JP5856135B2 - Vehicle drive system - Google Patents

Description

  The present invention relates to a vehicle drive system. More specifically, the present invention relates to a vehicle drive system that switches the drive state of a vehicle based on a plurality of conditions including slip generation, vehicle motion, and climbing.

  Conventionally, the distribution ratio is set so that the torque distributed to the rear axis increases as the road surface gradient detected by the gradient sensor increases as the climbing gradient, and the front and rear axes are required based on the set distribution ratio. There has been proposed a technique for controlling an engine and a motor so that required torque is distributed (see, for example, Patent Document 1). According to this patent document 1, even when an abnormality occurs on the brake ECU side, a two-wheel drive state (AWD) is possible, and compared to a case in which AWD is prohibited in such an abnormality, the required torque is more improved. It is said that it can respond reliably.

JP 2005-161961 A

  However, since the technique of the above-mentioned patent document is AWD that controls the road surface gradient as a parameter, for example, various cases such as when an excessive slip occurs in the vehicle or when the vehicle moves as a turning motion or a lateral motion of the vehicle. There is a possibility that the operation stability and running performance (hereinafter referred to as “vehicle stability”) of the AWD cannot be secured. Further, since the AWD is not adapted to such various cases, there is a possibility that fuel consumption and power consumption (hereinafter referred to as “driving efficiency”) may be deteriorated.

  The present invention is for solving the above-described problems, and an object of the present invention is to provide a vehicle drive system capable of improving drive efficiency while ensuring vehicle stability by switching vehicle drive force distribution at a more appropriate timing. Is to provide.

In order to achieve the above object, the present invention provides a vehicle having a front wheel (for example, front wheel Wf, Wf to be described later) and a rear wheel (for example, rear wheel Wr (RWr, LWr) to be described later). One of the first drive wheels (for example, first drive device 1 described later) for driving a first drive wheel (for example, front wheels Wf, Wf described later) and the front wheel and the rear wheel of the vehicle. A second drive device (for example, a second drive device 2 described later) that drives a second drive wheel (for example, a rear wheel Wr (RWr, LWr) described later), and controls the first drive device and the second drive device. A vehicle drive system (e.g., a vehicle drive system 10 described below) comprising a control device (e.g., an ECU 6 described later) for controlling the drive states of the first drive wheel and the second drive wheel, The control device is a grip between the wheel and the road surface. Based on the slip correlation amount (for example, an integrated slip point described later) correlated with an excess slip exceeding a predetermined amount among the slip generated on the front wheel or the rear wheel of the vehicle, The driving force distribution between the first driving device and the second driving device is switched so that the vehicle is driven by both the first driving wheel and the second driving wheel (for example, AWD described later). Based on a first determination means (for example, a first determination unit 61 described later) and a vehicle motion correlation amount (for example, a calculation “lateral G” described later) correlated with the turning motion or the lateral motion of the vehicle, A second determination unit (for example, a second determination unit 62 described later) that switches the driving force distribution and sets the two-wheel drive state, and the two-wheel drive after the switching by the first determination unit. A first driving force distribution is the driving force distribution in the state, the second driving force distribution and, the second driving force is the driving force distribution in the both-wheel drive state after the switching by said second determination means The distribution of the front wheels in the distribution is made different so as to be larger than the distribution of the front wheels in the first driving force distribution .

In the present invention, when it is assumed that the loss of grip between the wheels and the road surface is slip, the first drive device and the second drive device in the two-wheel drive state after being switched by the first determination means based on the slip correlation amount The second driving force distribution between the first driving device and the second driving device in the two-wheel drive state after being switched by the second determination means based on the vehicle motion correlation amount . The front wheel distribution in the driving force distribution is varied so as to be larger than the front wheel distribution in the first driving force distribution .
Accordingly, since the driving force distribution is switched based on the slip correlation amount and the vehicle motion correlation amount in the two-wheel driving state, the driving force distribution of the vehicle in the two-wheel driving state can be switched at a more appropriate timing.
For example, when the switching determination is performed by the first determination means based on the slip correlation amount, it is possible to switch to the driving force distribution according to the excess slip phenomenon that has occurred on the front wheel or the rear wheel of the vehicle. For this reason, in the two-wheel drive state, the driving force is distributed in accordance with the low μ state of the road surface, and vehicle stability can be ensured.
When the switching determination is performed by the second determination means based on the vehicle motion correlation amount, it is possible to switch to the driving force distribution according to the vehicle motion state in which the vehicle performs a turning motion or a lateral motion. For this reason, in the two-wheel drive state, the driving force is distributed according to the vehicle motion state, and the vehicle stability can be ensured.
The first driving force distribution in the two-wheel drive state after switching by the first determination means based on the slip correlation amount and the two-wheel drive state after switching by the second determination means based on the vehicle motion correlation amount The second driving force distribution is different from the front wheel distribution in the second driving force distribution so as to be larger than the front wheel distribution in the first driving force distribution . For this reason, it becomes different driving force distribution adapted according to the case where both-wheels drive state is both, and vehicle stability can be secured. Thereby, the driving force distribution of the vehicle is effectively switched at a more appropriate timing while ensuring the vehicle stability, and the driving efficiency can be improved.

  Preferably, the control device makes the front wheel distribution in the second driving force distribution larger than the front wheel distribution in the first driving force distribution.

In the present invention, the control device makes the front wheel distribution in the second driving force distribution larger than the front wheel distribution in the first driving force distribution.
Here, in general, when a vehicle moves in a turning direction or a lateral direction of the vehicle, the vehicle stability increases when the vehicle is in a front wheel single drive state that is understeering weaker than a rear wheel single drive state that oversteers. Tend. According to the present invention, the front wheel distribution in the second driving force distribution after switching by the second determination means based on the vehicle motion correlation amount is increased, and the front wheel single drive that weakly understeers tends to increase the vehicle stability. The vehicle stability can be ensured more closely to the state.

  The control device preferably prioritizes the switching determination by the first determination means among the switching determination by the first determination means and the switching determination by the second determination means.

In the present invention, the control device gives priority to the switching judgment by the first judging means among the switching judgment by the first judging means and the switching judgment by the second judging means.
Here, in general, the vehicle has a lower vehicle stability when an excess slip occurs on the front wheel or rear wheel of the vehicle than when the vehicle moves in a turning direction or a lateral direction. According to the present invention, priority is given to the switching determination when an excess slip occurs in the front wheel or the rear wheel of the vehicle in which the vehicle stability is further lowered, so that the vehicle stability can be further ensured.

  The control device switches the driving force distribution based on an inclination correlation amount (for example, an estimated uphill angle described later) having a correlation with an inclination of the vehicle or an inclination of a road surface on which the vehicle is located. It is preferable to further include third determination means (for example, a third determination unit 63 described later).

In the present invention, the control device further includes a third determination unit that switches the driving force distribution and sets the two-wheel drive state based on the inclination correlation amount correlated with the inclination of the vehicle or the inclination of the road surface on which the vehicle is located.
According to the present invention, since the driving force distribution is switched based on the slope correlation amount in addition to the slip correlation amount and the vehicle motion correlation amount in the two-wheel driving state, the vehicle driving force distribution in the two-wheel driving state at a more appropriate timing. Can be switched.
For example, when the switching determination is performed by the third determination unit based on the inclination correlation amount, the driving force distribution can be switched according to the vehicle inclination state. For this reason, in the two-wheel drive state, the driving force is distributed according to the inclination state of the vehicle, and vehicle stability can be secured.

  The third determining means makes a switching determination when the tilt correlation amount is equal to or greater than a predetermined amount, and the control device is the driving force distribution in the two-wheel drive state after being switched by the third determining means. The traveling direction wheel distribution in the three driving force distribution is preferably smaller than the traveling direction wheel distribution in the first driving force distribution.

