JP2008001185A - Driving force controller for vehicles - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a driving force controller for vehicles capable of securing 4WD performance when reconnecting a clutch. <P>SOLUTION: In the driving force controller for vehicles wherein the output of an engine 2 is transmitted to right and left front wheels 1L and 1R and also transmitted to a generator 7, the generated voltage of the generator 7 is supplied to a motor 4 and right and left rear wheels 3L and 3R are driven by the output of the motor 4, when shifting from a 2-wheel driving state to a 4-wheel driving state, in the case of turning the clutch to a connected state after idling the motor 4 so as to make the rotation speed of the motor 4 equal to a speed equivalent to the rotation speed of the right and left rear wheels 3L and 3R, the target motor torque of the motor 4 is limited in a prescribed period before the changeover of PWM voltage drive and rectangular wave voltage drive. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a driving force control apparatus for a vehicle that drives a generator with a heat engine (for example, an engine) that drives a main drive shaft, and drives a motor with the generator to realize a four-wheel drive state. .

As a conventional vehicle driving force control device configured to drive an axle through a clutch by an electric motor, the rotational speed of the electric motor becomes equal to the speed corresponding to the rotational speed of the axle before driving the axle. It is known that the clutch is turned on after the electric motor is idled (see, for example, Patent Document 1).
JP-A-11-243608

  However, in the above conventional vehicle driving force control device, when the clutch is reconnected, the electric motor is driven to raise the motor rotational speed and make the input / output rotational speed of the clutch coincide with each other while the engine rotational speed is already high. When a control method for switching and executing PWM wave drive control and rectangular wave drive control is adopted as switching control for the inverter to be operated, the PWM wave is generated in a state where the generator rotational speed (engine rotational speed) is higher than in normal 4WD traveling. The drive control is switched to the rectangular wave drive control.

In general, the rectangular wave drive control has higher motor efficiency than the PWM wave drive control. In addition, the operating point of the generator follows an isofield current line that uses the generator speed and the generator field current as parameters, and the higher the generator speed, the more the isofield current line. Has a steep slope.
Therefore, when the PWM wave drive control is switched to the rectangular wave drive control, the generated motor power is excessive due to the change in motor efficiency, and the generator operating point moves on the isofield current line to the high voltage side. At this time, if the engine speed is high and the isofield current line has a steep slope, the output voltage of the generator will be boosted and the 4WD performance may deteriorate due to high voltage failure. Becomes higher.
Therefore, the present invention has been made paying attention to the unsolved problems of the above-described conventional example, and an object thereof is to provide a vehicle driving force control device capable of ensuring 4WD performance at the time of control switching. .

  In order to achieve the above object, when the vehicle driving force control device according to the present invention shifts from the two-wheel driving state to the four-wheel driving state, the rotation speed of the motor is changed to the rotation speed of the driven wheel by the clutch control means. When the clutch is engaged after the motor is idled so as to be equal to the corresponding speed, and the clutch is connected by the clutch control means, the target motor torque limiting means switches from PWM voltage driving to rectangular wave voltage driving. The target motor torque of the motor is limited for a predetermined period before switching.

  According to the present invention, when the clutch is reconnected, the target motor torque is limited only for a predetermined period before switching between the PWM wave driving control and the rectangular wave driving control. Therefore, the power generation at the time of switching from the PWM wave driving control to the rectangular wave driving control is performed. It is possible to reduce the machine field current and suppress an increase in the generated voltage due to a change in motor efficiency, and it is possible to obtain an effect that the generation of a high voltage failure can be suppressed and 4WD performance can be ensured.

Hereinafter, embodiments 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 which is a heat engine (internal combustion engine), and left and right rear wheels 3L and 3R are This is a driven wheel that can be driven by the motor 4.

