JP2005348565A - Driving force controller of vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inhibit a degradation of the durability of a relay for connecting a power generator and a battery, and improve an initial response for driving a motor. <P>SOLUTION: The driving force controller of the vehicle basically and exclusively supplies power from the power generator 7 driven by an engine 2 to the battery 42 or the motor 4. If it determines that the battery ceases to be charged and the motor begins to be driven while the battery is charged, a current supplied to the battery 42 becomes zero or small by connecting the power generator 7 and the motor 4, and a switch SW for connecting the power generator 7 and the battery 42 is interrupted. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a vehicle driving force control apparatus that supplies electric power of a generator driven by an internal combustion engine to a motor and a battery.

In the apparatus described in Patent Document 1, in a vehicle in which front wheels are driven by an internal combustion engine and rear wheels are driven by a motor, a general electric component and a main that can supply power to the motor to a generator driven by the internal combustion engine. A battery and a sub battery dedicated to the motor are connected in parallel.
JP-A-8-175209

Normally, vehicle electrical components that operate at 12V are the mainstream. If such a device configuration is adopted, the motor for driving the rear wheels is also supplied with a voltage of about 12V. That is, it is assumed that a sufficient output for driving the rear wheels cannot be obtained at about 12V.
Therefore, in order to set the voltage supplied to the motor to 12 V or more without installing a battery separately, a relay as a switching mechanism is provided for the power supply from the generator to supply power to the battery for electrical components. The power supply to the wheel drive motor can be switched, and the power of the generator is supplied exclusively to the battery and motor. In other words, the voltage of the generator is adjusted to be equivalent to 12V while charging the battery for electrical components. However, during motor driving, it is conceivable to adjust the voltage of the generator so that it becomes a voltage necessary for motor driving.

  At this time, a motor drive command is issued from the battery charging state, and in order to stop charging the battery and supply the power of the generator to the motor, it is necessary to cut off the relay between the generator and the battery. However, switching from the connected state to the disconnected state in a state where current is flowing into the relay may adversely affect the durability of the relay.

On the other hand, if an attempt is made to avoid the operation of shutting off the relay while the current is flowing into the relay, the output voltage of the generator is reduced until the current stops flowing to the battery charging relay, and then the relay Is cut off, and then the electric power of the generator is supplied to the wheel driving motor. However, when such an operation is performed, the output voltage of the generator is once reduced until the battery charging current becomes zero, and then the supply of the generated power to the motor is started and the generated power corresponding to the required torque of the motor Thus, the initial response of the motor drive is reduced.
The present invention pays attention to the above points, and it is an object to improve the initial response of the motor drive while suppressing a decrease in durability of the relay connected to the generator and the battery.

  In order to solve the above-described problems, the present invention provides a vehicle driving force control device that supplies power of a generator driven by an internal combustion engine to a battery or a motor, and stops the battery charging during the battery charging to drive the motor. When it is determined to start, the connection between the generator and the battery is cut off after the current supplied to the battery is reduced to zero or small by connecting the generator and the motor.

  According to the present invention, the initial response of the motor drive is improved while the relay interposed between the generator and the battery is cut off while the current to the relay is small or not flowing. Is possible.

Next, 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, the left and right front wheels 1L and 1R are main drive wheels driven by the engine 2, and the left and right rear wheels 3L and 3R can be driven by the motor 4. It is a ring. 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 detection means 32 for detecting the current shift range, and the shift position detection means 32 outputs the detected shift position signal to the 4WD controller 8.
The transmission 30 performs a speed change operation based on a shift command from a speed change control unit (not shown). The shift control unit has, for example, a shift shift schedule based on the vehicle speed Vv and the accelerator opening θ as information such as a table, and shifts when it is determined that the shift point is passed based on the current vehicle speed Vv and the accelerator opening θ. The command is output to the transmission 30.

