Hybrid all-wheel drive vehicle control system

Abstract

An HEV-CU (60)determines, on the basis of the travel state of a vehicle, whether the travel state requires forward / backward driving force control (for example, whether in cornering or not) to be prioritized; and when it has been determined that the travel state requires the forward / backward driving force control (for example, during cornering) to be prioritized, preferentially executes the forward / backward driving force control for controlling the driving of an engine (20) and a motor generator (72) and for controlling the engagement force of a differential limiting clutch (42) in response to the friction forces of the front and back wheels (10) with the road surface, and when it has been determined that the travel state does not require the forward / backward driving force control (for example, during straight travel) to be prioritized, preferentially executes energy management control for controlling the driving of the motor generator (72) so that the state of charge (SOC) of a high-voltage battery (71) that supplies power to the motor generator (72) is held within a predetermined range.

Description

[Technical field]

[0001] The present invention relates to a control system for a hybrid all-wheel drive vehicle. [Background technology]

[0002] In recent years, hybrid all-wheel drive vehicles (AWD HEVs) have been proposed that are equipped with a rear axle drive motor and integrate control of the balance between engine output and motor output (power running / regeneration) to continuously vary the distribution of driving force to the front and rear wheels according to the frictional forces of the front and rear tires (front and rear driving force control), thereby achieving high driving stability.

[0003] For example, Patent Document 1 discloses a vehicle drive system (hybrid all-wheel drive vehicle) that has excellent traction performance and handling stability during cornering acceleration by providing a motor generator on the propeller shaft of an AWD (all-wheel drive) system with unequal torque distribution that has a rear-wheel bias, regenerating power when slippage or signs of slippage occur on the rear wheels during acceleration, and providing drive assistance when the ground load on the rear wheels increases due to load transfer during acceleration, etc., and there is room in the drive force transmission capacity. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2009-113570 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the vehicle drive system (hybrid all-wheel drive vehicle) described in Patent Document 1, for example, there may be cases where drive assist (front and rear drive force control) cannot be performed when it is desired due to a drive (powering / regenerative) request to the motor generator from the viewpoint of energy management, such as a drive (powering / regenerative) request to the motor generator to operate the engine in a driving range with good combustion efficiency (fuel consumption rate) or a drive (powering / regenerative) request to the motor generator to appropriately control the state of charge (SOC: State Of Charge) of the high-voltage battery that supplies power to the motor generator. In other words, there may be cases where the drive assist cannot be performed when it is desired to perform drive assist (front and rear drive force control) due to energy management (control).

[0006] The present invention has been made to solve the above problems, and aims to provide a control device for a hybrid all-wheel drive vehicle that is capable of executing front and rear driving force control as a priority (i.e., achieving both front and rear driving force control and energy management control) without being restricted by energy management control when front and rear driving force control is desired to be prioritized. [Means for solving the problem]

[0007] The control device for a hybrid all-wheel drive vehicle according to the present invention includes an engine, a center differential unit having a differential limiting clutch capable of limiting differential between front and rear wheels according to an engagement force, which distributes driving force input from the engine to the front wheels and rear wheels and outputs the same, a motor generator provided between the center differential unit and the rear wheels and connected so as to be able to transmit torque between the center differential unit and the rear wheels, a driving condition detection means for detecting the driving condition of the vehicle, and a control unit for controlling the drive of the engine and the motor generator and the engagement force of the differential limiting clutch, and the control unit is configured to detect the driving condition detected by the driving condition detection means. The system is characterized in that it determines whether the driving state requires that front and rear driving force control be prioritized based on the vehicle's driving state, and if it is determined that the driving state requires that front and rear driving force control be prioritized, it prioritizes front and rear driving force control, which controls the drive of the engine and motor generator and the fastening force of the differential limiting clutch in accordance with the frictional force between the front and rear wheels and the road surface, and if it is determined that the driving state does not require that front and rear driving force control be prioritized, it prioritizes energy management control, which controls the drive of the motor generator so that the charge state of the high-voltage battery that supplies power to the motor generator falls within a predetermined range.

[0008] According to the control device for a hybrid all-wheel drive vehicle of the present invention, it is determined whether or not the vehicle is in a driving state in which the front and rear driving force control needs to be prioritized, based on the vehicle's driving state. When it is determined that the vehicle is in a driving state in which the front and rear driving force control needs to be prioritized (e.g., cornering), the front and rear driving force control is preferentially performed, which controls the driving of the engine and the motor generator and the fastening force of the limited slip differential clutch according to the frictional force between the front and rear wheels and the road surface, and when it is determined that the vehicle is in a driving state in which the front and rear driving force control does not need to be prioritized (e.g., going straight), the energy management control is preferentially performed, which controls the driving of the motor generator so that the state of charge (SOC) of the high-voltage battery that supplies power to the motor generator falls within a predetermined range. Therefore, by preferentially performing the energy management control when the front and rear driving force control does not need to be preferentially performed, the state of charge (SOC) of the high-voltage battery can be kept within an appropriate range, and the power can be used in situations where the front and rear driving force control needs to be preferentially performed. Therefore, it is possible to achieve (appropriately mediate) both the front and rear driving force control and the energy management control. Effect of the Invention

[0009] As a result, according to the present invention, in situations where front and rear driving force control is desired to be prioritized, it is possible to execute front and rear driving force control as a priority without being restricted by energy management control (i.e., to achieve compatibility between front and rear driving force control and energy management control). [Brief description of the drawings]

[0010] [Figure 1] 1 is a block diagram showing an overall configuration of a control device for a hybrid all-wheel drive vehicle according to an embodiment, and a hybrid all-wheel drive vehicle (AWD HEV) equipped with the control device; [Diagram 2] 1 is a diagram showing a torque flow in a hybrid all-wheel drive vehicle (AWD HEV) equipped with a control device for a hybrid all-wheel drive vehicle according to an embodiment of the present invention; [Diagram 3]5 is a flowchart showing a process procedure for switching (arbitration) between front / rear driving force control and energy management control by a control device for a hybrid all-wheel drive vehicle according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same reference numerals will be used for the same or corresponding parts. In each drawing, the same reference numerals will be used for the same elements, and duplicated explanations will be omitted.

