Control device for a vehicle

Abstract

This invention provides a vehicle control device that, when the required driving force of the engine exceeds a predetermined value that degrades the characteristics of the engine mount, increases the RrMG torque, which is the driving requirement of the rear electric motor, thereby reducing the required driving force of the engine. As a result, the flattening of the engine mount supporting the engine is reduced, thus reducing engine vibration transmitted to the vehicle body via the engine mount.

Description

Technical Field

[0001] This invention relates to a control device for a vehicle capable of switching between two-wheel drive and four-wheel drive. Background Technology

[0002] Japanese Patent Application Publication No. 2021-124058 discloses a four-wheel drive vehicle based on rear-wheel drive, which has a rear wheel connected to an engine and a rear electric motor in a manner capable of transmitting power, and a front wheel connected to a front electric motor in a manner capable of transmitting power. Furthermore, Japanese Patent Application Publication No. 2021-124058 discloses a structure in which the engine is supported by a bracket component.

[0003] In addition, in vehicles that can switch between two-wheel drive and four-wheel drive, from a fuel economy perspective, under normal driving conditions, two-wheel drive, in which the engine powers one of the front or rear wheels, is preferred. However, the greater the driving force required by the engine, the more the insulators (rubber, etc.) supporting the engine mounts are flattened, which may make it difficult to reduce vibrations from the engine. Summary of the Invention

[0004] The present invention was made against the background described above, and its object is to provide a vehicle control device that can reduce the transmission of vibrations to the vehicle (body) caused by the flattening of the support components supporting the engine in a vehicle having one wheel driven by the power of the engine and another wheel driven by the power of a power source independent of the engine.

[0005] The key points of the first invention are (a) a vehicle control device, the vehicle having an engine mounted on the vehicle via a bracket member and a drive power source disposed independently of the engine, the engine being connected to one of the front wheels and the rear wheels in a power-transmitting manner, the drive power source being connected to the other of the front wheels and the rear wheels in a power-transmitting manner, the vehicle being capable of switching at least between two-wheel drive and four-wheel drive, the two-wheel drive driving one of the wheels via the engine, and the four-wheel drive driving one of the wheels via the engine and the other wheel via the drive power source; (b) the vehicle control device is characterized in that, when the drive demand of the engine during vehicle operation exceeds a predetermined value obtained based on the characteristics of the bracket member, the control device increases the drive demand of the drive power source.

[0006] The key points of the second invention are (a) a vehicle control device, the vehicle having an engine mounted on the vehicle via a bracket member and a drive power source disposed independently of the engine, the engine being connected to one of the front wheels and the rear wheels in a power-transmitting manner, the drive power source being connected to the other of the front wheels and the rear wheels in a power-transmitting manner, a transmission being provided in the power transmission path between the engine and the one wheel, the vehicle being able to switch at least between two-wheel drive and four-wheel drive, the two-wheel drive driving the one wheel via the engine, and the four-wheel drive driving the one wheel via the engine and the other wheel via the drive power source, (b) the vehicle control device being characterized in that, when the output of the drive power source is limited, the control device performs the gear shifting of the transmission in a manner that maintains the engine speed above a predetermined speed.

[0007] The key points of the third invention are (a) a vehicle control device, the vehicle having an engine mounted on the vehicle via a bracket member and a drive power source disposed independently of the engine, the engine being connected to one of the front wheels and the rear wheels in a power-transmitting manner, the drive power source being connected to the other of the front wheels and the rear wheels in a power-transmitting manner, the vehicle being capable of switching at least between two-wheel drive and four-wheel drive, the two-wheel drive driving one of the wheels via the engine, and the four-wheel drive driving one of the wheels via the engine and the other wheel via the drive power source; (b) the control device of the vehicle is characterized in that, when the engine speed is less than a predetermined speed set based on the characteristics of the bracket member, compared to when the engine speed is above the predetermined speed, the control device increases the driving demand of the drive power source.

[0008] The key point of the fourth invention is that, based on the first, second, or third invention, the control device of the vehicle is characterized in that the driving force source is an electric motor for driving, and the control device distributes the driving force to the front wheels and the rear wheels by controlling the output of the electric motor.

[0009] The key point of the fifth invention is based on the fourth invention, wherein the control device of the vehicle is characterized in that the vehicle has a second electric motor connected to the engine in a manner capable of transmitting power, the second electric motor being configured to generate electricity from the power of the engine, and the control device driving the electric motor by at least one of the power from a battery provided in the vehicle and the power generated by the second electric motor.

[0010] According to the first invention, during vehicle operation, when the engine's drive demand exceeds a predetermined value that degrades the characteristics of the support component, the drive demand of the drive power source is increased, thereby reducing the engine's drive demand. As a result, the flattening of the support component supporting the engine is reduced, thus reducing vibrations from the engine transmitted to the vehicle (body) via the support component.

[0011] According to the second invention, when the output of the driving force source is limited, the transmission shifts in a manner that maintains the engine speed at or above a predetermined speed. Therefore, the engine speed can be maintained at or above the predetermined speed, allowing continued driving even when the sensitivity of engine vibration transmission to the vehicle decreases. As a result, vibrations from the engine transmitted via the support components can be reduced.

[0012] According to the third invention, when the engine speed is lower than a predetermined speed set based on the characteristics of the bracket component, the drive demand on the drive power source is increased compared to when the engine speed is higher than the predetermined speed. Therefore, the drive demand on the drive power source is increased only when engine vibration transmitted to the vehicle via the bracket component is easily transmitted, thereby reducing the flattening of the bracket component and reducing engine vibration transmitted to the vehicle. As a result, both NV characteristics and fuel economy can be achieved.

[0013] According to the fourth invention, the driving force source is an electric motor, so the driving force distribution between the front and rear wheels can be achieved by controlling the output of the electric motor.

[0014] According to the fifth invention, the power of the engine is used to generate electricity in the second electric motor, and at least one of the power generated by the second electric motor and the power from the storage battery is supplied to the electric motor, thereby enabling the distribution of driving force between the front and rear wheels. Attached Figure Description

[0015] The features, advantages, technical and industrial significance of embodiments of the present invention are described below with reference to the accompanying drawings, wherein the same numbers denote the same elements.

[0016] Figure 1 This is a diagram illustrating the general structure of a hybrid vehicle to which the present invention is applicable, and also a diagram illustrating the various control functions and main parts of the control system in the vehicle.

[0017] Figure 2 This is a graph showing the relationship between the displacement of the engine support and the load on the engine support during engine operation.

[0018] Figure 3 This is a graph showing the relationship between the slope of the engine mount load and the mount displacement.

[0019] Figure 4 This is a diagram illustrating one possible mapping of the relationship between the required driving force of a vehicle and the driving force distribution ratio to the rear wheels.

[0020] Figure 5 This is a flowchart illustrating the main parts of the control function of an electronic control device.

[0021] Figure 6 It shows based on Figure 1 A timeline of the control results from the electronic control device.

[0022] Figure 7 This is a functional block diagram illustrating the main parts of the control function of an electronic control device corresponding to another embodiment of the present invention.

[0023] Figure 8 This is a graph showing the relationship between the engine frequency and the support transmission force during a single combustion cycle of the engine.

[0024] Figure 9 It is a graph showing the relationship between vehicle speed and engine speed in an automatic transmission.

[0025] Figure 10 It is a flowchart used to illustrate the main parts of the control operation of an electronic control device.