  A main throttle valve 15 and a sub-throttle valve 16 are interposed in the intake pipe line 14 (for example, an intake manifold) of the engine 2. The throttle opening of the main throttle valve 15 is adjusted and controlled in accordance with the amount of depression of an 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, or the engine controller 18 is electrically operated according to the depression amount detection value of the accelerator sensor 40 that detects the depression amount of the accelerator pedal 17. The throttle opening degree is adjusted by adjusting and controlling. The detected depression amount value of the accelerator sensor 40 is also output to the 4WD controller 8.

  The sub-throttle valve 16 is adjusted and controlled by a rotation angle corresponding to the number of steps using the step motor 19 as an actuator. 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, and the number of steps of the step motor 19 is feedback-controlled based on the throttle opening detection value detected by the throttle sensor. 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.

Further, an engine speed detection sensor 21 that detects the speed of the engine 2 is provided, and 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, and a stroke amount of the brake pedal 34 is detected by a brake stroke sensor 35. 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 through the braking devices 37FL, 37FR, 37RL, 37RR such as disc brakes equipped on the wheels 1L, 2R, 3L, 3R according to the input brake stroke amount. .
Reference numeral 39 denotes a drive mode switch that outputs a switching command between 2WD and 4WD.
Further, a part of the rotational torque Te of the engine 2 is transmitted to the generator 7 through the endless belt 6, so that the generator 7 is obtained by multiplying the rotational speed Ne of the engine 2 by the pulley ratio. Rotate at Nh.

  As shown in FIG. 2, the generator 7 includes a voltage regulator 22 (regulator) for adjusting the output voltage Vg, and a generator control command value c1 from the battery / generator control unit 8E of the 4WD controller 8. By adjusting the field current Ifh according to (duty ratio), the power generation load Th and the generated voltage Vg for the engine 2 are controlled. That is, the voltage regulator 22 receives the generator control command c1 (duty ratio) from the battery / generator control unit 8E, and sets the field current Ifh of the generator 7 to the duty ratio according to the generator control command c1. While adjusting, it can output to the 4WD controller 8 while detecting the output voltage Vg of the generator 7.

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.
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.

  In addition, a current sensor 23 is provided in the junction box 10, and the current sensor 23 detects the current value Ia of the electric power supplied from the generator 7 to the motor 4, and outputs the detected armature current signal to 4WD. Output to the controller 8. In addition, a voltage value (voltage of the motor 4) flowing through the electric wire 9 is detected by the 4WD controller 8. Reference numeral 24 denotes a relay that constitutes the first relay, and the cutoff and connection of the voltage (current) supplied to the motor 4 by the command from the 4WD controller 8 are controlled.

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. Reference numeral 25 denotes a thermistor that measures the temperature of the motor 4.
A motor rotation speed sensor 26 that detects the rotation speed Nm of the drive shaft of the motor 4 is provided, and the motor rotation speed sensor 26 outputs the detected rotation speed signal of the motor 4 to the 4WD controller 8.

The electric wire 9 branches to a second electric wire 41 at a position upstream from the junction box 10, and the second electric wire 41 is connected to a battery 42 for a general electrical component 44 through a switch SW. The switch SW is controlled to be connected / disconnected in accordance with a command from the 4WD controller 8. The switch SW includes a semiconductor rectifying element and a charging relay that constitutes a second relay. And the output destination of the generator 7 can be adjusted by controlling the said relay 24 and switch SW, respectively. The semiconductor rectifier element constitutes a backflow preventing means.
The battery 42 further includes a remaining capacity detecting means 43 for detecting the remaining capacity of the battery 42, and the remaining capacity detecting means 43 outputs a detected signal to the 4WD controller 8.

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 target motor torque calculation unit 8A, a motor variable adjustment unit 8B, a motor control unit 8C, a relay control unit 8D, a clutch control unit 8E, and a battery / generator control unit 8F. . The target motor torque calculation unit 8A, motor variable adjustment unit 8B, motor control unit 8C, relay control unit 8D, and clutch control unit 8E operate when the drive mode switch 39 is in the 4WD state.