[0012] First, the configuration of a control device 1 for a hybrid all-wheel drive vehicle according to an embodiment will be described with reference to Fig. 1. Fig. 1 is a block diagram showing the overall configuration of the control device 1 for a hybrid all-wheel drive vehicle and a hybrid all-wheel drive vehicle (AWD HEV) 4 on which the control device 1 is mounted.

[0013] The engine 20 may be of any type, but may be, for example, a horizontally opposed, direct-injection, four-cylinder gasoline engine. In the engine 20, air taken in through an air cleaner (not shown) is throttled by an electronically controlled throttle valve (hereinafter, simply referred to as a "throttle valve") provided in an intake pipe, passes through an intake manifold, and is taken in by each cylinder formed in the engine 20. Here, the amount of air taken in through the air cleaner is detected by an air flow meter 81. Furthermore, the throttle valve is provided with a throttle opening sensor 82 that detects the opening of the throttle valve. An injector that injects fuel is attached to each cylinder. Also, each cylinder is provided with an ignition plug that ignites the mixture, and an igniter-integrated coil that applies high voltage to the ignition plug. In each cylinder of the engine 20, the mixture of the taken in air and the fuel injected by the injector is ignited by the ignition plug and combusted. Exhaust gas after combustion is discharged through an exhaust pipe.

[0014] In addition to the air flow meter 81 and throttle opening sensor 82 described above, a cam angle sensor for identifying the cylinders of the engine 20 is attached near the camshaft of the engine 20. Also, a crank angle sensor for detecting the position of the crankshaft is attached near the crankshaft of the engine 20. These sensors are connected to an engine control unit (hereinafter referred to as "ECU") 80, which will be described later. Various sensors, such as a water temperature sensor 83 for detecting the temperature of the cooling water for the engine 20, are also connected to the ECU 80.

[0015] A manual transmission (MT) 30 that converts and outputs the driving force from the engine 20 is connected to an output shaft (crankshaft) 21 of the engine 20, for example, via a dry clutch 22. The manual transmission 30 is a transmission in which the gear shifting operation is performed manually, and for example, a transmission with input and output shafts concentric is used. As the manual transmission 30, a known one can be used, that is, a transmission in which the driving gear and the driven gear of each gear are arranged on two shafts, and a synchronization mechanism and a coupling sleeve, a shift fork, a striking rod, etc. that operate the synchronization mechanism are arranged next to the gears, and connected to a shift lever. Note that, instead of the manual transmission (MT), other types of transmissions, such as a stepped automatic transmission (AT), a continuously variable transmission (CVT), or a dual clutch transmission (DCT), may be used.

[0016] A center differential unit 40 is connected to the output shaft 30a of the manual transmission 30. The driving force converted by the manual transmission 30 is distributed by the center differential unit 40 and output (transmitted) to the front drive shaft 43 and the propeller shaft 46, respectively. In this embodiment, the center differential unit 40 is a combination of a center differential (41) consisting of a planetary gear unit 41 that distributes torque unequally between the front and rear, and a differential limiting mechanism consisting of a multi-plate clutch (corresponding to a differential limiting clutch described in the claims, hereinafter also referred to as an "LSD clutch") 42, and a system capable of electrically adjusting the fastening force (i.e., the strength of the differential limiting) of the LSD clutch 42 is adopted. In addition to the above-mentioned configuration, the center differential unit 40 also incorporates a cam mechanism that uses a torque difference to raise the clutch pressing force in order to generate a differential limiting force the moment a difference in road surface reaction force occurs. The center differential unit 40 distributes torque between the front wheels 41 and the rear wheels 59 as a basic ratio, for example, and ensures stability while exerting large driving force by distributing torque between the front and rear wheels according to the driving conditions using the LSD clutch 42.

[0017] More specifically, the planetary gear unit (center differential) 41 includes a sun gear 41a, a planetary pinion (planetary carrier) 41b, and a ring gear (internal gear) 41c. The output shaft 30a of the manual transmission 30 is connected to the planetary pinion (planetary carrier) 41b, and the driving force transmitted from the engine 20 is input. The front drive shaft 43 is connected to the sun gear 41a, and the driving force is transmitted (output) to the front wheels. The propeller shaft 46 is connected to the ring gear (internal gear) 41c, and the driving force is transmitted (output) to the rear wheels. Note that the connection relationship between each element of the planetary gear unit 41 and the output shaft 30a, the front drive shaft 43, and the propeller shaft 46 is not limited to this embodiment, and can be arbitrarily associated.

[0018] Furthermore, in the center differential unit 40, an LSD clutch (differential limiting clutch) 42 that performs differential limiting is incorporated between a ring gear 41c that is responsible for rear wheel output and a sun gear 41a that is responsible for front wheel output, and a clamping force (fastening force) is applied from an electromagnetic solenoid (electromagnet) and a torque cam (not shown) that are arranged opposite each other across the LSD clutch 42.

