Hybrid vehicle control device

Abstract

To provide a hybrid vehicle controller whereby: in a hybrid vehicle that is capable of series travelling and can be switched into a series travel mode during retreat travel, it is possible to prevent a sudden drop in the remaining battery level even if the power generation by a rotary electric machine during the series travel has decreased, so that the retreat travel can be continued for a long time.SOLUTION: During the execution of series travel, which is a kind of retreat travel, the levels of power WgFr generated by a front rotary electric machine FrMG limit driving power Pr that can be output from a rear unit 20. Even if the levels of power WgFr generated by the front rotary electric machine FrMG decrease, power consumption by a rear rotary electric machine RrMG is reduced due to the limitation of the driving power Pr output from the rear unit 20. As a result, a sudden rise in the power consumption during retreat travel is prevented, the retreat travel can be continued for a long time.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a control device for a hybrid vehicle capable of series running. [Background technology]

[0002] Patent Document 1 discloses a hybrid vehicle configured to drive the front wheels by an internal combustion engine and a first rotating electric machine, and the rear wheels by a second rotating electric machine. Patent Document 1 also discloses that in the hybrid vehicle configured as above, if a predetermined abnormality is detected while the vehicle is traveling in a series traveling mode in which the power of the internal combustion engine is used to generate power at the first rotating electric machine, and the generated power is used to drive the second rotating electric machine to travel the vehicle, the amount of power generated by the first rotating electric machine is limited. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-32829 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, when traveling in series driving mode and the power generation capacity of the first rotating electric machine is limited, if the second rotating electric machine is continuously controlled to output driving force according to the driver's request, the remaining battery charge may decrease rapidly, making it difficult to continue traveling.

[0005] The present invention has been made against the background of the above circumstances, and its object is to provide a control device for a hybrid vehicle that is capable of executing a series driving mode in which power from an internal combustion engine is used to generate electricity at a first rotating electric machine, and the generated electricity is used to drive a second rotating electric machine to run the vehicle, and that, even if the amount of electricity generated by the first rotating electric machine decreases, suppresses a sudden decrease in the remaining battery charge and enables long-term evacuation driving. [Means for solving the problem]

[0006] The gist of a first invention is that (a) a hybrid vehicle including a first drive device that drives one of front wheels and rear wheels, and a second drive device that drives the other of the front wheels and the rear wheels, the first drive device being configured to be capable of transmitting power of an internal combustion engine and a first rotating electric machine to one of the front wheels and the rear wheels, and the second drive device being configured to be capable of transmitting power of a second rotating electric machine to the other of the front wheels and the rear wheels, and when a predetermined abnormality is detected during traveling, power output from the internal combustion engine is used to generate power by the first rotating electric machine, and the power generated by the first rotating electric machine is When the driving amount output from the second drive device cannot be realized by the power supply alone, power from a battery is also supplied to the second rotating electric machine, A control device for a hybrid vehicle configured to perform evacuation running by driving the second rotating electric machine, comprising: (b) a power generation unit configured to generate power by the first rotating electric machine during the execution of the evacuation running; The upper limit of the drive amount output from the second drive device is set to be smaller as the difference between the power command value and the generated power increases, and the upper limit is not exceeded. The driving amount that can be output from the second driving device is limited. Effect of the Invention

[0007] According to the first aspect of the present invention, the electric power generated by the first rotating electric machine during the execution of the evacuation traveling is The upper limit of the drive amount output from the second drive device is set to be smaller as the difference between the command value and the generated power increases, and the upper limit is not exceeded. Since the amount of drive that can be output from the second drive device is limited, even if the power generated by the first rotating electric machine is reduced, the amount of power consumed by the second rotating electric machine is reduced by limiting the amount of drive that can be output from the second drive device. As a result, sudden consumption of power during evacuation travel is suppressed, and evacuation travel for a long period of time is possible. [Brief description of the drawings]

[0008] [Figure 1] 1 is a diagram for explaining a schematic configuration of a hybrid vehicle to which the present invention is applied, and is also a diagram for explaining main parts of control functions and a control system for various controls in the vehicle. [Diagram 2] 13 is one example of a relationship map used when setting an upper limit value of drive power based on the difference between a command value and an actual value of generated power. [Diagram 3] 1 is a flowchart illustrating the main control operations of an electronic control device, and is a flowchart illustrating the control operations when evacuation travel is performed due to detection of an abnormality in an automatic transmission or the like. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Here, in a further preferred embodiment, an electric storage device is provided that supplies electric power to the first rotating electric machine and the second rotating electric machine, and during evacuation driving, the second rotating electric machine is supplied with electric power generated by the first rotating electric machine and electric power from the electric storage device.

[0010] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that in the following embodiments, the drawings are appropriately simplified or modified, and the dimensional ratios and shapes of the various parts are not necessarily drawn accurately. EXAMPLES

[0011] FIG. 1 is a diagram for explaining a schematic configuration of a hybrid vehicle 10 (hereinafter, vehicle 10) to which the present invention is applied, and also a diagram for explaining main parts of control functions and a control system for various controls in the vehicle 10. In FIG. 1, the vehicle 10 is a hybrid vehicle equipped with an engine 12 and a front rotating electric machine FrMG that are the driving force sources for the front wheels 14, and a rear rotating electric machine RrMG that is the driving force source for the rear wheels 16. The vehicle 10 is equipped with a front unit 18 provided in a power transmission path between the engine 12 and the front wheels 14, and a rear unit 20 for driving the rear wheels 16. The front unit 18 corresponds to a first drive device of the present invention that drives one of the front wheels and the rear wheels, and the rear unit 20 corresponds to a second drive device of the present invention that drives the other of the front wheels and the rear wheels.

