. 6 is a time chart showing the control result based on the control operation of the electronic control unit 100. This time chart shows, as an example, the mode when an acceleration operation is performed from a vehicle stop state.

[0064] When the accelerator pedal is depressed at time t1 in FIG. 6, the vehicle required driving force Frdem increases after time t1. Further, as the vehicle required driving force Frdem increases, the required driving force Fedem of the engine 12 increases, so that the engine mount load Fmt increases. At time t2, when the engine mount load Fmt reaches the load Fα, thereafter the drive force distribution ratio R increases. After time t2, as the drive force distribution ratio R increases, the FrMG torque TmFr of the rear motor RrMG transmitted to the rear wheels 16 increases, so that the engine mount load Fmt is controlled so as not to exceed the load Fα. As a result, even when the vehicle required driving force Frdem increases, the engine mount load Fmt is maintained below the load Fα at which the characteristics of the engine mount 62 are good, so that the transmission sensitivity of the engine vibration is maintained within an allowable range. Therefore, deterioration of the NV characteristics due to the engine vibration being transmitted to the vehicle body via the engine mount 62 is suppressed.

[0065] As described above, according to the present embodiment, when the required driving force Fedem of the engine 12 becomes equal to or greater than a predetermined value Fcri that deteriorates the characteristics of the engine mount 62, the RrMG torque TmRr as the drive required amount of the rear motor RrMG is increased, so that the required driving force Fedem of the engine 12 can be reduced. As a result, since the crushing of the engine mount 62 that supports the engine 12 is reduced, the engine vibration transmitted to the vehicle 10 (vehicle body) via the engine mount 62 can be reduced.

[0066] Next, another embodiment of the present invention will be described. In the following description, parts common to the above-described embodiment are denoted by the same reference numerals and the description thereof is omitted.

Embodiment

[0067] In the above-described Example 1, when the engine mount load Fmt applied to the engine mount 62 becomes equal to or greater than the load Fα, the RrMG torque TmRr of the rear motor RrMG is increased to suppress the increase in the engine mount load Fmt and the deterioration of the NV performance. In this embodiment, the output of the rear motor RrMG is limited, and a case where the driving force distribution between the front and rear wheels as in the above-described Example 1 cannot be performed will be described. FIG. 7 is a functional block diagram for explaining the main part of the control function of the electronic control unit 200 corresponding to this embodiment. Note that since the structure of the vehicle controlled by the electronic control unit 200 is the same as that of the vehicle 10 in the above-described embodiment, the description thereof will be omitted.

[0068] The electronic control unit 200 functionally includes a hybrid control unit 202, a clutch control unit 104, and a shift control unit 206. Note that since the clutch control unit 104 has the same function as that in the above-described embodiment, the same reference numeral is given and the description thereof is omitted.

[0069] In addition to the functions provided by the hybrid control unit 102 in the above-described embodiment, the hybrid control unit 202 functionally includes a driving force distribution availability determination unit 204 (hereinafter, the availability determination unit 204) that functions as a driving force availability determination means.

[0070] The availability determination unit 204 determines whether or not the driving force distribution between the front and rear wheels can be appropriately realized. For example, when the RrMG torque TmRr output from the rear motor RrMG is limited, the availability determination unit 204 determines that the driving force distribution between the front and rear wheels cannot be appropriately realized. Further, when the power generation amount of the front motor FrMG is limited in a state where the rear motor RrMG is driven by the power generated by the front motor FrMG, the availability determination unit 204 determines that the driving force distribution between the front and rear wheels cannot be appropriately realized.

[0071] In addition, as cases where the RrMG torque TmRr output from the rear motor RrMG is restricted, for example, when an abnormality is detected in the rear motor RrMG, when the motor temperature THmRr of the rear motor RrMG is equal to or higher than the threshold value at which the output of the rear motor RrMG is restricted, when the state-of-charge value SOC of the HEV battery 28 is less than the threshold value at which the dischargeable power Wout is regulated to a predetermined value or less, when the battery temperature THbat of the HEV battery 28 is within the range where the output of the HEV battery 28 is regulated, etc. apply. Also, as cases where the power generation amount by the front motor FrMG is restricted, for example, when the motor temperature THmFr of the front motor FrMG is equal to or higher than a preset specified value, etc. apply. At this time, since the RrMG torque TmRr output from the rear motor RrMG is restricted and it becomes difficult to appropriately control the driving force distribution between the front and rear wheels, it becomes difficult to control the RrMG torque TmRr of the rear motor RrMG to suppress the engine vibration transmitted to the vehicle body side via the engine mount 62.