In the present invention, the control device performs the first driving force distribution in the traveling direction wheel distribution in the third driving force distribution that is the driving force distribution in the two-wheel driving state after being switched by the third determination means based on the inclination correlation amount. Make it smaller than the wheel direction distribution in the distribution.
Here, in general, when the vehicle is in an inclined state (uphill state), the traveling direction wheel becomes unstable and vehicle stability is deteriorated, compared to when an excessive slip occurs in the front wheel or the rear wheel of the vehicle. This is because in the inclined state (uphill state), the load on the traveling direction wheel is small, and the driving force that can be transmitted to the road surface of the traveling direction wheel is small. According to the present invention, the driving force capable of reducing the traveling direction wheel distribution in the third driving force distribution in the two-wheel driving state after being switched by the third determining means based on the inclination correlation amount and transmitting a large load to the road surface. The vehicle stability can be further ensured by supplying more driving force from the wheel on the opposite side of the traveling direction wheel having a large.

  The control device preferably prioritizes the switching determination by the third determination unit among the switching determination by the first determination unit and the switching determination by the third determination unit.

In the present invention, the control device gives priority to the switching judgment by the third judging means among the switching judgment by the first judging means and the switching judgment by the third judging means.
Here, in general, the vehicle stability is lower when the vehicle is in an inclined state (uphill state) than when an excessive slip occurs in the vehicle. According to the present invention, priority is given to switching determination in an inclined state (climbing state) in which vehicle stability is further reduced, and therefore vehicle stability can be further ensured.

  ADVANTAGE OF THE INVENTION According to this invention, the vehicle drive system which can improve drive efficiency can be provided, ensuring vehicle stability by switching the driving force distribution of a vehicle at a more suitable timing.

It is a figure showing a vehicle carrying a vehicle drive system concerning an embodiment of the present invention. It is a longitudinal cross-sectional view of the 2nd drive device which concerns on the said embodiment. FIG. 3 is a partially enlarged view of the second drive device shown in FIG. 2. It is a figure which shows the state of the electric motor in the driving | running | working state of the vehicle which concerns on the said embodiment, and the state of a separation mechanism. It is a functional block diagram which shows the structure of ECU which concerns on the said embodiment. It is a functional block diagram which shows the structure of the adjustment slip point calculation part which concerns on the said embodiment. It is a flowchart which shows the procedure of the drive state switching control routine which concerns on the said embodiment. It is a flowchart which shows the procedure of the 1st judgment subroutine which concerns on the said embodiment. It is a flowchart which shows the procedure of the 3rd judgment subroutine which concerns on the said embodiment. It is a flowchart which shows the procedure of the 2nd judgment subroutine which concerns on the said embodiment. It is a figure which shows vehicle stability based on the relationship between the side G which concerns on the said embodiment, and a turning radius ratio.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a diagram showing a vehicle equipped with a vehicle drive system 10 according to the present embodiment. The vehicle 3 equipped with the vehicle drive system 10 according to the present embodiment is a hybrid vehicle. As shown in FIG. 1, a vehicle drive system 10 mounted on a vehicle 3 includes a first drive device 1, a second drive device 2, and an electronic control unit as a control device that controls these drive devices 1 and 2. (Hereinafter referred to as “ECU”) 6, a PDU (power drive unit) 8, and a battery 9.

  The first drive device 1 is provided at the front portion of the vehicle 3 and drives the front wheels Wf and Wf as the first drive wheels. The first drive device 1 includes an internal combustion engine (ENG) 4, an electric motor 5, and a transmission 7. The internal combustion engine 4 and the electric motor 5 are connected in series, and torques of the internal combustion engine 4 and the electric motor 5 are transmitted to the front wheels Wf and Wf via the transmission 7.

  The internal combustion engine 4 is an in-line four-cylinder engine, for example, and generates torque for running the hybrid vehicle 3 by burning fuel. The crankshaft of the internal combustion engine 4 is connected to the output shaft of the electric motor 5.

  The electric motor 5 is, for example, a three-phase AC motor, and generates torque for causing the vehicle 3 to travel by using electric power stored in the battery 9. The electric motor 5 is connected to the battery 9 via a PDU 8 equipped with an inverter, and assists the driving force of the internal combustion engine 4.

  The transmission 7 converts the torque generated in the internal combustion engine 4 into a rotational speed and torque at a desired gear ratio, and transmits them to the front wheels Wf and Wf.

  The second drive device 2 is provided at the rear portion of the vehicle 3 and drives rear wheels Wr (RWr, LWr) as second drive wheels. The 2nd drive device 2 has electric motors 2A and 2B. The torques of these electric motors 2A and 2B are transmitted to the rear wheels Wr (RWr, LWr).

  Similarly to the electric motor 5, the electric motors 2 </ b> A and 2 </ b> B are, for example, three-phase AC motors, and generate torque for causing the vehicle 3 to travel using electric power stored in the battery 9. The electric motors 2A and 2B are connected to the battery 9 via the PDU 8 including an inverter. When a control signal from the ECU 6 is input to the PDU 8, power supply from the battery 9 and energy to the battery 9 are obtained. Regeneration is controlled.

  Each of the four front wheels Wf, Wf and the rear wheels Wr (RWr, LWr) is provided with a friction brake (not shown). This friction brake is composed of, for example, a hydraulic disc brake. When the driver depresses the brake pedal, the depressing force is amplified and transmitted to the brake pad via a hydraulic cylinder, etc., and a frictional force is generated between the brake disk and the brake pad attached to each drive wheel. Each drive wheel is braked.

The second drive device 2 will be described in more detail. The second driving device 2 is described in detail in Japanese Patent Application Laid-Open No. 2010-235051 filed and published by the present applicant.
FIG. 2 is a longitudinal sectional view of the second drive device 2 according to the present embodiment. FIG. 3 is a partially enlarged view of the second drive device 2 shown in FIG.
As shown in FIGS. 2 and 3, the second driving device 2 has output shafts 10 </ b> A and 10 </ b> B that transmit driving force to the rear wheels RWr and LWr of the vehicle 3, and is arranged coaxially in the vehicle width direction. Is done. These output shafts 10A and 10B are connected to the axles of the rear wheels RWr and LWr. Inside the speed reducer case 11, motors 2A and 2B for driving the output shafts 10A and 10B and planetary gear speed reducers 12A and 12B for reducing the drive rotation of the motors 2A and 2B are output shafts 10A and 10B. And coaxially arranged.
Here, the reduction gear case 11 has a cylindrical outer diameter side support portion 34 that extends in the axial direction slightly inside the outer wall portion. The outer diameter side support part 34 extends the support wall 39 to the inner peripheral side, and forms a cylindrical support part 40 at the inner peripheral tip of the support wall 39. The reduction gear case 11 is described in detail in Japanese Patent Application Laid-Open No. 2010-235051 filed and published by the present applicant.

  The stators 14A and 14B of the electric motors 2A and 2B are fixed inside the left and right ends of the speed reducer case 11. Annular rotors 15A and 15B are rotatably arranged on the inner peripheral side of the stators 14A and 14B. Cylindrical shafts 16A and 16B surrounding the outer periphery of the output shafts 10A and 10B are coupled to the inner peripheral portions of the rotors 15A and 15B, and the cylindrical shafts 16A and 16B are coaxially supported with the output shafts 10A and 10B so as to be relatively rotatable. Is done. Resolvers 20A and 20B that detect rotational position information of the rotors 15A and 15B are provided on the end walls 17A and 17B of the speed reducer case 11.

  The planetary gear speed reducers 12A and 12B support sun gears 21A and 21B meshed with the cylindrical shafts 16A and 16B, a plurality of planetary gears 22A and 22B meshed with the sun gears 21A and 21B, and the planetary gears 22A and 22B. Planetary carriers 23A, 23B and ring gears 24A, 24B meshed with the outer peripheral sides of the planetary gears 22A, 22B. The driving forces of the motors 2A, 2B are input from the cylindrical shafts 16A, 16B and the sun gears 21A, 21B. The decelerated driving force is output from the sun gears 21A and 21B to the output shafts 10A and 10B through the planetary carriers 23A and 23B. For details of the planetary gear type speed reducers 12A and 12B, refer to Japanese Patent Application Laid-Open No. 2010-235051.