[0012] The engine 12 is a known internal combustion engine such as a gasoline engine or a diesel engine. An engine control device 22 including a throttle actuator, a fuel injection device, an ignition device, and the like provided in the vehicle 10 is controlled by an electronic control device 100, which will be described later, to control an engine torque Te, which is an output torque of the engine 12.

[0013] The front rotating electric machine FrMG and the rear rotating electric machine RrMG 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.

[0014] The front rotating electric machine FrMG is connected to an HEV battery 28 via a front inverter 24 (FrPCU) and a system main relay 26 (SMR). The front rotating electric machine FrMG controls the front inverter 24 by an electronic control device 100 (described later), thereby controlling an FrMG torque TmFr, which is an output torque of the front rotating electric machine FrMG. For example, when the rotation direction of the front rotating electric machine FrMG is the forward rotation direction that is the same as the rotation direction when the engine 12 is in operation, the FrMG torque TmFr is a powering torque on the acceleration side, and a regenerative torque on the deceleration side, which is a negative torque.

[0015] The front rotating electric machine FrMG generates power for traveling using electric power supplied from the HEV battery 28 via the front inverter 24 and the system main relay 26 instead of or in addition to the engine 12. The front rotating electric machine FrMG also generates electric power using the power of the engine 12 and the driven force input from the front wheels 14. The electric power generated by the power generation of the front rotating electric machine 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 power generation of the front rotating electric machine FrMG is supplied to the rear rotating electric machine RrMG to drive the rear rotating electric machine RrMG. The electric power also means electric energy unless otherwise specified. The power also means torque or force unless otherwise specified.

[0016] The rear rotating electric machine RrMG is connected to the HEV battery 28 via a rear inverter 30 (RrPCU) and a system main relay 26 (SMR). The rear rotating electric machine RrMG controls the rear inverter 30 by an electronic control device 100 (described later), thereby controlling the RrMG torque TmRr, which is the output torque of the rear rotating electric machine RrMG. For example, when the rotation direction of the rear rotating electric machine RrMG is the positive rotation direction, which is the same as that during forward driving, the RrMG torque TmRr is a powering torque on the acceleration side, and a regenerative torque on the deceleration side, which is a negative torque.

[0017] The rear rotating electric machine RrMG generates power for traveling using electric power supplied from the HEV battery 28 via the rear inverter 30 and the system main relay 26, or electric power generated by the front rotating electric machine FrMG. The rear rotating electric machine RrMG also generates electric power using a driven force input from the rear wheels 16. The electric power generated by the rear rotating electric machine RrMG is stored in the HEV battery 28 via the rear inverter 30 and the system main relay 26. The HEV battery 28 is an electric storage device that supplies and receives electric power to the front rotating electric machine FrMG and the rear rotating electric machine RrMG.

[0018] The front unit 18 is configured to be able to transmit the power of the engine 12 and the front rotating electric machine FrMG to the front wheels 14. The front unit 18 includes the engine 12, a K0 clutch 34 (K0), an input clutch 36 (WSC), an automatic transmission 38, and the like. The K0 clutch 34 (K0), the input clutch 36 (WSC), and the automatic transmission 38 are each housed in a case 32, which is a non-rotating member attached to the vehicle body. The K0 clutch 34 is a clutch provided between the engine 12 and the front rotating electric machine 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 on the power transmission path between the engine 12 and the front rotating electric machine FrMG and the front wheels 14. The automatic transmission 38 is connected to the input clutch 36 and is interposed in the power transmission path between the input clutch 36 and the front wheels 14. The front unit 18 also includes a differential device 42 (DIFF) connected to an output rotating member 40 of the automatic transmission 38, and a pair of left and right front wheel axles 44 connected to the front wheels 14. The front unit 18 also includes an engine connecting shaft 46 that connects the engine 12 and the K0 clutch 34, a rotating electric machine connecting shaft 48 that connects the K0 clutch 34 and the input clutch 36, and a transmission input shaft 50 of the automatic transmission 38.

[0019] The front rotating electric machine FrMG is connected to a rotating electric machine connecting shaft 48 in the case 32 so as to be capable of transmitting power. The front rotating electric machine FrMG is connected to a power transmission path between the engine 12 and the front wheels 14, in particular to a power transmission path between the K0 clutch 34 and the input clutch 36. In other words, the front rotating electric machine FrMG is connected to the input clutch 36 and the automatic transmission 38 so as to be capable of transmitting power, without passing through the K0 clutch 34.