[0019] The LSD clutch 42 varies the torque distribution to the front and rear wheels according to the engagement force, and also exerts a differential limiting function. As the LSD clutch 42, for example, an electromagnetic clutch or the like that can electrically adjust the engagement force (engagement / disengagement) is suitably used. The engagement force (differential limiting) of the LSD clutch 42 is controlled by a hybrid control unit (hereinafter referred to as "HEV-CU") 60.

[0020] As described above, the input (driving force) from the manual transmission 30 is transmitted to the planetary gear unit 41, and is output from the sun gear 41a to the front wheels 10FL, 10FR, and from the outer circumferential ring gear 41c to the rear wheels 10RL, 10RR. More specifically, the input (driving force) from the manual transmission 30 is transmitted to the planetary pinion (planetary carrier) 41b, and is transmitted from the sun gear 41a to the front differential (hereinafter also referred to as "front differential") 44 via the front drive shaft 43. The front differential 44 is, for example, a bevel gear type differential device. The driving force from the front differential 44 is transmitted to the left front wheel 10FL via the left front wheel drive shaft 45L, and is transmitted to the right front wheel 10FR via the right front wheel drive shaft 45R.

[0021] Meanwhile, the input (driving force) transmitted to the planetary gear unit 41 is transmitted from the outer circumferential ring gear 41c via a propeller shaft 46 to a rear differential (hereinafter also referred to as "rear diff") 47. A left rear wheel drive shaft 48L and a right rear wheel drive shaft 48R are connected to the rear differential 47. The driving force from the rear differential 47 is transmitted to the left rear wheel 10RL via the left rear wheel drive shaft 48L, and to the right rear wheel 10RR via the right rear wheel drive shaft 48R.

[0022] Further, a motor generator (MG) 72 is connected to the propeller shaft 46 so as to be capable of transmitting torque. More specifically, the motor generator 72 is connected to the propeller shaft 46 via, for example, a motor reduction gear.

[0023] The motor generator 72 is configured as a synchronous generator motor that combines a function as a motor that converts supplied electric power into mechanical power and a function as a generator that converts input mechanical power into electric power. That is, the motor generator 72 operates as a motor that generates drive torque when driving the vehicle, and operates as a generator during regeneration.

[0024] Each of the wheels 10FR-10RR (hereinafter, all the wheels 10FR-10RR may be collectively referred to as wheels 10) is provided with a brake 11FR-11RR (hereinafter, all the brakes 11FR-11RR may be collectively referred to as brake 11) for braking the wheels 10FR-10RR. Also, each of the wheels 10FR-10RR is provided with a wheel speed sensor 12FR-12RR (hereinafter, all the wheel speed sensors 12FR-12RR may be collectively referred to as wheel speed sensor 12) for detecting the wheel rotation speed.

[0025] In this embodiment, a disc brake is used as the brake 11. The brake 11 is configured to have a brake disc attached to the wheel 10 of the AWD HEV 4, and a brake caliper incorporating brake pads and a wheel cylinder. During braking (when braking), the brake pads are pressed against the brake disc by hydraulic pressure, and the wheel 10 connected to the brake disc is braked by frictional force. Note that although the brake 10 used in this embodiment is a disc brake, a drum brake that applies braking by pressing a friction material against the inner peripheral surface of a drum may also be used.

[0026] The wheel speed sensor 12 is a non-contact sensor that detects changes in a magnetic field caused by a rotor (gear rotor or magnetic rotor) that rotates together with the wheel 10. For example, a semiconductor type that detects rotor rotation using a Hall element or MR element is preferably used.

[0027] As configured in this manner, in the hybrid all-wheel drive vehicle (AWD HEV) 4 according to this embodiment, as shown in FIG. 2, the output of the engine 20 is transmitted to the front drive shaft 43 and the propeller shaft 46 (front and rear wheel axles) via the center differential unit 40 with the LSD clutch 42. Meanwhile, the output (power running / regeneration) of the motor generator 72 is transmitted to the propeller shaft 46 (rear wheel axle). The balance between the engine output and the motor generator output is integrated and controlled, and the driving force to the front and rear wheels 10 is variably distributed as desired, while the motor generator 72 performs assist / regeneration to improve fuel efficiency. FIG. 2 is a diagram showing the torque flow in the hybrid all-wheel drive vehicle (AWD HEV) 4.

[0028] The drive of the engine 20 and the motor generator 72 is totally controlled by the HEV-CU 60. The engagement force (differential limiting) of the LSD clutch 42 is also controlled by the HEV-CU 60. In other words, the HEV-CU 60 functions as a control unit as defined in the claims.

[0029] Here, the HEV-CU 60 is connected via a CAN (Controller Area Network) 100 to an ECU 80 which comprehensively controls the engine 20, a PCU 70, a vehicle dynamics control unit (hereinafter referred to as "VDCU") 50 which improves driving stability by suppressing vehicle skidding, a driving assistance device 90, a car navigation system 91, etc., so as to be able to communicate with each other.

[0030] Each of the HEV-CU 60, ECU 80, VDCU 50, driving assistance device 90, and car navigation system 91 is configured to include a microprocessor that performs calculations, an EEPROM that stores programs and the like for causing the microprocessor to execute each process, a RAM that stores various data such as calculation results, a backup RAM in which the stored contents are maintained by a battery or the like, and an input / output I / F, etc.