  For example, a main throttle valve and a sub-throttle valve are interposed in the intake pipe line of the engine 2. The throttle opening of the main throttle valve is adjusted and controlled according to the amount of depression of the accelerator pedal. The sub-throttle valve uses a step motor or the like as an actuator, and the opening degree is adjusted and controlled by a rotation angle corresponding to the number of steps. Therefore, by adjusting the throttle opening of the sub-throttle valve to be equal to or less than the opening of the main throttle valve, the engine output torque can be reduced independently of the driver's operation of the accelerator pedal. That is, the adjustment of the opening degree of the sub-throttle valve is the driving force control that suppresses the acceleration slip of the front wheels 1L, 1R by the engine 2.

The output torque Te of the engine 2 is transmitted to the left and right front wheels 1L and 1R through the transmission and the reference gear 5. Further, a part of the output torque Te of the engine 2 is transmitted to the generator 7 via the endless belt 6, so that the generator 7 has a rotation speed Ng obtained by multiplying the rotation speed Ne of the engine 2 by the pulley ratio. Rotate.
The generator 7 includes a voltage regulator (regulator) for adjusting the output voltage V, and is adjusted to a field current Ifg corresponding to the generator control command value c1 (duty ratio) from the 4WD controller 8. The power generation load on the engine 2 and the voltage V to be generated are controlled.

The electric power generated by the generator 7 can be supplied to the motor 4 via the junction box 10 and the inverter 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. In addition, the motor 4 of this embodiment is an AC motor. Moreover, the code | symbol 13 in a figure shows a difference gear.
In the junction box 10, a relay for connecting and disconnecting the inverter 9 and the generator 7 is provided. In the state where the relay is connected, AC power supplied from the generator 7 is rectified to DC by a rectifier (not shown) and converted into a three-phase current in the inverter 9 to drive the motor 4. Here, the inverter 9 corresponds to power conversion means.

Further, a current sensor is provided in the junction box 10, and the current sensor detects an armature current value Iat of power supplied from the generator 7 to the motor 4, and a signal of the detected armature current Iat. Is output to the 4WD controller 8. In addition, a voltage value (voltage of the motor 4) flowing through the electric wire is detected by the 4WD controller 8.
In the motor 4, the field current Ifm is controlled by a command from the 4WD controller 8, and the drive torque is adjusted to the target motor torque Tm by adjusting the field current Ifm.

This vehicle is provided with a motor rotational speed sensor for detecting the rotational speed Nm of the drive shaft of the motor 4, and the motor rotational speed sensor outputs the detected rotational speed signal of the motor 4 to the 4WD controller 8.
The clutch 12 is, for example, a wet multi-plate clutch, and performs engagement and disengagement according to a command from the 4WD controller 8. In this embodiment, the clutch as the fastening means is a wet multi-plate clutch. However, for example, a powder clutch or a pump-type clutch may be used.

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. 2, the 4WD controller 8 includes a surplus torque calculation unit 8A, a motor control unit 8B, a generator control unit 8C, a relay control unit 8D, and a clutch control unit 8E, and outputs a switching command between 2WD and 4WD. It operates when a drive mode switch (not shown) is in the 4WD state.

The surplus torque calculation unit 8A executes a surplus torque calculation process of FIG. 3 described later, and calculates surplus engine torque corresponding to the acceleration slip of the front wheels.
The motor control unit 8B determines whether or not the vehicle is in the four-wheel drive state (motor drive request state) based on the excess torque calculated by the excess torque calculation unit 8A. By outputting a command signal to the unit 8E, the clutch 12 is connected and the four-wheel drive state is set.

  In the four-wheel drive state, the motor 4 is controlled based on the target motor torque Tm corresponding to the slip ratio of the front wheels and the accelerator opening, and the target generated voltage Vt of the generator 7 for setting the target motor torque Tm is described later. Output to the generator control unit 8C. Here, as a control method for controlling the motor 4, a PWM wave voltage is generated based on the electric power supplied from the generator 7 and applied to the motor 4 when the motor rotation speed Nm region is a low-speed rotation region. In the wave drive control, the medium-speed to high-speed rotation region, rectangular wave drive control that generates a rectangular wave voltage based on the power supplied from the generator 7 and applies it to the motor 4 is adopted.