A cylindrical space portion is secured between the outer diameter side support portion 34 of the reduction gear case 11 and the ring gears 24A, 24B, and hydraulic brakes 60A, 60B for braking the ring gears 24A, 24B are provided in the space portions. The first pinion 27A overlaps with the second pinion 26A in the radial direction and overlaps with the first pinion 27A in the axial direction. The hydraulic brakes 60A and 60B are spline-fitted to a plurality of fixed plates 35A and 35B that are spline-fitted to the inner peripheral surface of the outer diameter side support portion 34 of the speed reducer case 11 and the outer peripheral surfaces of the ring gears 24A and 24B. A plurality of rotating plates 36A, 36B are alternately arranged in the axial direction, and these plates 35A, 35B, 36A, 36B are fastened and released by annular pistons 37A, 37B.
The pistons 37 </ b> A and 37 </ b> B are provided between the outer diameter side support portion 34 of the reduction gear case 11, the support wall 39 extending to the inner peripheral side, and the cylindrical support portion 40 formed at the inner peripheral tip of the support wall 39. The pistons 37A and 37B are advanced by introducing high-pressure oil into the cylinder chambers 38A and 38B, and the oil is discharged from the cylinder chambers 38A and 38B. As a result, the pistons 37A and 37B are retracted. The hydraulic brakes 60A and 60B are connected to an oil pump.
The hydraulic brakes 60A and 60B advance the pistons 37A and 37B, thereby fastening the reduction gear case 11 and the ring gears 24A and 24B, and braking the ring gears 24A and 24B. Further, the hydraulic brakes 60A and 60B release the fastening between the reduction gear case 11 and the ring gears 24A and 24B by retreating the pistons 37A and 37B, and do not brake the ring gears 24A and 24B.
For details of the hydraulic brakes 60A and 60B and the pistons 37A and 37B, refer to Japanese Patent Application Laid-Open No. 2010-235051.

A cylindrical space is also secured between the pistons 37A and 37B and the ring gears 24A and 24B. In the space, only power in one direction is transmitted to the ring gears 24A and 24B and power in the other direction is transmitted. A one-way clutch 50 for disengaging is arranged. The one-way clutch 50 is configured by interposing a large number of sprags 53 between the inner race 51 and the outer race 52, and the inner race 51 is configured to be able to rotate integrally with the gear portions 28A and 28B of the ring gears 24A and 24B. The The outer race 52 is positioned by the inner peripheral surface of the cylindrical support portion 40 of the speed reducer case 11 and is prevented from rotating.
The one-way clutch 50 is configured to engage and lock (engage) the rotation of the ring gears 24A and 24B when the vehicle 3 travels forward by the driving force of the electric motors 2A and 2B. More specifically, the one-way clutch 50 is configured to lock (engage) or disconnect the ring gears 24A and 24B in the direction of the torque acting on the ring gears 24A and 24B, so that the vehicle 3 moves forward. When the rotation direction of the sun gears 21A and 21B is the forward rotation direction, when the torque in the reverse rotation direction acts on each of the ring gears 24A and 24B, the rotation of the ring gears 24A and 24B is locked (engaged).

  In the second drive device 2 configured as described above, the planetary gear type speed reducers 12A and 12B are opposed in the axial direction at the center, and the ring gear 24A of the planetary gear type speed reducer 12A and the ring gear 24B of the planetary gear type speed reducer 12B. And the connected ring gears 24A and 24B are rotatably supported by the cylindrical support portion 40 of the outer diameter side support portion 34 via a bearing (not shown). Further, hydraulic brakes 60A and 60B are provided in the space between the outer diameter side support portion 34 and the ring gears 24A and 24B. A one-way clutch 50 is provided in the space between the pistons 37A and 37B and the ring gears 24A and 24B. Pistons 37A and 37B that operate the hydraulic brakes 60A and 60B are arranged between the hydraulic brakes 60A and 60B and the one-way clutch 50 and on the outer diameter side of the bearings.

An operation during normal running of the second drive device 2 having the above configuration will be described.
FIG. 4 is a diagram illustrating a state of the electric motors 2A and 2B and a state of the separation mechanism (one-way clutch 50 and hydraulic brakes 60A and 60B) in the traveling state of the vehicle.
In FIG. 4, the front represents the first drive device 1 that drives the front wheels Wf, Wf, the rear represents the second drive device 2 that drives the rear wheels Wr (RWr, LWr), and ○ indicates operation (including drive and regeneration). And x means inactive (stopped). Further, the MOT state represents the state of the electric motors 2A and 2B of the second drive device 2. The ON of the separation mechanism means that the ring gears 24A and 24B are locked (engaged). OFF means that each of the ring gears 24A and 24B is in a free state. Moreover, OWC means the one-way clutch 50, and BRK means the hydraulic brakes 60A and 60B.

First, since the first drive device 1 on the front wheels Wf, Wf side and the second drive device 2 on the rear wheel Wr (RWr, LWr) side are both stopped, the electric motors 2A, 2B are stopped. The separation mechanism is also inactive.
Next, after the key position is turned ON, the electric motors 2A and 2B of the second drive device 2 are driven when the EV starts. At this time, the separation mechanism is turned on by the one-way clutch 50, and the power of the electric motors 2A and 2B is transmitted to the rear wheels RWr and LWr.
Subsequently, during acceleration, the two-wheel (four-wheel) drive state (AWD) in which both the first drive device 1 and the second drive device 2 are driven is entered. At this time, the separation mechanism is turned on by the one-way clutch 50. The power of the electric motors 2A and 2B is transmitted to the rear wheels RWr and LWr.
In the EV cruise in the low / medium speed range, since the motor efficiency is good, the first driving device 1 is in the non-operating state, and the rear wheel single driving state (RWD) in which only the second driving device 2 is driven is set. Also at this time, the separation mechanism is turned on by the one-way clutch 50, and the power of the electric motors 2A and 2B is transmitted to the rear wheels RWr and LWr.

On the other hand, in the high speed cruise, the front drive single drive state (FWD) by the first drive device 1 is entered because the engine efficiency is good. At this time, the one-way clutch 50 is disconnected and turned off (OWC free), the hydraulic brakes 60A and 60B are not operated, and the electric motors 2A and 2B are stopped.
Also, in the case of natural deceleration, the one-way clutch 50 is disengaged (OFFC free) in the disengaging mechanism, the hydraulic brakes 60A and 60B are not activated, and the electric motors 2A and 2B are stopped.

On the other hand, when decelerating and regenerating, for example, when driving by the driving force of the first drive device 1, the one-way clutch 50 of the separation mechanism is disconnected and turned OFF (OWC free). However, the hydraulic brakes 60A and 60B are engaged, and the power of the output shafts 10A and 10B is transmitted to the cylindrical shafts 16A and 16B, whereby regenerative charging is performed by the electric motors 2A and 2B.
In normal running, the motor 2A, 2B regenerates and collects the running energy in cooperation with the braking control for the friction brake, but the regeneration of the motors 2A, 2B is prohibited when emergency braking is required (for example, during ABS operation). Thus, priority is given to the braking control by the friction brake. In this case, the one-way clutch 50 is turned off (OWC free), and the hydraulic brakes 60A and 60B are not operated, thereby stopping the electric motors 2A and 2B.

  In the case of reverse travel, the first drive device 1 is stopped and the second drive device 2 is driven to become RWD, or the first drive device 1 and the second drive device 2 are both driven AWD. At this time, the motors 2A and 2B rotate in the reverse direction, and the one-way clutch 50 of the separation mechanism is disengaged and turned off (OWC free). However, by connecting the hydraulic brakes 60A and 60B, the power of the electric motors 2A and 2B is transmitted from the cylindrical shafts 16A and 16B to the rear wheels RWr and LWr via the output shafts 10A and 10B.

Next, the configuration of the ECU 6 as the control device according to the present embodiment will be described.
The ECU 6 shapes an input signal waveform from various sensors, corrects a voltage level to a predetermined level, converts an analog signal value into a digital signal value, and a central processing unit (hereinafter, referred to as a central processing unit). "CPU"). In addition, the ECU 6 includes a storage circuit that stores various calculation programs and calculation results executed by the CPU, and an output circuit that outputs a control signal to the PDU 8, the internal combustion engine 4, and the like.