[0031] The ECU 80 identifies the cylinder from the output of the cam angle sensor, and obtains the engine speed from the change in the rotational position of the crankshaft detected by the output of the crank angle sensor. The ECU 80 also obtains various information such as the intake air amount, the throttle opening, the air-fuel ratio of the mixture, and the water temperature based on the detection signals input from the various sensors described above.

[0032] Furthermore, the ECU 80 receives information such as the required output, the number of revolutions (rotation speed) of the motor generator 72, the amount of depression of the accelerator pedal (accelerator opening) and the like from the HEV-CU 60 via the CAN 100. Then, based on the required output from the HEV-CU 60 and the various pieces of information acquired, the ECU 80 controls the engine 20 by controlling the fuel injection amount, the ignition timing, and various devices such as a throttle valve.

[0033] The ECU 80 transmits various information such as engine speed, throttle opening, engine shaft torque, and engine water temperature (coolant temperature) to the HEV-CU 60 and the like via the CAN 100.

[0034] The PCU 70 has an inverter 70a that converts DC power of the high-voltage battery 71 into three-phase AC power and supplies it to the motor generator 72. The PCU 70 drives the motor generator 72 via the inverter 70a based on a torque command value received from the HEV-CU 60. Meanwhile, during regeneration, the inverter 70a converts the AC voltage generated by the motor generator 72 into a DC voltage to charge the high-voltage battery 71.

[0035] The VDCU 50 is connected to four wheel speed sensors 12FL-12RR, a steering angle sensor 16, a longitudinal acceleration (longitudinal G) sensor 55, a lateral acceleration (lateral G) sensor 56, a yaw rate sensor 57, and a brake switch 58. As described above, the wheel speed sensors 12FL-12RR detect the rotational state of the wheels 10FL-10RR by detecting the rotation of the gears attached to the centers of the wheels 10FL-10RR using a magnetic pickup or the like. The longitudinal acceleration sensor 55 detects the longitudinal acceleration (hereinafter also simply referred to as "acceleration") acting on the AWD HEV 4, and the lateral acceleration sensor 56 detects the lateral acceleration acting on the AWD HEV 4. The steering angle sensor 16 detects the turning angle of the front wheels 10FL, 10FR, which are steered wheels (i.e., the steering angle of the steering wheel 15), by detecting the rotation angle of the pinion shaft. The yaw rate sensor 57 detects the yaw rate of the AWD HEV 4.

[0036] The VDCU 50 drives a brake actuator according to the amount of operation (depression) of the brake pedal to brake the vehicle, and detects the vehicle behavior using various sensors (e.g., the wheel speed sensor 12, the steering angle sensor 16, the longitudinal acceleration sensor 55, the lateral acceleration sensor 56, the yaw rate sensor 57, etc.), and suppresses skidding by automatic pressurization brake control and engine 20 torque control to ensure vehicle stability during cornering. That is, the VDCU 50 prevents skidding and ensures excellent driving stability, for example, when the vehicle enters a corner at an overspeed or when the vehicle attitude (behavior) is disturbed due to a sudden steering operation. More specifically, the VDCU 50 detects the vehicle attitude (behavior) using the above sensors, etc., and automatically controls the vehicle according to the driving situation by applying the brakes to the front wheels 10FL, 10FR on the outside of the corner if it determines that the vehicle is oversteering, and by contrast, automatically controls the vehicle according to the driving situation by reducing engine power and applying the brakes to the rear wheels 10RL, 10RR on the inside of the corner if it determines that the vehicle is understeering. In addition to the above VDC (side slip prevention) function, the VDCU50 also has an ABS (anti-lock brake) function and a TCS (traction control) function.

[0037] The VDCU 50 transmits the detected wheel speed, steering angle, longitudinal acceleration, lateral acceleration, yaw rate, braking information, and the like of each wheel 10 to the HEV-CU 60 via the CAN 100.

[0038] The driving support device 90 has a function of detecting the external environment of the vehicle (for example, the driving environment in front of the vehicle) and issuing an alarm for an obstacle ahead and performing automatic braking (automatic braking function / pre-crash braking function).The driving support device 90 also has a function of assisting the driver in driving by performing following control and warning control for a detected preceding vehicle.

[0039] The driving support device 90 processes image data captured by, for example, a stereo camera 90a consisting of a pair of cameras that captures an image in front of the vehicle, and detects, for example, the driving environment (external environment) outside the vehicle, such as the state of the road, a preceding vehicle, obstacles, etc. In other words, the driving support device 90 functions as an external environment detection means described in the claims.

[0040] The driving support device 90 processes the image data and detects the lane (driving lane) based on the road dividing lines (white lines) drawn on the road on which the vehicle is traveling. Based on the detected lane, the driving support device 90 detects, for example, the presence or absence of a corner (curve), the distance to the corner, the radius of the corner (turning radius), and the width of the road. The driving support device 90 also extracts the preceding vehicle from the captured image by edge extraction, pattern recognition processing, etc., and calculates the inter-vehicle distance from the preceding vehicle by a triangulation method based on the difference in the position of the preceding vehicle in the left and right captured images, and calculates the relative speed (whether the preceding vehicle has decelerated or not) from the amount of change from the distance calculated in the previous frame.

