JP2010159020A - Drive control apparatus for vehicle and drive control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide drive control of a vehicle which suppresses shock upon clutch engagement and which has improved responsiveness from two wheel driving to four wheel driving. <P>SOLUTION: It is configured that a main drive wheel is driven by a main drive source and a subordinate drive wheel which is different from the main drive wheel is driven by a motor. A clutch is arranged along a torque transmission path from the motor to the subordinate drive wheel, and in a state where four wheel drive conditions are satisfied, the clutch is controlled to be in an engagement state to transmit a drive torque of the motor to the subordinate drive wheel, and, during two wheel driving where the four wheel drive conditions are not satisfied, the clutch is controlled to be in an open state. If it is estimated that a state is assumed in which the four wheel drive conditions are highly likely to be satisfied during the two wheel driving, the motor is driven so that the rotation number of the clutch at the subordinate drive wheel side is synchronized with the rotation number of the clutch at the motor side during opening of the clutch. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention drives a main drive wheel with a main drive source such as an internal combustion engine (engine), and drives a sub drive wheel with a motor as appropriate to drive a 4WD vehicle (four-wheel drive running state). In particular, the present invention relates to a vehicle drive control technique in which a clutch is interposed in the middle of a torque transmission path from a motor to a driven wheel.

As a conventional drive control apparatus for a 4WD vehicle, for example, there is an apparatus described in Patent Document 1. In this device, when the engine drive wheel slips during acceleration on a slippery road surface, the clutch is engaged and the electric motor is driven to transmit the drive torque to the motor drive wheel. This assists acceleration.
When the four-wheel drive condition is satisfied, first, the motor is idled so that the rotational speed of the electric motor is equal to the speed corresponding to the rotational speed of the axle, and then the clutch is brought into a connected state. Thereafter, the output torque of the motor is gradually increased. As a result, the occurrence of shock at the initial stage of motor driving is prevented.

JP-A-11-243608

However, in the vehicle drive control device, even if the four-wheel drive condition is satisfied, an effective driving force is transmitted to the motor drive wheels at least for the time required for the synchronization processing of the clutch input / output shafts due to the motor idling. I can't.
An object of the present invention is to control the driving of a vehicle with improved response from two-wheel drive traveling to four-wheel drive traveling while suppressing a shock at the time of clutch engagement.

  In order to solve the above problems, the present invention is configured such that the main drive wheel is driven by a main drive source, and a slave drive wheel different from the main drive wheel can be driven by a motor. In addition, a clutch is arranged in the middle of the torque transmission path from the motor to the driven wheel, and in a state where the four-wheel drive condition is satisfied, the clutch is controlled to be connected to transmit the motor driving torque to the driven wheel. During the two-wheel drive running that does not satisfy the four-wheel drive conditions, the clutch is controlled to be in an open state. If it is estimated that there is a high possibility that the four-wheel drive condition is reached during the two-wheel drive traveling, the rotation speed on the motor side of the clutch is synchronized with the rotation speed on the driven wheel side of the clutch while the clutch is released. To drive the motor.

  According to the present invention, the rotational speed on the motor side of the clutch can be synchronized with the rotational speed on the driven wheel side of the clutch before the four-wheel drive condition is satisfied. For this reason, the responsiveness from two-wheel drive running to four-wheel drive running can be improved.

It is an outline figure for explaining the vehicle composition concerning the embodiment based on the present invention. 1 is a schematic diagram of a circuit configuration of a vehicle according to an embodiment based on the present invention. It is a figure which shows the structure of the 4WD controller which concerns on embodiment based on this invention. It is a figure explaining the process of 4WD controller which concerns on embodiment based on this invention. It is a figure which shows the process of the surplus torque calculating part which concerns on embodiment based on this invention. It is a figure explaining the process of the target torque limiting part which concerns on embodiment based on this invention. It is a figure explaining the process of the surplus torque conversion part which concerns on embodiment based on this invention. It is a figure explaining the process of the clutch synchronous control part which concerns on 1st Embodiment based on this invention. It is a figure explaining the process of the engine controller which concerns on embodiment based on this invention. It is a time chart example explaining the operation | movement which concerns on 1st Embodiment based on this invention. It is an example of a time chart explaining operation in a comparative example. It is a time chart example explaining the operation | movement which concerns on the modification based on 1st Embodiment based on this invention. It is a figure which shows the process of the surplus torque calculating part which concerns on 2nd Embodiment based on this invention. It is a figure explaining the process of the clutch synchronous control part which concerns on 2nd Embodiment based on this invention. It is a time chart example explaining the operation | movement which concerns on 2nd Embodiment based on this invention. It is a figure explaining the outline | summary of a process of the clutch synchronous control part which concerns on 3rd Embodiment based on this invention. It is a time chart example explaining the operation | movement which concerns on 3rd Embodiment based on this invention.

Next, a first embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram illustrating a system configuration of a vehicle according to the present embodiment.
As shown in FIG. 1, in the vehicle of this embodiment, left and right front wheels 1L and 1R are main drive wheels driven by an engine 2 that is an internal combustion engine, and left and right rear wheels 3L and 3R are driven by a motor 4. Possible driven wheel.
That is, the output torque Te of the engine 2 is transmitted to the left and right front wheels 1L, 1R through the transmission 30 and the difference gear 31. The transmission 30 is provided with shift position detecting means 32 for detecting the current shift range. The shift position detecting means 32 outputs the detected shift position signal to the 4WD controller 8.

A part of the rotational torque Te of the engine 2 is transmitted to the generator 7 via the endless belt 6. The generator 7 rotates at a rotational speed Nh obtained by multiplying the rotational speed Ne of the engine 2 by a pulley ratio, and becomes a load on the engine 2 in accordance with the field current Ifh adjusted by the 4WD controller 8. A voltage corresponding to the power is generated.
The electric power generated by the generator 7 can be supplied to the motor 4 via the electric wire 9. A junction box 10 is provided in the middle of the electric wire 9. The drive shaft of the motor 4 can be connected to the rear wheels 3L and 3R via the speed reducer 11 and the clutch 12. Reference numeral 13 represents a differential.

