JP2014034915A - Drive control device for vehicle, and drive control method for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve traveling performance of a vehicle in a situation that acceleration slip of driving wheels easily occurs in starting.SOLUTION: Driving force of an engine 2 is controlled according to driver's pedal opening PPO. Whether a state of acceleration slip of driving wheels is predicted or not, is determined, and an upgrade θ is detected. In a case of determining the state that acceleration slip is predicted in starting a vehicle, and when the upgrade θ is a threshold value θt or more, the driving force of the engine 2 is reduced in comparison with a case when the upgrade θ is less than the threshold value θt. That is, an early opening control characteristic is determined when the upgrade θ is less than the threshold value θt in stopping the vehicle, a slow opening control characteristic is determined when the upgrade θ is the threshold value θt or more in stopping the vehicle, and the determined control characteristic is kept until a vehicle velocity V after starting the vehicle, reaches a set vehicle velocity Vt.

Description

  The present invention relates to a vehicle drive control device and a vehicle drive control method.

  The prior art described in Patent Document 1 is a vehicle in which a front wheel is driven by an engine, electric power is generated by a part of the engine torque, and a rear wheel is driven by a motor using the electric power. When it is determined that there is, the motor torque of the rear wheel is increased.

JP 2002-218605 A

Regardless of engine drive or motor drive, in general, on an uphill road with a low coefficient of friction on the road surface, the drive wheels tend to accelerate and slip mainly when starting. In such a situation, when the driving wheel actually slips by acceleration, it becomes more difficult for the driver to control the driving force by the accelerator operation, which affects the running performance.
An object of the present invention is to improve the running performance of a vehicle in a situation where an acceleration slip of a driving wheel is likely to occur at the time of starting.

  A vehicle drive control device according to an aspect of the present invention controls a driving force of a drive source in accordance with a driver's accelerator operation, and determines whether or not acceleration slip of a drive wheel is expected. Judgment is made and an uphill slope is detected. And when it is determined that the acceleration slip is expected at the time of starting the vehicle, when the climbing slope is equal to or higher than a preset threshold, the climbing slope is less than the threshold, Reduce the driving force of the driving source.

  According to the present invention, the acceleration slip at the time of start can be suppressed by reducing the driving force of the driving source when the climbing slope is equal to or higher than a preset threshold in a state where the acceleration slip is expected. . Therefore, the driving performance of the vehicle can be improved in a situation where acceleration slip of the drive wheels is likely to occur at the start.

1 is an overall configuration diagram of a vehicle drive control device. 1 is a system configuration diagram of a vehicle drive control device. It is a system block diagram of an electronically controlled throttle. It is a flowchart which shows an engine control process. It is a map used for calculation of target throttle opening degree SPO ^* . 4 is a block diagram of arithmetic processing executed by a 4WD controller 19. FIG. It is a block diagram of target motor torque calculating part 19A. It is a map used for calculation of power distribution ratio (alpha) according to pedal opening PPO. It is a map used for calculation of the first limit value TL1. It is a flowchart which shows a 2nd limit value calculation process. It is a map used for the setting of the power distribution ratio (alpha) according to road surface gradient (theta). It is a map used for calculation of the 2nd motor torque Tm2. It is a flowchart which shows a surplus torque calculation process. It is a map used for calculation of engine torque Te. It is a block diagram of power generation control part 19C. 4 is a block diagram of a control processing unit 43. FIG. It is a time chart which shows transition of target motor torque Tm ^* . It is a figure explaining power performance and four-wheel drive performance. It is a figure explaining the power performance and four-wheel drive performance of this embodiment. It is a map used for calculation of the 1st motor torque Tm1. It is a map used for calculation of 2nd restriction value TL2. It is a figure which shows the switching state of the engine control characteristic according to road surface gradient (theta). It is a figure which shows the switching state of the engine control characteristic according to the vehicle speed V. FIG. It is a time chart which assumed the actual driving scene.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
<< First Embodiment >>
"Constitution"
First, the configuration of the present embodiment will be described.
FIG. 1 is an overall configuration diagram of a vehicle drive control device.
FIG. 2 is a system configuration diagram of the motor drive system.
The vehicle according to the present embodiment is a so-called standby type four-wheel drive vehicle in which the front wheels 1FL and 1FR are main drive wheels driven by the engine 2 and the rear wheels 1RL and 1RR are auxiliary drive wheels that can be driven by the electric motor 3. .

  The output of the engine 2 is transmitted to the front wheels 1FL and 1FR via an automatic transaxle 4 having a torque converter, and is also transmitted to a generator 7 via a V-belt 6. The generator 7 generates power using the power transmitted via the V belt 6, and the generated power is directly supplied to the electric motor 3 through the power cable 8. The output of the electric motor 3 is transmitted to the rear wheels 1RL and 1RR through the reduction gear 9, the electromagnetic clutch 10 (clutch), and the differential gear 11 in this order.

Here, the output of the engine 2 is controlled by an engine controller 14 that controls the opening of a throttle valve 13 provided in the intake pipe 12 (for example, an intake manifold). Specifically, the rotation angle (throttle valve opening) of the throttle motor 17 connected to the throttle valve 13 is controlled according to the operation amount (accelerator pedal opening) of the accelerator pedal 16 detected by the accelerator sensor 15. ing.
Further, as shown in FIG. 2, the generator 7 includes a transistor type regulator 20 that adjusts the generated voltage V, and the regulator 20 controls the field current Ig in accordance with a power generation control command from the 4WD controller 19. As a result, the generated voltage V of the generator 7 is controlled.

  A junction box 21 provided in the middle of the power cable 8 is provided with a main relay 22 and a current sensor 23. The main relay 22 turns ON / OFF the power supply to the electric motor 3 in response to a relay control command from the 4WD controller 19, and the current sensor 23 detects the armature current Ia energized to the electric motor 3 to detect the 4WD controller. 19 output. Further, in the junction box 21, the power generation voltage V generated by the generator 7 and the motor induced voltage E are detected by the built-in monitor circuit and output to the 4WD controller 19.

The electric motor 3 is constituted by, for example, a separately-excited DC motor, and the drive torque Tm is controlled by controlling the field current Im in accordance with a motor control command from the 4WD controller 19. In the electric motor 3, the motor temperature is detected by the built-in thermistor 24, the motor rotation number Nm is detected by the motor rotation sensor 25, and each detection signal is output to the 4WD controller 19.
In addition, the electromagnetic clutch 10 is formed of a wet multi-plate type clutch, and by controlling energization of an excitation current in accordance with a clutch control command from the 4WD controller 19, the power transmission path is controlled.

The 4WD controller 19 receives detection signals from the engine rotation sensor 26, the throttle sensor 27, the wheel speed sensors 28FL to 28RR, the acceleration sensor 29, the shift sensor 30, and the brake switch 31.
The engine speed sensor 26 detects the engine speed Ne. The engine rotation sensor 26 detects, for example, the magnetic field lines of the sensor rotor by a detection circuit, converts the change in the magnetic field accompanying the rotation of the sensor rotor into a current signal, and outputs the current signal to the 4WD controller 19. The 4WD controller 26 determines the engine speed Ne from the input current signal.

The wheel speed sensor 28 detects the wheel speeds Vw _{FL to} Vw _RR of each wheel. The wheel speed sensor 28 detects, for example, the magnetic lines of force of the sensor rotor by a detection circuit, converts the change in the magnetic field accompanying the rotation of the sensor rotor into a current signal, and outputs the current signal to the 4WD controller 19. The 4WD controller 19 determines the wheel speeds Vw _{FL to} Vw _RR from the input current signal. Further, the 4WD controller 19 determines an average value of the wheel speeds Vw _{FL to} Vw _RR as the vehicle speed V.
The acceleration sensor 29 detects acceleration / deceleration in the vehicle longitudinal direction. The acceleration sensor 29 detects, for example, the displacement of the movable electrode relative to the fixed electrode as a change in capacitance, and converts it into a voltage signal proportional to the acceleration / deceleration and outputs it to the 4WD controller 19. The 4WD controller 19 determines acceleration / deceleration from the input voltage signal.

The shift sensor 30 detects the shift position of the transmission. The shift sensor 30 includes, for example, a plurality of hall elements, and outputs respective ON / OFF signals to the 4WD controller 19. The 4WD controller 19 determines the shift position from the combination of ON / OFF signals.
The brake switch 31 detects ON / OFF of the brake. The brake switch 31 outputs a voltage signal corresponding to ON / OFF of the brake to the 4WD controller 19 through, for example, a detection circuit of a normally closed contact. The 4WD controller 19 determines ON / OFF of the brake from the input voltage signal.