The ECU 6 having the above hardware configuration executes drive state switching control for switching the drive state of the vehicle 3.
FIG. 5 is a functional block diagram showing a configuration of the ECU 6 according to the present embodiment.
As shown in FIG. 5, the ECU 6 includes a wheel speed sensor 91, an accelerator opening sensor 92, an engine speed sensor 93, a motor current sensor 94, a lateral G sensor 95, a vehicle speed sensor 96, a steering angle sensor 97, and a yaw rate sensor 98. And detection signals of various sensors such as the front-rear G sensor 99 are input, and control signals are output to the PDU 8 and the internal combustion engine 4.
Further, the ECU 6 is a module for executing the drive state switching control, and includes a first determination unit 61, a second determination unit 62, a third determination unit 63, a drive state switching unit 64, and a stable travel determination unit 65. And comprising. Hereinafter, the function of each module will be described.

  The first determination unit 61 includes a slip acquisition unit 61a, an adjustable slip point calculation unit 61b, and an integrated slip point calculation unit 61c. In addition, the first determination unit 61 compares the integrated slip point with the slip threshold and sets the slip AWD request flag to “1” or “0”.

The slip acquisition unit 61a acquires that an excess slip, which is a predetermined slip or more, has occurred in the front wheels Wf, Wf as the first drive wheels or the rear wheels Wr (RWr, LWr) as the second drive wheels. Specifically, the slip acquisition unit 61a acquires that excess slip has occurred based on the wheel speed difference between the front wheels Wf, Wf and the rear wheels Wr (RWr, LWr) detected by the wheel speed sensor 91. . The slip acquisition unit 61a does not acquire that an excess slip has occurred when the vehicle 3 is stopped.
Here, it can be considered that the vehicle 3 is traveling while always generating minute slips on the drive wheels even on a dry road in a high μ state. Therefore, the “excess slip” in the present embodiment excludes such a minute slip.

  The adjusting / slipping point calculating unit 61b discretely calculates the adding / subtracting slip point that is the addition slip point or the subtraction slip point based on the fact that the slip acquisition unit 61a has acquired or has not acquired the occurrence of the excess slip. calculate. That is, the adjustment slip point calculation unit 61b calculates the addition slip point based on the fact that the slip acquisition unit 61a has acquired that an excess slip has occurred. Moreover, a subtraction slip point is calculated based on the fact that the slip acquisition unit 61a has not acquired that an excess slip has occurred.

FIG. 6 is a functional block diagram showing the configuration of the adjustable slip point calculating unit 61b according to this embodiment.
As shown in FIG. 6, when the slip acquisition unit 61a acquires that the excess slip has occurred, the adjustment slip point calculation unit 61b has a driving force correlation value correlated with the driving force of the drive wheel in which the excess slip has occurred. Based on this, an adjustable slip point is calculated.
Here, as the driving force correlation value, for example, a wheel (one wheel) driving force, a wheel (one wheel) torque, a driving force of the first driving device 1 and the second driving device 2 for driving the wheel, and a first for driving the wheel. Although the torque of the drive device 1 and the 2nd drive device 2 is mentioned, it demonstrates taking a wheel (one wheel) drive force as an example below.

Specifically, as shown in FIG. 6, the adjustment slip point calculation unit 61 b includes an addition slip point calculation unit 68 and a subtraction slip point calculation unit 69. When the slip acquisition unit 61a acquires that the excess slip has occurred, the addition / subtraction slip point calculation unit 61b calculates a positive addition slip point by the addition slip point calculation unit 68, and adds the calculated addition slip point to the integrated slip It transmits to the point calculation part 61c.
Further, when the slip acquisition unit 61a does not acquire that an excess slip has occurred, the addition / subtraction slip point calculation unit 61b calculates a minus value subtraction slip point by the subtraction slip point calculation unit 69, and calculates the calculated subtraction slip point. It transmits to the integrated slip point calculation part 61c.

  The addition slip point calculation unit 68 includes a slip generation driving force addition unit 681 and a slip generation duration addition unit 682. The addition slip point calculation unit 68 calculates the addition slip point by adding up each addition slip point of the plus value calculated by each of these addition units.

The driving force addition unit 681 at the time of slip occurrence searches the driving force addition slip point calculation table prepared and stored in advance according to the one-wheel driving force [N] at the time of occurrence of excess slip, thereby obtaining the added slip point as an addition slip point. A driving force addition slip point is calculated. The slip generation driving force addition unit 681 calculates a larger driving force addition slip point as the one-wheel driving force at the occurrence of excess slip is lower within a range that does not exceed the slip threshold.
Here, in the present specification, the one-wheel driving force [N] means the maximum driving force among the driving forces of the four wheels of the vehicle 3. The one-wheel driving force is detected by a sensor, for example, an accelerator opening detected by an accelerator opening sensor 92, an engine speed detected by an engine speed sensor 93, and motors 5, 2A, 2B. It is estimated and acquired based on each motor current detected by the motor current sensor 94.
The slip threshold is set to an appropriate value as an index for switching the driving state of the vehicle 3 to the AWD and excess slip front / rear distribution setting when the slip AWD request flag is set to “1” via the first determination unit 61. It is set in advance.

  The slip occurrence duration adding unit 682 calculates a time addition slip point that is created and stored in advance according to the slip occurrence duration [seconds], that is, the duration acquired by the slip acquisition unit 61a that an excess slip has occurred. By searching the table, a time addition slip point as an addition slip point is calculated. The slip occurrence duration adding unit 682 calculates a larger time addition slip point as the excess slip occurrence duration is longer until the accumulated value of the time addition slip point exceeds the slip threshold, and the accumulated value exceeds the slip threshold. Thereafter, a time addition slip point of approximately 0 is continuously calculated.

  Further, as shown in FIG. 6, the subtraction slip point calculation unit 69 includes a driving force subtraction unit 691, a slip non-occurrence duration subtraction unit 692, a slip non-occurrence lateral G subtraction unit 693, and a slip non-occurrence. And a vehicle speed subtraction unit 694 at the time of occurrence. The subtraction slip point calculation unit 69 calculates a subtraction slip point by adding the subtraction slip points of negative values calculated by the subtraction units.

  The driving force subtraction unit 691 when slip does not occur searches for a driving force subtraction slip point calculation table created and stored in advance according to the one-wheel driving force [N] when excess slip does not occur, thereby subtracting slip points. As a driving force subtraction slip point. The driving force subtraction unit 691 when no slip occurs calculates the driving force subtraction slip point as 0 when the one-wheel driving force when excess slip does not occur is less than a predetermined value, and the absolute value is relatively large when the slip is not less than a predetermined value. A constant driving force subtraction slip point is calculated.

  The slip non-occurrence continuation time subtracting unit 692 subtracts the time generated and stored in advance according to the excess slip non-occurrence continuation time [seconds], that is, the continuation time when the slip acquisition unit 61a does not acquire the occurrence of the excess slip. By searching the slip point calculation table, a time subtraction slip point is calculated as a subtraction slip point. The slip non-occurrence duration subtraction unit 692 calculates a constant time subtraction slip point having a relatively small absolute value regardless of the excess slip non-occurrence duration.

  When no slip occurs, the lateral G subtraction unit 693 searches the lateral G subtraction slip point calculation table created and stored in advance according to the lateral G detected by the lateral G sensor 95 when no excess slip occurs. A lateral G subtraction slip point is calculated as a subtraction slip point. When no slip occurs, the lateral G subtraction unit 693 calculates the lateral G subtraction slip point as 0 when the lateral G when the excess slip does not occur is less than a predetermined value, and the absolute value is relatively large when the slip is greater than the predetermined value. The lateral G subtraction slip point is calculated.

  The vehicle speed subtraction unit 694 when no slip occurs, searches for a stored vehicle speed subtraction slip point calculation table created in advance according to the vehicle speed detected by the vehicle speed sensor 96 when no excess slip occurs, thereby obtaining a subtraction slip point. The vehicle speed subtraction slip point is calculated. The vehicle speed subtraction unit 694 when no slip occurs calculates a constant vehicle speed subtraction slip point having a relatively large absolute value when the vehicle speed when the excess slip does not occur is less than a predetermined value. Is calculated as 0.