  A main throttle valve 15 and a sub-throttle valve 16 are interposed in the intake pipe 14 (for example, intake manifold) of the engine 2. The main throttle valve 15 adjusts and controls the throttle opening in accordance with the depression amount of the accelerator pedal 17 that is an accelerator opening instruction device (acceleration instruction operation unit). The main throttle valve 15 is mechanically linked to the depression amount of the accelerator pedal 17. Alternatively, the throttle opening degree is adjusted by the engine controller 18 being electrically adjusted and controlled in accordance with the depression amount detection value of the accelerator sensor that detects the depression amount of the accelerator pedal 17. The accelerator sensor depression amount detection value is also output to the 4WD controller 8.

  Further, the sub-throttle valve 16 uses the step motor 19 as an actuator, and adjusts and controls the opening degree by the rotation angle corresponding to the number of steps. The rotation angle of the step motor 19 is adjusted and controlled by a drive signal from the motor controller 20. The sub throttle valve 16 is provided with a throttle sensor. Based on the throttle opening detection value detected by the throttle sensor, the number of steps of the step motor 19 is feedback controlled. Here, by adjusting the throttle opening of the sub-throttle valve 16 to be less than or equal to the opening of the main throttle valve 15, the output torque of the engine 2 is controlled independently of the driver's operation of the accelerator pedal. Can do.

An engine speed detection sensor 21 that detects the speed of the engine 2 is also provided. The engine speed detection sensor 21 outputs the detected signal to the engine controller 18 and the 4WD controller 8.
Reference numeral 34 denotes a brake pedal that constitutes a braking instruction operation unit. A brake stroke sensor 35 detects the stroke amount of the brake pedal 34. The brake stroke sensor 35 outputs the detected brake stroke amount to the braking controller 36 and the 4WD controller 8.

The braking controller 36 controls the braking force acting on the vehicle according to the input brake stroke amount. The braking control is performed through braking devices 37FL, 37FR, 37RL, and 37RR such as disc brakes equipped on the wheels 1L, 2R, 3L, and 3R.
Moreover, the said generator 7 is provided with the voltage regulator 22 (regulator) for adjusting the output voltage V, as shown in FIG. By adjusting the field current Ifh by the 4WD controller 8, the power generation load torque Th for the engine 2 and the voltage V to be generated are controlled. The voltage regulator 22 receives a generator control command c1 (duty ratio) from the 4WD controller 8. The field current Ifh of the generator 7 is adjusted to a value corresponding to the generator control command c1, and the output voltage V of the generator 7 can be detected and output to the 4WD controller 8. The rotational speed Nh of the generator 7 can be calculated from the rotational speed Ne of the engine 2 based on the pulley ratio.

  A current sensor 23 is provided in the junction box 10. The current sensor 23 detects the current value Ia of the power supplied from the generator 7 to the motor 4 and outputs the detected armature current signal to the 4WD controller 8. Further, the 4WD controller 8 detects the voltage value flowing through the electric wire 9 (voltage of the motor 4). Reference numeral 24 denotes a relay, which controls interruption and connection of a voltage (current) supplied to the motor 4 according to a command from the 4WD controller 8.

The motor 4 controls the field current Ifm according to a command from the 4WD controller 8 and adjusts the drive torque Tm by adjusting the field current Ifm. Reference numeral 25 denotes a thermistor that measures the temperature of the motor 4.
A motor rotation speed sensor 26 for detecting the rotation speed Nm of the drive shaft of the motor 4 is provided. The motor rotation speed sensor 26 outputs the detected rotation speed signal of the motor 4 to the 4WD controller 8.

The clutch 12 is a hydraulic clutch or an electromagnetic clutch, and is connected or released according to a clutch control command from the 4WD controller 8. Specifically, it is in an open state when it is traveling with two wheels, and is in a connected state when it is traveling with four wheels.
Each wheel 1L, 1R, 3L, 3R is provided with a wheel speed sensor 27FL, 27FR, 27RL, 27RR. Each wheel speed sensor 27FL, 27FR, 27RL, 27RR outputs a pulse signal corresponding to the rotation speed of the corresponding wheel 1L, 1R, 3L, 3R to the 4WD controller 8 as a wheel speed detection value.

As shown in FIG. 3, the 4WD controller 8 includes a generator control unit 8A, a relay control unit 8B, a motor control unit 8C, a clutch control unit 8D, a surplus torque calculation unit 8E, a target torque limiting unit 8F, and a surplus torque conversion unit 8G. And a clutch synchronization control unit 8H.
The generator control unit 8A adjusts the field current Ifh of the generator 7 while monitoring the power generation voltage V of the generator 7 through the voltage regulator 22, so that the generator voltage V of the generator 7 is required. Adjust to the voltage of.

The relay control unit 8 </ b> B controls interruption / connection of power supply from the generator 7 to the motor 4.
The motor control unit 8C adjusts the field current Ifm of the motor 4 to adjust the torque of the motor 4 to a required value.
The clutch control unit 8D controls the state of the clutch 12 by outputting a clutch control command to the clutch 12.
Further, as shown in FIG. 4, processing is performed by circulating in the order of the surplus torque calculating unit 8E → the target torque limiting unit 8F → the surplus torque converting unit 8G based on each input signal at every predetermined sampling time.

First, the surplus torque calculation unit 8E performs processing as shown in FIG.
That is, first, in step S10, the rear wheels 3L, 3R (secondary driving wheels) are calculated from the wheel speeds of the front wheels 1L, 1R (main driving wheels) calculated based on the signals from the wheel speed sensors 27FL, 27FR, 27RL, 27RR. By subtracting the wheel speed, the slip speed ΔVF that is the acceleration slip amount of the front wheels 1L, 1R is obtained, and the process proceeds to step S20.

Here, the calculation of the slip speed ΔVF is performed as follows, for example.
An average front wheel speed VWf that is an average value of the left and right wheel speeds of the front wheels 1L and 1R and an average rear wheel speed VWr that is an average value of the left and right wheel speeds of the rear wheels 3L and 3R are calculated by the following equations, respectively.
VWf = (VWfl + VWfr) / 2
VWr = (VWrl + VWrr) / 2

Next, from the deviation between the average front wheel speed VWf and the average rear wheel speed VWr, the slip speed (acceleration slip amount) ΔVF of the front wheels 1L and 1R which are the main drive wheels is calculated by the following equation.
ΔVF = VWf -VWr
In step S20, it is determined whether or not the obtained slip speed ΔVF is equal to or greater than a predetermined value. If it is determined that the slip speed ΔVF is less than the predetermined value, it can be estimated that the front wheels 1L, 1R are not accelerating slipping, so the routine proceeds to step S30, where zero is substituted for TH, and then returns.