  The selection switch 32 detects the selection state of the driving method. This selection switch 32 is provided in the vicinity of the driver's seat so that the driver can operate, and either the two-wheel drive (2WD) method or the four-wheel drive (4WD) method is operated by the driver. One is selected. The two-wheel drive system is a drive mode in which the front wheels 1FL and 1FR are driven by the engine 2 and the rear wheels 1RL and 1RR are not driven by the electric motor 3. The four-wheel drive system is a drive mode in which the front wheels 1FL and 1FR are driven by the engine 2 and the rear wheels 1RL and 1RR are driven by the electric motor 3. The selection switch 32 outputs a voltage signal corresponding to the switching state between the two-wheel drive method and the four-wheel drive method to the 4WD controller 19 via, for example, a detection circuit for the c contact. The 4WD controller 19 determines the switching state between the two-wheel drive method and the four-wheel drive method from the input voltage signal.

The 4WD controller 19 inputs each detection signal from sensors and switches, but is not limited to this. The 4WD controller 19 may be connected to another control unit with a twisted pair line, and various data may be received via, for example, CSMA / CA multiplex communication (CAN: Controller Area Network).
The engine controller 14 receives various data such as a wheel speed signal, a brake signal, an acceleration / deceleration signal, and a selection switch signal by CAN communication with the 4WD controller 19.

Next, the electronic control throttle will be described.
FIG. 3 is a system configuration diagram of the electronically controlled throttle.
A throttle shaft 33 extending in the radial direction is supported in the intake pipe 12, and a disk-like throttle valve 13 having a diameter smaller than the inner diameter of the intake pipe 12 is fixed to the throttle shaft 33. . A throttle motor 17 is connected to the throttle shaft 33 via a speed reducer 34.

  Therefore, when the throttle motor 17 is rotated to change the rotation angle of the throttle shaft 33, the throttle valve 13 closes or opens the intake pipe 12. That is, when the surface direction of the throttle valve 13 is along the direction perpendicular to the axis of the intake pipe 12, the throttle opening is in the fully closed position, and when the surface direction of the throttle valve 13 is along the axis direction of the intake pipe 12, The throttle opening is the fully open position. When an abnormality occurs in the throttle motor 17, the motor drive system, the accelerator sensor 15 system, the throttle sensor 27 system, etc., the throttle shaft 33 is opened in the opening direction so that the throttle valve 13 is opened by a predetermined amount from the fully closed position. It is mechanically energized.

  The accelerator sensor 15 has two systems, and detects a pedal opening PPO that is a depression amount (operation amount) of the accelerator pedal 16. The accelerator sensor 15 is a potentiometer, for example, and converts the pedal opening of the accelerator pedal 16 into a voltage signal and outputs the voltage signal to the engine controller 14. The engine controller 14 determines the pedal opening PPO of the accelerator pedal 16 from the input voltage signal.

The throttle sensor 27 has two systems and detects the throttle opening SPO of the throttle valve 13. The throttle sensor 27 is, for example, a potentiometer, and converts the throttle opening of the throttle valve 13 into a voltage signal and outputs the voltage signal to the engine controller 14. The engine controller 14 determines the throttle opening SPO of the throttle valve 13 from the input voltage signal.
The engine controller 14 mainly sets a target throttle opening SPO ^* according to the pedal opening PPO, and sets a motor control amount according to a deviation ΔPO between the target throttle opening SPO ^* and the actual throttle opening SPO. . The motor control amount is converted into a duty ratio, and the throttle motor 17 is driven and controlled by a pulsed current value.

Next, engine control processing executed by the engine controller 14 will be described.
FIG. 4 is a flowchart showing the engine control process.
First, in step S301, various data are read.
In subsequent step S302, the road surface gradient (climbing gradient) θ [%] is calculated according to the acceleration / deceleration, and then the process proceeds to step S103. The road surface gradient θ is calculated as (vertical distance / horizontal distance) × 100, and the uphill side is represented by a positive value (+), and the downhill side is represented by a negative value (−). For example, a 1 Hz low-pass filter process is performed on the road surface gradient θ.

  In a succeeding step S303, it is determined whether or not the switching flag is reset to fs = 0. This switching flag fs is a flag indicating whether or not the engine control characteristic is switched according to the road surface gradient θ, and the initial value is reset to fs = 0. When the switching flag is fs = 0, the engine control characteristic is set to the basic base control characteristic, and when the switching flag is fs = 1, the engine control characteristic is set to either the early opening control characteristic or the slow opening control characteristic. Each engine control characteristic will be described later. Here, when the switching flag is reset to fs = 0, it is determined that the base control characteristic is set, and the process proceeds to step S304. On the other hand, when the switching flag is set to fs = 1, it is determined that the fast opening control characteristic or the slow opening control characteristic is set, and the process proceeds to step S309.

In step S304, it is determined whether or not the host vehicle is stopped. Here, it is determined whether or not the vehicle speed V is zero. Here, when the vehicle speed V is 0, it is determined that there is a possibility that the host vehicle is in a stopped state and the road surface gradient θ can be adopted, and the process proceeds to step S305. On the other hand, when the vehicle speed V is greater than 0, it is determined that the host vehicle is in a traveling state and the road surface gradient θ cannot be adopted, and the process proceeds to step S313.
In step S305, it is determined whether or not the brake is ON. Here, when the brake is ON, it is determined that the vehicle is in a braking state, and there is a possibility that the road surface gradient θ can be adopted, and the process proceeds to step S306. On the other hand, when the brake is OFF, it is determined that the vehicle is not in the braking state and the road surface gradient θ cannot be adopted, and the process proceeds to step S313.

In step S306, it is determined whether or not a predetermined time t1 (for example, 1 sec) has elapsed since the host vehicle was stopped and the vehicle was in a braking state. Here, when t1 has elapsed, it is determined that the road surface gradient θ can be adopted, and the process proceeds to step S307. On the other hand, when t1 has not elapsed, it is determined that the road surface gradient θ cannot be adopted, and the process proceeds to step S313.
In step S307, the road surface gradient θ is recorded.
In subsequent step S308, the switching flag is set to fs = 1, and then the process proceeds to step S313.

On the other hand, in step S309, it is determined whether or not the vehicle speed V is equal to or higher than a preset vehicle speed Vt (for example, 30 km / h). Here, when the vehicle speed V is equal to or higher than the set vehicle speed Vt, it is determined that the vehicle has shifted from the start to the steady travel, and switching of the engine control characteristics is unnecessary, and the process proceeds to step S310. On the other hand, when the vehicle speed V is less than the set vehicle speed Vt, it is determined that the vehicle has not yet shifted to steady running after starting, and the process proceeds to step S312.
In step S310, the road surface gradient θ is reset.
In subsequent step S311, the switching flag is reset to fs = 0, and then the process proceeds to step S313.

  In step S312, it is determined whether or not the accelerator is OFF. For example, it is determined whether or not the pedal opening PPO is smaller than a minute threshold value. Here, when the accelerator is OFF, there is a possibility that the vehicle will stop again, and it is determined that it is not necessary to switch the engine control characteristics, and the process proceeds to step S310 described above. On the other hand, when the accelerator is ON, it is determined that the vehicle is moving from starting to steady running, and the process proceeds to step S313.

  In step S313, it is determined whether the two-wheel drive method is selected by the selection switch 32 and the four-wheel drive method is OFF. Here, when the four-wheel drive system is not selected, that is, when the four-wheel drive system is OFF, it is determined that the acceleration slip of the front wheels 1FL and 1FR is not expected, and the engine control characteristic is set as the base control characteristic. The process proceeds to step S314 for setting. On the other hand, when the four-wheel drive method is selected, that is, when the four-wheel drive method is ON, it is determined that acceleration slip of the front wheels 1FL and 1FR is expected, and switching from the base control characteristics may be required. The process proceeds to step S315.

In step S314, referring to the map of FIG. 5 (characteristic line LB), the target throttle opening SPO ^* is set according to the pedal opening PPO so that the engine control characteristic becomes the basic base control characteristic, and then step S314 is performed. The process proceeds to S319.
FIG. 5 is a map used for calculating the target throttle opening SPO ^* .
According to the characteristic line LB, as pedal opening PPO is large, the target throttle opening SPO ^* increases, pedal opening PPO and the target throttle opening SPO ^* and ratio, 1: 1 relationship. That is, the characteristic line LB has a linear shape.

  In step 315, it is determined whether or not the switching flag is reset to fs = 0. Here, when the switching flag is reset to fs = 0, it is determined that switching from the base control characteristic is unnecessary, and the process proceeds to step S314 described above. On the other hand, when the switching flag is set to fs = 1, it is determined that switching from the base control characteristic is required, and the process proceeds to step S316.

  In step S316, it is determined whether or not the stored road surface gradient θ is less than a preset threshold value θt (for example, 10%). Here, when the stored road surface gradient θ is less than the threshold θt, it is determined that there is a low possibility that acceleration slip will occur in the front wheels 1FL and 1FR, and the process proceeds to step S317 to set the engine control characteristic to the quick opening control characteristic. Transition. On the other hand, when the stored road surface gradient θ is equal to or greater than the threshold θt, it is determined that there is no low possibility that acceleration slip will occur in the front wheels 1FL and 1FR, and the process proceeds to step S318 to set the engine control characteristic to the slow opening control characteristic. Transition.