[0026] Figure 11 This is a functional block diagram illustrating the main parts of the control function of an electronic control device corresponding to another embodiment of the present invention.

[0027] Figure 12 This is a graph showing the relationship between vehicle speed and engine speed in this embodiment.

[0028] Figure 13 This is a diagram showing the drive force distribution ratio considering resonance generated in the suspension components.

[0029] Figure 14 This is a flowchart illustrating the main parts of the control function of an electronic control device. Detailed Implementation

[0030] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that in the following embodiments, the drawings have been appropriately simplified or modified, and the dimensional ratios and shapes of the parts may not be accurately depicted.

[0031]

Example 1

[0032] Figure 1This is a diagram illustrating the schematic structure of a hybrid vehicle 10 (hereinafter referred to as vehicle 10) to which the present invention is applicable, and also a diagram illustrating the various control functions and main parts of the control system in vehicle 10. Figure 1 In this context, vehicle 10 is a hybrid vehicle with a four-wheel drive configuration based on front-wheel drive, comprising an engine 12 serving as the driving force source for the front wheels 14, a front electric motor FrMG, and a rear electric motor RrMG serving as the driving force source for the rear wheels 16. Vehicle 10 includes a front unit 18 disposed in the power transmission path between the engine 12 and the front wheels 14, and a rear unit 20 for driving the rear wheels 16.

[0033] Engine 12 is a known internal combustion engine such as a gasoline engine or a diesel engine. Engine 12 controls engine control device 22, including throttle actuator, fuel injection device, ignition device, etc. installed in vehicle 10, through electronic control device 100 described later, thereby controlling the output torque of engine 12, i.e., engine torque Te.

[0034] The engine 12 is connected to the vehicle component 64 that constitutes the vehicle body via an engine mount 62. In other words, the engine 12 is mounted on the vehicle 10 via the engine mount 62. The engine mount 62 is a support component that supports the engine 12, and an insulator such as rubber 66 is inserted in a manner that makes it difficult for vibrations of the engine 12 to be transmitted to the vehicle body side. It should be noted that the engine mount 62 is known technology, so a detailed description is omitted.

[0035] The front motor FrMG and the rear motor RrMG are electric generators that function as an engine that generates mechanical power from electricity and as a generator that generates electricity from mechanical power.

[0036] The front electric motor FrMG is connected to the HEV battery 28 via the front converter 24 (FrPCU) and the system main relay 26 (SMR). The front electric motor FrMG controls the front converter 24 through the electronic control unit 100 described later, thereby controlling the output torque of the front electric motor FrMG, namely the FrMG torque TmFr. When the front electric motor FrMG rotates in the same direction as the engine 12 during operation, for example, the positive torque on the acceleration side is the power operating torque, and when it is in the negative torque on the deceleration side, it is the regenerative torque.

[0037] The front electric motor FrMG replaces the engine 12 or, based on the engine 12, generates driving power from the HEV battery 28 via the front converter 24 and the system main relay 26. Furthermore, the front electric motor FrMG is configured to generate electricity from the power of the engine 12 and the driven force input from the front wheel 14 side. The electricity generated by the front electric motor FrMG is stored in the HEV battery 28 via the front converter 24 and the system main relay 26. Alternatively, the electricity generated by the front electric motor FrMG can be supplied to the rear electric motor RrMG to drive the rear electric motor RrMG. Unless otherwise specified, the term "electricity" is synonymous with "electrical energy." And unless otherwise specified, the term "power" is synonymous with "torque" or "force."

[0038] The rear electric motor RrMG is connected to the HEV battery 28 via the rear converter 30 (RrPCU) and the system main relay 26 (SMR). The rear electric motor RrMG controls the rear converter 30 via the electronic control unit 100 (described later), thereby controlling the output torque of the rear electric motor RrMG, i.e., the RrMG torque TmRr. When the rear electric motor RrMG rotates in the same direction as during forward driving, for example, the positive torque on the acceleration side is the power operating torque, and the negative torque on the deceleration side is the regenerative torque. The rear electric motor RrMG is driven by at least one of the power supplied by the HEV battery 28 and the power generated by the front electric motor FrMG.

[0039] The rear electric motor RrMG functions as a driving motor that generates driving force from at least one of the power supplied to the HEV battery 28 via the rear converter 30 and the system main relay 26, and the power generated by the front electric motor FrMG. Furthermore, the rear electric motor RrMG generates electricity using the driving force input from the rear wheel 16 side. The power generated by the rear electric motor RrMG is stored in the HEV battery 28 via the rear converter 30 and the system main relay 26. The HEV battery 28 is an energy storage device that receives and supplies power to both the front electric motor FrMG and the rear electric motor RrMG. It should be noted that the HEV battery 28 corresponds to the battery of the present invention, and the rear electric motor RrMG corresponds to the driving force source of the present invention, which is independently provided with respect to the engine.

[0040] The front unit 18 is configured to transmit power from the engine 12 and the front electric motor FrMG to the front wheels 14. The front unit 18 includes the engine 12, a K0 clutch 34 (K0), an input clutch 36 (WSC), and an automatic transmission 38. The K0 clutch 34 (K0), the input clutch 36 (WSC), and the automatic transmission 38 are each housed within a non-rotating component, housing 32, mounted on the vehicle body. The K0 clutch 34 is a clutch located 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 located 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. It should be noted that the front wheels 14 correspond to the wheels of one side of the invention, and the front electric motor FrMG corresponds to the second electric motor of the invention.

[0041] An automatic transmission 38 is disposed on the power transmission path between the engine 12 and the front electric motor FrMG and the front wheels 14. Furthermore, 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. The front unit 18 also includes an engine connecting shaft 46 connecting the engine 12 and the K0 clutch 34, and an electric motor connecting shaft 48 connecting the K0 clutch 34 and the input clutch 36. It should be noted that the automatic transmission 38 corresponds to the transmission of the present invention.

[0042] The front electric motor FrMG is connected to the electric motor connecting shaft 48 within the housing 32 in a power-transmitting manner. The front electric motor FrMG is connected in a power-transmitting manner along the power transmission path between the engine 12 and the front wheels 14, particularly along the power transmission path between the K0 clutch 34 and the input clutch 36. Therefore, the front electric motor FrMG is connected to the input clutch 36 and the automatic transmission 38 in a power-transmitting manner without passing through the K0 clutch 34.

[0043] The automatic transmission 38 is, for example, a known planetary gear type automatic transmission equipped with one or more sets of planetary gears (not shown) and multiple engagement devices CB. The engagement devices CB are, for example, hydraulic friction engagement devices consisting of multi-plate or single-plate clutches pressed by hydraulic actuators, brakes, band brakes tightened by hydraulic actuators, etc. The engagement devices CB change their respective torque capacities (Tcb) by adjusting the pressure of the CB hydraulic fluid PRcb supplied from the hydraulic control circuit 52, thereby switching between engagement, release, and other control states. The automatic transmission 38 switches the power transmission state according to the engagement state of the engagement devices CB. Therefore, the engagement devices CB are clamped in the power transmission path between the engine 12 and the front electric motor FrMG and the front wheel 14, and have the function of disconnecting or connecting the power transmission in said power transmission path.