[0020] The automatic transmission 38 is a known planetary gear type automatic transmission including, for example, one or more planetary gear sets (not shown) and a plurality of engagement devices CB. The engagement devices CB are hydraulic friction engagement devices including, for example, a multi-plate or single-plate clutch or brake pressed by a hydraulic actuator, or a band brake tightened by a hydraulic actuator. The engagement devices CB have their respective torque capacities, or CB torques Tcb, changed by the regulated CB hydraulic pressure PRcb supplied from the hydraulic control circuit 52, thereby switching between control states such as an engaged state and a released state.

[0021] The automatic transmission 38 is a stepped transmission in which one of a plurality of gear stages (also called gear stages) with different speed ratios (also called gear ratios) γat (=AT input rotation speed Ni / AT output rotation speed No) is formed by engaging one of the engagement devices CB. The automatic transmission 38 switches the gear stages formed according to the accelerator operation of the driver (=operator) and the vehicle speed V, etc., by an electronic control device 100 described later, that is, the automatic transmission 38 selectively forms a plurality of gear stages. The AT input rotation speed Ni is the rotation speed of the transmission input shaft 50, and is the input rotation speed of the automatic transmission 38. The AT output rotation speed No is the rotation speed of the output rotating member 40 of the automatic transmission 38, and is the output rotation speed of the automatic transmission 38.

[0022] The K0 clutch 34 is a wet or dry friction engagement device, for example, configured with a multiple-plate or single-plate clutch. The control state of the K0 clutch 34, such as an engaged state or a released state, is switched by an electronic control device 100, which will be described later. The control state of the K0 clutch 34 is switched by changing the K0 torque Tk0, which is the torque capacity of the K0 clutch 34, using the K0 oil pressure PRk0 supplied from the hydraulic control circuit 52.

[0023] The input clutch 36 is a wet or dry friction engagement device, for example, configured by a multiple-plate or single-plate clutch. The control state of the input clutch 36, such as an engaged state or a released state, is switched by an electronic control device 100, which will be described later. The control state of the input clutch 36 is switched by changing the WSC torque Twsc, which is the torque capacity of the input clutch 36, using the WSC oil pressure PRwsc supplied from the hydraulic control circuit 52.

[0024] In an engaged state of the K0 clutch 34, the engine 12 and the front rotating electric machine FrMG are connected to each other so as to be capable of transmitting power through the engine connecting shaft 46 and the rotating electric machine connecting shaft 48. That is, the K0 clutch 34 connects the engine 12 and the front rotating electric machine FrMG to be capable of transmitting power when engaged. On the other hand, in a released state of the K0 clutch 34, the power transmission between the engine 12 and the front rotating electric machine FrMG is interrupted. That is, the K0 clutch 34 separates the connection between the engine 12 and the front rotating electric machine FrMG when released. In other words, the K0 clutch 34 is a connecting / disconnecting clutch that connects the engine 12 and the front rotating electric machine FrMG to each other when engaged, and separates the connection between the engine 12 and the front rotating electric machine FrMG when released.

[0025] When the input clutch 36 is in an engaged state, the rotating electric machine connecting shaft 48 and the transmission input shaft 50 are connected to each other. At this time, the front rotating electric machine FrMG is connected to the front wheels 14 via the rotating electric machine connecting shaft 48, the input clutch 36, the transmission input shaft 50, the output rotating member 40, the differential device 42, and the front wheel axle 44 so as to be capable of transmitting power thereto. When the K0 clutch 34 and the input clutch 36 are in an engaged state, in addition to the front rotating electric machine FrMG, the engine 12 is connected to the front wheels 14 via the rotating electric machine connecting shaft 48, the input clutch 36, the transmission input shaft 50, the output rotating member 40, the differential device 42, and the front wheel axle 44 so as to be capable of transmitting power thereto. On the other hand, when the input clutch 36 is in a released state, the rotating electric machine connecting shaft 48 and the transmission input shaft 50 are disconnected from each other. In other words, the input clutch 36 is a disconnecting clutch that connects the engine 12 and the front rotating electric machine FrMG to the front wheels 14 when engaged, and disconnects the engine 12 and the front rotating electric machine FrMG to the front wheels 14 when released.

[0026] In the front unit 18, when the K0 clutch 34 and the input clutch 36 are engaged, the power output from the engine 12 is transmitted to the front wheels 14 via the engine connecting shaft 46, the rotating electric machine connecting shaft 48, the transmission input shaft 50, the automatic transmission 38, the output rotating member 40, the differential device 42, and the front wheel axle 44 in that order. Also, when the input clutch 36 is engaged, the power output from the front rotating electric machine FrMG is transmitted to the front wheels 14 via the rotating electric machine connecting shaft 48, the transmission input shaft 50, the automatic transmission 38, the output rotating member 40, the differential device 42, and the front wheel axle 44 in that order.

[0027] On the other hand, when the input clutch 36 is disengaged, the power transmission path between the engine 12 and the front rotating electric machine FrMG and the front wheels 14 is interrupted, and the power of the engine 12 and the front rotating electric machine FrMG is not transmitted to the front wheels 14. When the K0 clutch 34 is disengaged and the input clutch 36 is engaged, the power of the front rotating electric machine 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. When the K0 clutch 34 is engaged and the input clutch 36 is disengaged, the power of the engine 12 and the front rotating electric machine FrMG is not transmitted to the front wheels 14, but the engine 12 and the front rotating electric machine FrMG are connected to each other so as to be capable of transmitting power. At this time, the front rotating electric machine FrMG can generate power by the power of the engine 12.