In step S317, referring to the map of FIG. 5 (characteristic line LF), the target throttle opening degree SPO ^* is set according to the pedal opening degree PPO so that the engine control characteristic becomes the quick opening control characteristic, and then step S319. Migrate to
According to the characteristic line LF, the larger the pedal opening PPO, the larger the target throttle opening SPO ^*. However, the ratio between the pedal opening PPO and the target throttle opening SPO ^* is not 1: 1, and the SPO <SPO ^* . That is, the characteristic line LF is curved upward from the characteristic line LB, and the target throttle opening SPO ^* according to the characteristic line LF is equal to the characteristic line LB even if the pedal opening PPO is the same. It becomes relatively larger than the target throttle opening SPO ^* .

In step S318, referring to the map of FIG. 5 (characteristic line LL), the target throttle opening degree SPO ^* is set according to the pedal opening degree PPO so that the engine control characteristic becomes the slow opening control characteristic, and then step S319. Migrate to
According to the characteristic line LL, the larger the pedal opening PPO, the larger the target throttle opening SPO ^*. However, the ratio between the pedal opening PPO and the target throttle opening SPO ^* is not 1: 1, and the SPO <SPO ^* . That is, the characteristic line LL has a shape slightly curved below the characteristic line LB described above, and the target throttle opening SPO ^* according to the characteristic line LL is the characteristic line even if the pedal opening PPO is the same. It becomes relatively smaller than the target throttle opening SPO ^* according to LB.

In step S319, the engine output is controlled in accordance with the target throttle opening SPO ^* , and then the process returns to a predetermined main program. Specifically, a motor control amount is set according to a deviation ΔPO between the target throttle opening SPO ^* and the actual throttle opening SPO, the motor control amount is converted into a duty ratio, and the throttle is determined by a pulsed current value. Drive control of the motor 17 is performed.
The above is the engine control process based on the flowchart of FIG.

Next, arithmetic processing executed by the 4WD controller 19 will be described.
FIG. 6 is a block diagram of arithmetic processing executed by the 4WD controller 19.
The 4WD controller 19 includes a target motor torque calculator 19A, a motor required power calculator 19B, a power generation controller 19C, and a motor controller 19D. Although detailed description of the control of the main relay and the electromagnetic clutch 10 is omitted, the 4WD controller 19 outputs a relay control command to the main relay to drive the electric motor 3 when the electric motor 3 is driven and controlled. The power supply is controlled to be in an ON state, and a clutch control command to the electromagnetic clutch 11 is output to control the electromagnetic clutch 10 in an engaged state.

First, calculation processing executed by the target motor torque calculation unit 19A will be described.
FIG. 7 is a block diagram of the target motor torque calculator 19A.
The target motor torque calculator 19A includes a first motor torque calculator 51, a first limit value calculator 52, a second limit value calculator 53, a second motor torque calculator 54, and a surplus torque calculator 55. , A selection unit 56, a selection unit 57, a selection unit 58, and a switching unit 59.

First, the first motor torque calculation process executed by the first motor torque calculation unit 51 will be described.
The first motor torque calculation unit 51 calculates a power distribution ratio α from the pedal opening PPO with reference to the map of FIG. 8, and calculates a first motor torque Tm1 according to the power distribution ratio α. Here, the power distribution ratio α is a ratio of distribution from the engine 2 to the power of the electric motor 3 when converting the power of the engine 2 to the power of the electric motor 3.

FIG. 8 is a map used for calculating the power distribution ratio α according to the pedal opening PPO.
In this map, A1 to A4 having a relationship of 0 <A1 <A2 <A3 <A4 are predetermined for the pedal opening PPO, and α1 (for example, 20%) having a relationship of α1> α2 for the power distribution ratio. , Α2 (for example, 12%) is predetermined. When the pedal opening PPO is in the range from 0 to A1, the power distribution ratio α is maintained at 0. When the pedal opening PPO is in the range from A1 to A2, the larger the pedal opening PPO is, the more power distribution is achieved. The ratio α increases from 0 to α1. Further, when the pedal opening PPO is in the range of A2 to A3, the power distribution ratio α is maintained at α1, and when the pedal opening PPO is in the range of A3 to A4, the larger the pedal opening PPO is, the more power is distributed. The ratio decreases from α1 to α2. When the pedal opening PPO is larger than A4, the power distribution ratio α is maintained at α2.

Next, the first limit value calculation process executed by the first limit value calculation unit 52 will be described.
The first limit value calculation unit 52 calculates the first limit value TL1 from the engine speed Ne with reference to the map of FIG.
FIG. 9 is a map used for calculating the first limit value TL1.
In this map, N1 having a relationship of 0 <N1 is predetermined for the engine speed Ne. When the engine speed Ne is in the range from 0 to N1, the first limit value TL1 is maintained at 0. When the engine speed Ne is greater than N1, the larger the engine speed Ne, the higher the first limit value TL1. Increases from zero.

Next, the second limit value calculation process executed by the second limit value calculation unit 53 will be described.
The second limit value calculation unit 53 executes the second limit value calculation process of FIG. 10 every predetermined time (for example, 10 msec).
FIG. 10 is a flowchart showing the second limit value calculation process.
In step S101, after reading various data, the process proceeds to step S102.

In step S102, the road surface gradient θ [%] is calculated according to the acceleration / deceleration, and then the process proceeds to step S103. The road surface gradient θ is calculated as (vertical distance / horizontal distance) × 100, and the uphill side is represented by a positive value (+), and the downhill side is represented by a negative value (−). For example, a 1 Hz low-pass filter process is performed on the road surface gradient θ.
In step S103, it is determined whether or not the host vehicle is stopped. Here, it is determined whether or not the vehicle speed V is zero. Here, when the vehicle speed V is 0, it is determined that the host vehicle is stopped, and the process proceeds to step S104. On the other hand, when the vehicle speed V is greater than 0, it is determined that the host vehicle is in a traveling state, and the process proceeds to step S107.

In step S104, it is determined whether or not the brake is ON. Here, when the brake is ON, it is determined that the vehicle is in a braking state, and the process proceeds to step S105. On the other hand, when the brake is OFF, it is determined that the braking state is not established, and the process proceeds to step S107.
In step S105, it is determined whether or not a predetermined time t1 (for example, 1 sec) has elapsed since the host vehicle was stopped and the vehicle was in a braking state. Here, when t1 has elapsed, it is determined that the road surface gradient θ at the time of stopping has been detected, and the process proceeds to step S106. On the other hand, when t1 has not elapsed, it is determined that the road surface gradient θ at the time of stopping cannot be detected, and the process proceeds to step S107.

In step S106, the detection flag is set to fd = 1, and then the process proceeds to step S108.
In step S107, the detection flag is reset to fd = 0, and then the process proceeds to step S108.
In step S108, it is determined whether or not it is immediately after the setting is switched from four-wheel drive to two-wheel drive. Here, it is determined whether the four-wheel drive is set in the previous calculation and the two-wheel drive is set in the current calculation. Here, when it is immediately after the setting is switched to the two-wheel drive, the process proceeds to step S109. On the other hand, when the four-wheel drive is set or when the two-wheel drive is maintained, the process proceeds to step S110.

In step S109, the withdrawal flag is set to fw = 1, and then the process proceeds to step S112.
In step S110, it is determined whether or not the acceleration sensor 29 has an abnormality. If the acceleration sensor 29 is abnormal, the process proceeds to step S109. On the other hand, when the acceleration sensor 29 is normal, the process proceeds to step S111.
In step S111, the withdrawal flag is reset to fw = 0, and then the process proceeds to step S112.

  In step S112, it is determined whether or not the transmission shift position is set to the travel range. Here, when the shift position is set to a travel range such as a forward range (D or 1st speed) or a reverse range (R), the process proceeds to step S113. On the other hand, when the shift position is not set to the travel range such as the forward range (D or 1st speed) or the reverse range (R), that is, the parking range (P) or the neutral range (N) is set, step S119 is performed. Migrate to

In step S113, it is determined whether or not the transmission shift position is set to the reverse range (R). Here, when the shift position is set to the reverse range (R), the process proceeds to step S114. On the other hand, when the shift position is not set to the reverse range (R), that is, the forward range (D or 1st speed) is set, the process proceeds to step S115.
In step S114, the power distribution ratio α is set to a predetermined maximum value α _MAX (for example, 20%), and then the process proceeds to step S120.

In step S115, it is determined whether or not the withdrawal flag is set to fw = 1. Here, when the withdrawal flag is set to fw = 1, the process proceeds to step S116. On the other hand, when the withdrawal flag is reset to fw = 0, the process proceeds to step S117.
In step S116, the power distribution ratio α is set to a predetermined minimum value α _MIN (for example, 5%), and then the process proceeds to step S120.

In step S117, it is determined whether or not the detection flag is set to fd = 1. Here, when the detection flag is set to fd = 1, the process proceeds to step S118. On the other hand, when the detection flag is reset to fd = 0, the process proceeds to step S119.
In step S118, the map shown in FIG. 11 is referred to, and after the power distribution ratio α is set according to the road surface gradient θ, the process proceeds to step S120.