[0072] When the output of the rear motor RrMG is restricted in this way, the shift control unit 206 causes the automatic transmission 38 to perform a shift so that the engine rotational speed Ne of the engine 12 is maintained at a predetermined rotational speed Nea or higher.

[0073] FIG. 8 shows the relationship between the frequency Fz [Hz] of the vibration due to the explosion of the engine 12 and the mount transmission force S [dB]. The frequency Fz is the frequency Fz of the vibration due to the explosion of the engine 12 and is proportional to the engine rotational speed Ne. Also, the mount transmission force S [dB] corresponds to the magnitude of the vibration transmitted to the vehicle body side via the engine mount 62, and the larger the mount transmission force S, the larger the vibration transmitted to the vehicle body side via the engine mount 62. As shown in FIG. 8, the mount transmission force S decreases as the frequency Fz increases. In other words, the mount transmission force S decreases as the engine rotational speed Ne increases, and the vibration transmitted to the vehicle body side becomes smaller.

[0074] Therefore, when the output of the rear motor RrMG is restricted, the shift control unit 206 shifts the automatic transmission 38 so that the engine speed Ne is maintained at a predetermined speed Nea or higher that is set in advance. Here, the predetermined speed Nea is set to a value corresponding to the frequency Fza at which the mount transmission force S becomes equal to or less than the allowable value Sa that is set in advance. Also, the allowable value Sa of the mount transmission force S is set to a threshold value within the range where the vibration transmitted to the vehicle body side via the engine mount 62 is allowable.

[0075] FIG. 9 shows the relationship between the vehicle speed V and the engine speed Ne of the automatic transmission 38. The automatic transmission 38 of the present embodiment is configured to be shiftable into six forward gear positions. Therefore, in FIG. 9, straight lines indicating the relationship between the vehicle speed V and the engine speed Ne corresponding to each gear position (1st gear position 1st - 6th gear position 6th) are drawn respectively.

[0076] In FIG. 9, the solid line indicates the relationship between the vehicle speed V and the engine speed Ne that is applied during normal times, that is, when the RrMG torque TmRr of the rear motor RrMG is not restricted (normal times). During normal times, the engine speed Ne changes according to the vehicle speed V along the solid line. On the other hand, the dashed-dotted line indicates the relationship between the vehicle speed V and the engine speed Ne when the RrMG torque TmRr of the rear motor RrMG is restricted, that is, when the drive force distribution is restricted (during drive force distribution restriction). During drive force distribution restriction, the engine speed Ne changes according to the vehicle speed V along the dashed-dotted line. For both the engine speed Ne during normal times indicated by the solid line and the engine speed Ne during drive force distribution restriction indicated by the dashed-dotted line, as the vehicle speed V increases, the automatic transmission 38 is sequentially upshifted, and thus the engine speed Ne changes in a stepped manner.

[0077] During normal operation indicated by the solid line, a region where the engine rotational speed Ne is equal to or lower than a predetermined rotational speed Nea is used. During normal operation, when the engine rotational speed Ne becomes equal to or lower than the predetermined rotational speed Nea, the RrMG torque TmRr of the rear motor RrMG is increased to reduce the engine mount load Fmt, thereby suppressing the transmission sensitivity of engine vibration transmitted to the vehicle body side via the engine mount 62.

[0078] On the other hand, during the driving force distribution limit operation indicated by the dashed-dotted line, since the output of the rear motor RrMG cannot be controlled to reduce the engine mount load Fmt, the automatic transmission 38 is shifted so that the engine rotational speed Ne is maintained at a value equal to or higher than the predetermined rotational speed Nea. Therefore, since the engine rotational speed Ne is prevented from becoming lower than the predetermined rotational speed Nea, the engine vibration transmitted to the vehicle body side via the engine mount 62 remains within an acceptable range. The shift control unit 206 stores a shift map (shift line during driving force distribution limit operation) applied during the driving force distribution limit operation in which the engine rotational speed Ne is maintained at a value equal to or higher than the predetermined rotational speed Nea. When the driving force distribution is limited, the shift of the automatic transmission 38 is performed based on the shift map, thereby maintaining the engine rotational speed Ne at a value equal to or higher than the predetermined rotational speed Nea.

[0079] FIG. 10 is a flowchart for explaining the main part of the control operation of the electronic control unit 200, and is a flowchart for explaining a control operation capable of suppressing engine vibration transmitted to the vehicle body side via the engine mount 62 even when the driving force distribution between the front and rear wheels cannot be appropriately realized. This flowchart is repeatedly executed during vehicle travel.