[0028] The rear unit 20 is configured to be capable of transmitting the power of the rear rotating electric machine RrMG to the rear wheels 16. The rear unit 20 includes a rear inverter 30 controlled by an electronic control device 100 (described later), the rear rotating electric machine RrMG, and a pair of left and right rear wheel axles 54 connected to the left and right rear wheels 16. The rear rotating electric machine RrMG is connected to the pair of left and right rear wheel axles 54 directly or via a reduction gear or the like (not shown). Therefore, the rear rotating electric machine RrMG is connected to the rear wheels 16 via the rear wheel axles 54 or the like so as to be capable of transmitting power to the rear wheels 16, whereby the power output from the rear rotating electric machine RrMG is transmitted to the rear wheels 16 via the rear wheel axles 54 or the like.

[0029] The vehicle 10 includes the MOP 58, which is a mechanical oil pump, and the EOP 60, which is an electric oil pump. The MOP 58 is connected to the rotating electric machine connecting shaft 48 via gears or the like so as to be capable of transmitting power, and is rotated by at least one of the engine 12 and the front rotating electric machine FrMG to discharge hydraulic oil used in the front unit 18. The EOP 60 is rotated by a pump motor (not shown) to discharge hydraulic oil. The hydraulic oil discharged by the MOP 58 and the EOP 60 is supplied to a hydraulic control circuit 52. The hydraulic control circuit 52 supplies the CB hydraulic pressure PRcb, the K0 hydraulic pressure PRk0, the WSC hydraulic pressure PRwsc, and the like, which are adjusted based on the hydraulic oil discharged by the MOP 58 and the EOP 60.

[0030] The vehicle 10 further includes an electronic control device 100 (control device) including a control device of the vehicle 10 related to driving control, etc. The electronic control device 100 includes a so-called microcomputer equipped with, for example, a CPU, RAM, ROM, an input / output interface, etc., and the CPU executes various controls of the vehicle 10 by performing signal processing according to a program previously stored in the ROM while utilizing the temporary storage function of the RAM. The electronic control device 100 includes each ECU for engine control, rotating electrical machine control, hydraulic control, etc. as necessary.

[0031] The electronic control device 100 receives various signals based on detection values ​​from various sensors provided in the vehicle 10 (for example, an engine rotation speed sensor 70, an input rotation speed sensor 72, an output rotation speed sensor 74, an FrMG rotation speed sensor 76, an RrMG rotation speed sensor 78, an accelerator opening sensor 80, a throttle valve opening sensor 82, a brake switch 84, a battery sensor 86, an oil temperature sensor 88, etc.), and outputs various signals (for example, an engine rotation speed Ne which is the rotation speed of the engine 12, an AT input rotation speed Ni which is the rotation speed of the transmission input shaft 50 of the automatic transmission 38, an AT output rotation speed No which is the rotation speed of the output rotating member 40 of the automatic transmission 38 and corresponds to the vehicle speed V, The following are respectively supplied to the control circuit 52: FrMG rotation speed NmFr, which is the rotation speed of the front rotating electric machine FrMG; RrMG rotation speed NmRr, which is the rotation speed of the rear rotating electric machine RrMG; accelerator opening θacc, which is the amount of accelerator operation by the driver indicating the magnitude of the driver's acceleration operation; throttle valve opening θth, which is the opening of the electronic throttle valve; brake-on signal Bon, which is a signal indicating a state in which the brake pedal for operating the wheel brakes is being operated by the driver; battery temperature THbat, battery charge / discharge current Ibat, and battery voltage Vbat of the HEV battery 28; and hydraulic oil temperature THoil, which is the temperature of the hydraulic oil in the hydraulic control circuit 52.

[0032] The electronic control device 100 outputs various command signals (e.g., an engine control command signal Se for controlling the engine 12, an FrMG control command signal SmFr for controlling the front rotating electric machine FrMG, an RrMG control command signal SmRr for controlling the rear rotating electric machine RrMG, a CB hydraulic control command signal Sbc for controlling the engagement device CB, a K0 hydraulic control command signal Sko for controlling the K0 clutch 34, a WSC hydraulic control command signal Swsc for controlling the input clutch 36, a relay switching command signal Ssmr for switching the connected / disconnected state of the system main relay 26, etc.) to each device (e.g., an engine control device 22, a front inverter 24, a rear inverter 30, a hydraulic control circuit 52, a system main relay 26, etc.) provided in the vehicle 10. When the power switch of the vehicle 10 is switched to the on state, the system main relay 26 is switched to a connected state by the relay switching command signal Ssmr, and power supply from the HEV battery 28 becomes possible.

[0033] The electronic control unit 100 includes a hybrid control means, i.e., a hybrid control unit 102, a clutch control means, i.e., a clutch control unit 104, and a gear shift control means, i.e., a gear shift control unit 106, in order to realize various driving controls in the vehicle 10.