[0044] The automatic transmission 38 is a stepped transmission that forms any one of multiple gear stages (also called gear levels) with different gear ratios (also called gear ratios) γat (=AT input speed Ni / AT output speed No) by engaging any of the engaging devices in the engaging device CB. In this embodiment, the automatic transmission 38 is configured to be a gear stage capable of shifting to 6 forward gears and 1 reverse gear. The automatic transmission 38 switches between gear stages based on the driver's (=driver's) accelerator operation, vehicle speed V, etc., via the electronic control device 100 described later, i.e., selectively forming multiple gear stages. AT input speed Ni is the rotational speed of the transmission input shaft 50 of the automatic transmission 38, and is the input speed of the automatic transmission 38. AT output speed No is the rotational speed of the transmission output shaft 40 of the automatic transmission 38, and is the output speed of the automatic transmission 38.

[0045] The K0 clutch 34 is a wet or dry friction engagement device, for example, composed of a multi-plate or single-plate clutch. The K0 clutch 34 is controlled by switching between engagement and disengagement states via the electronic control device 100 described later. The K0 clutch 34 switches its control state by varying its torque capacity, i.e., the K0 torque Tk0, through the K0 hydraulic pressure PRk0 supplied from the hydraulic control circuit 52.

[0046] The input clutch 36 is a wet or dry friction engagement device, for example, composed of a multi-plate or single-plate clutch. The input clutch 36 is controlled by the electronic control device 100 (described later) to switch between engagement, disengagement, and other control states. The input clutch 36 switches its control state by varying its torque capacity, i.e., the torque Twsc, supplied from the hydraulic control circuit 52 (WSC hydraulic pressure PRwsc).

[0047] When clutch 34 is engaged, engine 12 and front electric motor FrMG are connected via engine connecting shaft 46 and electric motor connecting shaft 48 in a manner capable of transmitting power. That is, clutch 34 connects engine 12 and front electric motor FrMG to transmit power through engagement. Conversely, when clutch 34 is disengaged, power transmission between engine 12 and front electric motor FrMG is severed. That is, clutch 34 disconnects the connection between engine 12 and front electric motor FrMG. In short, clutch 34 is a disengageable clutch that connects engine 12 and front electric motor FrMG through engagement and disconnects them through disengagement.

[0048] When the input clutch 36 is engaged, the electric motor connecting shaft 48 and the transmission input shaft 50 are connected. At this time, the front electric motor FrMG is connected to the front wheels 14 via the electric motor connecting shaft 48, the input clutch 36, the transmission input shaft 50, the transmission output shaft 40, the differential 42, and the front axle 44 in a power-transmitting manner. Furthermore, when the K0 clutch 34 and the input clutch 36 are engaged, the engine 12, based on the front electric motor FrMG, is connected to the front wheels 14 via the electric motor connecting shaft 48, the input clutch 36, the transmission input shaft 50, the transmission output shaft 40, the differential 42, and the front axle 44 in a power-transmitting manner. On the other hand, when the input clutch 36 is disengaged, the connection between the electric motor connecting shaft 48 and the transmission input shaft 50 is severed. That is, the input clutch 36 is a disengagement clutch that connects the engine 12 and the front electric motor FrMG to the front wheels 14 by engagement and disconnects the engine 12 and the front electric motor FrMG from the front wheels 14 by disengagement.

[0049] In the front unit 18, power output from the engine 12 is transmitted sequentially to the front wheel 14 via the engine connecting shaft 46, the electric motor connecting shaft 48, the transmission input shaft 50, the automatic transmission 38, the transmission output shaft 40, the differential 42, and the front wheel axle 44, when the K0 clutch 34 and the input clutch 36 are engaged. Similarly, power output from the front electric motor FrMG is transmitted sequentially to the front wheel 14 via the electric motor connecting shaft 48, the transmission input shaft 50, the automatic transmission 38, the transmission output shaft 40, the differential 42, and the front wheel axle 44, when the input clutch 36 is engaged.

[0050] On the other hand, when the input clutch 36 is disengaged, the power transmission path between the engine 12 and the front electric motor FrMG and the front wheel 14 is cut off, and the power from the engine 12 and the front electric motor FrMG is no longer transmitted to the front wheel 14. Furthermore, when the K0 clutch 34 is disengaged and the input clutch 36 is engaged, the power from the front electric motor FrMG is transmitted to the front wheel 14 via the automatic transmission 38, etc., while the power from the engine 12 is no longer transmitted to the front wheel 14. Moreover, when the K0 clutch 34 is engaged and the input clutch 36 is disengaged, although the power from the engine 12 and the front electric motor FrMG is not transmitted to the front wheel 14, the engine 12 and the front electric motor FrMG are connected in a manner that allows power transmission. At this time, the power from the engine 12 can be used to generate electricity in the front electric motor FrMG.

[0051] The rear unit 20 is configured to transmit power from the rear electric motor RrMG to the rear wheels 16. The rear unit 20 includes a rear converter 30 controlled by the electronic control device 100 (described later), a rear electric motor RrMG, and a pair of left and right rear axles 54 connected to the left and right rear wheels 16. The rear electric motor RrMG is connected to the pair of left and right rear axles 54 directly or via a reducer (not shown). Therefore, the rear electric motor RrMG is connected to the rear wheels 16 via the rear axles 54 in a way that allows power transmission, thereby transmitting power output from the rear electric motor RrMG to the rear wheels 16 via the rear axles 54. It should be noted that the rear wheels 16 correspond to the wheels of the other party of the present invention, and the rear electric motor RrMG corresponds to the electric motor of the present invention.

[0052] 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 an electric motor shaft 48 via gears, belts, or chains to transmit power, and is driven by at least one of the engine 12 and the front electric motor FrMG to spray the working oil used in the front unit 18. The electric oil pump 60 is driven to rotate by a pump motor (not shown) to spray working oil. The working oil sprayed by the mechanical oil pump 58 and the electric oil pump 60 is supplied to a hydraulic control circuit 52. Based on the working oil sprayed by the mechanical oil pump 58 and the electric oil pump 60, the hydraulic control circuit 52 supplies pressure-regulated CB hydraulic PRcb, K0 hydraulic PRk0, WSC hydraulic PRwsc, etc.

[0053] The vehicle 10 also includes an electronic control unit 100 (control device) that includes control devices for the vehicle 10 related to driving control, etc. The electronic control unit 100 is configured to include a so-called microcomputer, which includes, for example, a CPU, RAM, ROM, input / output interfaces, etc. The CPU utilizes the temporary storage function of RAM and performs signal processing according to a program pre-stored in the ROM, thereby executing various controls of the vehicle 10. The electronic control unit 100 may be configured as needed to include various ECUs such as those for engine control, electric motor control, and hydraulic control.

[0054] The electronic control unit 100 is supplied with various signals obtained based on the detection values ​​of various sensors installed in the vehicle 10 (e.g., engine speed 70, input speed sensor 72, output speed sensor 74, FrMG speed sensor 76, RrMG speed sensor 78, accelerator opening sensor 80, throttle opening sensor 82, brake switch 84, battery sensor 86, oil temperature sensor 88, etc.). These signals include, for example, the engine speed Ne of the engine 12, the speed Ni of the transmission input shaft 50 of the automatic transmission 38 (i.e., AT input speed), and the speed V of the transmission output shaft 40 of the automatic transmission 38, which is related to the vehicle speed. The corresponding AT output speed No, the speed of the front motor FrMG (FrMG speed NmFr), the speed of the rear motor RrMG (RrMG speed NmRr), the driver's accelerator operation amount (accelerator opening θacc) indicating the magnitude of the driver's acceleration operation, the opening of the electronic throttle valve (throttle valve opening θth), the signal indicating the state of the brake pedal used to activate the wheel brakes (brake on signal Bon), the battery temperature THbat of the HEV battery 28, the battery charging and discharging current Ibat, the battery voltage Vbat, and the working oil temperature THoil in the hydraulic control circuit 52, etc.