[0041] Furthermore, the driving support device 90 detects the road surface gradient of the road. The driving support device 90 also recognizes, for example, whether the road surface is wet, snowy, or frozen, based on, for example, road surface reflectance information (i.e., detects the road surface friction coefficient of the road). The driving support device 90 then transmits external environment information including the detected corner information to the HEV-CU 60 via the CAN 100.

[0042] The car navigation system 91 detects the vehicle's position based on a GPS (Global Positioning System) satellite signal received by a GPS. The car navigation system 91 also calculates the travel distance based on vehicle speed information, and detects the vehicle's traveling direction based on a signal from a gyro sensor. The car navigation system 91 also acquires road information (i.e., external environment information such as the presence or absence of corners (curves), the distance to the corners, the corner radius, the road width, railroad crossings, pedestrian crossings, stop signs, and road surface gradient) of the road (travel path) on which the vehicle is traveling, from a map information storage device such as a built-in hard disk or DVD disk. The car navigation system 91 also acquires route information to the destination, and acquires appearance ratio information of corners and straight roads on the route to the destination. The car navigation system 91 then transmits the acquired vehicle position information and road information (external environment information such as the presence or absence of curves, the distance to the curves, the curve radius, and road surface gradient), appearance ratio information of corners and straight roads on the route to the destination, and the like, to the HEV-CU 60 via the CAN 100.

[0043] Various sensors are connected to the HEV-CU 60, including, for example, an accelerator opening sensor 61 that detects the amount of depression of the accelerator pedal (amount of accelerator operation), a resolver 62 that detects the rotation speed (rotational speed) of the motor generator 72, and a raindrop sensor (rain sensor) 63 that detects rainfall, snowfall, etc. (or a sensor that detects the differential of the wipers).

[0044] The HEV-CU 60 receives information such as engine speed, throttle opening, engine shaft torque (output torque), and engine water temperature (cooling water temperature) from the ECU 80 via the CAN 100. The HEV-CU 60 also receives information such as the wheel speed of each wheel 10, steering angle, longitudinal acceleration, lateral acceleration, yaw rate, and braking information from the VDCU 50 via the CAN 100. Furthermore, the HEV-CU 60 receives various external environment information including corner information from the driving assistance device 90 via the CAN 100, and also receives information such as route information to the destination and information on the appearance ratio of corners and straight lines on the route from the car navigation system 91.

[0045] The HEV-CU 60 controls the drive of the engine 20 and the motor generator 72, and the fastening force of the LSD clutch 42 of the center differential unit 40, based on information obtained from the various sensors mentioned above and various information obtained via the CAN 100.

[0046] In particular, the HEV-CU 60 has a function to execute the front / rear driving force control with priority without being restricted by the energy management control when the front / rear driving force control is to be prioritized (i.e., to achieve compatibility between the front / rear driving force control and the energy management control). In the HEV-CU 60, the above function is realized by the microprocessor executing a program stored in an EEPROM or the like.

[0047] In addition, in the front / rear driving force control (AWD control), for example, the drive of the engine 20 and the motor generator 72, and the fastening force (front / rear distribution ratio) of the LSD clutch 42 are controlled according to the friction force (slip) between the front and rear wheels 10 and the road surface, etc. Examples of such front and rear driving force control include, for example, during slow acceleration (acceleration on a low μ road, etc.), regenerating the motor generator 72 to distribute driving force weighted towards the front wheels in accordance with the front and rear load distribution (for example, driving force distribution of front wheels:rear wheels = 60:40), driving (powering) the motor generator 72 during rapid acceleration (acceleration on a high μ road, etc.) to distribute driving force weighted towards the rear wheels in accordance with the front and rear load distribution (for example, driving force distribution of front wheels:rear wheels = 40:60), and reducing the burden on the front wheels 10FL, 10FR (improving cornering performance) by distributing driving force weighted towards the rear wheels during (high G) cornering (for example, driving force distribution of front wheels:rear wheels = 40:60).

[0048] On the other hand, in the energy management control, for example, the driving of the motor generator 72 is controlled so that the state of charge (SOC) of the high-voltage battery 71 that supplies power to the motor generator 72 falls within a predetermined range. Examples of such energy management control include, for example, when the SOC of the high-voltage battery 71 is low (when continuously climbing a slope, during continuous high-load operation, etc.), generating (regenerating) electricity with the motor generator 72 to charge the high-voltage battery 71, using an operating region where the engine 20 has good combustion efficiency (fuel consumption rate) by generating (regenerating) electricity with the motor generator 72 to avoid a low-load operating region where the engine 20 has poor combustion efficiency (fuel consumption rate), consuming the power of the high-voltage battery 71 by providing driving assistance with the motor generator 72 when the SOC of the high-voltage battery 71 is high (when continuously descending a slope, etc.), and using an operating region where the engine 20 has good combustion efficiency (fuel consumption rate) by providing driving assistance with the motor generator 72 to avoid a high-load operating region where the engine 20 has poor combustion efficiency (fuel consumption rate).

[0049] The HEV-CU 60 judges whether or not the driving state requires the front and rear driving force control to be prioritized based on the driving state of the AWD HEV 4. If it is judged that the driving state requires the front and rear driving force control to be prioritized, the HEV-CU 60 preferentially executes the front and rear driving force control that controls the driving of the engine 20 and the motor generator 72 and the fastening force (front and rear distribution ratio) of the LSD clutch 42 according to the frictional force (slip) between the front and rear wheels 10 and the road surface. On the other hand, if it is judged that the driving state does not require the front and rear driving force control to be prioritized, the HEV-CU 60 preferentially executes the energy management control that controls the driving of the motor generator 72 so that the state of charge (SOC) of the high-voltage battery 71 that supplies power to the motor generator 72 falls within a predetermined range.