The relay control unit 8C controls the cut-off / connection of the power supply from the generator 7 to the motor 4, and during the four-wheel drive state, that is, when the target motor torque Tm described later is larger than zero, the relay control unit 8C 24 is set to the connected state, and when the target motor torque Tm is zero, the cut-off state is set.
The clutch control unit 8D controls the state of the clutch 12 and controls the clutch 12 to be in a connected state while determining that it is in the four-wheel drive state, that is, when a target motor torque Tm described later is larger than zero. When the motor torque Tm is zero, the motor is opened.

The target motor torque calculation unit 8A includes a surplus torque calculation unit 8Aa, an acceleration assist torque calculation unit 8Ab, and a motor torque determination unit 8Ac.
The surplus torque calculation unit 8Aa is a means for calculating surplus engine torque according to the acceleration slip of the front wheels 1L, 1R, and as shown in FIG. 4, based on each input signal for each predetermined sampling time, The following processing is performed.
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. Next, from 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 by the following equation.
ΔVF = VWf -VWr

In step S20, it is determined whether or not the determined slip speed ΔVF is greater than a predetermined value, for example, zero. If it is determined that the slip speed ΔVF is 0 or less, it is estimated that the front wheels 1L, 1R are not accelerated slipping, so the routine proceeds to step S30, where zero is substituted for Tm1, and then returns.
On the other hand, if it is determined in step S20 that the slip speed ΔVF is greater than 0, it is estimated that the front wheels 1L and 1R are slipping at acceleration, and therefore the process proceeds to step S40.

In step S40, the absorption torque TΔVF necessary for suppressing 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 · (Vg × Ia) / (K3 × Nh)
here,
Vg: 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 power generation load torque Th to be loaded by the generator 7 is obtained based on the following formula, and the process proceeds to step S70.
Th = TG + TΔVF
Next, in step S70, it is determined whether or not the power generation load torque Th is greater than the maximum load capacity HQ of the generator 7 determined from the specifications and the like. If it is determined that the power generation load torque Th is equal to or less than the maximum load capacity HQ of the generator 7, the process proceeds to step S90. On the other hand, if the target power generation load torque Th exceeds the maximum load capacity HQ of the generator 7, in step S80, the power generation load torque Th is limited to the maximum load capacity HQ, and the process proceeds to step S90.

  In step S90, the first target motor torque Tm1 corresponding to the generator load torque Th is obtained, and the process is terminated. The first target motor torque Tm1 is a target motor torque corresponding to the acceleration slip amount of the front wheels 1L, 1R. In the above process, the first target motor torque Tm1 is calculated after obtaining the load torque Th at the generator 7, but the first target motor torque Tm1 is directly calculated from the acceleration slip amounts of the front wheels 1L, 1R. May be calculated.

Next, processing of the acceleration assist torque calculation unit 8Ab will be described.
The acceleration assist torque calculator 8Ab calculates a second target motor torque Tm2 corresponding to the vehicle speed Vv and the accelerator opening θ (acceleration instruction amount by the driver) based on the map shown in FIG. The second target motor torque Tm2 is set to be larger as the accelerator opening θ is larger and smaller as the vehicle speed Vv is smaller, and to be zero at a predetermined vehicle speed or higher. The predetermined vehicle speed is, for example, a low vehicle speed that is estimated to be that the vehicle has left the start state.
Next, the motor torque determination unit 8Ac performs select high for the first and second target motor torques Tm1 and Tm2 calculated by the surplus torque calculation unit 8Aa and the acceleration assist torque calculation unit 8Ab, and sets the larger value to the target motor. The torque Tm is determined and output to the motor variable adjustment unit 8B.

  Next, the process of the motor variable adjustment unit 8B will be described with reference to FIG. The motor control unit 8B operates every predetermined sampling time. First, in step S200, it is determined whether or not the target motor torque Tm is larger than “0”. If it is determined that Tm> 0, since the front wheels 1L and 1R are in the four-wheel drive state (motor drive request state) such as acceleration slipping, the process proceeds to step S210. If it is determined that Tm ≦ 0, since the four-wheel drive state (motor drive request state) is not established, the process proceeds to step S310 to output various signals in the two-wheel drive state such as a power generation stop (Vm = 0) signal. And return.