On the other hand, if it is determined in step S20 that the slip speed ΔVF is greater than 0, it can be estimated that the front wheels 1L and 1R are slipping at acceleration, and therefore the process proceeds to step S25. Here, in this embodiment, it is an example in case the front wheels 1L and 1R are in the four-wheel drive condition when the acceleration slip occurs.
In step S25, it is determined whether the accelerator pedal is depressed and the accelerator is off. If the accelerator is off, the process proceeds to step S30. If the accelerator is not off, the process proceeds to step S26.

In step S26, the 4WD standby flag TKFLG is turned on and the process proceeds to step S40.
In step S40, the absorption torque TΔVF required to suppress the acceleration slip of the front wheels 1L, 1R is calculated by the following equation, and the process proceeds to step S50. The absorption torque TΔVF is an amount proportional to the acceleration slip amount.
TΔVF = K1 × ΔVF
Here, K1 is a gain obtained through experiments or the like.

In step S50, the current load torque TG of the generator 7 is calculated based on the following equation, and then the process proceeds to step S60.
TG = K2 · (V × Ia) / (K3 × Nh)
here,
V: Voltage of the generator 7
Ia: Armature current of the generator 7
Nh: Number of rotations of the generator 7
K3: Efficiency
K2: coefficient
It is.
In step S60, the surplus torque, that is, the target power generation load torque Th to be loaded by the generator 7 is obtained based on the following formula, and the process returns.
Th = TG + TΔVF

Next, the processing of the target torque limiting unit 8F will be described based on FIG.
That is, first, in step S110, it is determined whether or not the target power generation load torque Th is larger than the maximum load capacity HQ of the generator 7. When the target power generation load torque Th is determined to be equal to or less than the maximum load capacity HQ of the generator 7, the power generation load torque Th is restored. On the other hand, when it is determined that the target power generation load torque Th is larger than the maximum load capacity HQ of the generator 7, the process proceeds to step S120.

In step S120, an excess torque ΔTb exceeding the maximum load capacity HQ at the target power generation load torque Th is obtained by the following equation, and the process proceeds to step S130.
ΔTb = Th−HQ
In step S130, the current engine torque Te is calculated based on signals from the engine speed detection sensor 21 and the throttle sensor, and the process proceeds to step S140.

In step S140, an engine torque upper limit value TeM obtained by subtracting the excess torque ΔTb from the engine torque Te is calculated as shown in the following equation, and the calculated engine torque upper limit value TeM is output to the engine controller 18, and then the process proceeds to step S150. Transition.
TeM = Te−ΔTb
In step S150, after the maximum load capacity HQ is substituted for the target power generation load torque Th, the process returns.

Next, the process of the surplus torque converter 8G will be described with reference to FIG.
First, in step S200, it is determined whether Th is greater than zero. If it is determined that Th> 0, the four-wheel drive condition is satisfied, and the process proceeds to step S205. If it is determined that Th ≦ 0, the four-wheel drive condition is not satisfied and the vehicle is in the two-wheel drive traveling state, and the process proceeds to step S207.

In step S205, a clutch-on command is output and the process proceeds to step S210. In step S207, a clutch-off command is output and the process proceeds to step S290.
In step S210, the rotational speed Nm of the motor 4 detected by the motor rotational speed sensor 21 is input, a target motor field current Ifm corresponding to the rotational speed Nm of the motor 4 is calculated, and the target motor field current Ifm is calculated. Is output to the motor control unit 8C, and then the process proceeds to step S220.

  Here, the target motor field current Ifm with respect to the rotational speed Nm of the motor 4 is a constant predetermined current value when the rotational speed Nm is equal to or lower than the predetermined rotational speed, and when the motor 4 exceeds the predetermined rotational speed. First, the field current Ifm of the motor 4 is reduced by a known field weakening control method. That is, when the motor 4 is rotated at a high speed, the motor torque decreases due to the increase of the motor induced voltage E. Therefore, as described above, when the rotational speed Nm of the motor 4 exceeds a predetermined value, the field current Ifm of the motor 4 is By reducing the induced voltage E, the current flowing through the motor 4 is increased to obtain the required motor torque Tm. As a result, even if the motor 4 rotates at a high speed, the required motor torque Tm can be obtained because the increase in the motor induced voltage E is suppressed and the decrease in the motor torque is suppressed. In addition, by controlling the motor field current Ifm in two stages of less than a predetermined rotation speed and more than a predetermined rotation speed, the control electronic circuit can be made cheaper than continuous field current control.

  Note that motor torque correction means for continuously correcting the motor torque Tm may be provided by adjusting the field current Ifm according to the rotational speed Nm of the motor 4 with respect to the required motor torque Tm. That is, for the two-stage switching, the field current Ifm of the motor 4 is preferably adjusted according to the motor rotation speed Nm. As a result, the required motor torque Tm can be obtained in order to suppress the increase in the induced voltage E of the motor 4 and suppress the decrease in the motor torque even when the motor 4 rotates at a high speed. In addition, since smooth motor torque characteristics can be achieved, the vehicle can travel more stably than in the two-stage control, and the motor drive efficiency can always be improved.

In step S220, the induced voltage E of the motor 4 is calculated from the target motor field current Ifm and the rotational speed Nm of the motor 4, and the process proceeds to step S230.
In step S230, the corresponding target motor torque Tm is calculated based on the power generation load torque Th calculated by the surplus torque calculator 8E, and the process proceeds to step S240.
In step S240, the corresponding target armature current Ia is calculated using the target motor torque Tm and the target motor field current Ifm as variables, and the process proceeds to step S250.

In step S250, the target voltage V of the generator 7 is calculated from the target armature current Ia, resistance R, and induced voltage E based on the following equation, and the process proceeds to step S310.
V = Ia × R + E
The resistance R is the resistance of the electric wire 9 and the resistance of the coil of the motor 4.
In step S310, the target voltage V of the generator 7 is output to the generator control unit 8A and then returned.

On the other hand, when Th is “0”, the process proceeds to step S290. In step S290, if the clutch synchronization flag GATAFLG is “1”, that is, if there is a clutch synchronization process, the process proceeds to step S300, the clutch synchronization target voltage GaV is substituted for V, and the process proceeds to step S310. If the clutch synchronization flag GATAFLG is “0”, that is, if the clutch synchronization process is not in progress, the process is terminated and the process returns.
Here, the surplus torque converter 8G calculates the target voltage V at the generator 7 according to the target power generation load torque Th in consideration of the control on the motor side, but from the target power generation load torque Th. The voltage value V that becomes the target power generation load torque Th may be directly calculated.