  Further, when the clutch is shifted from the two-wheel drive state to the four-wheel drive state, a clutch engagement control process shown in FIG. 4 described later is executed, and the motor rotation speed Nm is idled so as to coincide with the target motor rotation speed Nm1. The clutch 12 is brought into a connected state. Further, when the clutch is connected, the target motor torque Tm is limited only for a predetermined period before the control is switched from the PWM wave drive control to the rectangular wave drive control.

The generator control unit 8C calculates the generator control command value to be the target generated voltage Vt while inputting the current generated voltage V, and according to the generator control command c1 via the voltage regulator 22. The output voltage of the generator is controlled by adjusting the field current Ifg of the generator 7 to the value.
The relay control unit 8D controls the cutoff / connection of the power supply from the generator 7 to the motor 4, and keeps the relay 24 in the connected state while in the four-wheel drive state.
The clutch control unit 8E controls the state of the clutch 12 based on a command signal from the motor control unit 8B, and controls the clutch 12 to the connected state (on state) while determining the four-wheel drive state.

  Next, the surplus torque calculation process executed by the surplus torque calculation unit 8A will be described based on the flowchart shown in FIG. This surplus torque calculation process is executed at every predetermined sampling time. First, in step S1, the 4WD controller 8 accelerates slips of the front wheels 1L, 1R based on signals from the wheel speed sensors 27FL, 27FR, 27RL, 27RR. The slip speed ΔVF, which is a quantity, is obtained, and the process proceeds to step S2.

Specifically, the slip speed ΔVF is obtained as follows.
First, based on signals from the wheel speed sensors 27FL, 27FR, 27RL, and 27RR, 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 value of the left and right wheel speeds of the rear wheels 3L and 3R. The average rear wheel speed VWr is calculated. Next, based on the deviation between the average front wheel speed VWf and the average rear wheel speed VWr, a slip speed (acceleration slip amount) ΔVF indicating the degree of acceleration slip of the front wheels 1L and 1R as the main drive wheels is calculated based on the following equation: calculate.
ΔVF = VWf−VWr (1)

In step S2, the 4WD controller 8 determines whether or not the slip speed ΔVF is equal to or higher than a predetermined value ΔVF _TH (for example, 3 km / h). When it is determined that ΔVF <ΔVF _TH, it is determined that the front wheels 1L and 1R are not accelerating and slipping and there is no surplus of engine output, the process proceeds to step S3, and surplus torque (power generation load torque) is determined. After setting Th to “0”, the surplus torque calculation process is terminated.

On the other hand, when the 4WD controller 8 determines in the step S2 that ΔVF ≧ ΔVF _TH, it is determined that the front wheels 1L and 1R are slipping at acceleration, and the process proceeds to step S4.
In step S4, the 4WD controller 8 calculates the absorption torque TΔVF necessary for suppressing the acceleration slip of the front wheels 1L, 1R based on the following equation, and proceeds to step S5. The absorption torque TΔVF is an amount proportional to the acceleration slip amount.
TΔVF = K1 × ΔVF (2)

In step S5, the 4WD controller 8 calculates the current load torque TG of the generator 7 based on the following equation, and proceeds to step S6.
TG = K2 · (V × Ia) / (K3 × Nh) (3)
Here, V is the output voltage of the generator 7, Ia is the armature current of the generator 7, Nh is the rotational speed of the generator 7, K3 is efficiency, and K2 is a coefficient.
In step S6, the 4WD controller 8 obtains the surplus torque, that is, the power generation load torque Th to be loaded by the generator 7, by adding the absorption torque TΔVF calculated in step S4 and the load torque TG calculated in step S5. The process proceeds to step S7.
Th = TG + TΔVF (4)

In step S7, the 4WD controller 8 determines that the vehicle speed Vs that can be obtained based on the average front wheel speed VWf and the average rear wheel speed VWr is the lower limit value of the vehicle speed range in which the motor 4 is over-rotated when the clutch 12 is engaged. It is determined whether or not the rotational vehicle speed is lower than Vs _TH (for example, 30 km / h). When Vs ≧ Vs _TH , the motor 4 is over-rotated and its durability is lowered, so that the process proceeds to step S3 so that the four-wheel drive is not performed.