FIG. 11 is a map used for setting the power distribution ratio α according to the road surface gradient θ.
In this map, with respect to the road surface gradient θ, θ2 (for example, 10%) and θ1 (for example, 15%) that have a relationship of 0 <θ2 <θ1 on the uphill side (positive side) are predetermined. When the road surface gradient θ is in the range of 0 to θ2, the power distribution ratio α maintains the minimum value α _MIN , and when the road surface gradient θ is in the range of θ2 to θ1, the greater the road surface gradient θ, the greater the power distribution. The ratio α increases from the minimum value α _MIN to the maximum value α _MAX . When the road surface gradient θ is larger than θ1, the power distribution ratio α maintains the maximum value α _MAX . When the road surface gradient θ is on the downhill side (negative side), the power distribution ratio α maintains the minimum value _αMIN .

In step S119, the power distribution ratio α is set to the previous value αz, and then the process proceeds to step S120.
In step S120, after calculating the second limit value TL2 according to the power distribution ratio α, the process returns to the predetermined main program.

Next, the second motor torque calculation process executed by the second motor torque calculation unit 54 will be described.
The second motor torque calculation unit 54 calculates the second motor torque Tm2 from the front wheel slip speed ΔV with reference to the map of FIG. Here, the front wheel slip speed ΔV is calculated by subtracting the average wheel speed Vwr of the rear wheels 1RL and 1RR from the average wheel speed Vwf of the front wheels 1FL and 1FR, for example, as shown in the following equation (1).
_{Vwf = (Vw FL + Vw FR} ) / 2
_{Vwr = (Vw RL + Vw RR} ) / 2
ΔV = Vwf−Vwr (1)

FIG. 12 is a map used for calculating the second motor torque Tm2.
In this map, the front wheel slip speed [Delta] V, 0 <[Delta] V1 <a relationship of [Delta] V2 [Delta] V1, predetermining [Delta] V2, the second motor torque Tm2, predetermined maximum value _{T MAX} for a relationship of _{0 <T MAX} ing. When the front wheel slip speed ΔV is in the range of 0 to ΔV1, the second motor torque Tm2 is maintained at 0. When the front wheel slip speed ΔV is in the range of ΔV1 to ΔV2, the larger the front wheel slip speed ΔV, The two-motor torque Tm2 increases from 0 to the maximum value T _MAX . Further, when the front wheel slip speed ΔV is higher than ΔV2, the second motor torque Tm2 maintains the maximum value T _MAX .

Next, the surplus torque calculation process executed by the surplus torque calculation unit 55 will be described.
The surplus torque calculation unit 55 executes the surplus torque calculation process of FIG. 13 every predetermined time (for example, 10 msec).
FIG. 13 is a flowchart showing surplus torque calculation processing.
In step S201, after reading various data, the process proceeds to step S202.
In step S202, the map of FIG. 14 is referred to, and the engine torque Te is calculated (estimated) according to the engine speed Ne and the pedal opening PPO, and then the process proceeds to step S203.

FIG. 14 is a map used for calculating the engine torque Te.
In this map, the engine torque Te increases as the pedal opening PPO increases. In the region where the pedal opening PPO is relatively small, the engine torque Te decreases as the engine speed Ne increases. Further, in a region where the pedal opening degree PPO is relatively large, the engine torque Te initially increases as the engine speed Ne increases, and then suddenly decreases from a certain position.

In step S203, as shown in the following equation (2), the load torque Tg of the generator 7 is calculated according to the voltage V of the generator 7, the armature current Ia, and the rotation speed Ng, and then the process proceeds to step S204. Here, K2 and K3 are predetermined coefficients.
Tg = K2 × (V × Ia) / (K3 × Ng) (2)
In step S204, as shown in the following formula (3), the front wheel acceleration torque Ta is calculated according to the moment of inertia J and the angular acceleration a, and then the process proceeds to step S205. Here, the moment of inertia J is the inertia of the drive system including the gear ratio. The angular acceleration a is obtained from the wheel speeds Vw _FL and Vw _FR of the front wheels.
Ta = J × a (3)

In step S205, as shown in the following equation (4), the front wheel driving force Tf is calculated according to the engine torque Te, the load torque Tg, and the acceleration torque Ta, and then the process proceeds to step S206. Here, Rt is the amplification ratio of the torque converter, and Rg is the gear ratio of the transmission. The front wheel driving force Tf corresponds to the road surface reaction force with respect to the front wheels 1FL and 1FR.
Tf = (Te−Tg) × (Rt × Rg) −Ta (4)

In step S206, it is determined whether or not the host vehicle is in a traveling state. Here, it is determined whether or not the vehicle speed V is greater than zero. Here, when the vehicle speed V is 0, it is determined that the host vehicle is not in a traveling state, that is, is in a stopped state, and the process proceeds to step S207. On the other hand, when the vehicle speed V is greater than 0, it is determined that the host vehicle is in a traveling state, and the process proceeds to step S208.
In step S207, the stored maximum value Tf _MAX is reset to 0, and then the process proceeds to step S215.

  In step S208, it is determined whether or not the front wheels have a slip tendency. Here, it is determined whether or not the front wheel slip speed ΔV is less than a predetermined threshold th. Here, when the front wheel slip speed ΔV is less than the threshold th, it is determined that the front wheel has no slip tendency, and the process proceeds to step S209. On the other hand, when the front wheel slip speed ΔV is equal to or higher than the threshold th, it is determined that the front wheel has a slip tendency and the process proceeds to step S212.

In step S209, it is determined whether or not the front wheel driving force Tf is greater than the stored maximum value Tf _MAX . Here, when the front wheel drive force Tf is greater than the maximum value _{Tf MAX,} it is determined that it is necessary to update the maximum value _{Tf MAX} proceeds to step S210. On the other hand, when the front wheel drive force Tf is less than or equal to the maximum value _{Tf MAX} is updated maximum value _{Tf MAX,} it is determined that it is not necessary the process proceeds to step S211.
In step S210, the stored maximum value Tf _MAX is updated to the current front wheel driving force Tf, and then the process proceeds to step S215.

In step S211, the stored maximum value Tf _MAX is maintained, and the process proceeds to step S215.
In step S212, it is determined whether or not the front wheel driving force Tf is smaller than the stored maximum value Tf _MAX . Here, when the front wheel drive force Tf is less than the maximum value _{Tf MAX,} it is determined that it is necessary to update the maximum value _{Tf MAX} proceeds to step S213. On the other hand, when the front wheel drive force Tf is equal to or more than the maximum value _{Tf MAX} is updated maximum value _{Tf MAX,} it is determined that it is not necessary the process proceeds to step S214.
In step S213, the stored maximum value Tf _MAX is updated to the current front wheel driving force Tf, and then the process proceeds to step S215.

In step S214, the stored maximum value Tf _MAX is maintained, and the process proceeds to step S215.
In step S215, as shown in the following equation (5), the limit torque Te _MAX for the engine torque Te is calculated according to the stored maximum value Tf _MAX , and then the process proceeds to step S216. Here, Rt is the amplification ratio of the torque converter, and Rg is the gear ratio of the transmission. The limit torque Te _MAX corresponds to an upper limit value that can suppress acceleration slip of the front wheels 1FL and 1FR.
Te _MAX = Tf _MAX / (Rt × Rg) (5)

In step S216, it is determined whether or not the engine torque Te is greater than the limit torque Te _MAX . Here, when the engine torque Te is larger than the limit torque Te _MAX, it is determined that there is a surplus torque Tp in the engine torque Te, and the process proceeds to step S217. On the other hand, when the engine torque Te is equal to or less than the limit torque Te _MAX, it is determined that there is no surplus torque Tp in the engine torque Te, and the process proceeds to step S218.

In step S217, as shown in the following equation (6), the surplus torque Tp is calculated by subtracting the limit torque Te _MAX from the engine torque Te, and then the process returns to a predetermined main program.
Tp = Te-Te _MAX (6)
In step S218, the surplus torque Tp is reset to 0, and then the process returns to the predetermined main program.

Next, the selection process executed by the selection unit 56 will be described.
The selection unit 56 calculates the smallest one of the first motor torque Tm1, the first limit value TL1, and the second limit value TL2 as a new first motor torque Tm1, as shown in the following equation (7). .
Tm1 = min [Tm1, TL1, TL2] (7)

Next, the selection process executed by the selection unit 57 will be described.
The selection unit 57 calculates the largest motor torque TS among the first motor torque Tm1 and the second motor torque Tm2 as shown in the following equation (8).
TS = max [Tm1, Tm2] (8)

Next, the selection process executed by the selection unit 58 will be described.
In the selection unit 58, as shown in the following equation (9), the largest one of the second motor torque Tm2 and the surplus torque Tp is calculated as the running motor torque TD.
TD = max [Tm2, Tp] (9)

Next, switching processing executed by the switching unit 59 will be described.
The switching unit 59 determines whether or not the vehicle speed V is equal to or less than a predetermined threshold value Vs (for example, 5 km / h). Here, when the vehicle speed V is equal to or lower than the threshold value Vs, the starting motor torque TS is output as the final target motor torque Tm ^* . On the other hand, when the vehicle speed V is greater than the threshold value Vs, the running motor torque TD is output as the final target motor torque Tm ^* .