Next, the process of the clutch synchronization control unit 8H will be described.
In the clutch synchronization control unit 8H, the processing shown in FIG. 8 is performed based on each input signal at every predetermined sampling time.
First, in step S400, it is determined whether or not Th ≦ 0, that is, whether or not two-wheel drive is being performed. If Th ≦ 0, the process proceeds to step S410. On the other hand, if Th> 0, the process returns as it is.
In step 410, it is determined whether or not the clutch synchronization flag GATAFLG is “0”, that is, whether or not the clutch synchronization process is being performed. If it is determined that “0”, that is, the clutch synchronization process is not being performed, the process proceeds to step S420. On the other hand, if it is determined that “1”, that is, clutch synchronization processing is being performed, the process proceeds to step S700.

In step S420, based on the signal from the shift position detecting means 31, it is determined whether or not the shift is in the drive range (D · R · 1 · 2), that is, a range other than parking or neutral. If it is determined that the torque is transmitted from the drive range, that is, the engine 2 to the front wheels 1L, 1R, the process proceeds to step S430. On the other hand, if it is determined as the non-driving range, the process is terminated and the process returns.
In step S430, it is determined whether the 4WD standby flag TKFLG is ON. If it is ON, the process proceeds to step S440. On the other hand, when it is not ON, it returns as it is.

In step S440, it is determined whether or not the brake switch is ON. If the brake switch is ON, the process proceeds to step S450. On the other hand, when the brake switch is OFF, the process proceeds to step S460.
In step S450, the brake-on flag BONFLG is turned ON and the process proceeds to step S460.
In step S460, it is determined whether or not the brake on flag BONFLG is ON. If the brake on flag BONFLG is ON, the process proceeds to step S470. If the brake on flag BONFLG is not ON, the process proceeds to step S440.

In step S470, it is determined whether or not the vehicle speed is equal to or higher than a predetermined value. If the vehicle speed is lower than the predetermined value, the process proceeds to step S480. On the other hand, if the vehicle speed is equal to or higher than the predetermined value, the process proceeds to step S490. Here, as the predetermined value, for example, an upper limit vehicle speed that can be regarded as being stopped or just before stopping, or an upper limit vehicle speed that can be regarded as being traveling at a low speed due to traffic congestion is adopted. The predetermined value is, for example, 10 (km / h).
In step S480, the 4WD standby flag TKFLG is turned OFF to return.

On the other hand, in step S490, it is determined whether or not the brake switch is OFF. If the brake switch is OFF, the process proceeds to step S500. On the other hand, if the brake switch is ON, the process proceeds to step S470.
In step S500, the brake-off flag BOFFFLG is turned ON and the process proceeds to step S510.
In step S510, the brake-on flag BONFLG is turned off and the process proceeds to step S520.
In step S520, the re-acceleration standby flag A-TKFLG is turned ON and the process proceeds to step S530.
In step S530, the rotational speed of the output shaft side of the clutch 12 is read, and the process proceeds to step S540.

In step S540, the clutch synchronization target motor torque GaTm is calculated from a preset map or function according to the rotation speed of the clutch 12 on the output shaft side, and then the process proceeds to step S550.
In step S550, the target armature current GaIa used for the corresponding clutch synchronization process is calculated using the clutch synchronization target motor torque GaTm as a variable, and in step S560, the motor field current Imf fixed to a predetermined value and the motor field current Imf are calculated. The induced voltage GaE of the motor is calculated from the rotational speed Nm, and the process proceeds to step S570.

In step S570, the target voltage GaV for clutch synchronization of the generator is calculated. Subsequently, in step S580, the corresponding target power generation load torque GaTh is calculated using the target voltage GaV as a variable, and output in step S590. The process proceeds to step S600.
In step S600, the clutch synchronization flag GATAFLG is set to “1”, and then the process proceeds to step S610. By setting the clutch synchronization flag GATAFLG to “1”, the surplus torque converter 8G or the like performs processing such as the output target voltage GaV and the motor torque according to the target power generation load torque GaTh. That is, the motor 4 enters a minute torque generation state for clutch synchronization processing.
In step S610, both the 4WD standby flag TKFLG and the re-acceleration standby flag A-TKFLG are turned off, and then the process returns.

On the other hand, when the process proceeds to step S700, it is determined whether the input / output rotational speed difference ΔVc between the input shaft and the output shaft of the clutch 12 is zero or almost zero, and the input / output rotational speed difference ΔVc is zero or almost zero. If it is determined, the process is returned. Otherwise, the process proceeds to step S710.
In step S710, the clutch synchronization target motor torque GaTm is calculated from a preset map or function according to the rotational speed of the output shaft side of the clutch 12, and then the process proceeds to step S720.
In step S720, the target armature current GaIa used for the corresponding clutch synchronization process is calculated using the clutch synchronization target motor torque GaTm as a variable, and in step S730, the motor field current Imf fixed to a predetermined value and the motor field current Imf are calculated. The induced voltage GaE of the motor is calculated from the rotation speed Nm, and the process proceeds to step S740.

In step S740, the generator clutch synchronization target voltage GaV is calculated. Subsequently, in step S750, the corresponding target power generation load torque GaTh is calculated using the target voltage GaV as a variable, and output in step S760. Return.
Here, the input / output rotational speed difference ΔVc is obtained by multiplying the detection value of the motor rotational speed detection sensor of the motor 4 on the input side by the reduction ratio of the speed reducer 11 and the rear wheels 3L and 3R on the output side. It can be calculated from the difference between the left and right average wheel rotational speed and the gear ratio of the rear differential 3.

Next, processing of the engine controller 18 will be described.
The engine controller 18 performs processing as shown in FIG. 9 based on each input signal at every predetermined sampling time.
That is, first, in step S610, the target output torque TeN requested by the driver is calculated based on the detection signal from the accelerator sensor 20, and the process proceeds to step S620.