[0055] The electronic control unit 100 outputs various command signals to various devices installed in the vehicle 10 (e.g., engine control unit 22, front converter 24, rear converter 30, hydraulic control circuit 52, system main relay 26, etc.). These signals include: engine control command signal Se for controlling the engine 12; FrMG control command signal SmFr for controlling the front electric motor FrMG; RrMG control command signal SmRr for controlling the rear electric motor RrMG; CB hydraulic control command signal Scb for controlling the engagement device CB; K0 hydraulic control command signal Sk0 for controlling the K0 clutch 34; WSC hydraulic control command signal Swsc for controlling the input clutch 36; and relay switching command signal Ssmr for switching the disconnected state of the system main relay 26. For example, when the power switch of the vehicle 10 is switched to the ON state, the system main relay 26 switches to the ON state according to the relay switching command signal Ssmr, thus enabling power supply from the HEV battery 28.

[0056] The electronic control unit 100 is functionally equipped with a hybrid power control unit 102 that functions as a hybrid power control unit, a clutch control unit 104 that functions as a clutch control unit, and a transmission control unit 106 that functions as a transmission control unit in order to realize various driving controls in the vehicle 10.

[0057] The hybrid power control unit 102 functionally includes an engine control unit 102a that acts as an engine control unit that controls the operation of the engine 12, an Fr motor control unit 102b that acts as an Fr motor control unit that controls the operation of the front electric motor FrMG via the front converter 24, and an Rr motor control unit 102c that acts as an Rr motor control unit that controls the operation of the rear electric motor RrMG via the rear converter 30. Through those control functions, hybrid drive control based on the engine 12, the front electric motor FrMG, and the rear electric motor RrMG is performed.

[0058] The hybrid power control unit 102 calculates the driver's driving demand for the vehicle 10 by applying the accelerator opening θacc and vehicle speed V in a driving demand mapping. This driving demand mapping is a pre-determined relationship that is experimentally or intentionally derived and stored beforehand. The driving demand is, for example, the vehicle's required driving force Frdem. Other driving demands, such as the required driving torque Trdem or the required AT output torque in the transmission output shaft 40 of the automatic transmission 38, can also be used. Furthermore, in calculating the driving demand, the AT output speed No can be used instead of the vehicle speed V.

[0059] The hybrid power control unit 102 takes into account transmission losses, auxiliary machine load, the gear ratio γat of the automatic transmission 38, the rechargeable power Win and dischargeable power Wout of the HEV battery 28, and outputs an engine control command signal Se for controlling the engine 12, a FrMG control command signal SmFr for controlling the front electric motor FrMG, and a RrMG control command signal SmRr for controlling the rear electric motor RrMG in a manner that achieves the required drive power Prdem. The engine control command signal Se is, for example, a command value for the engine power Pe of the engine 12, which is the engine torque Te at the current engine speed Ne. The FrMG control command signal SmFr is, for example, a command value for the power consumption WmFr of the front electric motor FrMG, which is the FrMG torque TmFr at the current FrMG speed NmFr. Similarly, the RrMG control command signal SmRr is, for example, a command value for the power consumption WmRr of the rear electric motor RrMG, which is the RrMG torque TmRr at the current RrMG speed NmRr.

[0060] The rechargeable power Win of the HEV battery 28 is the maximum power that can be input into the HEV battery 28, which limits its input power. The dischargeable power Wout of the HEV battery 28 is the maximum power that can be output from the HEV battery 28, which limits its output power. The rechargeable power Win and dischargeable power Wout of the HEV battery 28 are calculated, for example, by the electronic control device 100 based on the battery temperature THbat and the state of charge (SOC) value of the HEV battery 28. The state of charge (SOC) value of the HEV battery 28 is a value representing the state of charge of the HEV battery 28, and is calculated, for example, by the electronic control device 100 based on the battery charging / discharging current Ibat and the battery voltage Vbat.

[0061] When the hybrid power control unit 102 can maintain the required drive torque Trdem using only the output of at least one of the front electric motor FrMG and the rear electric motor RrMG, it sets the driving mode to electric motor driving (=BEV driving) mode. In BEV driving mode, the hybrid power control unit 102 operates BEV (Battery Electric Vehicle) driving with at least one of the front electric motor FrMG and the rear electric motor RrMG as the driving force source while the K0 clutch 34 is disengaged and the input clutch 36 is engaged.

[0062] On the other hand, when the hybrid power control unit 102 cannot maintain the required drive torque Trdem when at least the output of the engine 12 is not used, it switches the driving mode to engine driving mode, i.e., hybrid driving (=HEV driving) mode. In HEV driving mode, the hybrid power control unit 102 operates engine driving, i.e., HEV (Hybrid Electric Vehicle) driving, with the K0 clutch 34 and input clutch 36 engaged, at least using the engine 12 as the driving force source. Furthermore, even when the output of at least one of the front electric motor FrMG and the rear electric motor RrMG can maintain the required drive torque Trdem, the hybrid power control unit 102 maintains the HEV driving mode in cases where the state of charge (SOC) of the HEV battery 28 is less than a predetermined engine start threshold, or when preheating of the engine 12 is required. The engine start threshold is a predetermined threshold used to determine the state of charge (SOC) of the HEV battery 28 as requiring forced starting of the engine 12 and charging of the HEV battery 28. Thus, the hybrid power control unit 102 switches between BEV driving mode and HEV driving mode based on the required drive torque Trdem, required drive power Prdem, etc., to automatically stop the engine 12 during HEV driving, or to restart the engine 12 after it stops, or to start the engine 12 during BEV driving.

[0063] Furthermore, in HEV driving mode, during driving, the power of engine 12 is transmitted to the front wheels 14 as driving force, and a portion of the power of engine 12 is transmitted to the front electric motor FrMG, thereby enabling power generation based on the front electric motor FrMG. Moreover, by supplying the generated electricity WgFr from the front electric motor FrMG to the rear electric motor RrMG, the rear electric motor RrMG can be driven, enabling the vehicle 10 to drive in four-wheel drive mode. Therefore, the vehicle 10 is configured to switch between two-wheel drive mode, where the front wheels 14 are driven entirely by the power of engine 12, and four-wheel drive mode, where the front wheels 14 are driven entirely by the power of engine 12, and the rear wheels 16 are driven entirely by the power of the rear electric motor RrMG.

[0064] The hybrid power control unit 102 functionally includes a drive force distribution control unit 102d, which controls the distribution of drive force between the front and rear wheels (front wheels 14 and rear wheels 16) according to the driving state of the vehicle 10 to obtain appropriate driving performance. The drive force distribution control unit 102d calculates an appropriate front-to-rear drive force distribution ratio R based on the driving state of the vehicle 10. Furthermore, the drive force distribution control unit 102d calculates the outputs of the engine 12, the front electric motor FrMG, and the rear electric motor RrMG as the calculated drive force distribution ratio R. The hybrid power control unit 102 controls the engine 12, the front electric motor FrMG, and the rear electric motor RrMG to achieve the calculated outputs. As a result, by controlling the outputs of the engine 12, the front electric motor FrMG, and the rear electric motor RrMG to achieve the calculated drive force distribution ratio R, the drive force distribution between the front and rear wheels is performed. Thus, the vehicle 10 is configured to adjust the drive force distribution between the front and rear wheels. In this embodiment, the drive force distribution ratio R is defined by the proportion of drive force transmitted to the rear wheel 16 in the vehicle's required drive force Frdem. For example, when the drive force distribution ratio R is zero, it becomes a two-wheel drive system where only the front wheel 14 is driven. And when the drive force distribution ratio R is 0.2, it becomes a four-wheel drive system where the ratio of drive force between the front wheel 14 and the rear wheel 16 is 80:20.