On the other hand, when the 4WD controller 8 determines in step S7 that Vs <Vs _TH , the process proceeds to step S8, and the maximum load torque Thmax of the generator 7 is calculated.
Next, in step S9, the 4WD controller 8 determines whether or not the power generation load torque Th calculated in step S6 is equal to or greater than the maximum load torque Thmax. When Th ≧ Thmax, the process proceeds to step S10 to limit the final power generation load torque Th to the maximum load torque Thmax, and when Th <Thmax, the surplus torque calculation process is terminated as it is.

Next, the clutch engagement time control process executed by the motor control unit 8B will be described based on the flowchart shown in FIG.
First, in step S21, the 4WD controller 8 determines whether or not the power generation load torque Th is greater than 0. When it is determined that Th> 0, the process proceeds to step S22, and when it is determined that Th ≦ 0. Then, it is determined that the clutch 12 is to be released, and the clutch engagement control process is terminated as it is.

In step S22, the 4WD controller 8 calculates a target motor torque Tm based on the power generation load torque Th. In the present embodiment, the result of selecting the first target motor torque Tm1 according to the power generation load torque Th and the second target motor torque Tm2 according to the vehicle speed Vs and the accelerator opening θ is calculated as the target motor torque Tm. It shall be.
The first target motor torque Tm1 is a target motor torque corresponding to the acceleration slip amount of the front wheels. Further, the second target motor torque Tm2 is larger as the accelerator opening θ is larger and smaller as the vehicle speed Vs is smaller, and is zero when the vehicle speed Vs is higher than a predetermined vehicle speed. Here, the predetermined vehicle speed is, for example, a low-speed vehicle speed that is estimated to have been taken out of the starting state.

Next, in step S23, the 4WD controller 8 limits the target motor torque Tm calculated in step S22 using the maximum torque characteristic that the motor 4 can output.
In step S24, the 4WD controller 8 calculates a control switching motor torque Tmlim when the motor control is switched from the PWM wave drive control to the rectangular wave drive control. Here, the motor torque Tmlim at the time of control switching is set to be proportionally smaller as the engine speed Ne is higher. Even if the slope of the If constant line of the generator 7 is steep, a high voltage abnormality Torque value that does not become is set.

  In step S25, the 4WD controller 8 calculates a torque change rate Tmrate at the time of control switching, which is a torque change rate when limiting the motor torque when switching the motor control from the PWM wave drive control to the rectangular wave drive control. Here, the torque change rate Tmrate at the time of control switching is set to be proportionally smaller as the engine speed Ne is higher. Even if the slope of the If constant line of the generator 7 is steep, the high voltage The torque change rate is set so that it does not become abnormal.

Next, in step S26, the 4WD controller 8 controls the torque limit rotation speed range at the time of control switching, which is a motor rotation speed range where motor torque limitation is started when the motor control is switched from PWM wave drive control to rectangular wave drive control. Nmlim is calculated. Here, the torque limit rotation speed range Nmlim at the time of control switching is set so as to be proportionally smaller as the engine rotation speed Ne is higher, and the target motor torque changes to the target motor torque Tmlim at the torque change rate Tmrate. Is set in consideration of the time required until the motor control is switched.
In step S27, the 4WD controller 8 determines a final target motor torque Tm based on the calculation results of steps S22 to S26.

  That is, when the target motor torque Tm calculated in step S23 is set as the final target motor torque Tm in the normal state and the motor rotation speed Nm is within the torque limit rotation speed range Nmlim during control switching, step S23 is performed. The value obtained by limiting the target motor torque Tm calculated in step 1 to the target motor torque Tmlim with the torque change rate Tmrate is set as the final target motor torque Tm. Further, after switching from PWM wave drive control to rectangular wave drive control, the value obtained by releasing the restriction at the torque change rate Tmrate from the target motor torque Tmlim to the target motor torque Tm calculated in step S23 is used as the final target motor. Set as torque Tm.