[0034] The hybrid control unit 102 includes a function as an engine control means, i.e., an engine control unit 102a, that controls the operation of the engine 12, a function as an Fr rotating machine control means, i.e., an Fr rotating machine control unit 102b, that controls the operation of the front rotating machine FrMG via the front inverter 24, and a function as an Rr rotating machine control means, i.e., an Rr rotating machine control unit 102c, that controls the operation of the rear rotating machine RrMG via the rear inverter 30, and performs hybrid drive control, etc., using the engine 12, the front rotating machine FrMG, and the rear rotating machine RrMG.

[0035] The hybrid control unit 102 calculates the driving demand amount of 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 that is experimentally or design-wise obtained and stored in advance, that is, a predetermined relationship. The driving demand amount is, for example, a required driving torque Trdem at the front wheels 14 and the rear wheels 16. In other words, the required driving torque Trdem [Nm] is the required driving power Prdem [W] at the vehicle speed V at that time. The driving demand amount can also be a required driving force Frdem [N], a required AT output torque at the output rotating member 40 of the automatic transmission 38, or the like. In calculating the driving demand amount, an AT output rotation speed No, or the like, can be used instead of the vehicle speed V.

[0036] 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 rotating electric machine FrMG, and an RrMG control command signal SmRr for controlling the rear rotating electric machine RrMG so as to realize the required driving power Prdem, taking into consideration the transmission loss, the auxiliary load, the gear ratio γat of the automatic transmission 38, the chargeable electric power Win and the dischargeable electric 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 rotation 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 rotating electric machine FrMG that outputs the FrMG torque TmFr at the FrMG rotation speed NmFr at that time. Also, the RrMG control command signal SmRr is, for example, a command value for power consumption WmRr of the rear rotating electric machine RrMG that outputs an RrMG torque TmRr at the RrMG rotation speed NmRr at that time.

[0037] The chargeable power Win of the HEV battery 28 is the maximum power that can be input, which specifies the limit on the input power of the HEV battery 28, and indicates the input limit of the HEV battery 28. The dischargeable power Wout of the HEV battery 28 is the maximum power that can be output, which specifies the limit on the output power of the HEV battery 28, and indicates the output limit of the HEV battery 28. The chargeable power Win and dischargeable power Wout of the HEV battery 28 are calculated by the electronic control device 100, for example, based on the battery temperature THbat and the state of charge value SOC [%] of the HEV battery 28. The state of charge value SOC of the HEV battery 28 is a value that indicates the state of charge of the HEV battery 28, and is calculated by the electronic control device 100, for example, based on the battery charge / discharge current Ibat and the battery voltage Vbat.

[0038] When the required drive torque Trdem can be satisfied by the output of at least one of the front rotating electric machine FrMG and the rear rotating electric machine RrMG, the hybrid control unit 102 sets the drive mode to the motor drive (=BEV drive) mode. In the BEV drive mode, the hybrid control unit 102 performs BEV (Battery Electric Vehicle) drive using at least one of the front rotating electric machine FrMG and the rear rotating electric machine RrMG as a drive force source with the K0 clutch 34 in the released state and the input clutch 36 in the engaged state.

[0039] On the other hand, when the required drive torque Trdem cannot be satisfied without using at least the output of the engine 12, the hybrid control unit 102 sets the drive mode to the engine drive mode, i.e., hybrid drive (=HEV drive) mode. In the HEV drive mode, the hybrid control unit 102 performs engine drive, i.e., HEV (Hybrid Electric Vehicle) drive, in which at least the engine 12 is used as a drive power source, with the K0 clutch 34 and the input clutch 36 in an engaged state. Furthermore, even if the required drive torque Trdem can be satisfied with the output of at least one of the front rotating electric machine FrMG and the rear rotating electric machine RrMG, the hybrid control unit 102 establishes the HEV drive mode when the state of charge value SOC of the HEV battery 28 falls below a predetermined engine start threshold value or when the engine 12 needs to be warmed up. The engine start threshold value is a predetermined threshold value for determining that the state of charge value SOC is at a value at which the engine 12 needs to be forcibly started and the HEV battery 28 needs to be charged. In this way, the hybrid control unit 102 automatically stops the engine 12 during HEV driving based on the required driving torque Trdem and the required driving power Prdem, etc., restarts the engine 12 after the engine has been stopped, and starts the engine 12 during BEV driving, thereby switching between the BEV driving mode and the HEV driving mode.

[0040] Also, the hybrid control unit 102 distributes the driving force between the front wheels 14 and the rear wheels 16 according to the running state of the vehicle 10, and controls so as to obtain appropriate running performance. For example, when the vehicle starts, accelerates, or runs on a slippery low μ road, the hybrid control unit 102 drives the rear wheels 16 in addition to the front wheels 14 to run the vehicle 10, thereby performing four-wheel drive running. At this time, the hybrid control unit 102 calculates an appropriate driving force distribution ratio between the front and rear wheels based on the running state of the vehicle 10, and controls the output of the engine 12, the front rotating electric machine FrMG, and the rear rotating electric machine RrMG so that the driving force distribution between the front and rear wheels is the calculated driving force distribution ratio. For example, while running in the HEV running mode, the power of the engine 12 is transmitted to the front wheels 14 as driving force, and part of the power of the engine 12 is transmitted to the front rotating electric machine FrMG, thereby generating electricity by the front rotating electric machine FrMG. Furthermore, the generated electric power WgFr generated by the front rotary electric machine FrMG is supplied to the rear rotary electric machine RrMG, thereby driving the rear rotary electric machine RrMG and causing the vehicle 10 to run.