In step S620, it is determined whether there is an input of the limited output torque TeM from the 4WD controller 8. If it is determined that there is an input, the process proceeds to step S630. On the other hand, if it is determined that there is no input, the process proceeds to step S650.
In step S630, it is determined whether the limited output torque TeM is greater than the target output torque TeN. If it is determined that the limit output torque TeM is larger, the process proceeds to step S640. On the other hand, if the limited output torque TeM is smaller or equal to the target output torque TeN, the process proceeds to step S650.

In step S640, the target output torque TeN is increased by substituting the limited output torque TeM for the target output torque TeN, and the process proceeds to step S650.
In step S650, it is determined whether the clutch synchronization flag GATAFLG = 1, that is, whether the clutch synchronization process is being performed. If it is determined that the clutch synchronization process is being performed, the process proceeds to step S660. On the other hand, if it is determined that the clutch synchronization process is not being performed, the process proceeds to step S670.

In step S660, the target output torque TeN is increased by the clutch synchronization target load torque GaTh, and the process proceeds to step S670.
In step S670, the current output torque Te is calculated based on the throttle opening, the engine speed, etc., and the process proceeds to step S680.
In step S680, the deviation ΔTe ′ of the target output torque TeN with respect to the current output torque Te is output based on the following equation, and the process proceeds to step S690.
ΔTe ′ = TeN−Te
In step S690, a change Δθ of the throttle opening θ corresponding to the deviation ΔTe is calculated, and an opening signal corresponding to the change Δθ of the opening is output to the step motor 19 to return.

(Operation / Action)
Next, the operation and action of the apparatus configured as described above will be described.
FIG. 10 shows a time chart example of the first embodiment.
Prior to time t1, it is assumed that the vehicle is in a four-wheel drive mode due to a four-wheel drive request. Then, at time t1, it is assumed that the accelerator pedal 17 is returned by the driver's operation and the accelerator is turned off, so that the four-wheel drive traveling is finished and the two-wheel drive traveling is started. In this case, since it can be estimated that the running road surface is a low μ road having a friction coefficient lower than a predetermined friction coefficient (for example, half of the dry road surface), it is determined that 4WD standby is necessary, and the 4WD standby flag TKFLG Set to ON.

Further, at time t2, when a driver's operation is detected in which the brake pedal is depressed and the brake switch is turned on at a predetermined vehicle speed or higher, and the brake pedal 34 is returned and the brake switch is turned off, the driver re-accelerates. It is predicted that there is a request, and the re-acceleration standby flag A-TKFLG is turned ON.
Then, it is determined that the 4WD standby flag TKFLG is ON and the re-acceleration standby flag A-TKFLG is ON. From time t2, the motor rotational speed matching control mode is entered, and synchronization with the rotational speed of the clutch output shaft is started. To do.

Subsequently, when the rotation speed is synchronized at time t3, the operation shifts to the rotation speed synchronization control mode, maintains the synchronization state, and prepares for the driver acceleration request and clutch reconnection.
When the four-wheel drive condition is satisfied at time t4, the four-wheel drive control mode is entered, the clutch 12 is reconnected, and the four-wheel drive motor torque can be output.
If the 4WD standby flag TKFLG is OFF or the re-acceleration standby flag A-TKFLG is OFF when the four-wheel drive condition is satisfied during two-wheel drive traveling, the clutch 12 is connected before the clutch 12 is connected. A process for executing the twelve rotational speed synchronization process may be provided separately.

For comparison, FIG. 11 shows an example of a time chart when the rotational speed control of the input shaft and the output shaft of the clutch 12 is performed when the four-wheel drive condition is satisfied at time t4.
In this example, the driver's accelerator and brake operations are the same as in FIG. 10, and the time shifts to 2WD at time t1 when the accelerator is off. In the comparative example, when the four-wheel drive condition is satisfied at time t4, synchronous control of the rotational speed of the motor is started (t4 to t5). Then, at time t5 after the completion of synchronization, the process finally shifts to the four-wheel drive control, and the four-wheel drive motor torque can be output.

As a result, the drive force cannot be transmitted to the motor drive wheels as a response delay time until the time t5 when the actual four-wheel drive motor torque output is started after the four-wheel drive conditions are satisfied. For this reason, when it is a low μ road, desired vehicle acceleration and stability cannot be obtained.
In any of the above time chart examples, the rising and falling gradients of the motor torque are omitted for simplification. Also, clutch synchronization processing torque control at the time of transition from rotation synchronization control to four-wheel drive control is omitted.

  Here, the front wheels 1L and 1R constitute main drive wheels. The rear wheel constitutes a driven wheel. The engine 2 constitutes a main drive source. Step S430 constitutes a low friction coefficient road surface estimating means. Steps S440 to S490 constitute reacceleration request prediction means. Steps S410 to S520 constitute a four-wheel drive prediction unit. Steps S530 to S760 constitute motor preliminary drive means.

(Effect of this embodiment)
(1) The four-wheel drive prediction means estimates whether or not there is a high possibility that the four-wheel drive condition is satisfied during the two-wheel drive traveling. When it is estimated that the four-wheel drive predicting means is likely to be in the four-wheel drive condition, the motor preliminary drive means determines that the number of revolutions of the clutch 12 on the motor side is equal to the number of revolutions of the clutch 12 on the driven wheel side. The motor is rotationally driven to synchronize. If it is determined that the four-wheel drive condition is satisfied, the clutch 12 is controlled to be in a connected state.
Before satisfying the four-wheel drive condition, the rotation speed on the motor side of the clutch 12 can be synchronized with the rotation speed on the driven wheel side of the clutch 12. For this reason, the responsiveness from two-wheel drive running to four-wheel drive running can be improved.
For example, when accelerating on a low μ road (snowy road), the rotation speed of the clutch input / output is synchronized in anticipation of the four-wheel drive request in advance without waiting for the four-wheel drive request due to the occurrence of acceleration slip. For this reason, the response time of 4WD re-drive is improved by the amount of motor idling time required for rotation speed synchronization.

(2) The four-wheel drive predicting means includes a low friction coefficient road surface estimating means for estimating whether or not the road surface of the vehicle is a low μ road, and a reacceleration request for predicting a state where the driver has a reacceleration request. Prediction means. Then, if the low friction coefficient road surface estimating means estimates that the road is a low μ road and the reacceleration request predicting means predicts that there is a reacceleration request, it is estimated that there is a high possibility of four-wheel drive conditions.
Estimate the case where 4WD re-drive is required, and eliminate unnecessary motor synchronization processing. As a result, when 4WD is not required, generation | occurrence | production of the electric power which idles a motor and the electric power which maintains a clutch synchronous process can be suppressed.