Next, in step S28, the 4WD controller 8 calculates a target motor field current Ifm corresponding to the rotational speed Nm of the motor 4, sets the target motor field current Ifm as a target value of the motor field current, and performs step S29. Migrate to Thus, feedback control is performed based on the deviation of the field current value detected by the sensor from the target motor field current Ifm.
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. The field current Ifm of the motor 4 is reduced by a known field weakening control method.

In step S29, the 4WD controller 8 calculates a target armature current Ia by referring to a previously stored map based on the target motor torque Tm and the target motor field current Ifm.
In step S30, the 4WD controller 8 determines the target generated voltage Vt (= Ia × R + E: E is the induced voltage of the motor, and R is the generator and motor based on the target armature current Ia. Between the two and the like, and outputs this to the generator control unit 8C.

Next, in step S31, the 4WD controller 8 determines whether or not the current motor rotation speed Nm matches the target motor rotation speed Nm1. Here, the target motor rotation speed Nm1 is a rotation speed corresponding to the rotation speed of the rear wheels 3L and 3R which are the driven wheels.
When Nm = Nm1, the process proceeds to step S32, a clutch-on command is output to the clutch control unit 8D, and the clutch engagement control process is terminated. When Nm ≠ Nm1, the process proceeds to step S22.
In FIG. 4, the processes in steps S24 to S26 correspond to the target motor torque limiting means, the process in step S27 corresponds to the restriction releasing means, and the processes in steps S31 and S32 correspond to the clutch control means.

Next, the operation and effect of this embodiment will be described. It is assumed that the drive mode switch is operated in the 4WD state.
At the time of starting, if acceleration slip does not occur on the front wheels, the motor 4 and the generator 7 are controlled based on the target motor torque corresponding to the accelerator opening.
Thereafter, when the road surface μ is small or the amount of depression of the accelerator pedal 17 by the driver is large, when the front wheels 1L and 1R which are the main drive wheels 1L and 1R are accelerated and slipped, the 4WD controller 8 responds to the accelerated slip. Calculate the target motor torque. The target motor torque and the target motor torque corresponding to the accelerator opening are selected high, and the motor and the generator 7 are controlled based on the larger target motor torque. This improves the acceleration of the vehicle at the start.

In the present embodiment, when the front wheel slip is detected and the vehicle shifts from the two-wheel drive state to the four-wheel drive state, the clutch is connected after matching the motor rotation speed to the rotation speed corresponding to the rotation speed of the driven wheel. This reduces the shock when the clutch is engaged. When the clutch is reconnected, the motor speed is raised from 0 with the engine speed already high.
By the way, as a control method for controlling the motor 4, a control method for switching between PWM wave drive control and rectangular wave drive control is adopted. When the motor rotation speed is low, PWM wave drive control, medium speed to high speed rotation is adopted. In the area, rectangular wave drive control is executed.

As described above, when the motor control method is switched according to the motor rotation speed region, when the clutch is reconnected, the PWM wave drive control is changed to the rectangular wave drive control during the startup of the motor rotation speed before the clutch is connected. Control switching is performed.
At this time, if the method of limiting the target motor torque for a predetermined period before the control switching is not adopted as in the present embodiment, a high voltage failure may occur at the time of control switching. This will be described in detail below.

In general, the rectangular wave drive control has higher motor efficiency than the PWM wave drive control. Therefore, when the PWM wave drive control is switched to the rectangular wave drive control, the balance between the power supplied on the generator side and the power consumption on the motor side is lost as the motor efficiency changes, and the generated power tends to be excessive.
The operating point of the generator follows an isofield current line with the generator speed and generator field current as parameters, so if the generated power is excessive, the output voltage of the generator is high on the isofield current line. Move to the side.

Here, since the above-mentioned isofield current line has a characteristic that it has a steeper slope as the generator speed is higher, the PWM wave is generated in a state where the engine speed (generator speed) is high as in the case of clutch reconnection. When the drive control is switched to the rectangular wave drive control, a jump in the output voltage of the generator is promoted, and there is a high possibility that the 4WD performance deteriorates due to a high voltage failure.
On the other hand, in the present embodiment, by limiting the target motor torque for a predetermined period before the control switching, it is possible to limit the supply power of the generator, so it is possible to suppress a jump in the output power of the generator, Generation of high voltage failure can be suppressed.