[0041] Furthermore, in a low vehicle speed region or a low load region, the hybrid control unit 102 can perform series running, in which the front rotating electric machine FrMG generates electricity using the power of the engine 12 while the input clutch 36 is disengaged and the rear rotating electric machine RrMG is driven by the generated electric power WgFr generated by the front rotating electric machine FrMG. At this time, since the input clutch 36 is disengaged, no driving force is transmitted to the front wheels 14. Furthermore, the generated electric power WgFr generated by the front rotating electric machine FrMG is distributed to the rear rotating electric machine RrMG and the HEV battery 28. For example, of the generated electric power WgFr generated by the front rotating electric machine FrMG, an amount of electric power sufficient to realize the required driving power Prdem is supplied to the rear rotating electric machine RrMG, and the remaining electric power is supplied to the HEV battery 28. The driving mode in which the power of the engine 12 is used exclusively to generate power for the front rotating electric machine FrMG and the generated power WgFr is supplied to the rear rotating electric machine RrMG to drive the vehicle 10 as described above is referred to as the series driving mode.

[0042] Furthermore, during deceleration, the hybrid control unit 102 executes regenerative running, in which the vehicle runs while recovering energy through regeneration by the front rotating electric machine FrMG and the rear rotating electric machine RrMG.

[0043] During at least HEV driving using the engine 12 as a driving force source, the clutch control unit 104 engages the K0 clutch 34 and the input clutch 36 to switch to a state in which the power of the engine 12 can be transmitted to the front wheels 14. During motor driving, the clutch control unit 104 disengages the K0 clutch 34 while engaging the input clutch 36 to switch to a state in which driving is possible using the front rotating electric machine FrMG and the rear rotating electric machine RrMG. During deceleration driving, the clutch control unit 104 engages the input clutch 36 to switch to a state in which power can be transmitted between the front rotating electric machine FrMG and the front wheels 14 so that regeneration by the front rotating electric machine FrMG is possible. During driving in the series driving mode, the clutch control unit 104 engages the K0 clutch 34 while disengaging the input clutch 36 to switch to a state in which the power of the engine 12 is transmitted to the front rotating electric machine FrMG while the transmission of driving force to the front wheels 14 is interrupted.

[0044] The shift control unit 106 judges whether or not to shift the automatic transmission 38 by using, for example, a shift map which is a predetermined relationship, and outputs a CB hydraulic control command signal Sbc to the hydraulic control circuit 52 as necessary to execute shift control of the automatic transmission 38. The shift map is a predetermined relationship having a shift line for judging whether or not to shift the automatic transmission 38 on a two-dimensional coordinate system having, for example, vehicle speed V and required driving torque Trdem as variables. In the shift map, the AT output rotation speed No or the like may be used instead of the vehicle speed V, and the required driving force Frdem, accelerator opening θacc, throttle valve opening θth, or the like may be used instead of the required driving torque Trdem.

[0045] Meanwhile, when a predetermined abnormality such as a failure of the automatic transmission 38 is detected while traveling in the HEV traveling mode, the hybrid control unit 102 switches the traveling mode from the HEV traveling mode to the series traveling mode as evacuation traveling. Therefore, the power output from the engine 12 is transmitted to the front rotating electric machine FrMG to generate power by the front rotating electric machine FrMG, and the generated electric power WgFr generated by the front rotating electric machine FrMG is supplied to the rear rotating electric machine RrMG. Furthermore, the rear rotating electric machine RrMG is driven using the generated electric power WgFr generated by the front rotating electric machine FrMG, and evacuation traveling is performed by driving the rear rotating electric machine RrMG. At this time, the rear rotating electric machine RrMG is supplied with electric power that realizes the required driving power Prdem, and when the generated electric power WgFr generated by the front rotating electric machine FrMG alone cannot realize the required driving power Prdem, electric power is also supplied from the HEV battery 28 to satisfy the required driving power Prdem by the driver. That is, the driving power PRr output from the rear rotating electric machine RrMG is expressed by the following formula (1): In formula (1), WgFr represents the generated power of the front rotating electric machine FrMG, and Wbat represents the discharged power discharged from the HEV battery 28. As shown in formula (1), the sum of the generated power WgFr of the front rotating electric machine FrMG and the discharged power Wbat of the HEV battery 28 is equivalent to the driving power PRr of the rear rotating electric machine RrMG. PRr = WgFr + Wbat (1)

[0046] Here, if an abnormality occurs in the engine 12 or the front rotating electric machine FrMG during evacuation running, and the generated electric power WgFr generated by the front rotating electric machine FrMG decreases, the discharge electric power Wbat discharged from the HEV battery 28 to realize the required driving power Prdem increases. That is, if the generated electric power WgFr decreases in the formula (1), it is necessary to increase the discharge electric power Wbat of the HEV battery 28 to ensure the driving power PRr. As a result, the state of charge value SOC, which is the charge amount of the HEV battery 28, decreases faster, and there is a risk that the time during which the vehicle 10 can perform evacuation running will be shortened. In response to this, the hybrid control unit 102 limits the driving power Pr (driving amount) that can be output from the rear unit 20 during evacuation running according to the generated electric power WgFr (generated electric power amount) generated by the front rotating electric machine FrMG. In other words, the driving power PRr that can be output from the rear rotating electric machine RrMG is limited according to the generated electric power WgFr. As a result, a sudden increase in the discharge power Wbat discharged from the HEV battery 28 can be suppressed, enabling long-term evacuation driving. Below, a description will be given of the control when evacuation driving is executed due to detection of a predetermined abnormality during driving.