(3) The low friction coefficient road surface estimation means estimates that the low μ road is traveling when the four-wheel drive condition is canceled because the driver no longer requests acceleration.
As a result, it can be determined that there is a high possibility that the currently running road surface is a low μ road.
Here, during the previous acceleration (while the accelerator is on), the vehicle is running with the four-wheel drive request ON. There is a high possibility that the vehicle has been turned off, and there is a high possibility that the vehicle is still traveling on a low μ road.

(4) The low friction coefficient road surface estimation means estimates that the vehicle is traveling on a low μ road when detecting a state where slippage or more than a predetermined amount has occurred on the drive wheels in a state where the driver has requested acceleration. .
Estimate whether the running road surface is a low μ road and determine whether or not it is necessary to wait for 4WD. For example, whether or not the drive wheel slip occurred during the previous acceleration, traction control It is determined whether one of them is operating or a combination thereof. That is, the slip itself may be detected, or a state in which the slip occurs may be detected by traction control that operates by the slip.
As a result, it can be determined that there is a high possibility that the currently running road surface is a low μ road.

(5) When the reacceleration request prediction means detects that the braking request from the driver has been released in a state where the vehicle speed is equal to or higher than the predetermined vehicle speed, the reacceleration request prediction means predicts that the reacceleration request is issued by the driver.
That is, the prediction of the driver's reacceleration request is determined by a brake OFF operation at a certain vehicle speed or higher (for example, 10 km / h or higher).
Thus, the driver's reacceleration request can be reliably predicted.
That is, by setting the speed to a certain speed or higher, it is possible to prevent an erroneous determination due to a brake operation during braking, just before stopping, a traffic jam mode at a low speed, or a brake operation while entering a garage, and a reacceleration request can be predicted.

(Modification)
(1) In the above embodiment, the re-acceleration standby flag A-TKFLG is set to ON by a brake OFF operation at a constant vehicle speed or higher (for example, 10 km / h or higher). The condition for turning on the re-acceleration standby flag A-TKFLG may be set as the following condition.
That is, the reacceleration request predicting means predicts that a reacceleration request is made by the driver when detecting a steering operation or turning behavior of the vehicle by the driver when the revolving acceleration request flag is detected at a predetermined vehicle speed or higher. Set A-TKFLG to ON.
When the turning operation is performed at a certain vehicle speed or higher, it can be regarded as turning right or left at an intersection or turning operation on a turning circuit or a winding road. For this reason, it is very likely that the driver next performs an acceleration operation, and the driver's reacceleration request can be reliably predicted. In addition, by setting the vehicle speed to a certain vehicle speed or higher, it is possible to prevent erroneous determination due to a turning operation at the time of stopping, entering a garage at a low speed, or stopping at a parking lot, and the reacceleration request can be predicted with higher accuracy.

The steering operation or vehicle turning behavior that is greater than or equal to a predetermined value by the driver is set to a steering operation or vehicle turning behavior that can be regarded as turning right or left at an intersection or turning operation on a turning circuit or a winding road.
An example of a time chart in this case is shown in FIG.
In this example, at the time t1, during the four-wheel drive control, 4WD ends with the driver's accelerator OFF, and the 4WD standby flag TKFLG = ON, as in the above embodiment. However, instead of the brake operation, the driver's steering operation is detected by a steering angle sensor mounted on the vehicle, and at time t2, when the detected steering angle exceeds a predetermined threshold th_c, it is determined that the vehicle is turning, and the turning detection flag Set to ON.

In general, when the accelerator is turned off and the turning operation is performed at a certain vehicle speed or more, it is a left / right turn at an intersection, a turning operation on a turning circuit or a winding road, and the driver can then perform an acceleration operation. The nature is extremely high. For this reason, when it is detected that the vehicle speed exceeds the predetermined vehicle speed and the turning detection flag is ON, the re-acceleration standby flag A-TKFLG is turned ON (time t2).
Then, when the 4WD standby flag TKFLG is ON and the re-acceleration standby flag A-TKFLG is ON, the mode shifts to the motor rotation speed matching control mode for the clutch 12 synchronization processing.

In the above example, the driver's steering operation is detected by the steering angle sensor. For example, when a vehicle-mounted lateral G sensor or yaw rate sensor is installed, the driver's steering operation may be determined based on the detected values. In addition, the steering operation of the turner may be determined by a combination of the steering angle sensor value and the G sensor or yaw rate sensor value. In short, it is only necessary to determine that the vehicle is turning.
Further, a means for predicting the driver's re-acceleration request when the brake OFF operation, the driver's steering operation, or the determination of the turning behavior of the vehicle, or both conditions are satisfied, that is, The re-acceleration standby flag A-TKFLG may be set as the ON condition.

(2) Preliminary drive stop means for stopping the motor drive by the motor preliminary drive means may be provided when the motor drive for synchronization by the motor preliminary drive means continues for a predetermined time.
For example, in step S600, a timer may be started and it may be determined whether or not a predetermined time has passed immediately before step S700.
When there is no shift to the four-wheel drive running, it is possible to prevent the rotation speed from being continuously synchronized unnecessarily. This prevents energy loss and sound vibration performance from deteriorating.

(3) Moreover, although the direct current motor is illustrated as a motor in the said embodiment, an alternating current motor may be sufficient. Any motor capable of controlling the rotational speed may be used. Moreover, although the case where the torque is controlled so as to be the predetermined rotational speed is illustrated, other rotational speed control such as performing the rotational speed control with a constant voltage may be used.
(4) The four-wheel drive conditions are not limited to the above conditions. For example, the four-wheel drive condition may be satisfied immediately when the driver turns on the accelerator.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected and demonstrated about the structure similar to the said 1st Embodiment.
The basic configuration of this embodiment is the same as that of the first embodiment.
However, in the surplus torque calculation unit 8E that determines whether or not the four-wheel drive condition is satisfied, as shown in FIG. 13, when the four-wheel drive condition is satisfied and the process proceeds to step S26, the first embodiment and Similarly, after the 4WD standby flag TKFLG is turned ON, the process proceeds to step S27.
In step S27, the timer is reset and the process proceeds to step S40. In the present embodiment, the acceleration slip exceeding a predetermined value is set as the four-wheel drive condition, so the timer is reset unconditionally. When there are conditions other than a predetermined acceleration slip or more as the four-wheel drive condition, it is determined whether or not the acceleration slip is performed, and if the acceleration slip is performed, the timer may be reset. Also, every time the timer is reset, the timer counting process is started. The processing of the other surplus torque calculation unit 8E is the same as that in the first embodiment.