[0050] At that time, when the AWD HEV4 is turning a corner (cornering), HEV-CU60 determines that the driving state requires that front and rear drive force control be prioritized, and when the AWD HEV4 is driving (moving straight) on a straight road (other than cornering), HEV-CU60 determines that the driving state does not require that front and rear drive force control be prioritized (i.e., energy management control may be prioritized).

[0051] More specifically, the HEV-CU 60 determines whether the AWD HEV 4 is rounding a corner (turning) based on, for example, the steering angle, the lateral acceleration, and / or the yaw rate.

[0052] Furthermore, it is preferable that the HEV-CU 60 executes the front-rear driving force control with priority when a predetermined time (e.g., about one second) has elapsed after the AWD HEV 4 starts turning a corner (after entering the corner). Note that the reason why the front-rear driving force control is started after the predetermined time is that it is preferable to reliably execute the front-rear driving force control after entering a corner, particularly when accelerating at the exit of the corner (at the timing when the accelerator pedal is depressed).

[0053] However, since it is preferable for HEV-CU60 to promptly start executing front and rear driving force control when, for example, the rate of change of the steering angle is equal to or greater than a predetermined speed, when the corner radius (turning radius) is equal to or less than a predetermined value, and / or when rainfall or snowfall is detected (i.e., when the frictional resistance of the road surface is estimated to be equal to or less than a predetermined value), HEV-CU60 starts front and rear driving force control without waiting for the above-mentioned predetermined time to elapse.

[0054] The HEV-CU 60 also predicts entry into a corner based on the distance to the corner and the vehicle speed. To avoid a sudden change in the front / rear drive power distribution during cornering, the HEV-CU 60 also determines whether or not the front / rear drive power control can be preferentially executed while the vehicle is turning the corner (while turning) based on the radius of the corner (turning radius) and the like.

[0055] On the other hand, when performing energy management control, the HEV-CU 60 controls the fastening force of the LSD clutch 42 (i.e., transmits torque from the high distribution drive wheel side to the low distribution drive wheel side) so that the driving force distribution ratio of the front and rear wheels 10 falls within a predetermined range (i.e., so as not to be excessively biased toward the front wheels 10FL, 10FR or the rear wheels 10RL, 10RR).

[0056] At that time, the HEV-CU 60 controls (adjusts) the engagement force of the LSD clutch 42 based on the following equation (1). TM and the motor generator output P MG The target rear wheel power distribution ratio is set based on the balance between the DER The differential limiting power P LSD (= Differential limiting torque x rotation speed) can be calculated using the following formula (1). P LSD =(2D ER -D ER ×D DR -1)P TM -(1-D ER )×P MG (1) P LSD : Differential limited power (transmission from front to rear is considered positive) P TM : Transmission output, P MG : Motor generator (MG) output D DR : Center differential rear wheel power distribution ratio, D ER :Target rear wheel power distribution ratio

[0057] In addition, when performing energy management control, HEV-CU 60 controls the drive (power running / regeneration) of motor generator 72 so that engine 20 can be operated in a predetermined operating range in which the combustion efficiency (fuel consumption) of engine 20 is higher than a predetermined value.

[0058] Furthermore, the HEV-CU 60 executes energy management control (charging) on ​​straight roads (straight sections) so that the state of charge (SOC) of the high-voltage battery 71 falls within a predetermined range (so as not to be excessively biased toward the discharging or charging side) based on the ratio of corners and straight roads on the route to the destination received from the car navigation system 91 and the state of charge (SOC) of the high-voltage battery 71. That is, the HEV-CU 60 predicts the appearance of corners on the route to the searched destination, and controls the charge and discharge balance of the high-voltage battery 71 so as to maintain the state of charge (SOC) of the high-voltage battery 71 so that the longitudinal driving force control can be preferentially executed during cornering. That is, the HEV-CU 60 controls so that the electric power required for longitudinal driving force control during cornering is charged on straight roads.

[0059] Next, the operation of the control device 1 of a hybrid all-wheel drive vehicle will be described with reference to Fig. 3. Fig. 3 is a flow chart showing the procedure of switching (arbitration) between front / rear driving force control and energy management control by the control device 1 of a hybrid all-wheel drive vehicle. This process is repeatedly executed at a predetermined timing in the HEV-CU 60.

[0060] In step S100, a determination is made as to whether or not the preconditions for executing the front / rear driving force control are satisfied. More specifically, a determination is made as to whether or not three conditions (preconditions) are satisfied, for example, whether or not the system is operating normally, whether or not the SOC of the high-voltage battery 71 is within a predetermined range, and whether or not the vehicle speed is equal to or greater than a predetermined value. If the preconditions for executing the front / rear driving force control are not satisfied (if any one of them is not satisfied), the process proceeds to step S112, where the energy management control is executed, and then the process is temporarily terminated. On the other hand, if all (three) preconditions are satisfied, the process proceeds to step S102.

[0061] In step S102, it is determined whether the absolute value of the steering angle is equal to or greater than a predetermined value. If the absolute value of the steering angle is equal to or greater than the predetermined value, the process proceeds to step S114. On the other hand, if the absolute value of the steering angle is less than the predetermined value, the process proceeds to step S104. Note that hysteresis is provided to prevent hunting in the threshold value (predetermined value) of the steering angle and the threshold values ​​(predetermined values) of the lateral acceleration and yaw rate described below.