[0047] When a predetermined abnormality is detected, such as an abnormality occurring in a solenoid that controls the CB hydraulic pressure PRcb supplied to the engagement device CB provided in the automatic transmission 38, making it difficult to transmit power to the front wheels 14, the hybrid control unit 102 determines to switch to the series driving mode as evacuation driving. At this time, the clutch control unit 104 determines the current driving mode, and if the current driving mode is a driving mode other than the series driving mode, it switches the driving mode to the series driving mode by engaging the K0 clutch 34 and releasing the input clutch 36. Note that if the vehicle is already traveling in the series driving mode, the series driving mode is maintained.

[0048] When the traveling mode is switched to the series traveling mode, the hybrid control unit 102 calculates the difference ΔWgFr (=WgFrdem-WgFr) between the command value WgFrdem of the power generation electric power WgFr of the front rotating electric machine FrMG and the actual power generation electric power WgFr, and determines whether the difference ΔWgFr is equal to or greater than a preset determination threshold value α. The determination threshold value α is set to a value at which it is determined that the driving power Pr that can be output from the rear unit 20 needs to be limited due to a decrease in the power generation electric power WgFr by the front rotating electric machine FrMG. In other words, the determination threshold value α is set to a value at which it is determined that the driving power PRr that can be output from the rear rotating electric machine RrMG needs to be limited. When the difference ΔWgFr becomes equal to or greater than the determination threshold value α, the hybrid control unit 102 limits the driving power Pr that can be output from the rear unit 20 according to the power generation electric power WgFr generated by the front rotating electric machine FrMG.

[0049] The hybrid control unit 102 sets an upper limit value Prlim of the driving power Pr that can be output from the rear unit 20, which is determined based on, for example, the difference ΔWgFr (=WgFrdem-WgFr) between the command value WgFrdem of the generated power WgFr and the generated power WgFr, and limits the driving power Pr so that the driving power Pr does not exceed the set upper limit value Prlim. For example, when the required driving power Prdem, which is determined based on the accelerator opening θacc, the vehicle speed V, etc., is larger than the upper limit value Prlim, the required driving power Prdem is corrected (limited) to the upper limit value Prlim. Therefore, the driving power Pr that can be output from the rear unit 20 is limited by controlling the driving power Pr so that it does not exceed the upper limit value Prlim.

[0050] The upper limit value Prlim is determined based on a relationship map such as that shown in Fig. 2. As shown in the relationship map in Fig. 2, the upper limit value Prlim is set to decrease as the difference ΔWgFr increases. Therefore, as the generated electric power WgFr generated by the front rotating electric machine FrMG decreases, the difference ΔWgFr increases, and therefore the upper limit value Prlim decreases as the generated electric power WgFr decreases. As a result, the limit amount of the drive power Pr increases as the difference ΔWgFr increases, i.e., as the generated electric power WgFr decreases.

[0051] The hybrid control unit 102 calculates the driving power PRr of the rear electric rotating machine RrMG within a range in which the driving power Pr does not exceed an upper limit value Prlim. Next, the hybrid control unit 102 calculates the discharge power Wbat from the HEV battery 28 required for the calculated driving power PRr to be output from the rear electric rotating machine RrMG, from relationships such as equation (1). At this time, as the driving power Pr is limited to the upper limit value Prlim, the driving power PRr output from the rear electric rotating machine RrMG becomes smaller, so that the discharge power Wbat discharged from the HEV battery 28 decreases (compared to when the driving power Pr is not limited). As a result, a sudden decrease in the state of charge value SOC of the HEV battery 28 is suppressed.

[0052] 3 is a flowchart explaining the main control operations of the electronic control unit 100, and is a flowchart explaining the control operations when evacuation running is performed due to detection of an abnormality in the automatic transmission 38, etc. This flowchart is executed while traveling in the series traveling mode as evacuation running in response to detection of an abnormality.