Next, calculation processing executed by the motor required power calculation unit 19B will be described.
The required motor power calculation unit 19B calculates the required motor power Pm ^* required for the electric motor 3 according to the target motor torque Tm ^* and the motor rotation speed Nm as shown in the following equation (10).
Pm ^* = Tm ^* × Nm (10)

Next, calculation processing executed by the power generation control unit 19C will be described.
FIG. 15 is a block diagram of the power generation control unit 19C.
The power generation control unit 19C includes a target power calculation unit 40, a limit value calculation unit 41, a final target power calculation unit 42, and a control processing unit 43.
First, calculation processing executed by the target power calculation unit 40 will be described.
The target power calculation unit 40 calculates the target power Pg ^* to be output by the generator 7 according to the required motor power Pm ^* and the motor efficiency ηm as shown in the following equation (11).
Pg ^* = Pm ^* / ηm (11)

Next, calculation processing executed by the limit value calculation unit 41 will be described.
The limit value calculation unit 41 calculates limit values PL1 and PL2 for the output power.
Here, the limit value PL1 is an upper limit value capable of suppressing the belt slip of the V belt 6, and as shown in the following equation (12), the torque upper limit value TL that can be transmitted by the V belt 6, the generator rotational speed Ng, It is calculated according to the generator efficiency ηg.
PL1 = TL × Ng × ηg (12)
The limit value PL2 is an upper limit value that can suppress engine stall or drivability deterioration due to overload of the engine 2, and may be calculated according to the engine speed Ne or may be a predetermined value.

Next, calculation processing executed by the final target power calculation unit 42 will be described.
The final target power calculation unit 42 calculates the smallest one of the target power Pg ^* and the limit values PL1 and PL2 as the final target power Pg ^* as shown in the following equation (13).
Pg ^* = min [Pg ^* , PL1, PL2] (13)

Next, arithmetic processing executed by the control processing unit 43 will be described.
The control processing unit 43 controls the field current Ig of the generator 7 so that the generator 7 outputs the target power Pg ^* . Here, the field current Ig is controlled by feedback control so that the target power Pg ^* matches the actual output power Pg.
FIG. 16 is a block diagram of the control processing unit 43.
The control processing unit 43 includes an output power calculation unit 43a, a target field current calculation unit 43b, and a field current control unit 43c.

First, the output power calculation unit 43a calculates the actual output power Pg (= Vg × Ia) by multiplying the generator voltage Vg and the energization current Ia.
Then, the target field current calculation unit 43b calculates a target field current Ig ^* such that the deviation ΔPg between the actual output power Pg and the target power Pg ^* is zero.
In the field current control unit 44c, the field current Ig flowing through the rotor coil 7a is passed through the IC regulator so that the deviation ΔIg between the actual field current Ig and the target field current Ig ^* becomes zero. Control. The actual field current Ig is detected by a current sensor.

Next, calculation processing executed by the motor control unit 19D will be described.
The motor control unit 19D first calculates the target motor field current Im ^* from the motor rotation speed Nm. The target motor field current Im ^* is reduced by the known field weakening control when the motor rotation speed Nm reaches the high speed range. That is, when the electric motor 3 rotates at a high speed, the induced voltage increases and the motor torque Tm decreases. Therefore, the increase of the induced voltage is suppressed by reducing the field current Im, and the motor torque Tm is prevented from decreasing.
Then, the field current Im of the electric motor 3 is adjusted to the target motor field current Im ^* so that the target motor torque Tm ^* is output.

Next, calculation processing executed by the clutch control unit 19E will be described.
When the target motor torque Tm ^* is 0, the clutch control unit 19E controls the electromagnetic clutch 10 to the non-engaged state, thereby interrupting the power transmission from the electric motor 3 to the rear wheels 1RL and 1RR, and the target motor torque Tm. ^{When *} is larger than 0, power transmission from the electric motor 3 to the rear wheels 1RL and 1RR is performed by controlling the electromagnetic clutch 10 to the engaged state.

<Action>
Next, the operation of this embodiment will be described.
First, an outline of four-wheel drive traveling will be described.
When the accelerator pedal is depressed or the front wheels 1FL and 1FR are slipped by acceleration (idling), the target motor torque Tm ^* is calculated as the pedal opening PPO increases and the front wheel slip speed ΔV increases. . Accelerated slip is caused by a low friction coefficient of the road surface such as a rainy road, a snowy road, or a frozen road, a road surface gradient in the vehicle traveling direction is large on the uphill side, or the pedal opening PPO is too large. .

When the target motor torque Tm ^* is calculated, power generation of the generator 7 is started accordingly. Therefore, assuming that the front wheels 1FL and 1FR are slipping at an acceleration, the output of the engine 2 is suppressed by converting the rotational energy lost by the acceleration slip into electric energy, and the acceleration slip of the front wheels 1FL and 1FR is reduced. Can be suppressed.
In addition, by supplying the electric power generated by the generator 7 to the electric motor 3 and driving the rear wheels 1RL and 1RR by the electric motor 3, that is, in a four-wheel drive state, not only energy efficiency is improved, Smooth and stable starting performance and running performance can be exhibited.
The target motor torque Tm ^* mainly depends on the first motor torque Tm1 corresponding to the pedal opening PPO, the second motor torque Tm2 corresponding to the front wheel slip speed ΔV, and the surplus torque Tp exceeding the limit torque Te _MAX. Is calculated.

FIG. 17 is a time chart showing the transition of the target motor torque Tm ^* .
First, when the vehicle speed V is, for example, 5 km / h or less, the starting motor torque TS obtained by the select high of the first motor torque Tm1 and the second motor torque Tm2 is output as the final target motor torque Tm ^* . As a result, if acceleration slip occurs in the front wheels 1FL and 1FR, the target motor torque Tm ^* corresponding to the front wheel slip speed ΔV is output, and the acceleration slip occurs in the front wheels 1FL and 1FR as shown in FIG. Even when it does not occur, the target motor torque Tm ^* corresponding to the pedal opening PPO is output. In this way, the driver's intention to accelerate and the detected acceleration slip state can be reflected in the target motor torque Tm ^* with a higher priority.

Further, when the vehicle speed V exceeds 5 km / h, for example, the running motor torque TD obtained by the select high of the second motor torque Tm2 and the surplus torque Tp is output as the final target motor torque Tm ^* . Accordingly, as shown in FIG. 17B, when an acceleration slip occurs in the front wheels 1FL and 1FR, the target motor torque Tm ^* corresponding to the front wheel slip speed ΔV is output, and the acceleration slip occurs in the front wheels 1FL and 1FR. Even when it does not occur yet, the target motor torque Tm ^* corresponding to the surplus torque Tp estimated to exceed the limit torque Te _MAX is output. In this way, the detected acceleration slip state and the estimated acceleration slip tendency can be reflected in the target motor torque Tm ^* with a higher priority.

When calculating the surplus torque Tp, the limit torque Te _MAX is constantly updated according to the road surface condition. That is, when the front wheels 1FL and 1FR are not accelerating and slipping (determination in S208 is “Yes”), when the front wheel driving force Tf is greater than the maximum value Tf _MAX (determination in S209 is “Yes”), the engine torque Te This means that there is still a margin before the torque reaches the limit torque Te _MAX . In such a case, it is considered that the friction coefficient of the road surface is increasing. Therefore, the limit value Te _MAX is increased by updating the maximum value Tf _MAX to the current front wheel driving force Tf (S210). On the other hand, when the front wheels 1FL and 1FR are accelerating and slipping (determination in S208 is “No”), when the front wheel driving force Tf is smaller than the maximum value Tf _MAX (determination in S212 is “Yes”), the engine torque still remains. That is, Te exceeds the limit torque Te _MAX . In such a case, it is considered that the friction coefficient of the road surface is lowered. Therefore, the limit value Te _MAX is reduced by updating the maximum value Tf _MAX to the current front wheel driving force Tf (S213). As described above, the surplus torque Tp can be accurately calculated by constantly updating the limit torque Te _MAX according to the road surface condition.

Moreover, to calculate the required power Pm required for the electric motor 3 ^*, calculates the required power Pm ^* target power generator 7 to be output from the Pg ^*, and the target power Pg ^* is the actual output power Pg Since the field current Ig of the generator 7 is controlled so as to match, the generator 7 can accurately supply the necessary electric power Pm ^* required for the electric motor 3 and accurately output the target motor torque Tm ^*. be able to.
Further, the field current Ig of the generator 7 is detected by a current sensor, and feedback control is performed so that the actual field current Ig follows the target field current Ig ^* , so that the output power Pg can be reliably set to the target power Pg ^*. Can be followed.