  The integrated slip point calculating unit 61c integrates the added slip point calculated by the added slip point calculating unit 68 and the subtracted slip point calculated by the subtracted slip point calculating unit 69, thereby calculating the accumulated slip point over time. To calculate.

  The second determination unit 62 includes a lateral G calculation unit 62a. The second determination unit 62 compares the calculated “lateral G” with the first and second lateral G thresholds, and sets the “horizontal G” AWD request flag to “1” or “0”.

The lateral G calculation unit 62a calculates that lateral G (lateral acceleration) has occurred in the vehicle 3. Specifically, the lateral G calculation unit 62 a detects the lateral G by the lateral G sensor 95.
Alternatively, the lateral G calculation unit 62a, as disclosed in JP2013-209048A,
Horizontal G = (V ² × σ) / (1 + A + V ² ) / L (1)
To calculate the lateral G.
Here, in Equation (1), V is the vehicle speed detected by the vehicle speed sensor 96, σ is the tire steering angle detected by the steering angle sensor 97, A is the stability factor, and L is the wheelbase. .
Similarly, the lateral G calculation unit 62a, as disclosed in Japanese Patent Laid-Open No. 2013-209048,
Horizontal G = Yr × V (2)
To calculate the lateral G.
Here, in equation (2), Yr is the yaw rate detected by the yaw rate sensor 98, and V is the vehicle speed detected by the vehicle speed sensor 96.

  The third determination unit 63 includes an uphill angle estimation unit 63a. Further, the third determination unit 63 compares the estimated climb angle and the climb threshold value, and sets the climb AWD request flag to “1” or “0”.

  The uphill angle estimation unit 63a estimates that a traveling direction uphill angle, which is an amount that increases as the traveling direction wheel of the vehicle 3 inclines above the opposite side wheel, is generated in the vehicle 3. Specifically, the uphill angle estimation unit 63a estimates the uphill angle by the front / rear G sensor 99, which is a G sensor arranged separately in the front and rear of the vehicle 3.

Based on the switching determination of the first determination unit 61, the switching determination of the second determination unit 62, and the switching determination of the third determination unit 63, the driving state switching unit 64 and the front wheels Wf, Wf as the first driving wheel and the second From the one-wheel single drive state (2WD) in which the vehicle 3 is driven by only one of the rear wheels Wr (RWr, LWr) as drive wheels, the front wheels Wf, Wf and the second drive wheels as first drive wheels. The driving force distribution is changed and switched to AWD that drives the vehicle 3 by both the rear wheel Wr (RWr, LWr).
Here, the one-wheel single drive state includes FWD that drives the vehicle 3 only by the front wheels Wf and Wf and RWD that drives the vehicle 3 only by the rear wheels Wr (RWr and LWr).
In addition to switching from 2WD to AWD, the driving state switching unit 64 executes switching of driving force distribution while maintaining AWD.
Specifically, when the slip AWD request flag is set to “1” via the first determination unit 61, the driving state switching unit 64 switches the driving state of the vehicle 3 to AWD and excess slip front / rear distribution setting. . In addition, when the “horizontal G” AWD request flag is set to “1” via the second determination unit 62, the driving state switching unit 64 switches the driving state of the vehicle 3 to the AWD and lateral G front / rear distribution setting. . In addition, when the uphill AWD request flag is set to “1” via the third determination unit 63, the driving state switching unit 64 switches the driving state of the vehicle 3 to AWD and uphill front / rear distribution setting.
Here, the front / rear distribution setting means a distribution ratio of the driving force [N] between the traveling direction wheel of the vehicle 3 and its opposite side wheel. The driving force [N] is detected by the sensor, for example, the accelerator opening detected by the accelerator opening sensor 92, the engine speed detected by the engine speed sensor 93, and the electric motors 5, 2A, 2B, respectively. It is estimated and acquired based on each motor current detected by the provided motor current sensor 94.
Further, the front / rear distribution setting may be a distribution difference of the driving force [N] between the traveling direction wheel of the vehicle 3 and its opposite wheel.

  The stable traveling determination unit 65 determines whether or not the vehicle 3 is traveling stably. Specifically, when the slip AWD request flag, the “lateral G” AWD request flag, or the climbing AWD request flag is “1”, detection of the rudder angle sensor 97, the yaw rate sensor 98, the vehicle speed sensor 96, the wheel speed sensor 91, and the like. Whether or not the vehicle 3 is traveling stably is determined based on the value and the estimated value using the detected value. For example, if the detected value of the vehicle speed sensor 96 is equal to or greater than a predetermined vehicle speed threshold, the stable travel determination unit 65 determines that the vehicle 3 is traveling stably. The stable travel determination unit 65 sets the stable travel determination flag to “1” when it is determined that the vehicle 3 is traveling stably, and the stable travel determination flag is set to “0” when it is determined that the vehicle 3 is not traveling stably. Set to. The stable travel determination flag is a permission determination flag for changing the setting of other flags, and is not forcibly set when the vehicle 3 travels stably with priority over other flags.

Next, drive state switching control executed by the ECU 6 according to the present embodiment will be described.
FIG. 7 is a flowchart showing a procedure of a drive state switching control routine according to the present embodiment. This control processing routine is repeatedly executed by the ECU 6.

  In step S1, the ECU 6 executes a first determination subroutine. In the first determination subroutine, the slip AWD request flag is set to “1” or “0”.

FIG. 8 is a flowchart showing the procedure of the first determination subroutine according to the present embodiment.
In step S101, the ECU 6 determines whether or not the vehicle 3 is traveling. When this determination is YES, since it is FWD, RWD, or AWD, the process proceeds to step S102, and after calculating the adjustable slip point, the process proceeds to step S103. In the case of NO, even if the internal combustion engine 4 is operating, the vehicle 3 stops, and the wheel speed sensor 91 does not detect the wheel speed difference between the front wheels Wf, Wf and the rear wheels Wr (RWr, LWr), Since excess slip does not occur, the process proceeds to step S106.

  In step S102, the ECU 6 calculates an adjustment slip point by the adjustment slip point calculation unit 61b. Specifically, the ECU 6 calculates each added slip point by the driving force added slip point calculating process and the time added slip point calculating process, and then executes a process of adding the calculated added slip points. Similarly, after each subtraction slip point is calculated by the driving force subtraction slip point calculation process, the time subtraction slip point calculation process, the lateral G subtraction slip point calculation process and the vehicle speed subtraction slip point calculation process, each subtraction slip calculated Execute the process of adding points.

  In step S103, the ECU 6 calculates the integrated slip point by integrating the added slip point or the subtracted slip point calculated in step S102 with the previous value of the integrated slip point by the integrated slip point calculating unit 61c. Thereafter, the process proceeds to step S104.

  In step S104, the ECU 6 determines whether or not the integrated slip point calculated in step S103 is greater than or equal to the slip threshold. The slip threshold is set in advance to an appropriate value as an index for switching the driving state of the vehicle 3 to AWD and excess slip front / rear distribution setting when the slip AWD request flag is set to “1” via the first determination unit 61. Is done. If this determination is YES, the process proceeds to step S105. If NO, the process proceeds to step S106.

  In step S105, the ECU 6 sets the slip AWD request flag to “1” and ends the first determination subroutine. As a result, switching to the AWD and excess slip front / rear distribution setting is executed.

  In step S106, the ECU 6 determines whether or not the slip AWD request flag is “1”. If this determination is YES, the process proceeds to step S107. If NO, the first determination subroutine is terminated. When the first determination subroutine is completed in this step, the slip AWD request flag is “0”, but other flags maintain the previous settings.

  In step S107, the ECU 6 determines whether or not the vehicle 3 is traveling stably by the stable traveling determination unit 65. When it is determined that the vehicle 3 is traveling stably, the stable traveling determination flag is set to “1”, and when it is determined that the vehicle 3 is not traveling stably, the stable traveling determination flag is set to “0”.

  In step S108, the ECU 6 determines whether or not the stable travel determination flag set by the stable travel determination in step S107 is “1”. If this determination is YES, since the stability of the vehicle 3 is secured, the process proceeds to step S109, the slip AWD request flag is set to “0”, and the first determination subroutine is terminated. When the slip AWD request flag is set to “0” and the first determination subroutine is terminated, the slip AWD request flag is set to “0”, but the other flags maintain the previous settings. If NO, the process proceeds to step S105, the slip AWD request flag is set to “1”, and then the first determination subroutine is terminated.