That is, when the clutch 12 is engaged after the motor rotational speed Nm is matched with the target motor rotational speed Nm1 corresponding to the rotational speed of the rear wheels 3L and 3R, the PWM wave is controlled by the clutch connection time control shown in FIG. The target motor torque Tm is limited for a predetermined period before switching from drive control to rectangular wave drive control.
When acceleration slip occurs in the front wheels 1L and 1R, the power generation load torque Th is calculated to be a positive value according to the front wheel slip ratio. Therefore, the 4WD controller 8 determines YES in step S21 of FIG. 4, and in step S22. A target motor torque Tm corresponding to the power generation load torque Th is calculated, and the target motor torque Tm is limited based on the maximum torque characteristic in step S23.

At this time, since the engine speed Ng is relatively high, the 4WD controller 8 calculates a small motor torque Tmlim at the time of control switching in step S24, and calculates a small torque change rate Tmrate at the time of control switching at step S25. The torque limit rotation speed range Nmlim during control switching is calculated to be small.
That is, in this case, the target motor torque Tm is limited from the low rotation speed region to a small value gently.

If the motor rotation speed Nm is very small and not within the torque limit rotation speed range Nmlim at the time of control switching, the 4WD controller 8 sets the target motor torque Tm calculated in step S23 to the final target motor torque Tm in step S27. Based on this, the motor 4 and the generator 7 are controlled.
Thereafter, when the motor rotational speed Nm increases and reaches the torque limit rotational speed range Nmlim at the time of control switching, the 4WD controller 8 sets a value obtained by limiting the target motor torque Tm by the torque change rate Tmrate in step S27. Set to torque Tm. As a result, the target power generation voltage Vt of the generator 7 calculated in step S30 is limited as compared with the normal time. The limitation of the target motor torque Tm is continued until the target motor torque Tm becomes the motor torque Tmlim at the time of control switching.

When the motor rotation speed Nm reaches the switching rotation speed from PWM wave drive control to rectangular wave drive control, the motor control system is switched from PWM wave drive control to rectangular wave drive control.
At this time, even if the generated voltage rises due to a change in motor efficiency, the amount of jumping of the generated voltage is suppressed, so that the generated voltage can be prevented from exceeding the high voltage threshold.

  After the motor control method is switched from the PWM wave drive control to the rectangular wave drive control, the 4WD controller 8 calculates the final target motor torque Tm so as to release the restriction of the target motor torque Tm in step S27. Specifically, the target motor torque Tm is calculated so as to increase at a torque change rate Tmrate from the control-switching motor torque Tmlim to the target motor torque Tm calculated in step S23. That is, the restriction release of the target motor torque is performed over a predetermined time after the control switching, which is the same as the time required to limit the target motor torque before the control switching.

By the way, if the target motor torque is limited to a small value until the clutch is engaged in order to reduce the excessive generated power at the time of control switching, the increase in the motor rotation speed will be delayed, and the clutch reconnection time will increase. End up.
In contrast, in the present embodiment, after the control is switched, the target motor torque limit is released and returned to the normal value, so that the time for limiting the target motor torque can be shortened and the increase in the motor rotation speed is slow. It is possible to avoid an increase in clutch engagement time due to the fact that

In addition, since the restriction is released at the same rate of change as when the target motor torque is restricted, the balance between the power supply on the generator side and the power consumption on the motor side caused by suddenly releasing the restriction is suppressed. Can do.
Thereafter, when the motor rotation speed Nm gradually increases and the motor rotation speed Nm matches the target motor rotation speed Nm1, the 4WD controller 8 determines YES in step S31 of FIG. 4 and proceeds to step S32. Is output to the clutch control unit 8E. As a result, the clutch 12 is engaged and the four-wheel drive state is entered.