In the present embodiment, the first motor torque Tm1 is calculated according to the front wheel slip speed ΔV, but the present invention is not limited to this. In short, since the first motor torque Tm1 may be calculated according to the slip tendency of the front wheels 1FL and 1FR, for example, the first motor torque Tm1 may be calculated according to the wheel acceleration and the slip ratio of the front wheels 1FL and 1FR. .
In the present embodiment, the front wheels 1FL and 1FR are the main drive wheels that are driven by the engine 2, and the rear wheels 1RL and 1RR are auxiliary drive wheels that can be driven by the electric motor 3. However, the present invention is not limited to this. The rear wheels 1RL and 1RR may be main driving wheels, and the front wheels 1FL and 1FR may be auxiliary driving wheels.

In the present embodiment, a one-motor type power train that drives the rear wheels 1RL and 1RR with one electric motor 3 is employed, but the present invention is not limited to this. For example, a two-motor system in which the left and right wheels are individually driven by two electric motors, or an in-wheel motor system in which the motor is disposed under the spring (wheel side) may be employed.
In this embodiment, a DC motor is used as the electric motor 3, but an AC motor may be used.
Furthermore, in the present embodiment, the present invention is applied to a four-wheel vehicle, but may be applied to a two-wheel vehicle, a three-wheel vehicle, or a vehicle having five or more wheels.

Next, power performance and four-wheel drive performance will be described.
As described above, when a part of the engine torque Te is converted into electric energy and converted into the motor torque Tm, there is energy loss based on the conversion efficiency. For example, when converting to motor torque Tm using 20% of engine torque Te, assuming that the conversion efficiency at that time is 60%, 0.2 × 0.6 = 0.12, and the motor with respect to engine torque Te The torque Tm is substantially 12%. That is, when the engine torque Te is 0.8 + the motor torque Tm is 0.12, the total driving force of the vehicle is 0.92. Therefore, if the distribution ratio of the motor torque Tm is increased in a state where there is no acceleration slip in the front wheels 1FL and 1FR, the total driving force of the vehicle is reduced due to energy loss. The acceleration performance of the vehicle decreases, and there is a possibility that the vehicle will be sluggish particularly when starting.

FIG. 18 is a diagram illustrating the power performance and the four-wheel drive performance.
Since the rear wheel driving force is generated from a part of the engine torque, if the power distribution ratio from the engine torque to the rear wheel driving force is increased, the total driving force of the vehicle is reduced by the loss based on the conversion efficiency. Resulting in. At this time, if acceleration slip is likely to occur in the front wheels 1FL and 1FR, smooth and stable starting and running can be realized by increasing the power distribution ratio α. Wheel drive performance can be demonstrated. However, in a situation where acceleration slip is unlikely to occur in the front wheels 1FL and 1FR, it is preferable to suppress a reduction in power performance rather than an improvement in four-wheel drive performance.

Therefore, a power distribution ratio α from the engine torque Te to the motor torque Tm when a part of the engine torque Te is converted to the motor torque Tm via the generator 7 is set, and the road surface gradient θ is small on the uphill side. The power distribution ratio α is limited (step S118).
Specifically, when the road surface gradient θ is equal to or higher than a predetermined θ1 (for example, 15%) on the uphill side, the power distribution ratio α is set to a predetermined maximum value α _MAX (for example, 20%), and the road surface gradient θ is When the slope is equal to or smaller than θ2 (for example, 10%) smaller than θ1 on the uphill side, the power distribution ratio α is set to the minimum value _αMIN (for example, 5%). When the road surface gradient θ is in the range of θ1 to θ2 on the uphill side, the power distribution ratio α is set to be smaller in the range of the maximum value _αMAX to the minimum value _{αMIN as} the road surface gradient θ is smaller on the uphill side.

  Then, a second limit value TL2 according to the power distribution ratio α is set (step S120), and the first motor torque Tm1 corresponding to the pedal opening degree PPO is limited to the second limit value TL2 or less. That is, by the selection process executed by the selection unit 56, the smallest one of the first motor torque Tm1 and the second limit value TL2 is calculated as a new first motor torque Tm1.

  As described above, the smaller the road surface gradient θ is on the uphill side, that is, the more difficult the acceleration slip of the front wheels 1FL and 1FR occurs, the less the energy loss based on the conversion efficiency by limiting the power distribution ratio α. The total driving force according to the driver's acceleration request can be ensured. Therefore, even in a vehicle with a small engine displacement such as a three-cylinder engine, for example, it is possible to suppress a decrease in acceleration performance such as shakiness when starting.

FIG. 19 is a diagram illustrating the power performance and the four-wheel drive performance of the present embodiment.
In a situation where the road surface gradient θ is large on the uphill side (θ1 or more) and acceleration slip is likely to occur on the front wheels 1FL and 1FR, the restriction on the power distribution ratio α is relaxed, and the power distribution ratio α is set to the maximum value α _MAX (for example, 20%). ). As a result, a certain power distribution ratio α is ensured and smooth and stable start-up and running are realized, so that a reduction in power performance can be compensated for and the remaining four-wheel drive performance can be exhibited. On the other hand, when the road surface gradient θ is small on the uphill side and acceleration slip is unlikely to occur on the front wheels 1FL and 1FR, the limit on the power distribution ratio α is increased and the power distribution ratio α is made smaller than the maximum value α _MAX . Thereby, the reduction in power performance can be suppressed rather than the improvement in four-wheel drive performance.

In the present embodiment, as shown in FIG. 11, the power distribution ratio α is continuously changed in the range of θ1 to θ2, but the present invention is not limited to this, and the power distribution ratio α is stepped. The shape may be changed. Further, it may be only one stage, and may be configured to be switched between the maximum value α _MAX and the minimum value α _MIN .
In the present embodiment, the power distribution ratio α is set according to the pedal opening PPO and then converted into the first motor torque Tm1, or the power distribution ratio α is limited according to the road surface gradient θ. Although it is converted into the two limit value TL2, it is not limited to this. For example, referring to the map of FIG. 20, the first motor torque Tm1 is directly calculated according to the pedal opening PPO, or the map of FIG. 21 is directly referred to according to the road surface gradient θ. The limit value TL2 may be calculated.

FIG. 20 is a map used for calculating the first motor torque Tm1.
In this map, for the pedal opening PPO, A1 to A4 having a relationship of 0 <A1 <A2 <A3 <A4 are determined in advance, and for the first motor torque Tm1, T1 having a relationship of T1> T2 (for example, 10 Nm) ), T2 (for example, 6 Nm) is predetermined. When the pedal opening PPO is in the range from 0 to A1, the first motor torque Tm1 is maintained at 0. When the pedal opening PPO is in the range from A1 to A2, the larger the pedal opening PPO, One motor torque Tm1 increases from 0 to T1. Further, when the pedal opening PPO is in the range of A2 to A3, the first motor torque Tm1 is maintained at T1, and when the pedal opening PPO is in the range of A3 to A4, the larger the pedal opening PPO, the more One motor torque Tm1 decreases from T1 to T2. Further, when the pedal opening degree PPO is larger than A4, the first motor torque Tm1 maintains T2.

FIG. 21 is a map used for calculating the second limit value TL2.
In this map, with respect to the road surface gradient θ, θ2 (for example, 10%) and θ1 (for example, 15%) satisfying the relationship of 0 <θ2 <θ1 on the uphill side (positive side) are determined in advance, and the second limit value TL2 With respect to, T4 (for example, 3 Nm) and T3 (for example, 10 Nm) satisfying a relationship of 0 <T4 <T3 are predetermined. When the road surface gradient θ is in the range from 0 to θ2, the second limit value TL2 maintains T4. When the road surface gradient θ is in the range from θ2 to θ1, the second limit value increases as the road surface gradient θ increases. TL2 increases from T4 to T3. When the road surface gradient θ is larger than θ1, the second limit value TL2 maintains T3. When the road surface gradient θ is on the downhill side (negative side), the second limit value TL2 maintains T4.

In the present embodiment, the driving force of the electric motor 3 is limited to a small value by limiting the power distribution ratio α to a small value, but the present invention is not limited to this. In short, since it is sufficient that the driving force of the electric motor 3 can be limited to a small value, the driving force of the electric motor 3 is limited by limiting the command value (for example, the target motor torque Tm ^* ) of the electric motor 3 instead of the power distribution ratio α. May be limited to a small value. Further, the driving force of the electric motor 3 may be limited to a small value by limiting the power generation command value (for example, the target power Pg ^* ) to the generator 7 to be small.

Next, the main part of this embodiment will be described.
On an uphill road with a low coefficient of friction on the road surface, the front wheels 1FL and 1FR, which are the main drive wheels, tend to accelerate and slip easily when starting. In such a situation, if the front wheels 1FL and 1FR are actually slipped by acceleration, it becomes more difficult for the driver to control the driving force by the accelerator operation, which affects the running performance.

  Therefore, in the present embodiment, first, when the state in which the brake is on at the time of stopping is continued for t1 (the determination in steps S304 to S306 is “Yes”), the climbing gradient θ is detected (step S307), and the switching flag Is set to fs = 1 (step S308). When the four-wheel drive system is selected by the selection switch 32 (determination in step 313 is “No”), it is determined that acceleration slip of the front wheels 1FL and 1FR is expected. When the road surface gradient θ is equal to or greater than the threshold θt (the determination in step S317 is “No”), the engine control characteristic is set to the slow opening control characteristic, and the throttle opening SPO with respect to the pedal opening PPO is reduced (step S318). ).