In step S2 that proceeds from the first determination subroutine of step S1 in FIG. 7 , the ECU 6 determines whether or not the slip AWD request flag is “1”. If this determination is YES, the process proceeds to step S3. If NO, the process proceeds to step S7.

  In step S3, the ECU 6 switches the driving state of the vehicle 3 to AWD and excess slip front / rear distribution setting. For example, the front / rear distribution setting is switched to AWD with 55:45 (ratio when the total driving force is 100).

  In step S4, the ECU 6 executes the third determination subroutine 1. In the third determination subroutine 1, the uphill AWD request flag is set to “1” or “0”.

FIG. 9 is a flowchart showing a procedure of the third determination subroutine 1 according to the present embodiment.
In step S201, the ECU 6 determines whether or not the vehicle 3 is stopped. When this determination is YES, since the vehicle 3 is stopped, the process proceeds to step S202, and the estimated climbing angle is compared with the first climbing threshold value. In the case of NO, since the vehicle 3 is traveling, the process proceeds to step S206.

  In step S202, the ECU 6 determines whether or not the estimated climb angle is equal to or greater than a first climb threshold. The estimated uphill angle is estimated from the detection value of the front / rear G sensor 99. When the climbing AWD request flag is set to “1” via the third determination unit 63, the first climbing threshold is set to an appropriate value in advance as an index for switching the driving state of the vehicle 3 to the AWD and the climbing front / rear distribution setting. Is set. If this determination is YES, the process proceeds to step S203. If no, the process proceeds to step S204.

  In step S203, the ECU 6 sets the uphill AWD request flag to “1” and ends the third determination subroutine 1. Thereby, switching to AWD and the up-and-down slope distribution setting is executed. That is, the climbing AWD request flag is set to “1” in preference to switching to the AWD and excess slip front / rear distribution setting due to the slip AWD request flag being set to “1” in step S3, which will be described later. In step S6, the setting is forcibly switched to the AWD and the up-and-down distribution setting.

In step S204, the ECU 6 determines whether or not the estimated climbing angle is equal to or smaller than the second climbing threshold value. The estimated uphill angle is estimated from the detection value of the front / rear G sensor 99. When the climbing AWD request flag is set to “1” via the third determination unit 63, the second climbing threshold is set to an appropriate value in advance as an index for switching the driving state of the vehicle 3 to the AWD and the climbing front / rear distribution setting. Is set. The second uphill threshold is smaller than the first uphill threshold. When this determination is YES, the process proceeds to step S205, the climbing AWD request flag is set to “0”, and the third determination subroutine 1 is ended. In the case of NO, the process proceeds to step S205, the climbing AWD request flag is set to “1”, and the third determination subroutine 1 is ended.
In step S204, the determination from step S202 in the third determination unit 63 is made redundant so that it can be processed even when the estimation error of the estimated climb angle is large.

  In step S206, the ECU 6 determines whether or not the uphill AWD request flag is “1”. If this determination is YES, the process proceeds to step S207. If NO, the third determination subroutine 1 is terminated. When the third judgment subroutine 1 is completed in this step, switching to AWD and excess slip front / rear distribution setting is executed. That is, switching to the AWD and excess slip front / rear distribution setting due to the slip AWD request flag being set to “1” in step S3 is maintained.

  In step S207, the ECU 6 determines whether or not the vehicle speed of the vehicle 3 detected by the vehicle speed sensor 96 is greater than or equal to the first vehicle speed threshold value. When the climbing AWD request flag is set to “0” via the third determination unit 63, the first vehicle speed threshold is set to an appropriate value in advance as an index for switching the driving state of the vehicle 3 from the AWD and the climbing front / rear distribution setting. Is set. For example, the first vehicle speed threshold is set to 20 km / h or the like that can be surely confirmed that the vehicle has stopped. When this determination is YES, the process proceeds to step S205, the climbing AWD request flag is set to “0”, and the third determination subroutine 1 is ended. When the uphill AWD request flag is set to “0” and the third determination subroutine 1 is terminated, switching to the AWD and excess slip front / rear distribution setting is executed. That is, switching to the AWD and excess slip front / rear distribution setting due to the slip AWD request flag being set to “1” in step S3 is maintained. In the case of NO, the third determination subroutine 1 is terminated while the uphill AWD request flag is maintained at “1”.

  In step S5 proceeding from the third determination subroutine 1 in step S4, the ECU 6 determines whether or not the climbing AWD request flag is “1”. If this determination is YES, the process proceeds to step S6. If NO, this routine is terminated. When this routine is finished in this step, switching to the AWD and excess slip front / rear distribution setting due to the slip AWD request flag being set to “1” in step S3 is maintained.

In step S6, the ECU 6 switches the driving state of the vehicle 3 to AWD and ascending / descending distribution setting. For example, it is switched to AWD with the front / rear distribution setting set to 50:50 (ratio when the total driving force is 100). Then, this routine ends.
The ECU 6 sets the uphill AWD request flag to “1” in preference to switching to the AWD and excess slip front / rear distribution setting due to the slip AWD request flag being set to “1” in step S3. Forcibly switch to AWD and up / down distribution setting for uphill. That is, the switching determination of the third determination unit 63 has priority over the switching determination of the first determination unit 61.

  On the other hand, in step S7, the ECU 6 executes the third determination subroutine 2. In the third determination subroutine 2, the uphill AWD request flag is set to “1” or “0”.

FIG. 9 is also a flowchart showing the procedure of the third determination subroutine 2 according to the present embodiment.
In step S201, the ECU 6 determines whether or not the vehicle 3 is stopped. When this determination is YES, since the vehicle 3 is stopped, the process proceeds to step S202, and the estimated climbing angle is compared with the first climbing threshold value. In the case of NO, since the vehicle 3 is traveling, the process proceeds to step S206.

  In step S202, the ECU 6 determines whether or not the estimated climb angle is equal to or greater than a first climb threshold. The estimated uphill angle is estimated from the detection value of the front / rear G sensor 99. When the climbing AWD request flag is set to “1” via the third determination unit 63, the first climbing threshold is set to an appropriate value in advance as an index for switching the driving state of the vehicle 3 to the AWD and the climbing front / rear distribution setting. Is set. If this determination is YES, the process proceeds to step S203. If no, the process proceeds to step S204.

  In step S203, the ECU 6 sets the uphill AWD request flag to “1” and ends the third determination subroutine 2. Thereby, switching to AWD and the up-and-down slope distribution setting is executed.

In step S204, the ECU 6 determines whether or not the estimated climbing angle is equal to or smaller than the second climbing threshold value. The estimated uphill angle is estimated from the detection value of the front / rear G sensor 99. When the climbing AWD request flag is set to “1” via the third determination unit 63, the second climbing threshold is set to an appropriate value in advance as an index for switching the driving state of the vehicle 3 to the AWD and the climbing front / rear distribution setting. Is set. When this determination is YES, the process proceeds to step S205, the climbing AWD request flag is set to “0”, and the third determination subroutine 1 is ended. In the case of NO, the process proceeds to step S205, the climbing AWD request flag is set to “1”, and the third determination subroutine 1 is ended.
In step S204, the determination from step S202 in the third determination unit 63 is made redundant so that it can be processed even when the estimation error of the estimated climb angle is large.

In step S206, the ECU 6 determines whether or not the uphill AWD request flag is “1”. If this determination is YES, the process proceeds to step S207. If NO, the third determination subroutine 2 is terminated. When the third determination subroutine 2 is completed in this step, the slip AWD request flag and the climbing AWD request flag are “0” .

  In step S207, the ECU 6 determines whether or not the vehicle speed of the vehicle 3 detected by the vehicle speed sensor 96 is greater than or equal to the first vehicle speed threshold value. When the climbing AWD request flag is set to “0” via the third determination unit 63, the first vehicle speed threshold is set to an appropriate value in advance as an index for switching the driving state of the vehicle 3 from the AWD and the climbing front / rear distribution setting. Is set. For example, the first vehicle speed threshold is set to 20 km / h or the like that can be surely confirmed that the vehicle has stopped. If this determination is YES, the process proceeds to step S205, the climbing AWD request flag is set to “0”, and the third determination subroutine 2 is ended. When the uphill AWD request flag is set to “0” and the third determination subroutine 2 is terminated, the slip AWD request flag and the uphill AWD request flag are “0”. In the case of NO, the third determination subroutine 2 is terminated while the uphill AWD request flag is maintained at “1”.