  In step S210, it is determined whether or not the shift is from the four-wheel drive state to the two-wheel drive state. It returns after performing the wheel drive end processing. For example, if it is determined that the motor rotation speed has approached the allowable limit rotation speed, or if the range of the transmission 30 is in the non-drive range (parking or neutral), it is determined that the shift to the two-wheel drive state has occurred. On the other hand, if it is a four-wheel drive state, it will transfer to step S215.

  In step S215, it is determined whether or not the switch SW is ON, that is, the battery 42 is in a connected state. If it is determined that the battery 42 is in a connected state, the process proceeds to step S260, where the switch SW is OFF and the battery 42 is disconnected. In this case, the process proceeds to step S220, and the process proceeds to calculation of the target motor field current Ifm for normal motor drive control. That is, in step S260, it is determined whether or not the target motor field current Ifm is “0” (whether or not it is the first cycle of motor driving), and if it is determined to be “0”, that is, the target motor for motor driving. If the field current Ifm is not set, the process proceeds to step S220 and the target motor field current Ifm for driving the motor is set.

On the other hand, if the target motor field current Ifm is not “0”, the process proceeds to step S270, and after the target motor field current Ifm is reduced as a process for disconnecting the battery, the process proceeds to step S230. This step S270 constitutes a field adjusting means.
Next, in step S220, 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 process proceeds to step S230. To do. The motor control unit 8C performs feedback control 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. 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 and reducing the induced voltage E, the current flowing through the motor 4 is increased to obtain the required motor torque. As a result, even if the motor 4 rotates at high speed, the increase in the motor induced voltage E is suppressed and the decrease in the motor torque is suppressed, so that the required motor torque can be obtained. 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 by adjusting the field current Ifm according to the rotational speed Nm of the motor 4 with respect to the required motor torque may be provided. 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, even if the motor 4 rotates at high speed, the increase in the induced voltage E of the motor 4 is suppressed and the decrease in the motor torque is suppressed, so that the required motor torque can be obtained. 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.

Next, at step S230, the target motor torque Tm and the target motor field current Ifm are used as variables, the corresponding target armature current Ia is obtained based on a map or the like, and the process proceeds to step S240.
In step S240, based on the target armature current Ia, the generated voltage Vm (= Ia × R + E: E is the induced voltage E of the motor, and R is the voltage between the generator 7 and the motor 4 for setting the target motor torque Tm. After calculating and outputting the resistance, the process is terminated.

Further, the motor control unit 8C performs feedback control of the motor field current with the target field current Ifm determined by the motor variable adjustment unit 8B as a target value.
The battery / generator control unit 8F includes a power generation variable adjustment unit 8Fa and a power generation control unit main body 8Fb.
The power generation variable adjustment unit 8Fa is a processing unit that adjusts the determination of the target power generation voltage Vt and the battery charging, and performs the process shown in FIG. 7 at every predetermined sampling time.

That is, in step S410, it is determined whether there is a motor drive request, for example, whether the target motor torque Tm is greater than zero. If it is determined that there is a motor drive request, the process proceeds to step S420, and it is determined that there is no motor drive request. If so, the process proceeds to step S470.
First, a case where the target motor torque Tm is greater than zero and it is determined that there is a motor drive request will be described. When there is a motor drive request, the relay 24 is ON and the generator 7 and the motor 4 are connected.

In step S420, it is determined whether or not the switch SW is ON. If the switch SW is ON, that is, if the battery 42 is connected, the process proceeds to step S430, and if not, the process proceeds to step S550.
In step S550, the power generation target voltage Vt is set as the motor target voltage Vm, and the process ends.
In Step S430, it is determined whether or not the current Ib to the battery 42 is zero. If it is zero, the process proceeds to Step S460, and if not, the process proceeds to Step S440. Whether or not the current Ib is zero may be determined by detecting whether or not the current directly flows into the battery 42 or by determining whether or not the generated voltage has become equal to or lower than the battery voltage.
In step S460, the switch SW is turned off, the battery 42 is disconnected from the generator 7 and the motor 4, and the process ends.