Further, a part of the clutch synchronization control unit 8H is different from the first embodiment.
The processing of the clutch synchronization control unit 8H of this embodiment is shown in FIG.
In the present embodiment, when the reacceleration standby state is determined in step S520 and the reacceleration standby flag A-TKFLG is turned on, the process proceeds to step S525.
In step S525, it is determined whether the timer is equal to or less than the maximum standby time Ts. If it is determined that the timer is equal to or less than the maximum standby time Ts, the 4WD standby state is determined and the process proceeds to step S530. On the other hand, if the maximum standby time Ts is exceeded, the 4WD standby state is not established, so the process proceeds to step S526, where the 4WD standby flag TKFLG is turned OFF to return.
Other processes are the same as those in the first embodiment.

(Operation / Action)
FIG. 15 shows a time chart example of the present embodiment.
In this embodiment, the timer is reset every time a predetermined acceleration slip or more is detected during four-wheel drive running, and the time until the maximum count time Ts is counted by the timer is set as a condition that the 4WD standby flag TKFLG is ON. .
That is, in the second embodiment, when the front wheel (ENG drive wheel) slip is detected during the previous acceleration, not the four-wheel drive state or the accelerator off operation, the maximum waiting time from the last acceleration slip is detected. During Ts, it is determined that there is a high possibility that the running road surface is a low μ road, and the 4WD standby flag TKFLG is kept ON.

(Effect of this embodiment)
(1) The low friction coefficient road surface estimation means travels on a low μ road until a predetermined time elapses when a predetermined or more slip is generated on the drive wheels or a slip is generated in a state where the driver has requested acceleration. Estimated to be medium.
As a means to estimate whether the running road surface is a low μ road and to determine whether it is necessary to wait for 4WD, for example, with a timer for slip occurrence and traction control operation history, a low μ road The flag that estimates that the vehicle is traveling is maintained.
Thereby, it can be determined that there is a high possibility that the currently running road surface is a low μ road.
Further, it is possible to eliminate erroneous determination that the vehicle is traveling on a low μ road unnecessarily for changes in the road surface.

(Modification)
(1) The 4WD standby flag TKFLG is ON, that is, the condition for starting the timer is the occurrence of slip during acceleration. However, for example, slip convergence, TCS control operation start / end, and ABS operation may be used as the start condition.
(2) The maximum waiting time Ts of the 4WD waiting flag TKFLG may not be a fixed value. The maximum waiting time Ts may be made variable according to the number of occurrences of slip and the amount of slip.

(Third embodiment)
Next, a third embodiment will be described with reference to the drawings. The same components as those in the above embodiment will be described with the same reference numerals.
The basic configuration of this embodiment is the same as that of the above embodiment.
However, the possibility of a reacceleration request is set under a plurality of conditions, and the possibility of a reacceleration request is set higher as the conditions overlap. That is, rank the possibility of re-acceleration requests and change the standby method to prepare for four-wheel drive requests.

In the present embodiment, the following two reacceleration request prediction conditions are provided for detecting the possibility of a reacceleration request.
That is,
(A) When a brake ON → OFF is detected at a predetermined vehicle speed or higher (b) When a steering operation or vehicle turning behavior is detected at a predetermined vehicle speed or higher and the vehicle turning behavior is detected. When one is detected, the clutch 12 is synchronized.
Further, when both of the two conditions are detected, the connection process is performed with the clutch 12 completely or slipped.

For example, 1 is added to the re-acceleration standby flag each time one of the above two re-acceleration request possibility detection conditions is satisfied. However, during four-wheel drive, the re-acceleration standby flag is cleared to zero.
If the re-acceleration standby flag is 1 when the 4WD standby state is recognized, the motor drive for the synchronization process of the clutch 12 is performed. Further, when the 4WD standby state is recognized, if the reacceleration standby flag is 2, the clutch 12 is connected. However, if the synchronization process of the clutch 12 is not completed, the clutch 12 is connected after the synchronization process of the clutch 12 is performed.

The processing according to the present embodiment of the clutch synchronization control unit 8H is shown in FIG.
In this process, it is determined in step S900 whether the vehicle is traveling on two wheels. It returns if it is not running on two-wheel drive. If the vehicle is traveling on two wheels, the process proceeds to step S910.
In step S910, it is determined whether or not one reacceleration request prediction condition is satisfied. However, it is assumed that the traveling road surface is estimated to be a low μ road surface. If the acceleration request condition is satisfied, the process proceeds to step S920.

In step S920, the re-acceleration standby flag A-TKFLG = 1 is set, the motor is driven, and the clutch 12 is synchronized.
Subsequently, in step S930, it is determined whether other reacceleration request prediction conditions are satisfied. That is, the reacceleration standby flag A-TKFLG is added to determine whether or not the reacceleration standby flag A-TKFLG = 2. However, it is assumed that the traveling road surface is estimated to be a low μ road surface. If the acceleration request condition is satisfied, the process proceeds to step S940.
In step S950, the clutch 12 is connected.
When the clutch 12 is connected, the processes in steps S910 to 940 are not performed even in the two-wheel drive travel port. In addition, when the clutch 12 is not connected in step S950 and does not shift to 4WD for a predetermined time or more, it is preferable to release the clutch 12.

(Operation / Action)
An example of a time chart of the present embodiment of FIG. 17 is shown.
At time t1, during the four-wheel drive control, 4WD ends when the driver's accelerator is OFF, and the 4WD standby flag TKFLG = ON is the same as in the above embodiments.
At time t2, a brake OFF operation is detected, and it is first determined that the possibility of a request for reacceleration is at a certain level, and a reacceleration standby flag A-TKFLG 0 → 1 is set.
Further, at time t3, the turning operation is detected, it is determined that the possibility of the driver's reacceleration request is higher, and the reacceleration standby flag A-TKFLG is changed from 1 to 2.
In this embodiment, when “4WD standby flag TKFLG is ON” and “re-acceleration standby flag A-TKFLG = 1” at time t 1, the process shifts to motor rotation synchronization control, and the motor rotation speed is changed to the clutch output rotation speed. Keep synchronized.