[0080] First, in S100 corresponding to the control function of the approval determination unit 204, it is determined whether the drive force distribution between the front and rear wheels can be appropriately realized. When S100 is affirmed, in S110 corresponding to the control function of the shift control unit 206, the shift of the automatic transmission 38 is executed based on the shift map (normal shift line) used during normal times. On the other hand, when the determination of S100 is negative, in S120 corresponding to the control function of the shift control unit 206, the shift of the automatic transmission 38 is executed based on the shift map (shift line during drive force distribution limit) in which the engine rotational speed Ne is maintained at a predetermined rotational speed Nea or higher.

[0081] As described above, according to this embodiment, when the output of the rear motor RrMG is restricted, since the shift of the automatic transmission 38 is carried out so that the engine rotational speed Ne is maintained at a predetermined rotational speed Nea or higher, the engine rotational speed Ne is maintained at a predetermined rotational speed Nea or higher, and driving can be continued in a state where the transmission sensitivity of the engine vibration to the vehicle body is reduced. As a result, the engine vibration transmitted via the engine mount 62 can be reduced.

Embodiment

[0082] FIG. 11 is a functional block diagram for explaining the main part of the control function of the electronic control device 300 corresponding to still another embodiment of the present invention. Note that since the structure of the vehicle controlled by the electronic control device 300 is the same as that of the vehicle 10 in the above-described embodiment, the description thereof is omitted.

[0083] The electronic control device 300 functionally includes a hybrid control unit 302, a clutch control unit 104, and a shift control unit 106. Note that since the functions of the clutch control unit 104 and the shift control unit 106 are the same as those in the above-described embodiment, the same reference numerals are given and the description thereof is omitted.

[0084] The hybrid control unit 302 functionally includes an engine control unit 102a, a front motor control unit 102b, a rear motor control unit 102c, and a driving force distribution control unit 304. Since the functions of the engine control unit 102a, the front motor control unit 102b, and the rear motor control unit 102c are the same as those in the above-described embodiment, they are denoted by the same reference numerals and their descriptions are omitted.

[0085] The driving force distribution control unit 304 detects the engine rotational speed Ne, and when the engine rotational speed Ne is less than a predetermined rotational speed Neb set in advance, it compares with the driving force distribution ratio R set when the engine rotational speed Ne is equal to or higher than the predetermined rotational speed Neb, and increases the driving force distribution ratio R. That is, when the engine rotational speed Ne is less than the predetermined rotational speed Neb, the driving force distribution control unit 304 increases the RrMG torque TmRr as the driving request amount of the rear motor RrMG compared with the case where the engine rotational speed Ne is equal to or higher than the predetermined rotational speed Neb. The predetermined rotational speed Neb is obtained experimentally or design-wise in advance and is set based on the characteristics of the engine mount 62. The predetermined rotational speed Neb is set to the threshold value of the engine rotational speed Ne at which the engine vibration transmitted to the vehicle body side via the engine mount 62 is within the allowable range.

[0086] FIG. 12 shows the relationship between the vehicle speed V and the engine rotational speed Ne in this embodiment. In FIG. 12, a straight line showing the relationship between the vehicle speed V and the engine rotational speed Ne is drawn for each gear stage (1st gear stage 1st - 6th gear stage 6th) of the automatic transmission 38. As shown by the solid line in FIG. 12, as the automatic transmission 38 is upshifted as the vehicle speed V increases, the engine rotational speed Ne changes in a stepped manner as it transitions to another gear stage along the straight line of each gear stage.

[0087] In the vehicle speed range X shown in FIG. 12 where the engine rotational speed Ne is less than the predetermined rotational speed Neb, the engine vibration transmitted to the vehicle body side via the engine mount 62 increases. On the other hand, when the vehicle speed range X where the engine rotational speed Ne becomes less than the predetermined rotational speed Neb is reached, the driving force distribution control unit 304 increases the driving force distribution to the rear wheels 16. Therefore, since the required driving force Fedem of the engine 12 relatively decreases, an increase in the engine mount load Fmt is suppressed, and the engine vibration transmitted to the vehicle body side via the engine mount 62 is suppressed. Thus, in the vehicle speed range X where the engine rotational speed Ne is less than the predetermined rotational speed Neb, a driving force distribution (NV priority distribution) that prioritizes NV reduction is implemented.