  In step S8 which proceeds from the third determination subroutine 2 of step S7, the ECU 6 determines whether or not the uphill AWD request flag is “1”. If this determination is YES, the process proceeds to step S9. If no, the process proceeds to step S10.

  In step S <b> 9, the ECU 6 switches the driving state of the vehicle 3 to AWD and ascending / descending distribution setting. For example, it is switched to AWD with the front / rear distribution setting set to 50:50 (ratio when the total driving force is 100). Then, this routine ends.

  In step S10, the ECU 6 executes a second determination subroutine. In the second determination subroutine, the “lateral G” AWD request flag is set to “1” or “0”.

FIG. 10 is a flowchart showing the procedure of the second determination subroutine according to the present embodiment.
In step S301, the ECU 6 determines whether or not the vehicle 3 is in RWD. If this determination is YES, since the vehicle 3 is in RWD, the process proceeds to step S302, and the calculated “lateral G” is compared with the first lateral G threshold. In the case of NO, since the vehicle 3 is in FWD or AWD, the process proceeds to step S304.

  In step S302, the ECU 6 determines whether or not the calculated “lateral G” is equal to or greater than a first lateral G threshold value. The calculation “lateral G” is calculated from the detection value of the lateral G sensor 95 or the like. When the “horizontal G” AWD request flag is set to “1” via the second determination unit 62 during the RWD, the first lateral G threshold is set to the AWD and lateral G longitudinal distribution setting when the driving state of the vehicle 3 is set. An appropriate value is preset as an index to be switched. If this determination is YES, the process proceeds to step S303. If no, the process proceeds to step S305.

  In step S303, the ECU 6 sets the “lateral G” AWD request flag to “1” and ends the second determination subroutine. Thereby, switching to the AWD and lateral G front / rear distribution setting is executed.

  On the other hand, in step S304, the ECU 6 determines whether or not the calculation “lateral G” is equal to or greater than the second lateral G threshold value. The calculation “lateral G” is calculated from the detection value of the lateral G sensor 95 or the like. The second lateral G threshold is determined when the “horizontal G” AWD request flag is set to “1” via the second determination unit 62 during FWD or AWD, and the driving state of the vehicle 3 is AWD and lateral G front / rear allocation. As an index for switching to the setting, an appropriate value is set in advance. The second lateral G threshold is greater than the first lateral G threshold. If this determination is YES, the process proceeds to step S303, the “horizontal G” AWD request flag is set to “1”, and then the second determination subroutine is terminated. If no, the process proceeds to step S305.

  In step S305, the ECU 6 determines whether or not the “lateral G” AWD request flag is “1”. If this determination is YES, the process proceeds to step S306. If NO, the second determination subroutine is terminated. When the second determination subroutine is completed in this step, the slip AWD request flag, the uphill AWD request flag, and the “lateral G” AWD request flag are “0”.

  In step S306, the ECU 6 determines whether or not the vehicle 3 is traveling stably by the stable traveling determination unit 65. When it is determined that the vehicle 3 is traveling stably, the stable traveling determination flag is set to “1”, and when it is determined that the vehicle 3 is not traveling stably, the stable traveling determination flag is set to “0”.

  In step S307, the ECU 6 determines whether or not the stable travel determination flag set by the stable travel determination in step S306 is “1”. If this determination is YES, since the stability of the vehicle 3 can be secured, the process proceeds to step S308, the “lateral G” AWD request flag is set to “0”, and then the second determination subroutine ends. When the second determination subroutine is completed in this step, the slip AWD request flag, the uphill AWD request flag, and the “lateral G” AWD request flag are “0”. If no, the process proceeds to step S309.

  In step S309, the ECU 6 determines whether or not the vehicle speed of the vehicle 3 detected by the vehicle speed sensor 96 is equal to or less than a second vehicle speed threshold value. The second vehicle speed threshold is suitable as an index for switching the driving state of the vehicle 3 from the AWD and the lateral G front / rear distribution setting when the “lateral G” AWD request flag is set to “0” via the second determination unit 62. A preset value is set in advance. If this determination is YES, the process proceeds to step S308, the “lateral G” AWD request flag is set to “0”, and the second determination subroutine ends. When the “lateral G” AWD request flag is set to “0” and the second determination subroutine is completed, the slip AWD request flag, the uphill AWD request flag, and the “lateral G” AWD request flag are “0”. In the case of NO, the second determination subroutine is terminated while the “horizontal G” AWD request flag is maintained at “1”.

In step S11 which proceeds from the second determination subroutine of step S10, the ECU 6 determines whether or not the “lateral G” AWD request flag is “1”. If this determination is YES, the process proceeds to step S12. If NO, the process proceeds to step S13.
Here, when the slip AWD request flag is determined to be “0” in step S2 and the climbing AWD request flag is determined to be “0” in step S8, the ECU 6 determines in step S11. To implement. Thus, the switching determination of the first determination unit 61 using step S2 is positioned upstream in the flow on the drive state switching control routine than the switching determination of the second determination unit 62 using step S11. That is, the switching determination of the first determination unit 61 has priority over the switching determination of the second determination unit 62.

  In step S12, the ECU 6 switches the driving state of the vehicle 3 to the AWD and lateral G front / rear distribution setting. For example, the front / rear distribution setting is switched to AWD with 60:40 (ratio when the total driving force is 100).

  In step S13, the ECU 6 confirms that the various AWD request flags are set to “0”, and switches the driving state of the vehicle 3 to 2WD, that is, FWD or RWD, or the front-rear distribution setting according to the present embodiment. Switching to AWD is not limited to this.

  According to this embodiment, the following effects are produced.

In the present embodiment, the driving force distribution between the first driving device 1 and the second driving device 2 in the AWD after switching by the first determination unit 61 based on the integrated slip point, and the calculation “lateral G” is used. The driving force distribution between the first driving device 1 and the second driving device 2 in the AWD after switching by the second determination unit 62 is made different.
Thus, since the driving force distribution is switched based on the integrated slip point and the calculated “lateral G” in AWD, the driving force distribution of the vehicle 3 in the AWD can be switched at a more appropriate timing.
For example, when the switching determination is performed by the first determination unit 61 based on the calculated slip point, the driving force distribution according to the excess slip phenomenon that has occurred in the vehicle 3 can be switched. For this reason, the driving force is distributed according to the low μ state of the road surface in AWD, and vehicle stability can be ensured.
When the switching determination is performed by the second determination unit 62 based on the calculation “lateral G”, it is possible to switch to driving force distribution according to the state in which the lateral G acts on the vehicle 3. For this reason, it becomes drive force distribution according to the state where the side G acts on the vehicle 3 in AWD, and vehicle stability can be ensured.
Further, the driving force distribution in the AWD after switching by the first determination unit 61 based on the calculated slip point, and the driving force distribution in the AWD after switching by the second determination unit 62 based on the calculated “lateral G”. And make them different. For this reason, the driving force distribution is adapted to the AWD in both cases, and vehicle stability can be ensured. Thereby, the driving force distribution of the vehicle 3 can be effectively switched at a more appropriate timing while ensuring the vehicle stability, and the driving efficiency can be improved.