Furthermore, if “4WD standby flag TKFLG is ON” and “re-acceleration standby flag A-TKFLG = 2” at time t2, the possibility of the driver requesting acceleration immediately after is very high. In response, the clutch 12 is turned on to prepare for a four-wheel drive request.
In this embodiment, at time t3, the clutch 12 is immediately turned on. However, half-clutch control is started so that the clutch 12 is gradually engaged without being completely engaged. You may do it.

(Effect of this embodiment)
(1) The reacceleration request prediction means has a plurality of reacceleration request prediction conditions for predicting that there is a reacceleration request by the driver. The four-wheel drive predicting means estimates that the road surface of the vehicle is a low μ road, and satisfies the reacceleration request prediction condition of 1, the motor side of the clutch has a rotational speed on the driven wheel side of the clutch. The motor is driven so that the rotation speeds of the motors are synchronized. If two or more reacceleration request prediction conditions are satisfied, the clutch is completely or slipped even before the four-wheel drive conditions are satisfied.

That is, the reacceleration request prediction is determined by a combination of determination by brake operation and determination of driver steering operation or turning behavior of the vehicle. Then, re-acceleration requests are ranked according to possibility, and the standby method for preparing for four-wheel drive requests is changed.
By combining the conditions, the reacceleration request can be predicted more reliably.
In addition, if the possibility of reacceleration is extremely high by ranking the reacceleration requests according to possibility, four wheels that give priority to responsiveness even if sacrificing comfort due to motor idling or clutch connection are somewhat sacrificed. By preparing for driving requirements, it is possible to achieve both acceleration, stability and comfort during re-acceleration on snowy roads.

2 Engine 4 Motor 8A Generator controller 8B Relay controller 8C Motor controller 8D Clutch controller 8E Surplus torque calculator 8F Target torque limiter 8G Surplus torque converter 8H Clutch synchronization controller 12 Clutch

Claims (10)

The main drive wheel is driven by a main drive source, and a sub drive wheel different from the main drive wheel can be driven by a motor, and a clutch is arranged in the middle of the torque transmission path from the motor to the sub drive wheel. During four-wheel drive running that satisfies the conditions, the clutch is controlled to be in a connected state, and the driving torque of the motor is transmitted to the driven wheels, and during two-wheel drive running that does not satisfy the four-wheel drive conditions, the clutch is released. A drive control device for a vehicle to be controlled,
A four-wheel drive prediction means for estimating whether or not there is a high possibility that the four-wheel drive condition is satisfied during the two-wheel drive traveling;
If it is estimated that the four-wheel drive predicting means is likely to be a four-wheel drive condition, the motor is driven so that the rotational speed of the clutch on the driven wheel side is synchronized with the rotational speed of the clutch on the motor side. Motor preliminary drive means;
With
A vehicle drive control device that controls a clutch to a connected state when it is determined that a four-wheel drive condition is satisfied. The four-wheel drive prediction means includes
Low friction coefficient road surface estimating means for estimating whether or not the friction coefficient of the traveling road surface of the vehicle is lower than a predetermined value;
Re-acceleration request prediction means for predicting a state where there is a re-acceleration request by the driver;
With
When the low friction coefficient road surface estimation means estimates that the road friction coefficient is a road surface lower than a predetermined value and the reacceleration request prediction means predicts that there is a reacceleration request, there is a high possibility that the four-wheel drive condition will occur. The vehicle drive control apparatus according to claim 1, wherein the drive control apparatus estimates the vehicle.   The low friction coefficient road surface estimation means estimates that the road surface having a friction coefficient lower than a predetermined value is traveling when the four-wheel drive condition is canceled because the driver no longer requests acceleration. 2. The vehicle drive control device described in 2.   The low friction coefficient road surface estimating means detects that a slip more than a predetermined amount has occurred on the drive wheels or a state in which a slip occurs in a state where the driver has requested acceleration, and that the vehicle is traveling on a road surface having a friction coefficient lower than a predetermined value. The vehicle drive control device according to claim 2, wherein the drive control device estimates the vehicle.   The low friction coefficient road surface estimation means has a friction coefficient lower than a predetermined value until a predetermined time elapses when a slip more than a predetermined amount is generated on the drive wheel or a slip is generated in a state where the driver has requested acceleration. The vehicle drive control device according to any one of claims 2 to 4, wherein the vehicle is estimated to be traveling on a road surface.   The re-acceleration request predicting means predicts that a re-acceleration request is made by the driver when detecting that the braking request from the driver is released in a state of a predetermined vehicle speed or higher. The vehicle drive control device according to claim 5.   The re-acceleration request predicting means predicts a state where there is a re-acceleration request by the driver when detecting a steering operation or turning behavior of the vehicle by a driver at a predetermined vehicle speed or higher. The vehicle drive control device according to any one of claims 2 to 6. The reacceleration request prediction means has a plurality of reacceleration request prediction conditions for predicting that there is a reacceleration request by the driver,
The four-wheel drive predicting means estimates that the road surface of the vehicle is a road surface having a friction coefficient lower than a predetermined value, and satisfies the reacceleration request prediction condition of 1, the rotational speed of the clutch on the driven wheel side is increased. Drive the motor so that the rotation speed on the motor side of the clutch is synchronized,
Further, when two or more reacceleration request prediction conditions are satisfied, the clutch is completely or slipped even before the four-wheel drive conditions are satisfied. 8. A drive control apparatus for a vehicle according to any one of 7 above.   9. The apparatus according to claim 1, further comprising preliminary drive stopping means for stopping the motor driving by the motor preliminary driving means when the motor driving for synchronization by the motor preliminary driving means continues for a predetermined time. A vehicle drive control device according to claim 1. The main drive wheel is driven by a main drive source, and a sub drive wheel different from the main drive wheel can be driven by a motor, and a clutch is arranged in the middle of the torque transmission path from the motor to the sub drive wheel. During four-wheel drive running that satisfies the conditions, the clutch is controlled to be connected to transmit the motor drive torque to the driven wheel, and during two-wheel drive driving that does not satisfy the four-wheel drive conditions, the clutch is controlled to be opened. A vehicle drive control method
If it is estimated that there is a high possibility of four-wheel drive conditions during the two-wheel drive running, the motor is controlled so that the number of rotations of the clutch on the motor side is synchronized with the number of rotations of the clutch on the driven wheel side. A drive control method for a vehicle, wherein the vehicle is driven to rotate.

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