[0088] Also, in the vehicle speed range Y shown in FIG. 12 where the engine rotational speed Ne is equal to or higher than the predetermined rotational speed Neb, the engine vibration transmitted to the vehicle body side via the engine mount 62 is within an acceptable range. At this time, the driving force distribution control unit 304 implements a driving force distribution (fuel efficiency priority distribution) that prioritizes fuel efficiency. Specifically, the driving force distribution control unit 304 reduces the driving force distribution ratio R and increases the driving force distribution to the front wheels 14 so that the vehicle 10 is driven by the driving force of the engine 12, which is more efficient from the perspective of fuel efficiency. Thus, as shown in FIG. 12, the NV priority distribution (vehicle speed range X) and the fuel efficiency priority distribution (vehicle speed range Y) are alternately realized. Here, if the NV priority distribution and the fuel efficiency priority distribution are repeated according to the change in the vehicle speed V, there is a risk of deterioration in drivability because the driving force distribution ratio R is changed every time the vehicle speed range changes. On the other hand, using the vehicle speed Va shown in FIG. 12 as a threshold value, it may be controlled such that the NV priority distribution is implemented in the region where the vehicle speed is less than Va, and the fuel efficiency priority distribution is implemented when the vehicle speed becomes Va or higher. Note that the vehicle speed Va is a lower limit threshold value at which the engine rotational speed Ne is always equal to or higher than the predetermined rotational speed Neb.

[0089] Here, the vehicle speed Va at which the fuel efficiency priority distribution can be switched is set to a value that suppresses engine vibrations transmitted to the vehicle body side via the engine mount 62. However, the vehicle speed Va can also be set taking into account vibrations generated by other factors, such as resonance occurring in the suspension members. FIG. 13 shows the driving force distribution ratio R when considering resonance occurring in the suspension members, for example. When not considering the resonance occurring in the suspension members, the vehicle speed Va is set to, for example, 80 km / h. Here, when the resonance of the suspension members occurs at a vehicle speed V of 85 km / h, the vehicle speed Va is changed to 90 km / h in consideration of this resonance of the suspension members. Therefore, as shown in FIG. 13, when the vehicle speed V becomes 90 km / h or more, the driving force distribution ratio R gradually decreases. Thus, the vehicle speed Va can also be set to an appropriate value considering other factors.

[0090] FIG. 14 is a flowchart for explaining the main part of the control function of the electronic control device 300, and is a flowchart for explaining a control function capable of achieving both fuel efficiency and NV characteristics. This flowchart is repeatedly executed during vehicle travel.

[0091] First, in S200 corresponding to the control function of the driving force distribution control unit 304, the engine rotational speed Ne is detected. Next, in S210 corresponding to the control function of the driving force distribution control unit 304, it is determined whether the engine rotational speed Ne is less than a predetermined rotational speed Neb. If the determination in S210 is affirmative, in S220 corresponding to the control function of the driving force distribution control unit 304, the driving force distribution between the front and rear wheels is controlled so that the NV characteristics are prioritized. Specifically, by increasing the driving force distribution of the rear wheel 16 by the rear motor RrMG, the driving force of the engine 12 is reduced. As a result, since the engine mount load Fmt applied to the engine mount 62 decreases, the engine vibration transmitted through the engine mount 62 is reduced. On the other hand, if the determination in S210 is negative, in S230 corresponding to the control function of the driving force distribution control unit 304, the driving force distribution between the front and rear wheels is controlled so that fuel efficiency is prioritized. Specifically, it is controlled so that the front wheel 14 is driven solely by the driving force of the engine 12. As a result, since the ratio of the power transmitted to the rear wheel 16 via the electrical path among the power of the engine 12 decreases, the energy loss decreases and the fuel efficiency improves.

[0092] As described above, according to this embodiment, when the engine rotational speed Ne is less than the predetermined rotational speed Neb set based on the characteristics of the engine mount 62, compared with the case where the engine rotational speed Ne is equal to or higher than the predetermined rotational speed Neb, in order to increase the RrMG torque TmRr of the rear motor RrMG, only when the engine vibration transmitted to the vehicle body side through the engine mount 62 is likely to occur, the RrMG torque TmRr of the rear motor RrMG increases, so that the crushing of the engine mount 62 is reduced and the engine vibration transmitted to the vehicle body side is reduced. As a result, it is possible to achieve both NV characteristics and fuel efficiency.

[0093] As described above, the embodiments of the present invention have been described in detail based on the drawings, but the present invention is also applicable in other aspects.

[0094] For example, the aforementioned Examples 1 to 3 were each implemented independently, but it is also possible to implement them by appropriately combining each of Examples 1 - 3. For example, when Examples 1 and 2 are combined and the driving force distribution between the front and rear wheels can be realized, the aspect of Example 1 is implemented. When the driving force distribution between the front and rear wheels can no longer be appropriately realized, the aspect of Example 2 can also be implemented. Similarly, it is also possible to implement by combining Examples 2 and 3.