  In step S440, it is determined whether or not the motor rotation speed Nm is greater than zero, that is, whether or not the motor 4 is rotating. If the motor 4 is rotating, the process is terminated as is. Is not rotating, the target voltage Vt of the generator 7 is reduced and the process is terminated. When the motor 4 is rotating, the switch SW is unconditionally changed to OFF when the current Ib to the battery 42 is flowing even after a predetermined time has elapsed since the motor drive request was made. Anyway.

Next, processing when there is no request for motor drive will be described. In this case, the relay 24 is OFF and the generator 7 and the motor 4 are not connected.
In step S470, it is determined whether or not it is necessary to charge the battery 42 based on the signal from the remaining capacity detecting means 43. If it is determined that charging is necessary, the process proceeds to step S480, and if it is determined that charging is not required. The process proceeds to step S500. In step S500, the power generation target voltage Vt is set to zero. Subsequently, in step S510, the switch SW is turned off, and then the process ends.

In step S480, after setting the power generation target voltage Vt to the battery charge voltage VD, the switch SW is turned on in step S490 and the process is terminated.
The power generation control unit main body 8Fb obtains a field current value for setting the power generation target voltage Vt based on the power generation target voltage Vt and the current output voltage Vg, and generates a generator control command value corresponding to the field current value ( The output voltage Vg of the generator 7 is controlled by obtaining the duty ratio and outputting it to the voltage regulator 22 of the generator 7.

Next, processing of the engine controller 18 will be described.
In the engine controller 18, processing as shown in FIG. 8 is performed based on each input signal for every predetermined sampling time.
That is, first, in step S600, the acceleration slip amount ΔV of the front wheels 1L and 1R as the main drive wheels is obtained, and the process proceeds to step S610 to determine whether or not the acceleration slip amount ΔV exceeds the target slip amount Tslip. If it exceeds the target slip amount Tslip, the process proceeds to step S660. On the other hand, when the acceleration slip amount ΔV is equal to or less than the target slip amount Tslip, the process proceeds to step S620. The target slip amount Tslip is set to, for example, about 10% in terms of slip rate.

In step S620, the target output torque TeN requested by the driver is calculated based on the detection signal from the accelerator sensor 40, and the process proceeds to step S630.
In step S630, the current output torque Te is calculated based on the throttle opening, the engine speed Ne, and the like, and the process proceeds to step S640.
In step S640, 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 S650.
ΔTe = TeN−Te

On the other hand, in step S660, so-called engine TCS control is performed, and a predetermined TCS torque change is substituted for the deviation ΔTe, and the process proceeds to step S650. This step constitutes internal combustion engine output suppression means.
In step S650, a change Δα of the throttle opening α corresponding to the deviation ΔTe is calculated, and an opening signal corresponding to the change Δα of the opening is output to the step motor 19 to return. . In the above description, the opening degree signal Δα corresponding to the deviation ΔTe is output for the sake of easy understanding. However, in practice, in order to smooth the change of the torque or the like, every time the engine is started. The torque is changed by a predetermined torque increase or torque decrease.

Next, the operation of the apparatus having the above configuration will be described. In the following description, it is assumed that the drive mode switch 39 is operated to the 4WD state.
When the vehicle is traveling, because the road surface μ is small or the accelerator pedal 17 is depressed by the driver, the torque transmitted from the engine 2 to the front wheels 1L, 1R becomes larger than the road surface reaction force limit torque. When the front wheels 1L and 1R, which are the main drive wheels 1L and 1R, are accelerated and slipped, the clutch 12 is connected, and the generator 7 generates electric power with a power generation load corresponding to the acceleration slip amount ΔV with respect to the engine. Is driven, and the state shifts to the four-wheel drive state. At this time, the motor 4 is driven by surplus power generated by the generator 7 and the rear wheels 3L and 3R which are driven wheels are also driven, thereby improving the acceleration of the vehicle. In addition, since the motor 4 is driven with an excess torque exceeding the road surface reaction force limit torque of the main drive wheels 1L, 1R, energy efficiency is improved and fuel efficiency is improved.