[0053] In FIG. 3, in step S10 (hereinafter, step will be omitted) corresponding to the control function of the hybrid control unit 102, when performing evacuation traveling, it is determined whether or not the current traveling mode is the series traveling mode. If the determination in S10 is positive, the process proceeds to S30. If the determination in S10 is negative, the traveling mode is switched to the series traveling mode in S20 corresponding to the control function of the clutch control unit 104. Specifically, the K0 clutch 34 is engaged and the input clutch 36 is released, thereby switching the traveling mode to the series traveling mode. Next, in S30 corresponding to the control function of the hybrid control unit 102, it is determined whether or not the generated power WgFr, which is the amount of power generated by the front rotating electric machine FrMG, is in a reduced state based on whether or not the difference ΔWgFr between the command value WgFrdem of the generated power WgFr of the front rotating electric machine FrMG and the actual generated power WgFr is equal to or greater than the determination threshold value α. If the determination in S30 is negative, the process proceeds to S50. If the determination in S30 is positive, in S40 corresponding to the control function of the hybrid control unit 102, the driving power Pr is limited according to the generated power WgFr of the front rotary electric machine FrMG. For example, a difference ΔWgFr between a command value WgFrdem of the generated power WgFr and the actual generated power WgFr is calculated, and an upper limit value Prlim of the driving power Pr according to this difference ΔWgFr is set, thereby limiting the driving power Pr. In S50 corresponding to the control function of the hybrid control unit 102, when the required driving power Prdem set based on the accelerator opening θacc etc. exceeds the upper limit value Prlim, the required driving power Prdem is limited to the upper limit value Prlim, and the driving power PRr of the rear rotary electric machine RrMG is calculated based on the limited required driving power Prdem. Next, the discharge power Wbat discharged from the HEV battery 28 is calculated based on the above-mentioned formula (1), and the rear rotary electric machine RrMG is driven by the generated power WgFr of the front rotary electric machine FrMG and the discharge power Wbat from the HEV battery 28.In this way, when the generated power WgFr of the front rotating electric machine FrMG decreases, the driving power Pr is limited in accordance with the difference ΔWgFr, and the driving power PRr of the rear rotating electric machine RrMG is also limited, so that the discharge power Wbat discharged from the HEV battery 28 is reduced compared to when the driving power PRr is not limited.

[0054] As described above, according to this embodiment, during series traveling, which is an evacuation traveling, the driving power Pr that can be output from the rear unit 20 is limited according to the generated electric power WgFr generated by the front rotating electric machine FrMG, so that even if the generated electric power WgFr generated by the front rotating electric machine FrMG decreases, the amount of electric power consumed by the rear rotating electric machine RrMG is reduced by limiting the driving power Pr output from the rear unit 20. As a result, sudden consumption of electric power during evacuation traveling is suppressed, and evacuation traveling for a long period of time is possible.

[0055] Although the embodiment of the present invention has been described in detail above with reference to the drawings, the present invention can be applied to other embodiments.

[0056] For example, in the above-described embodiment, the hybrid vehicle 10 is configured so that the front wheels 14 are driven by the engine 12 and the front rotating electric machine FrMG and the rear wheels 16 are driven by the rear rotating electric machine RrMG, but the hybrid vehicle 10 may be configured so that the rear wheels 16 are driven by the engine 12 and the rear rotating electric machine RrMG and the front wheels 14 are driven by the front rotating electric machine FrMG, and during series running, the power of the engine 12 is transmitted to the rear rotating electric machine RrMG to generate power by the rear rotating electric machine RrMG, and the power generated by the rear rotating electric machine RrMG is supplied to the front rotating electric machine FrMG to drive the front rotating electric machine FrMG (i.e., the front wheels 14 are driven). In this case, the engine 12 and the rear rotating electric machine RrMG constitute a first drive device, and the front rotating electric machine FrMG constitutes a second drive device.

[0057] In the above-described embodiment, the input clutch 36 is interposed between the rotating electric machine connecting shaft 48 and the transmission input shaft 50, but the input clutch 36 is not necessarily required and may be omitted. Even in the case where the input clutch 36 is omitted, the automatic transmission 38 can be switched to a neutral state by controlling the engagement state of the engagement device CB of the automatic transmission 38, thereby achieving a state substantially the same as when the input clutch 36 is released.

[0058] It should be noted that the above is merely one embodiment, and the present invention can be embodied in various modified and improved forms based on the knowledge of those skilled in the art. [Explanation of symbols]

[0059] 10: Hybrid vehicles 12: Engine (internal combustion engine) 14: Front wheel 16: Rear wheel 18: Front unit (first drive unit) 20: Rear unit (second drive unit) 100: Electronic control device (control device) FrMG: Front rotating motor (first rotating motor) RrMG: Rear rotating motor (second rotating motor)

Claims

[Claim 1] A control device for a hybrid vehicle, the control device being applied to a hybrid vehicle comprising a first drive device that drives one of front wheels and rear wheels, and a second drive device that drives the other of the front wheels and the rear wheels, the first drive device being configured to be capable of transmitting power of an internal combustion engine and a first rotating electric machine to one of the front wheels and the rear wheels, and the second drive device being configured to be capable of transmitting power of a second rotating electric machine to the other of the front wheels and the rear wheels, the control device being configured to perform evacuation running in which the second rotating electric machine is driven by using power output from the internal combustion engine when a predetermined abnormality is detected during running, and when the power generated by the first rotating electric machine alone cannot achieve the driving amount output from the second drive device, by also supplying power from a battery to the second rotating electric machine, During the execution of the evacuation traveling, an upper limit value of the drive amount output from the second drive device is set so as to decrease as the difference between a command value of the power generated by the first rotating electric machine and the generated power increases, and the drive amount output from the second drive device is limited so as not to exceed the upper limit value. A control device for a hybrid vehicle.

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