[0095] In addition, in the aforementioned embodiments, the engine 12 and the front motor FrMG were connected to the front wheels 14 so as to be able to transmit power, and the rear motor RrMG was connected to the rear wheels 16 so as to be able to transmit power. However, it is also possible that the engine 12 and the rear motor RrMG are connected to the rear wheels 16 so as to be able to transmit power, and the front motor FrMG is connected to the front wheels 14 so as to be able to transmit power. In this case, the front wheels 14 correspond to the other wheel of the present invention, and the rear wheels 16 correspond to one wheel of the present invention. Also, the front motor FrMG corresponds to the motor of the present invention, and the rear motor RrMG corresponds to the second motor of the present invention.

[0096] In addition, in the aforementioned embodiments, the rear wheels 16 were driven by the rear motor RrMG, but they may be driven by another driving force source such as a hydraulic motor. That is, as long as the driving force distribution between the front and rear wheels can be realized by connecting the other wheel, which is connected to the engine 12 so as to be able to transmit power, to a driving force source different from the engine 12 so as to be able to transmit power, the present invention can be appropriately applied.

[0097] In addition, in the aforementioned embodiments, the automatic transmission 38 was configured to be shiftable to a gear stage of 6 forward speeds and 1 reverse speed, but the present invention is not limited to a gear stage of 6 forward speeds. For example, a transmission that can be shifted to a gear stage of 10 speeds or the like, as long as it is a transmission that can be shifted to a plurality of gear stages, can be appropriately applied.

[0098] In the above-described embodiment, the driving force distribution between the front and rear wheels was changed based on the magnitude of the required driving force Fedem of the engine 12. However, it may be possible to change the driving force distribution between the front and rear wheels based on the magnitude of the required engine torque Tedem of the engine 12. That is, the required engine torque Tedem may be used as the driving requirement amount of the present invention instead of the required driving force Fedem of the engine 12.

[0099] Also, in the above-described embodiment, the driving force distribution ratio R was defined as the ratio of the driving force transmitted to the rear wheels 16 among the vehicle required driving force Frdem. However, the driving force distribution ratio R may be defined as the ratio of the driving force transmitted to the front wheels 14 among the vehicle required driving force Frdem.

[0100] Also, the specific numerical values in the above-described embodiment are merely examples and may be appropriately changed according to the type and structure of the vehicle, etc.

[0101] Note that the above is merely one embodiment, and the present invention can be implemented in various modified and improved forms based on the knowledge of those skilled in the art.

Explanation of Reference Numerals

[0102] 10: Vehicle 12: Engine 14: Front Wheel (One of the Wheels) 16: Rear Wheel (The Other Wheel) 28: HEV Battery (Battery) 38: Automatic Transmission (Transmission) 62: Engine Mount (Mounting Member) 100, 200, 300: Electronic Control Unit (Control Unit) FrMG: Front Motor (Second Motor) RrMG: Rear Motor (Driving Force Source, Electric Motor for Traveling) Fedem: Required Driving Force of Engine Fcri: Predetermined Value Ne: Engine Rotation Speed (Rotation Speed of Engine) Nea: Predetermined Rotation Speed Neb: Predetermined rotational speed

Claims

【Claim 1】 An engine provided to a vehicle via a mounting member, and an electric motor which is a power source provided separately from the engine, wherein the engine is connected to be capable of transmitting power to one of a front wheel and a rear wheel, the electric motor is connected to be capable of transmitting power to the other of the front wheel and the rear wheel, a transmission is provided in a power transmission path between the engine and the one wheel, and the control device of the vehicle is capable of at least switching between two-wheel drive running in which the one wheel is driven by the engine and four-wheel drive running in which the one wheel is driven by the engine and the other wheel is driven by the electric motor, wherein the control device during vehicle running, when a driving demand amount of the engine becomes equal to or more than a predetermined value based on characteristics of the mounting member, a driving force distribution control unit that executes a driving force distribution control for increasing a driving demand amount of the electric motor; a feasibility determination unit that determines whether or not the driving force distribution control can be performed based on the fact that torque output from the electric motor is restricted; and when it is determined by the feasibility determination unit that the output of the electric motor is restricted and the driving force distribution control cannot be performed, a shift control unit that performs a shift of the transmission so that the rotational speed of the engine is maintained at a predetermined rotational speed or more. A control device for a vehicle, characterized by the above.

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