Subsequently, the driving torque transmitted to the front wheels 1L, 1R is adjusted so as to approach the road surface reaction force limit torque of the front wheels 1L, 1R, thereby shifting to the two-wheel driving state. As a result, the acceleration slip at the front wheels 1L and 1R which are the main drive wheels is suppressed.
Further, at the time of starting, even if the acceleration slip on the front wheels 1L, 1R is zero or small, the motor is driven with the target motor torque Tm2 corresponding to the accelerator opening θ to ensure start acceleration. .
When the motor 4 is not driven and the battery needs to be charged, the switch SW is turned on, and the power generation voltage is adjusted to the charging voltage VD to charge the battery.
If it is determined during the battery charging that the motor drive is necessary as described above, the battery 42 is disconnected and the control shifts to the four-wheel drive control.

This migration process in the present embodiment is performed as follows.
That is, the generator 7 and the motor 4 are connected to supply a part of the output of the generator 7 to the motor 4, that is, a part of the generated current flows to the motor 4 side, so that the generator 7 is not reduced. Voltage drops. Further, if the vehicle is running, the target motor field current Ifm is once set to a target value for motor control, and then adjusted so as to reduce the target motor field current Ifm until no current flows into the battery 42. When the current stops flowing to the battery 42 side, the relay of the switch SW is turned off to disconnect the battery 42, and then the target motor field current Ifm is returned to the field current value for driving the motor and the power generation target The voltage is also changed from the battery voltage VD to the power generation Vm corresponding to the target motor torque, and the control is completely shifted to the control for four-wheel drive.

Here, the output voltage-current characteristic of power generation has a relationship as shown in FIG. 9, and when the power generation output is the same, the output voltage decreases as the output current increases. As the motor field current is decreased, the motor induced voltage E is decreased and the current flowing into the motor 4 is increased. Therefore, the output voltage of the generator 7 follows the voltage-current characteristic line as shown in FIG. The voltage drops. In addition, since the current flows to the motor 4 side simply by connecting regardless of the magnitude of the motor field current, when the generated voltage is reduced to a voltage value at which the current does not flow to the battery 42 side by connecting the relay 24 In this case, the motor field control for the 4WD drive is performed without adjusting the motor field current for the transition as described above.
Here, at the time of transition during the rotation of the motor, it is not always necessary to reduce the power generation output of the generator 7 in order to prevent the current from flowing to the battery 42. The power generation output may also be reduced by reducing the power.

  As described above, if it is determined that the battery charging state shifts to the motor driving control, the motor field current may be suppressed to a small value, but the motor 4 can be immediately driven and set to the four-wheel driving state. In both cases, it is possible to prevent deterioration of the durability of the switch SW by cutting the switch SW in a state where no current flows. Also, since the motor field current at the time of the above transition is as close as possible to the target field current of the motor control, the switch SW is turned OFF and the return to the original target motor field current is performed at an early stage. Is called. Here, although the motor torque during the transition may be reduced by reducing the target motor field current below the target value, the motor current increases by suppressing the field current. The motor torque is increased by the amount and compensated.

  Here, as a comparison, assuming that the current flowing into the battery 42 is simply reduced by reducing the output of the generator 7 when switching from the charged state to the motor drive, as shown in FIG. Next, the field current of the generator 7 is lowered (see arrow i), the generator output is reduced, the switch SW is turned off, the relay 24 is turned on, the motor 4 is connected, and then the power is generated again. The field current of the machine 7 is increased and adjusted to the voltage / current of the power generation output for obtaining the target motor torque. For this reason, the initial response of the motor drive is slower than in the present embodiment.

FIG. 11 shows a time chart example at the time of transition from battery charging to motor drive control in the present embodiment.
Further, when the motor 4 is not rotating, such as when the vehicle starts, the battery 24 is switched to the motor drive, the relay 24 is turned on and the generator 7 and the motor 4 are connected, that is, the motor 4 side. To reduce the power generation voltage without reducing the power generation output, and if the current still flows into the battery 42 side, the field of the generator 7 is reduced so that the voltage of the power generator 7 is lowered, When the current stops flowing to the battery 42 side, the switch SW is turned off to disconnect the battery 42.