In the present embodiment, the ECU 6 calculates the front wheel distribution (60 (ratio when the total driving force is 100)) in the driving force distribution after being switched by the second determination unit 62 based on the calculation “lateral G”. The front wheel distribution after switching by the first determination unit 61 based on the slip point (55 (ratio when the total driving force is 100)) is made larger.
FIG. 11 is a diagram showing vehicle stability based on the relationship between the lateral G and the turning radius ratio according to the present embodiment. The horizontal axis represents the size of the horizontal G. The vertical axis represents the magnitude of the turning radius ratio (R / R0). The FWD line shows the characteristics at the FWD, the AWD line shows the characteristics at the AWD, and the RWD line shows the characteristics at the RWD.
As shown in FIG. 11, the vehicle 3 generally has a tendency that the vehicle stability becomes higher when the vehicle 3 is acted by the lateral G and is FWD that is weakly understeered than RWD that is oversteered. According to the present embodiment, the front-wheel distribution in the driving force distribution after switching by the second determination unit 62 based on the calculated “lateral G” is set to 60:40 (when the total driving force is 100). The vehicle stability can be further ensured by increasing the ratio) and bringing it closer to a weakly understeered FWD that tends to increase the vehicle stability.

In the present embodiment, the ECU 6 gives priority to the switching determination by the first determination unit 61 among the switching determination by the first determination unit 61 and the switching determination by the second determination unit 62.
Here, the vehicle 3 generally has a lower vehicle stability when an excess slip occurs in the vehicle 3 than in a vehicle motion in which a lateral G acts on the vehicle 3. According to the present embodiment, priority is given to the switching determination when an excess slip occurs in the vehicle 3 in which the vehicle stability is further lowered, so that the vehicle stability can be further ensured.

In the present embodiment, the ECU 6 further includes a third determination unit 63 that switches the driving force distribution to AWD based on the estimated climbing angle of the vehicle 3.
According to the present embodiment, since the driving force distribution is switched based on the estimated climb angle in addition to the integrated slip point and the calculated “lateral G” in the AWD, the driving force distribution of the vehicle 3 in the AWD is switched at a more appropriate timing. Can do.
For example, when the switching determination is performed by the third determination unit 63 based on the estimated climbing angle, the driving force distribution according to the climbing state of the vehicle 3 can be switched. For this reason, it becomes drive force distribution according to the climbing state of the vehicle 3 in AWD, and vehicle stability can be ensured.

In the present embodiment, the ECU 6 calculates the front wheel distribution (50 (ratio when the total driving force is 100)) in the driving force distribution after being switched by the third determining unit 63 based on the estimated climb angle as an integrated slip point. It is made smaller than the front wheel distribution (55 (ratio when the total driving force is 100)) after switching by the first determination unit 61 based on the above.
Here, the vehicle 3 generally makes the front wheels Wf and Wf more unstable when the vehicle 3 is in an uphill state than when an excessive slip occurs in the vehicle 3, and the vehicle stability is lowered. This is because in the uphill state, the load on the front wheels Wf, Wf is small, and the driving force that can be transmitted to the road surface of the front wheels Wf, Wf is small. According to the present embodiment, the front-wheel distribution in the driving force distribution after switching by the third determination unit 63 based on the estimated climb angle is 50:50 (the ratio when the total driving force is 100). The vehicle stability can be further ensured by supplying a larger amount of driving force from the rear wheels Wr (RWr, LWr) having a large load and a large driving force that can be transmitted to the road surface.

In the present embodiment, the ECU 6 gives priority to the switching determination by the third determination unit 63 among the switching determination by the first determination unit 61 and the switching determination by the third determination unit 63.
Here, in general, the vehicle 3 is less stable when it is in an uphill state than when an excessive slip occurs in the vehicle 3. According to the present embodiment, priority is given to the switching determination in the uphill state in which the vehicle stability is further reduced, so that the vehicle stability can be further ensured.

It should be noted that the present invention is not limited to the above-described embodiment, and modifications, improvements, etc. within a scope that can achieve the object of the present invention are included in the present invention.
For example, the AWD in which the front-to-back distribution according to the embodiment is set is switched from 2WD (FWD, RWD) or another AWD.
Here, the front / rear distribution of the AWD is a distribution ratio or a distribution difference of the driving force [N] between the traveling direction wheel of the vehicle 3 and its opposite wheel.
In the power distribution control to the front and rear wheels, not only the driving force according to the embodiment described above but also torque, output, etc. correlated with the driving force may be used.

  In the above embodiment, the second determination unit 62 switches the driving force distribution based on the calculated “lateral G”. However, the present invention is not limited to this. For example, the second determination unit may switch the driving force distribution based on the vehicle motion correlation amount correlated with the turning direction motion or the lateral direction motion of the vehicle 3 other than the lateral G.

In the above embodiment, the drive source for the rear wheels is only the electric motors 2A and 2B, but it may be engine driven.
Moreover, in the said embodiment, although the 2nd drive device 2 on the rear-wheel side was made into the 2 motor system which comprises two electric motors 2A and 2B, a 1 motor system may be sufficient.

DESCRIPTION OF SYMBOLS 1 ... 1st drive device 2 ... 2nd drive device 3 ... Vehicle 6 ... ECU (control apparatus)
10 ... Vehicle drive system 61 ... 1st judgment part (1st judgment means)
62 ... 2nd judgment part (2nd judgment means)
63 ... Third determination section (third determination means)

Claims (5)

A first drive device that drives a first drive wheel that is one of a front wheel and a rear wheel of the vehicle;
A second drive device for driving a second drive wheel which is either the front wheel or the rear wheel of the vehicle;
A vehicle drive system comprising: a control device that controls the first drive device and the second drive device and controls the drive states of the first drive wheel and the second drive wheel;
The controller is
When slipping the loss of grip between the wheel and the road surface,
Switching the driving force distribution between the first driving device and the second driving device based on a slip correlation amount correlated with an excess slip exceeding a predetermined amount among the slips generated on the front wheels or rear wheels of the vehicle. First determination means for setting a two-wheel drive state in which the vehicle is driven by both the first drive wheel and the second drive wheel;
Second determination means for switching the driving force distribution to the two-wheel drive state based on a vehicle motion correlation amount correlated with a turning direction motion or a lateral direction motion of the vehicle,
The first driving force distribution that is the driving force distribution in the two-wheel drive state after switching by the first determination means, and the driving force distribution in the two-wheel drive state that is switched by the second determination means. A vehicle drive system , wherein a certain second driving force distribution is made different so that a front wheel distribution in the second driving force distribution is larger than a front wheel distribution in the first driving force distribution . The vehicle drive system according to claim 1 ,
The control device prioritizes the switching determination by the first determination means among the switching determination by the first determination means and the switching determination by the second determination means. The vehicle drive system according to claim 1 or 2 ,
The control device further includes third determination means for switching the driving force distribution to enter the two-wheel drive state based on an inclination correlation amount correlated with an inclination of the vehicle or an inclination of a road surface on which the vehicle is located. A vehicle drive system characterized by that. A first drive device that drives a first drive wheel that is one of a front wheel and a rear wheel of the vehicle;
A second drive device for driving a second drive wheel which is either the front wheel or the rear wheel of the vehicle;
A vehicle drive system comprising: a control device that controls the first drive device and the second drive device and controls the drive states of the first drive wheel and the second drive wheel;
The control device includes:
When slipping the loss of grip between the wheel and the road surface,
Switching the driving force distribution between the first driving device and the second driving device based on a slip correlation amount correlated with an excess slip exceeding a predetermined amount among the slips generated on the front wheels or rear wheels of the vehicle. First determination means for setting a two-wheel drive state in which the vehicle is driven by both the first drive wheel and the second drive wheel;
A second determination means for switching the driving force distribution to the two-wheel drive state based on a vehicle motion correlation amount correlated with a turning direction motion or a lateral direction motion of the vehicle;
And a third determination means for switching the driving force distribution and setting the two-wheel drive state based on an inclination correlation amount correlated with an inclination of the vehicle or an inclination of a road surface on which the vehicle is located,
The first driving force distribution that is the driving force distribution in the two-wheel drive state after switching by the first determination means, and the driving force distribution in the two-wheel drive state that is switched by the second determination means. Different from the second driving force distribution,
The third determining means determines to switch when the tilt correlation amount is a predetermined amount or more,
The control device performs a wheel direction distribution in a third driving force distribution, which is the driving force distribution in the two-wheel drive state after being switched by the third determining means, as a traveling direction in the first driving force distribution. A vehicle drive system characterized by being smaller than a wheel distribution . The vehicle drive system according to claim 3 or 4 ,
The control device prioritizes the switching determination by the third determination means among the switching determination by the first determination means and the switching determination by the third determination means.

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