[0065] The drive force distribution control unit 102d sets the drive force distribution ratio R to zero, for example, when the vehicle is traveling at low speeds or with low load. That is, when the vehicle is traveling at low speeds or with low load, the drive force distribution control unit 102d stops the rear electric motor RrMG and performs two-wheel drive by using all the power from the engine 12 to drive the front wheels 14. Furthermore, the drive force distribution control unit 102d sets the drive force distribution ratio R to a value greater than zero, for example, when the vehicle starts, accelerates, or travels on low-μ roads where slippage is likely, thereby performing four-wheel drive by driving the rear wheels 16 in addition to driving the front wheels 14.

[0066] Furthermore, when the electricity generated by the front electric motor FrMG is supplied to the rear electric motor RrMG, the power of the engine 12 is converted into electrical energy and sent to the rear electric motor RrMG, which then converts it back into driving force, thus reducing energy efficiency. Therefore, from a fuel economy perspective, it is preferable to use all the power of the engine 12 to drive the front wheels 14. On the other hand, when the vehicle 10 is driven by the driving force of the engine 12, the displacement of the rubber 66 constituting the engine mount 62 (i.e., the amount of flattening of the rubber 66) increases due to the reaction force relative to the driving force of the engine 12. At this time, the rubber 66 hardens, making it easier to transmit the vibration of the engine 12 (engine vibration) to the vehicle side via the engine mount 62. It should be noted that the engine mount 62 corresponds to the mount component of the present invention.

[0067] Figure 2 The relationship between the bracket displacement L [mm] and the engine bracket load Fmt [N] during engine 12 operation is shown. The bracket displacement L corresponds to the deformation (i.e., flattening) of the rubber 66 constituting the engine bracket 62. Furthermore, the engine bracket load Fmt is the load applied to the engine bracket 62 during engine operation, corresponding to the reaction force relative to the driving force of the engine 12. The engine bracket load Fmt increases proportionally to the driving force of the engine 12. Figure 2 As shown, the larger the bracket displacement L, the steeper the increase in the engine bracket load Fmt. Therefore, the larger the engine bracket load Fmt, the harder the rubber 66 becomes, and the less easily it deforms, resulting in higher sensitivity to engine vibration transmission. In other words, the larger the engine bracket load Fmt, the easier it is for engine vibration to be transmitted to the vehicle body side via the engine bracket 62.

[0068] In contrast, when the required driving force Fedem of the engine during vehicle operation reaches or exceeds a preset predetermined value Fcri, the drive force distribution control unit 102d increases the drive force distribution ratio R compared to the current value. That is, when the drive demand of the engine 12, i.e., the required driving force Fedem, reaches or exceeds a preset predetermined value Fcri during vehicle operation, the drive force distribution control unit 102d increases the drive demand of the rear electric motor RrMG, i.e., the RrMG torque TmRr.

[0069] Here, the predetermined value Fcri of engine 12 is determined experimentally or by design in advance, based on the characteristics of engine mount 62. Figure 3 The relationship between the engine mount load Fmt and the slope M of the mount displacement L is shown. For example... Figure 3As shown, within a small range of engine mount load Fmt, the slope M of mount displacement L is a constant value M1. However, when the engine mount load Fmt exceeds a predetermined value, the slope M of mount displacement L decreases as the engine mount load Fmt increases. That is, when the engine mount load Fmt exceeds the predetermined value, the rubber 66 of the engine mount 62 hardens, and the function of suppressing engine vibration transmission sensitivity based on the elastic deformation of the rubber 66 decreases.

[0070] Therefore, the predetermined value Fcri of engine 12 is set as the value corresponding to the load Fα of engine mount load Fmt, where the slope M of the bracket displacement L becomes a slope Mα smaller than the constant value M1. This load Fα is set as the threshold value at which the engine vibration transmitted to the vehicle body side via engine mount 62 is within the allowable range. Furthermore, the driving force of engine 12 and the engine mount load Fmt have a one-to-one relationship, so when the engine mount load Fmt is determined, the corresponding driving force of engine 12 is uniquely determined.

[0071] When the driving force distribution control unit 102d reaches a predetermined value Fcri, it determines the driving force distribution control unit based on... Figure 4 The relationship mapping shown determines the distribution of driving force between the front and rear wheels (i.e., the driving force distribution ratio R).

[0072] Figure 4 This illustrates an example of the mapping between the vehicle's required driving force Frdem[N] and the driving force distribution to the rear wheels 16, i.e., the driving force distribution ratio R. Figure 4 The following example illustrates the relational mapping applicable during dual-wheel drive operation. During dual-wheel drive operation, the vehicle's required driving force Frdem is equivalent to the engine 12's required driving force Fedem. For example... Figure 4 As shown, when the vehicle's required driving force Frdem (i.e., the engine 12's required driving force Fedem) is less than a predetermined value Fcri, the drive force distribution ratio R is set to zero, allowing two-wheel drive operation. On the other hand, during two-wheel drive operation, when the vehicle's required driving force Frdem (i.e., the engine 12's required driving force Fedem) becomes above the predetermined value Fcri, the more the vehicle's required driving force Frdem increases, the more the drive force distribution ratio R increases. The drive force distribution ratio R, relative to the vehicle's required driving force Frdem within the range where the vehicle's required driving force Frdem is above the predetermined value Fcri, is set considering the characteristics of the engine mount 62, and is set so that even if the vehicle's required driving force Frdem increases, the engine 12's required driving force Fedem does not exceed the predetermined value Fcri. Thus, as... Figure 4 As shown, the driving force distribution ratio R changes curvilinearly depending on the vehicle's required driving force Frdem, or it changes linearly depending on the vehicle's required driving force Frdem.

[0073] and, Figure 4 Although the mapping is applicable during two-wheel drive driving, it can also be used during four-wheel drive driving. Figure 4 The driving force distribution ratio R is determined by a relational mapping. For example, it can be determined by adding the driving force distribution ratio R set at the current moment to a value based on... Figure 4 The new drive force distribution ratio R is determined by the drive force distribution ratio R obtained from the relational mapping. Alternatively, a relational mapping of the drive force distribution ratio R relative to the vehicle's required drive force Frdem, taking into account the current drive force distribution ratio R, can be obtained, and the drive force distribution ratio R is set based on this relational mapping during four-wheel drive operation.

[0074] Figure 5 This is a flowchart illustrating the main parts of the control function of the electronic control device 100, and it is a flowchart illustrating the control operation that can effectively reduce engine vibration transmitted to the vehicle body side (vehicle side) via the engine mount 62. This flowchart is repeatedly executed during vehicle operation.

[0075] First, in step S10 (steps omitted below), corresponding to the control function of the drive force distribution control unit 102d, the required drive force Fedem of the engine 12 is calculated. For example, the drive force distribution ratio R is determined based on the driving state of the vehicle 10 (uphill driving, turning driving, etc.), and then the required drive force Fedem of the engine 12 to achieve the determined drive force distribution ratio R is calculated based on the determined drive force distribution ratio R and the required drive force Frdem of the vehicle calculated according to the accelerator opening θacc, etc. Next, in step S20, corresponding to the control function of the drive force distribution control unit 102d, it is determined whether the required drive force Fedem of the engine 12 calculated in S10 is less than a preset predetermined value Fcri. If the determination in S20 is affirmed, the routine ends.