[0062] In step S104, it is determined whether the absolute value of the lateral acceleration is equal to or greater than a predetermined value. If the absolute value of the lateral acceleration is equal to or greater than the predetermined value, the process proceeds to step S114. On the other hand, if the absolute value of the lateral acceleration is less than the predetermined value, the process proceeds to step S106.

[0063] In step S106, it is determined whether the absolute value of the yaw rate is equal to or greater than a predetermined value. If the absolute value of the yaw rate is equal to or greater than the predetermined value, the process proceeds to step S114. On the other hand, if the absolute value of the yaw rate is less than the predetermined value, the process proceeds to step S108.

[0064] In step S108, it is determined whether the distance to the corner (entrance) is less than a predetermined value. If the distance to the corner (entrance) is less than the predetermined value, the process proceeds to step S114. On the other hand, if the distance to the corner (entrance) is equal to or greater than the predetermined value, the process proceeds to step S110.

[0065] In step S110, a delay timer that measures the time that has elapsed since the AWD HEV 4 started to turn the corner (the time that has elapsed since entering the corner) is set to zero. Then, the process proceeds to step S112.

[0066] In step S112, the energy management control is executed with priority. Since the energy management control is as described above, detailed description will be omitted here. After that, the process temporarily exits.

[0067] On the other hand, if any of steps S102, S104, S106, and S108 is positive, i.e., if it is determined that the vehicle is cornering or if it is expected to enter a corner, in step S114, the value of the delay timer is incremented (+1) and a determination is made as to whether or not the value of the delay timer is one second or more, i.e., whether or not one second has passed since the AWD HEV4 started to turn the corner (entered the corner). If the value of the delay timer is one second or more, the process proceeds to step S120. On the other hand, if the value of the delay timer is less than one second, the process proceeds to step S116.

[0068] In step S116, it is determined whether the delay cut conditions are satisfied. More specifically, it is determined whether three conditions are satisfied: whether the speed of change of the steering angle is equal to or greater than a predetermined value; whether the turning radius of the corner is equal to or less than a predetermined value; and whether rain or snow has been detected (i.e., whether the friction resistance of the road surface is estimated to be equal to or less than a predetermined value). If none of the delay cut conditions are satisfied, the process proceeds to step S112, where the energy management control is preferentially executed, and then the process temporarily exits. On the other hand, if the delay cut conditions are satisfied (if at least one of them is satisfied), the process proceeds to step S118.

[0069] In step S118, the delay timer is set to one second (or a value greater than this). Then, in step S120, the front and rear driving force control is executed with priority. Note that the front and rear driving force control is as described above, and therefore a detailed description thereof will be omitted here. After that, the process temporarily exits.

[0070] As described above in detail, according to this embodiment, it is determined whether or not the vehicle is in a driving state in which the front-rear driving force control needs to be prioritized based on the driving state of the AWD HEV 4. When it is determined that the vehicle is in a driving state in which the front-rear driving force control needs to be prioritized (for example, during cornering), the front-rear driving force control is preferentially executed to control the driving of the engine 20 and the motor generator 72 and the fastening force (front-rear distribution ratio) of the LSD clutch 42 according to the frictional force between the front and rear wheels 10 and the road surface. On the other hand, when it is determined that the vehicle is in a driving state in which the front-rear driving force control does not need to be prioritized (for example, other than going straight / cornering), the energy management control is preferentially executed to control the driving of the motor generator 72 so that the state of charge (SOC) of the high-voltage battery 71 that supplies power to the motor generator 72 falls within a predetermined range. Therefore, by preferentially executing the energy management control when it is not necessary to preferentially execute the front-rear driving force control, the state of charge (SOC) of the high-voltage battery 71 can be kept within an appropriate range, and the electric power can be used in situations where it is necessary to preferentially execute the front-rear driving force control. Therefore, it becomes possible to achieve (appropriately balance) both the front and rear driving force control and the energy management control.

[0071] As a result, according to this embodiment, in situations where it is desired to give priority to the front and rear driving force control, it is possible to execute the front and rear driving force control with priority without being restricted by the energy management control.

[0072] Note that switching between front / rear driving force control and energy management control for the convenience of the system while cornering may affect vehicle behavior (i.e., may cause the driver (passengers) to feel uncomfortable). On the other hand, the SOC (remaining charge) of the high-voltage battery 71 changes gradually and is therefore predictable, and by selecting a straight road or the like and performing energy management, it is possible to prevent the driver (passengers) from feeling uncomfortable.

[0073] Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment and various modifications are possible. For example, the configuration of the driving force transmission system described above (e.g., the arrangement of gears, shafts, etc.) is one example and is not limited to the above embodiment. Furthermore, in the above embodiment, an electromagnetic clutch is used as the LSD clutch 42, but a hydraulic clutch may also be used. Furthermore, the configuration (type) of the center differential unit 40 is not limited to the above embodiment and other types may also be used.

[0074] Furthermore, the system configuration of the controllers such as the HEV-CU 60 and the ECU 80, and the allocation of functions among the controllers are not limited to the above embodiment. In the above embodiment, the HEV-CU 60, the ECU 80, the PCU 70, the VDCU 50, the driving assistance device 90, and the car navigation system 91 are connected to each other via the CAN 100 so that they can communicate with each other, but the system configuration is not limited to this form and can be changed as desired, for example, in consideration of functional requirements, costs, and the like.