Thus, even when the pedal opening PPO is the same, the target throttle opening SPO ^* is relatively smaller than when the road surface gradient θ is less than the threshold θt, and the engine output is suppressed. Acceleration slip can be suppressed. Therefore, the traveling performance of the vehicle can be improved in a situation where acceleration slip of the front wheels 1FL and 1FR is likely to occur at the time of start.
On the other hand, when the road surface gradient θ is less than the threshold value θt (the determination in step S317 is “Yes”), it is less likely that acceleration slip of the front wheels 1FL and 1FR will occur than when the road surface gradient θ is equal to or greater than the threshold value θt. Therefore, the engine control characteristic is set to the quick opening control characteristic, and the throttle opening SPO with respect to the pedal opening PPO is increased (step S317).

As a result, even when the pedal opening PPO is the same, the target throttle opening SPO ^* becomes relatively larger and the engine output is higher than when the road surface gradient θ is equal to or greater than the threshold θt. Acceleration performance is not sacrificed. Accordingly, it is possible to improve the running performance at the start while securing the 4WD performance.
As described above, when the four-wheel drive system is selected by the selection switch 32, the engine control characteristic is switched to either the slow opening control characteristic or the quick opening control characteristic in accordance with the road surface gradient θ.

FIG. 22 is a diagram illustrating a switching state of the engine control characteristics according to the road surface gradient θ.
That is, when the road surface gradient θ is less than the threshold value θt, the engine control characteristic is set to the early opening control characteristic, and when the road surface gradient θ is equal to or greater than the threshold value θt, the engine control characteristic is set to the slow opening control characteristic.
After the vehicle has started, until the vehicle speed V reaches the set vehicle speed Vt (the determination in step S309 is “No”), the switching flag remains set to fs = 1, and the engine control characteristics set while the vehicle is stopped. To maintain. Therefore, it is possible to suppress a decrease in drivability due to frequent switching of engine control characteristics in a scene where slow driving and stopping are repeated due to traffic jams and the like.

When the vehicle speed V reaches the set vehicle speed Vt (“Yes” in step S309), the switching flag is reset to fs = 0 (step S310). As a result, the engine control characteristic is switched from the engine control characteristic set while the vehicle is stopped to the basic base control characteristic (step S314).
As described above, when the four-wheel drive system is selected by the selection switch 32, the engine control characteristic is switched between the base control characteristic and the other according to the vehicle speed V.

FIG. 23 is a diagram showing a switching state of the engine control characteristics according to the vehicle speed V.
That is, when the vehicle speed V is less than the set vehicle speed Vt, the engine control characteristic is set to either the early opening control characteristic or the slow opening control characteristic, and when the vehicle speed V is equal to or higher than the set vehicle speed Vt, the engine control characteristic is set as a base. Set to control characteristics.
Further, as described above, the power distribution ratio α from the engine torque Te to the motor torque Tm when the part of the engine torque Te is converted into the motor torque Tm via the generator 7 is set, and the road surface gradient θ Is smaller on the uphill side, the power distribution ratio α is made smaller (step S118).

Thus, the smaller the road surface gradient θ is on the uphill side, that is, the more difficult the acceleration slip of the front wheels 1FL and 1FR occurs, the smaller the power distribution ratio α, while ensuring 4WD performance, at the time of starting. Acceleration performance can be improved.
When the four-wheel drive system is selected by the selection switch 32 (“No” at step 313), it is determined that acceleration slip of the front wheels 1FL and 1FR is expected. That is, the engine control characteristic is switched to the slow opening control characteristic or the quick opening control characteristic only when the four-wheel drive system is selected.

  Thus, by switching the engine control characteristics when the four-wheel drive system is selected, the difference in acceleration performance is less noticeable than when the engine control characteristics are switched when the two-wheel drive system is selected. In other words, when the two-wheel drive method is selected, it is easy for the driver to perceive the switching of the engine control characteristics, but when the four-wheel drive method is selected, a part of the engine torque is distributed to the motor torque. Therefore, it is difficult for the driver to perceive the switching of the engine control characteristics. Therefore, the uncomfortable feeling that can be given due to the difference in acceleration performance can be reduced.

Next, a time chart assuming an actual traveling scene will be described.
FIG. 24 is a time chart assuming an actual traveling scene.
Here, a driving scene is assumed in which the road surface slope θ is constant at 15% and the vehicle stops and restarts.
When the accelerator pedal 16 is switched to the brake pedal, the vehicle decelerates and the vehicle speed V decreases. At this time, the road surface gradient θ calculated according to the acceleration / deceleration becomes a negative value due to vehicle deceleration, and the road surface gradient θ is between a positive value and a negative value as the deceleration disappears immediately after the vehicle stops. It swings and is not stable. Then, the calculated value of the road surface gradient θ is stabilized as the acceleration / deceleration is stabilized by the time t1 elapses after the vehicle stops. The road surface gradient θ at the time when t1 has elapsed since the vehicle stopped is an accurate value and is stored.

  Here, since the road surface gradient θ is 15% larger than the threshold θt, the engine control characteristic is switched from the base control characteristic to the slow opening control characteristic. When the brake pedal is released and the accelerator pedal 16 is depressed again, the vehicle starts and the vehicle speed V increases from 0 km / h. At this time, since the engine control characteristic is set to the slow opening control characteristic, the throttle opening SPO becomes smaller than that of the base control characteristic and the engine output is suppressed, so that the acceleration slip at the start is suppressed. Can do.

After the vehicle starts, the engine control characteristic remains set to the slow opening control characteristic until the vehicle speed V reaches the set vehicle speed Vt. As a result, it is possible to suppress a decrease in drivability due to frequent switching of engine control characteristics in a scene where slow driving and stopping are repeated due to traffic jams or the like. When the vehicle speed V reaches the set vehicle speed Vt, the engine control characteristic is switched from the slow opening control characteristic to the base control characteristic. As a result, it is possible to prevent the engine output from being unnecessarily suppressed after shifting to the steady running exceeding the set vehicle speed Vt.
Thereafter, the flow when the accelerator pedal 16 is switched to the brake pedal and then stopped and restarted is the same as described above.

<< Modification 1 >>
In this embodiment, the four-wheel drive method and the two-wheel drive method can be arbitrarily selected, and when the four-wheel drive method is selected, the engine control characteristics are switched according to the road surface gradient θ. It is not limited to. For example, even if the configuration is only for the two-wheel drive system, when the snow mode switch is turned on, the gear ratio at start is set to the second speed (second range), and the engine control characteristic is set to the slow opening characteristic. There is something.

  First, when the snow mode switch is turned ON, if the speed ratio at the time of starting is set to 2nd speed, the engine control characteristic is switched to the slow opening control characteristic when the climbing gradient θ is larger than the threshold θt. Just do it. If the engine control characteristic is switched to the slow opening characteristic when the snow mode switch is turned on, the engine control characteristic is changed from the first slow opening control characteristic when the climbing gradient θ is larger than the threshold θt. Further, it may be switched to the second slow opening control characteristic for reducing the throttle opening.

That is, when an acceleration slip of the driving wheel is predicted due to the ON of the snow mode switch, the climbing gradient θ becomes larger than the threshold θt in a measure for suppressing the acceleration slip of the driving wheel. Sometimes, it is only necessary to take further measures to suppress the acceleration slip of the drive wheel. Therefore, any driving system can be used as long as the four-wheel drive system is selected by the selection switch 32 or the engine output is further suppressed by the snow mode switch and the driving force of the drive wheel is further suppressed. Good.
Furthermore, although the case where the engine is the drive source has been described, the present invention is not limited to this, and the present invention can also be applied to the case where the motor is the drive source.

<< Modification 2 >>
In this embodiment, it is possible to set three engine control characteristics such as a base control characteristic, a quick opening control characteristic, and a slow opening control characteristic. However, the present invention is not limited to this, and at least two control characteristics having different characteristics are set. I can do it. For example, when the climbing gradient θ is less than the threshold θt, the quick opening control characteristic may be set, and when the climbing gradient θ is equal to or greater than the threshold θt, the base control characteristic may be set. If the base slope is set to the base control characteristic when the climbing slope θ is less than the threshold value θt, the slow opening control characteristic may be set when the climbing slope θ is equal to or greater than the threshold value θt. That is, it is only necessary that the driving force of the driving source can be made smaller when the climbing gradient θ is equal to or greater than the threshold θt than when the climbing gradient θ is less than the threshold θt.

Furthermore, one threshold value θt is set for the climbing gradient θ, and the engine control characteristics are switched depending on whether or not the threshold value θt is equal to or greater than the threshold value θt. However, the present invention is not limited to this. May be switched to three or more engine control characteristics depending on which range the climbing gradient θ corresponds to.
From the above, the processing in steps S303 to S312 and S314 to S319 corresponds to “driving force control means”, the processing in step S313 corresponds to “state determination means”, and the processing in step S302 corresponds to “gradient detection means”. To do. Further, the early opening control characteristic set in the process of step S317 corresponds to the “first control characteristic”, and the slow opening control characteristic set in the process of step S318 corresponds to the “second control characteristic”. Further, the front wheels 1FL and 1FR correspond to “main drive wheels”, the rear wheels 1RL and 1RR correspond to “auxiliary drive wheels”, and the generator 7 corresponds to “generator”. The 4WD controller 19 corresponds to “motor control means”.