[0076] On the other hand, if the determination in S20 is rejected, the engine 12 requires the driving force Fedem to be above the predetermined value Fcri. At this time, in S30, which corresponds to the control function of the driving force distribution control unit 102d, based on... Figure 4 The mapping shown increases the drive force distribution ratio R. Therefore, the drive force distribution to the rear wheels 16 increases, while the drive force distribution to the front wheels 14 decreases. Consequently, the required drive force Fedem of the engine 12 decreases, and the required drive force Fedem becomes below a predetermined value Fcri. As a result, the engine mount load Fmt applied to the engine mount 62 becomes smaller than the load Fα, thus improving the condition of the engine mount 62 and keeping the engine vibration transmitted to the vehicle body side via the engine mount 62 within acceptable limits. This also suppresses the deterioration of NV characteristics caused by engine vibration, such as muffled noise and mount vibration.

[0077] Figure 6 This is a timeline showing the control results based on the control operation of the electronic control device 100. The timeline uses an acceleration operation performed from a stationary vehicle state as an example.

[0078] Through Figure 6 At time t1, the accelerator pedal is depressed, and after time t1, the vehicle's required driving force Frdem increases. Furthermore, as the vehicle's required driving force Frdem increases, the engine 12's required driving force Fedem increases, thereby increasing the engine mount load Fmt. At time t2, when the engine mount load Fmt reaches load Fα, the driving force distribution ratio R increases. After time t2, as the driving force distribution ratio R increases, the FrMG torque TmFr of the rear electric motor RrMG transmitted to the rear wheels 16 increases, thereby controlling the engine mount load Fmt to avoid exceeding load Fα. As a result, even if the vehicle's required driving force Frdem increases, the engine mount load Fmt is maintained below the optimal load Fα for the engine mount 62, thus keeping the transmission sensitivity of engine vibration within an acceptable range. Therefore, the deterioration of NV characteristics caused by engine vibration transmitted to the vehicle body via the engine mount 62 is suppressed.

[0079] As described above, according to this embodiment, when the required driving force Fedem of the engine 12 becomes a predetermined value Fcri or higher that degrades the characteristics of the engine mount 62, the torque TmRr of the RrMG, which is the driving requirement of the rear electric motor RrMG, is increased, thereby reducing the required driving force Fedem of the engine 12. As a result, the flattening of the engine mount 62 supporting the engine 12 is reduced, thus reducing the engine vibration transmitted to the vehicle 10 (body) via the engine mount 62.

[0080] Next, other embodiments of the present invention will be described. It should be noted that in the following description, the same reference numerals are used for parts that are common to the foregoing embodiments, and the description is omitted.

[0081]

Example 2

[0082] In the aforementioned Embodiment 1, when the engine mount load Fmt applied to the engine mount 62 becomes a load Fα or higher, the increase in engine mount load Fmt and the deterioration of NV performance are suppressed by increasing the RrMG torque TmRr of the rear electric motor RrMG. In this embodiment, the case where the output of the rear electric motor RrMG is limited and the front and rear wheel drive force distribution as in Embodiment 1 cannot be performed will be described. Figure 7This is a functional block diagram illustrating the main parts of the control function of the electronic control device 200 corresponding to this embodiment. It should be noted that the structure of the vehicle controlled by the electronic control device 200 is no different from that of the vehicle 10 in the aforementioned embodiment, therefore its description is omitted.

[0083] The electronic control unit 200 functionally includes a hybrid power control unit 202, a clutch control unit 104, and a transmission control unit 206. It should be noted that the function of the clutch control unit 104 is no different from that in the aforementioned embodiment; therefore, it is labeled with the same reference numerals and its description is omitted.

[0084] In addition to the functions of the hybrid power control unit 102 in the aforementioned embodiment, the hybrid power control unit 202 also functionally includes a drive force distribution determination unit 204 (hereinafter referred to as the determination unit 204) that functions as a drive force determination unit.

[0085] The possibility determination unit 204 determines whether the drive force distribution between the front and rear wheels can be properly achieved. For example, if the torque TmRr output from the rear motor RrMG is limited, the possibility determination unit 204 determines that the drive force distribution between the front and rear wheels cannot be properly achieved. Furthermore, if the rear motor RrMG is driven by electricity generated by the front motor FrMG, and the power generation of the front motor FrMG is limited, the possibility determination unit 204 determines that the drive force distribution between the front and rear wheels cannot be properly achieved.

[0086] It should be noted that the limitation of the RrMG torque TmRr output from the rear motor RrMG can occur in situations such as: an abnormality detected in the rear motor RrMG; the motor temperature THmRr of the rear motor RrMG exceeding a threshold that limits the output of the rear motor RrMG; the state of charge (SOC) of the HEV battery 28 being less than a threshold that limits the dischargeable power Wout to a predetermined value; and the battery temperature THbat of the HEV battery 28 being within the range where the output of the HEV battery 28 is limited. Furthermore, the limitation of the power generation based on the front motor FrMG can occur in situations such as: the motor temperature THmFr of the front motor FrMG exceeding a predetermined value. In these cases, the limitation of the RrMG torque TmRr output from the rear motor RrMG makes it difficult to properly control the drive force distribution between the front and rear wheels, thus making it difficult to control the RrMG torque TmRr of the rear motor RrMG and suppress engine vibration transmitted to the vehicle side via the engine mount 62.

[0087] When the output of the rear electric motor RrMG is limited, the transmission control unit 206 performs the transmission shift of the automatic transmission 38 in a manner that maintains the engine speed Ne of the engine 12 at a predetermined speed Nea or higher.

[0088] Figure 8 The relationship between the frequency Fz [Hz] of the vibration caused by the detonation of engine 12 and the support transmission force S [dB] is shown. The frequency Fz is the vibration frequency caused by the detonation of engine 12 and is proportional to the engine speed Ne. Furthermore, the support transmission force S [dB] corresponds to the magnitude of the vibration transmitted to the vehicle body side via engine support 62; the larger the support transmission force S, the larger the vibration transmitted to the vehicle body side via engine support 62. Figure 8 As shown, the higher the frequency Fz, the lower the force S transmitted by the bracket. In other words, the higher the engine speed Ne, the lower the force S transmitted by the bracket, and the less vibration is transmitted to the vehicle body.

[0089] Therefore, when the output of the rear electric motor RrMG is limited, the transmission control unit 206 shifts the automatic transmission 38 in a manner that maintains the engine speed Ne at or above a preset predetermined speed Nea. Here, the predetermined speed Nea is determined experimentally or by design in advance, and is set to a value corresponding to the frequency Fza where the bracket transmission force S is below a preset allowable value Sa. Furthermore, the allowable value Sa of the bracket transmission force S is set as a threshold value that allows the range of vibrations transmitted to the vehicle body side via the engine mount 62.

[0090] Figure 9 The relationship between vehicle speed V and engine speed Ne of the automatic transmission 38 is shown. In this embodiment, the automatic transmission 38 is configured to shift to a 6-speed forward gear system. Therefore, in... Figure 9 The diagram depicts straight lines representing the relationship between vehicle speed V and engine speed Ne, corresponding to each gear stage (1st gear stage to 6th gear stage).