[0075] In the above embodiment, the stereo camera 90a is used to detect the external environment (corners, etc.), but instead of the stereo camera, for example, a millimeter wave radar, a laser radar, an ultrasonic sensor, etc. may be used. Also, a combination of different sensors may be used. [Explanation of symbols]

[0076] 1 Hybrid all-wheel drive vehicle control device 4 Hybrid All-Wheel Drive Vehicle (AWD HEV) 10FL,10FR,10RL,10RR wheels 11FL, 11FR, 11RL, 11RR Brake 12FL, 12FR, 12RL, 12RR Wheel speed sensor 16 Steering angle sensor 20 Engine 22 Dry clutch 30 Manual transmission 40 Center differential unit 41 Planetary gear unit (center differential) 41a Sun gear 41b Planetary pinion (planetary carrier) 41c Ring gear (internal gear) 42 LSD clutch (limited differential clutch) 43 Front drive shaft 46 Propeller shaft 50 VDCU 55 Front and rear acceleration sensor 56 Lateral acceleration sensor 57 Yaw rate sensor 58 Brake switch 60 HEV-CU 61 Accelerator opening sensor 62 Resolver 63 Rain sensor 70 PCU 72 Motor generator 80 ECU 81 Air flow meter 82 Throttle opening sensor 90 Driving assistance device 91 Car navigation system 100 CAN

Claims

1. The engine, a center differential unit having a differential limiting clutch that can limit differential between front and rear wheels in accordance with a fastening force, and that distributes driving force input from the engine to the front wheels and the rear wheels and outputs the driving force; a motor generator provided between the center differential unit and rear wheels and connected to the rear wheels so as to be capable of transmitting torque therebetween; A vehicle running condition detection means for detecting a running condition of a vehicle; a control unit that controls the drive of the engine and the motor generator, and the fastening force of the differential limiting clutch, the control unit determines whether or not the vehicle is in a driving state in which priority should be given to front and rear drive force control, based on the driving state of the vehicle detected by the driving state detection means; When it is determined that the vehicle is in a driving state in which priority should be given to the front and rear driving force control, the front and rear driving force control is preferentially executed, which controls the drive of the engine and the motor generator and the fastening force of the differential limiting clutch in accordance with the frictional force between the front and rear wheels and the road surface. When it is determined that the vehicle is in a driving state in which the front and rear driving force control does not need to be prioritized, the fastening force of the differential limiting clutch is controlled so that the driving force distribution ratio of the front and rear wheels falls within a predetermined range that is narrower than when the front and rear driving force control is prioritized, and energy management control is preferentially performed to control the operation of the motor generator so that the state of charge of the high-voltage battery that supplies power to the motor generator falls within a predetermined range. A control device for a hybrid all-wheel drive vehicle.

2. 2. The control device for a hybrid all-wheel drive vehicle according to claim 1, wherein the control unit determines that the vehicle is in a driving state in which it is necessary to prioritize the front and rear drive force control when the vehicle is turning a corner, and determines that the vehicle is in a driving state in which it is not necessary to prioritize the front and rear drive force control when the vehicle is traveling on a straight road.

3. the driving condition detection means includes a steering angle sensor that detects a steering angle of a steering wheel, a lateral acceleration sensor that detects a lateral acceleration of the vehicle, and / or a yaw rate sensor that detects a yaw rate of the vehicle; The control device for a hybrid all-wheel drive vehicle according to claim 2 , wherein the control unit determines whether the vehicle is turning a corner based on the steering angle, the lateral acceleration, and / or the yaw rate.

4. 4. The control device for a hybrid all-wheel drive vehicle according to claim 3, wherein the control unit executes the front and rear driving force control with priority when a predetermined time has elapsed after the vehicle starts to turn a corner.

5. 5. The control device for a hybrid all-wheel drive vehicle according to claim 4, wherein the control unit starts the front and rear driving force control without waiting for the predetermined time to elapse when the rate of change of the steering angle is equal to or greater than a predetermined rate, when the radius of the corner is equal to or less than a predetermined value, or when the frictional resistance of the road surface is equal to or less than a predetermined value.

6. Further comprising an external environment detection means for detecting an external environment of the vehicle, The external environment detection means detects the presence or absence of a corner in front of the vehicle, the distance to the corner, and the radius of the corner; 6. The control device for a hybrid all-wheel drive vehicle according to claim 2, wherein the control unit predicts an entry into the corner based on a distance to the corner, and determines whether or not the front / rear driving force control can be executed with priority while the vehicle is turning the corner based on a radius of the corner.

7. 7. The control device for a hybrid all-wheel drive vehicle according to claim 2, wherein the control unit controls the fastening force of the differential limiting clutch so that a driving force distribution ratio between the front and rear wheels falls within a predetermined range when executing the energy management control.

8. 8. The control device for a hybrid all-wheel drive vehicle according to claim 2, wherein the control unit, when executing the energy management control, controls the drive of the motor generator so that the engine can be operated in an operating range in which combustion efficiency is higher than a predetermined value.

9. Further comprising a car navigation system for acquiring route information to a destination, the car navigation system acquires information on the ratio of appearance of corners and straight roads on a route to the destination; The control device for a hybrid all-wheel drive vehicle according to any one of claims 2 to 8, characterized in that the control unit executes energy management control on the straight road based on the appearance ratio information of corners and straight roads and the charge state of the high-voltage battery so that the charge state of the high-voltage battery falls within a predetermined range.

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