  As described above, in the present embodiment, when the clutch is connected after the motor rotational speed is matched with the target motor rotational speed corresponding to the rotational speed of the driven wheel, switching from PWM wave drive control to rectangular wave drive control is performed. Since the motor torque is limited only for the previous predetermined period, it is possible to suppress a sudden increase in the generated voltage due to the control switching being performed in a state where the generator rotational speed is high, and to suppress the occurrence of a high voltage failure. 4WD performance can be ensured.

In addition, since the motor torque at the time of control switching is set to be smaller as the engine speed is higher, the motor torque limit amount can be increased as the generator high-speed rotation has a larger jump of the generated voltage. It can be suppressed.
Furthermore, since the motor torque change rate at the time of control switching is reduced as the engine speed is higher, a stable operation can be ensured while maintaining the balance between the operation of the generator and the motor.

In addition, the higher the engine speed, the lower the motor speed range for starting the motor torque limit is set to the lower speed side, so the motor torque limit can be started at an earlier timing, and the generator and motor are operated. The motor torque can be limited to an appropriate value while maintaining the balance.
Furthermore, after switching from PWM wave drive control to rectangular wave drive control, the motor torque limit is released over a predetermined period of time, preventing the motor torque from being limited and increasing the clutch reconnection time. Can be suppressed.
In the present embodiment, the case where the control switching motor torque Tmlim, the control switching torque change rate Tmrate, and the control switching torque limit rotation speed range Nmlim are calculated based on a preset map has been described. However, it can also be calculated based on the generator characteristics.

It is a schematic structure figure showing an embodiment of the present invention. It is a block diagram which shows the 4WD controller in FIG. It is a flowchart which shows the surplus torque calculation process performed in a surplus torque calculating part. It is a flowchart which shows the control process at the time of clutch connection performed with a motor control part.

Explanation of symbols

1L, 1R Front wheel 2 Engine 3L, 3R Rear wheel 4 Motor 6 Belt 7 Generator 8 4WD controller 8A Target motor torque calculation unit 8B Motor control unit 8C Generator control unit 8D Relay control unit 8E Clutch control unit 10 Junction box 11 Reducer 12 Clutch 27FL, 27FR, 27RL, 27RR Wheel speed sensor

Claims (5)

A heat engine that drives the main drive wheel, a generator that is driven by the heat engine, a motor that is supplied with electric power from the generator via power conversion means to drive the slave drive wheel, and a motor that drives the slave drive wheel. A clutch interposed in a torque transmission path to the drive wheel, wherein the power conversion means generates a rectangular wave voltage from the supplied power and applies the rectangular wave voltage to the AC motor; and the supply In a vehicle driving force control device that generates a PWM wave voltage from the generated electric power and performs switching between PWM wave voltage driving applied to the AC motor,
When shifting from the two-wheel drive state to the four-wheel drive state, the motor is idled so that the rotation speed of the motor is equal to the rotation speed corresponding to the rotation speed of the slave drive wheel, and then the clutch is engaged. And a target motor torque limit for limiting the target motor torque of the motor for a predetermined period before switching from the PWM voltage drive to the rectangular wave voltage drive when the clutch is connected by the clutch control means. A driving force control apparatus for a vehicle.   2. The vehicle driving force control device according to claim 1, wherein the target motor torque limiting unit sets the target motor torque limit amount to be larger as the rotational speed of the generator is higher.   3. The driving force of a vehicle according to claim 1, wherein the target motor torque limiting unit sets a torque change rate when limiting the target motor torque as the rotational speed of the generator is higher. 4. Control device.   The target motor torque limiting means sets the motor rotation speed region where the limit of the target motor torque is started to the lower rotation speed side as the rotation speed of the generator is higher. The vehicle driving force control apparatus according to claim 1.   2. The apparatus further comprises restriction release means for releasing the restriction of the target motor torque by the target motor torque restriction means over the predetermined period after switching from the PWM voltage drive to the rectangular wave voltage drive. 5. The driving force control device for a vehicle according to any one of 4 above.

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