[0091] exist Figure 9In the diagram, the solid line shows the relationship between vehicle speed V and engine speed Ne when the torque TmRr of the rear electric motor RrMG is not limited (normal state). Under normal conditions, as shown along the solid line, the engine speed Ne changes according to vehicle speed V. On the other hand, the dashed line shows the relationship between vehicle speed V and engine speed Ne when the torque TmRr of the rear electric motor RrMG is limited, i.e., when drive force distribution is limited (drive force distribution restricted). Under drive force distribution restriction, as shown along the dashed line, the engine speed Ne changes according to vehicle speed V. Both the engine speed Ne under normal conditions (represented by the solid line) and the engine speed Ne under drive force distribution restriction (represented by the dashed line) cause the automatic transmission 38 to shift up sequentially as vehicle speed V increases, resulting in a broken-line variation in engine speed Ne.

[0092] In the normal state, represented by the solid line, the engine speed Ne is used to be in the range of a predetermined speed Nea or lower. In the normal state, when the engine speed Ne becomes below the predetermined speed Nea, the RrMG torque TmRr of the rear electric motor RrMG is increased and the engine mount load Fmt is decreased, thereby suppressing the transmission sensitivity of engine vibration transmitted to the vehicle body side via the engine mount 62.

[0093] On the other hand, when the drive force distribution is limited by a single-dot line, the output of the rear electric motor RrMG cannot be controlled, and the engine mount load Fmt cannot be reduced. Therefore, the automatic transmission 38 shifts gears in a manner that maintains the engine speed Ne at or above a predetermined speed Nea. Thus, the engine speed Ne is prevented from falling below the predetermined speed Nea, and the engine vibration transmitted to the vehicle body side via the engine mount 62 is within an acceptable range. The transmission control unit 206 stores a transmission mapping (transmission line for drive force distribution limitation) applicable when the drive force distribution is limited, thereby maintaining the engine speed Ne at or above the predetermined speed Nea. When the drive force distribution is limited, the automatic transmission 38 shifts gears based on this transmission mapping, thereby maintaining the engine speed Ne at or above the predetermined speed Nea.

[0094] Figure 10 This is a flowchart illustrating the main part of the control operation of the electronic control unit 200, and it is a flowchart illustrating the control operation that can suppress engine vibration transmitted to the vehicle body side via the engine mount 62 even when the drive force distribution between the front and rear wheels cannot be properly achieved. This flowchart is repeatedly executed during vehicle operation.

[0095] First, in S100, corresponding to the control function of the approval / disapproval determination unit 204, it is determined whether the drive force distribution between the front and rear wheels can be appropriately achieved. If S100 is approved, in S110, corresponding to the control function of the transmission control unit 206, the automatic transmission 38 is shifted based on the normally used shift mapping (normal shift line). On the other hand, if the decision in S100 is denied, in S120, corresponding to the control function of the transmission control unit 206, the automatic transmission 38 is shifted based on the shift mapping (drive force distribution limited shift line) that maintains the engine speed Ne at a predetermined speed Nea or higher.

[0096] As described above, according to this embodiment, when the output of the rear electric motor RrMG is limited, the automatic transmission 38 is operated to maintain the engine speed Ne at a predetermined speed Nea or higher. Therefore, the engine speed Ne can be maintained at a predetermined speed Nea or higher, allowing continued driving even when the sensitivity of engine vibration transmission to the vehicle body decreases. As a result, engine vibration transmitted via the engine mount 62 can be reduced.

[0097]

Example 3

[0098] Figure 11 This is a functional block diagram illustrating the main parts of the control function of the electronic control device 300 corresponding to another embodiment of the present invention. It should be noted that the structure of the vehicle controlled by the electronic control device 300 is no different from that of the vehicle 10 in the aforementioned embodiment, therefore its description is omitted.

[0099] The electronic control unit 300 functionally includes a hybrid power control unit 302, a clutch control unit 104, and a transmission control unit 106. It should be noted that the clutch control unit 104 and the transmission control unit 106 function the same as in the aforementioned embodiment; therefore, they are labeled with the same reference numerals and their descriptions are omitted.

[0100] The hybrid power control unit 302 functionally includes an engine control unit 102a, an Fr electric motor control unit 102b, an Rr electric motor control unit 102c, and a drive force distribution control unit 304. The functions of the engine control unit 102a, the Fr electric motor control unit 102b, and the Rr electric motor control unit 102c are no different from those in the aforementioned embodiment; therefore, they are marked with the same reference numerals and their descriptions are omitted.

[0101] The drive force distribution control unit 304 detects the engine speed Ne. When the engine speed Ne is less than a preset predetermined speed Neb, it compares the drive force distribution ratio R set when the engine speed Ne is greater than or equal to the predetermined speed Neb, and increases the drive force distribution ratio R. That is, when the engine speed Ne is less than the predetermined speed Neb, the drive force distribution control unit 304 compares the engine speed Ne with the engine speed Ne being greater than or equal to the predetermined speed Neb, and increases the RrMG torque TmRr, which is the drive requirement of the rear electric motor RrMG. The predetermined speed Neb is determined experimentally or by design in advance, based on the characteristics of the engine mount 62. The predetermined speed Neb is set as the threshold of the engine speed Ne at which the engine vibration transmitted from the engine mount 62 to the vehicle body side is within an acceptable range.

[0102] Figure 12 The relationship between vehicle speed V and engine speed Ne in this embodiment is shown. Figure 12 In the diagram, a straight line representing the relationship between vehicle speed V and engine speed Ne is depicted according to each gear stage of the automatic transmission 38 (1st gear stage to 6th gear stage). For example... Figure 12 As shown by the solid line, the automatic transmission shifts to gear 38 as the vehicle speed V increases. As a result, the engine speed Ne moves along the straight line of each gear level and to other gear levels, thus the engine speed Ne changes in a broken line shape.

[0103] exist Figure 12 Within the vehicle speed range X where the engine speed Ne is less than the predetermined speed Neb, the engine vibration transmitted to the vehicle body side via the engine mount 62 increases. In contrast, the drive force distribution control unit 304 increases the drive force distribution to the rear wheels 16 when the vehicle speed range X is within the engine speed Ne less than the predetermined speed Neb. Therefore, the required drive force Fedem of the engine 12 decreases relatively, thus suppressing the increase in the engine mount load Fmt and suppressing the engine vibration transmitted to the vehicle body side via the engine mount 62. Thus, within the vehicle speed range X where the engine speed Ne is less than the predetermined speed Neb, a drive force distribution that prioritizes reducing NV (Noise, Vibration, and Air) is implemented (NV priority distribution).

[0104] Furthermore, in Figure 12 The engine speed Ne shown is within the vehicle speed range Y above the predetermined speed Neb, and the engine vibration transmitted to the vehicle body side via the engine mount 62 is within an acceptable range. At this time, the drive force distribution control unit 304 implements a drive force distribution that prioritizes fuel economy (fuel economy priority distribution). Specifically, the drive force distribution control unit 304 decreases the drive force distribution ratio R and increases the drive force distribution to the front wheels 14 by using the drive force of the engine 12, which has higher efficiency from a fuel economy perspective, to drive the vehicle 10. Thus, as Figure 12 As shown, NV priority allocation (vehicle speed range X) and fuel economy priority allocation (vehicle speed range Y) are alternately implemented. Here, when NV priority allocation and fuel economy priority allocation are repeatedly implemented according to changes in vehicle speed V, the drive force distribution ratio R changes each time the vehicle speed range changes, potentially worsening drivability. In contrast, it can be... Figure 12 The vehicle speed Va shown is set as a threshold. Within a range below the vehicle speed Va, control is performed with NV priority allocation; when the vehicle speed exceeds Va, control is performed with fuel economy priority allocation. It should be noted that the vehicle speed Va is the lower threshold threshold at which the engine speed Ne is always above a predetermined speed Neb.