"effect"
(1) The vehicle drive control device of the present embodiment controls the driving force of the engine 2 in accordance with the driver's pedal opening PPO, and is in a state where acceleration slip of the drive wheels is expected. Is determined, and the uphill gradient θ is detected. When it is determined that an acceleration slip is expected when the vehicle starts, when the uphill gradient θ is equal to or greater than the threshold θt, the uphill gradient θ is less than the threshold θt. The driving force of the engine 2 is reduced.

As described above, when the uphill gradient θ is equal to or greater than the threshold θt, the driving force of the engine 2 is reduced so that the road surface gradient θ is less than the threshold θt even at the same pedal opening PPO. The target throttle opening SPO ^* becomes relatively small. Therefore, since the engine output is suppressed, the acceleration slip at the start can be suppressed. In other words, the traveling performance of the vehicle can be improved in a situation where acceleration slip of the front wheels 1FL and 1FR is likely to occur at the start.

(2) The vehicle drive control device of the present embodiment has at least two control characteristics that change the driving force of the engine 2 relative to the same pedal opening PPO amount of the driver. A control characteristic that relatively increases the driving force of the engine 2 with respect to the pedal opening PPO amount of the driver is defined as a quick opening control characteristic, and the driving force of the engine 2 with respect to the pedal opening PPO amount of the driver is defined. A control characteristic that is relatively small is defined as a slow opening control characteristic. When the climbing gradient θ when the vehicle is stopped is less than the threshold θt, the quick opening control characteristic is set. When the climbing gradient θ when the vehicle is stopped is greater than or equal to the threshold θt, the slow opening control characteristic is set. The set control characteristics are maintained until the vehicle speed V reaches the set vehicle speed Vt.
Thus, until the vehicle speed V reaches the set vehicle speed Vt, the engine control characteristics set during the stop of the early opening control characteristics and the slow opening control characteristics are maintained, so that slowing down and stopping due to traffic jams or the like. It is possible to suppress a decrease in drivability due to frequent switching of engine control characteristics in repeated scenes.

(3) The vehicle drive control device of the present embodiment includes a generator 7 that generates power using the power of the engine 2 and an electric motor 3 that drives the rear wheels 1RL and 1RR with the power generated by the generator 7. When it is determined that an acceleration slip is expected when the vehicle starts, when the uphill gradient θ is less than the threshold θ2, the uphill gradient θ is greater than or equal to the threshold θ2. The driving force of the electric motor 3 is reduced.
As described above, when the uphill slope θ is less than the threshold value θ2, by reducing the driving force of the electric motor 3, it is possible to improve the acceleration performance at the start while ensuring the 4WD performance.

(4) The vehicle drive control device of the present embodiment is a two-wheel drive system in which the front wheels 1FL and 1FR are driven by the engine 2 and the rear wheels 1RL and 1RR are not driven by the electric motor 3, and the front wheels 1FL and 1FR are driven by the engine. 2 and a four-wheel drive system that drives the rear wheels 1RL and 1RR with the electric motor 3, and a selection switch 32 that allows the driver to select one of them. When the driver selects the four-wheel drive system with the selection switch 32, it is determined that the acceleration slip is expected.
As described above, when the four-wheel drive method is selected, it is determined that acceleration slip is expected, and the engine control is performed when the two-wheel drive method is selected by switching the engine control characteristics. Rather than switching the characteristics, it is possible to reduce the uncomfortable feeling that may be caused by the difference in acceleration performance.

  (5) The vehicle drive control method of the present embodiment controls the driving force of the engine 2 according to the driver's pedal opening PPO, and is in a state where acceleration slip of the drive wheels is expected. If it is determined that acceleration slip is expected when the vehicle starts, the climbing gradient θ is less than the threshold θt when the climbing gradient θ is equal to or greater than the threshold θt. The driving force of the engine 2 is made smaller than the time.

As described above, when the uphill gradient θ is equal to or greater than the threshold θt, the driving force of the engine 2 is reduced so that the road surface gradient θ is less than the threshold θt even at the same pedal opening PPO. The target throttle opening SPO ^* becomes relatively small. Therefore, since the engine output is suppressed, the acceleration slip at the start can be suppressed. In other words, the traveling performance of the vehicle can be improved in a situation where acceleration slip of the front wheels 1FL and 1FR is likely to occur at the start.
Although the present invention has been described with reference to a limited number of embodiments, the scope of rights is not limited thereto, and modifications of the embodiments based on the above disclosure are obvious to those skilled in the art.

1FL, 1FR Front wheel 1RL, 1RR Rear wheel 2 Engine 3 Electric motor 4 Automatic transaxle 6 V belt 7 Generator 8 Power cable 9 Reducer 10 Electromagnetic clutch 11 Differential gear 12 Intake pipe 13 Throttle valve 14 Engine controller 15 Accelerator sensor 16 Accelerator Pedal 17 Throttle motor 19 4WD controller 19A Target motor torque calculator 19B Motor required power calculator 19C Power generation controller 19D Motor controller 19E Clutch controller 20 Regulator 21 Junction box 22 Main relay 23 Current sensor 24 Thermistor 25 Motor rotation sensor 26 Engine Rotational speed sensor 27 Throttle sensor 28FL to 28RR Wheel speed sensor 29 Acceleration sensor 30 Shift sensor 31 Brake switch 32 Selection switch 33 Throttle shaft 34 Reducer 40 Target power calculation unit 41 Limit value calculation unit 42 Final target power calculation unit 43 Control processing unit 43a Output power calculation unit 43b Target field current calculation unit 43c Field current Control unit 51 First motor torque calculation unit 52 First limit value calculation unit 53 Second limit value calculation unit 54 Second motor torque calculation unit 55 Surplus torque calculation unit 56 Selection unit 57 Selection unit 58 Selection unit 59 Switching unit Tm Motor torque (Tm ^* is the target value)
Tm1 First motor torque TL1 First limit value TL2 Second limit value Tm2 Second motor torque TP Surplus torque TS Motor torque at start TD Motor torque at travel

Claims (5)

Driving force control means for controlling the driving force of the driving source in accordance with the driver's accelerator operation;
State determination means for determining whether or not acceleration slip of the drive wheel is expected;
A slope detecting means for detecting a slope uphill,
The driving force control means includes
When starting the vehicle, if the state determining means determines that an acceleration slip is expected, the climbing is performed when the climbing slope detected by the slope detecting means is greater than or equal to a preset threshold value. The vehicle drive control device, wherein the drive force of the drive source is made smaller than when the gradient is less than the threshold value. The driving force control means includes
It has at least two control characteristics for changing the driving force of the driving source relative to the same accelerator operation amount of the driver, and the driving force of the driving source is relative to the driver's accelerator operating amount. The control characteristic to be greatly increased is defined as the first control characteristic, the control characteristic to relatively reduce the driving force of the drive source with respect to the driver's accelerator operation amount is defined as the second control characteristic,
When the climbing slope at the time of vehicle stop detected by the slope detection means is less than the threshold value, the first control characteristic is set, and when the climbing slope at the time of vehicle stop detected by the slope detection means is greater than or equal to the threshold value. Set the second control characteristic;
The control characteristic set when the vehicle is stopped is maintained among the first control characteristic and the second control characteristic until the vehicle speed after starting the vehicle reaches a preset vehicle speed set in advance. The vehicle drive control device according to claim 1. The drive source is an engine that drives main drive wheels,
A generator for generating electric power by the engine;
An electric motor that drives the auxiliary drive wheel by the electric power generated by the generator;
Motor control means for controlling the driving force of the electric motor,
The motor control means includes
When starting the vehicle, if the state determining means determines that an acceleration slip is expected, the climbing is performed when the climbing slope detected by the slope detecting means is less than a preset threshold value. 3. The vehicle drive control device according to claim 1, wherein the driving force of the electric motor is made smaller than when the gradient is equal to or greater than the threshold value. 4. A main drive system in which the main drive wheel is driven by the engine and the auxiliary drive wheel is not driven by the electric motor, and the main drive wheel is driven by the engine and the auxiliary drive wheel is driven by the electric motor. Auxiliary drive system that includes a selection switch that allows the driver to select either one of
The state determination means includes
4. The vehicle drive control device according to claim 3, wherein when the driver selects the auxiliary drive method with the selection switch, it is determined that an acceleration slip is expected. It controls the driving force of the driving source according to the driver's accelerator operation,
Determine whether the driving wheel is expected to accelerate slip,
When it is determined that an acceleration slip is expected when the vehicle starts, when the climb slope is equal to or higher than a preset threshold value, the climb slope is less than the threshold value. A drive control method for a vehicle, wherein the drive force of the drive source is reduced.

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