[0105] Here, the vehicle speed Va, which is switched to prioritize fuel economy, is set to suppress engine vibrations transmitted to the vehicle side via the engine mount 62. However, it is also possible to take into account vibrations caused by other factors, such as resonance generated in the suspension components, when setting the vehicle speed Va. Figure 13 The drive force distribution ratio R is shown, taking into account, for example, resonance generated in the suspension components. Without considering resonance generated in the suspension components, the vehicle speed Va is set to, for example, 80 km / h. Here, considering the case where resonance in the suspension components occurs at a vehicle speed Va of 85 km / h, the vehicle speed Va is changed to 90 km / h. Therefore, as... Figure 13 As shown, the drive force distribution ratio R decreases when the vehicle speed V exceeds 90 km / h. This also allows the vehicle speed Va to be an appropriate value that takes into account other factors.

[0106] Figure 14 This is a flowchart illustrating the main parts of the control function of the electronic control unit 300, and it is a flowchart illustrating the control function that can balance fuel economy and NV characteristics. This flowchart is repeatedly executed during vehicle operation.

[0107] First, in S200, corresponding to the control function of the drive force distribution control unit 304, the engine speed Ne is detected. Next, in S210, corresponding to the control function of the drive force distribution control unit 304, it is determined whether the engine speed Ne is less than a predetermined speed Neb. If the determination in S210 is affirmed, in S220, corresponding to the control function of the drive force distribution control unit 304, the drive force distribution between the front and rear wheels is controlled in a manner prioritizing NV characteristics. Specifically, the drive force distribution to the rear wheels 16 based on the rear electric motor RrMG is increased, while the drive force of the engine 12 is reduced. As a result, the engine mount load Fmt applied to the engine mount 62 is reduced, thus reducing engine vibration transmitted via the engine mount 62. On the other hand, if the determination in S210 is denied, in S230, corresponding to the control function of the drive force distribution control unit 304, the drive force distribution between the front and rear wheels is controlled in a manner prioritizing fuel economy. Specifically, control is performed so that the front wheels 14 are driven entirely by the drive force of the engine 12. As a result, the proportion of power transmitted from engine 12 to rear wheel 16 via an electrical path decreases, thus reducing energy loss and improving fuel economy.

[0108] As described above, according to this embodiment, when the engine speed Ne is less than a predetermined speed Neb set based on the characteristics of the engine mount 62, compared to the case where the engine speed Ne is greater than or equal to the predetermined speed Neb, the RrMG torque TmRr of the rear electric motor RrMG is increased. Therefore, only when engine vibrations transmitted to the vehicle body side via the engine mount 62 are easily transmitted, the increased RrMG torque TmRr of the rear electric motor RrMG reduces the flattening of the engine mount 62 and reduces engine vibrations transmitted to the vehicle body side. As a result, both NV characteristics and fuel economy can be balanced.

[0109] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings; however, the present invention is also applicable to other embodiments.

[0110] For example, embodiments 1 to 3 described above can be implemented independently, but embodiments 1-3 can also be appropriately combined and implemented. For example, embodiments 1 and 2 can be combined. If the driving force distribution between the front and rear wheels can be achieved, the solution of embodiment 1 can be implemented. If the driving force distribution between the front and rear wheels cannot be appropriately achieved, the solution of embodiment 2 can also be implemented. Similarly, embodiments 2 and 3 can also be combined and implemented.

[0111] Furthermore, in the aforementioned embodiments, the engine 12 and the front electric motor FrMG are connected to the front wheel 14 in a manner capable of transmitting power, and the rear electric motor RrMG is connected to the rear wheel 16 in a manner capable of transmitting power. However, it is also possible that the engine 12 and the rear electric motor RrMG are connected to the rear wheel 16 in a manner capable of transmitting power, and the front electric motor FrMG is connected to the front wheel 14 in a manner capable of transmitting power. In this case, the front wheel 14 corresponds to the wheel of the other party of the present invention, and the rear wheel 16 corresponds to the wheel of the first party of the present invention. Furthermore, the front electric motor FrMG corresponds to the electric motor of the present invention, and the rear electric motor RrMG corresponds to the second electric motor of the present invention.

[0112] Furthermore, in the aforementioned embodiment, the rear wheel 16 is driven by a rear electric motor RrMG, but it can also be driven by other driving power sources such as a hydraulic electric motor. That is, as long as a structure in which the driving force distribution between the front and rear wheels can be realized, where one wheel is connected to the engine 12 in a manner capable of transmitting power, and the other wheel is connected to a driving power source different from the engine 12 in a manner capable of transmitting power, the present invention can be appropriately applied.

[0113] Furthermore, in the aforementioned embodiments, the automatic transmission 38 is configured to have a gear system capable of shifting to 6 forward gears and 1 reverse gear. However, the present invention is not limited to a gear system with 6 forward gears. For example, a transmission capable of shifting to 10 gears or any other transmission capable of shifting to multiple gear systems can be appropriately used.

[0114] Furthermore, in the aforementioned embodiments, the distribution of driving force between the front and rear wheels is changed based on the magnitude of the required driving force Fedem of the engine 12. However, the distribution of driving force between the front and rear wheels can also be changed based on the magnitude of the required engine torque Tedem of the engine 12. That is, as the driving requirement of the present invention, the required engine torque Tedem can be used instead of the required driving force Fedem of the engine 12.

[0115] Furthermore, in the aforementioned embodiments, the drive force distribution ratio R is defined by the proportion of drive force transmitted to the rear wheel 16 in the vehicle's required drive force Frdem. However, the drive force distribution ratio R can also be defined by the proportion of drive force transmitted to the front wheel 14 in the vehicle's required drive force Frdem.

[0116] Furthermore, the specific values ​​in the aforementioned embodiments are just examples and may be appropriately changed depending on the vehicle's model, structure, etc.

[0117] It should be noted that the above content is only one implementation method, and the present invention can be implemented with various modifications and improvements based on the knowledge of those skilled in the art.

Claims

1. A control device for a vehicle, the vehicle comprising an engine mounted on the vehicle via a bracket member and an electric motor as a drive power source independently of the engine, the engine being connected to one of the front wheels and the rear wheels in a power-transmitting manner, the electric motor being connected to the other of the front wheels and the rear wheels in a power-transmitting manner, a transmission being provided in the power transmission path between the engine and the one wheel, the vehicle being capable of switching at least between two-wheel drive and four-wheel drive, the two-wheel drive driving the one wheel via the engine, and the four-wheel drive driving the one wheel via the engine and the other wheel via the electric motor, the control device for the vehicle being characterized in that... The control device includes: The drive force distribution control unit performs drive force distribution control that increases the drive force demand of the electric motor when the drive demand of the engine during vehicle operation exceeds a predetermined value obtained based on the characteristics of the bracket component. The determination unit determines whether the drive force distribution control can be performed based on the condition that the torque output from the motor is limited; and The transmission control unit, when the failure determination unit determines that the output of the electric motor is limited and the drive force distribution control cannot be performed, performs the transmission speed change in a manner that maintains the engine speed at or above a predetermined speed.

Images