  Even in this case, as soon as there is a motor drive request, the motor 4 can be driven, so that the initial response is improved. In addition, although there is a possibility of reducing the power generation output, the power generation output itself is reduced after the current is supplied to the motor 4 side to reduce the power generation voltage, so that the power generation output itself is reduced as compared with the comparative example shown in FIG. Therefore, the amount of reduction in the generated power can be suppressed to a small value, and therefore the transition time to the generated power corresponding to the target motor torque after the switch SW is turned off can be shortened.

  In principle, it is assumed that the electric power from the generator 7 is supplied to the battery 42 or the motor 4. However, in this embodiment, in the transition process from battery charging to motor driving, the generator is temporarily 7, both the battery 42 and the motor 4 are connected in parallel. At this time, although the case where the voltage of the battery 42 is higher than the required voltage of the motor 4 is also assumed, in this embodiment, the switch SW is provided with a semiconductor rectifier element for preventing a reverse flow of the battery current. Further, it is possible to prevent an excessive current from flowing from the battery 42 to the motor 4. In other words, if excessive current flows to the motor 4 as described above on a low μ road such as an icing road and the motor torque becomes excessively larger than necessary, the rear wheels 3L and 3R may slip (idle). In the embodiment, since the semiconductor rectifier is provided as means for preventing the backflow of the battery current, such inconvenience is prevented.

  Here, in the above embodiment, the control is performed so that the switch SW is turned off after the current flowing into the battery 42 is reliably zero, but the present invention is not limited to this. For example, when the motor 4 is not rotating, such as when starting, the switch SW may be turned off unconditionally if the generated voltage is reduced by simply connecting the generator 7 to the motor 4. Although the inflow current may not be zero, the switch SW can be turned off in a state where the current flowing into the battery 42 is small.

It is a schematic device block diagram concerning the embodiment based on the present invention. It is a system configuration figure concerning an embodiment based on the present invention. It is a block diagram which shows the 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 which shows the relationship between the accelerator opening which concerns on embodiment based on this invention, and the 2nd target motor torque. It is a figure which shows the motor variable adjustment part which concerns on embodiment based on this invention. It is a figure which shows the process of the electric power generation variable adjustment part which concerns on embodiment based on this invention. It is a figure which shows the process of the engine controller which concerns on embodiment based on this invention. It is a figure which shows the predetermined vehicle speed which concerns on embodiment based on this invention. It is a figure explaining the behavior at the time of transfer concerning the embodiment based on the present invention. It is a figure explaining the behavior at the time of transfer in a comparative example.

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 calculator 8Aa Surplus torque calculator 8Ab Acceleration assist torque calculator 8Ac Motor torque determiner 8B Motor variable adjuster 8C Motor Control unit 8D Relay control unit 8E Clutch control unit 8F Battery / generator control unit 8Fa Power generation variable adjustment unit 8Fb Power generation control unit main body 9 Electric wire 10 Junction box 11 Reducer 12 Clutch 14 Intake line 15 Main throttle valve 16 Sub throttle valve 18 Engine controller 19 Step motor 20 Motor controller 21 Engine speed sensor 22 Voltage regulator 23 Current sensor 26 Motor speed sensor 27FL, 27FR, 27RL, 27RR
Wheel speed sensor 30 Transmission 31 Differential gear 32 Shift position detecting means 34 Brake pedal 35 Brake stroke sensor 36 Brake controller 37FL, 37FR, 37RL, 37RR
Braking device 39 Drive mode switch 40 Accelerator sensor 41 Second electric wire 42 Battery Tm Target motor torque Tm1 First target motor torque Tm2 Second target motor torque Tslip Target slip amount Ifh Generator field current Vg Generator voltage Vt Generator Target voltage Vm motor power generation target voltage VD battery charging voltage Nh generator speed Ia target armature current Ifm target motor field current E motor induced voltage Nm motor speed (rotation speed)
θ Accelerator opening Th Generator load torque Te Engine output torque

Claims (5)

  In a vehicle driving force control device that supplies electric power of a generator driven by an internal combustion engine to a battery or a motor, if it is determined that the battery charging is stopped and the motor driving is started during battery charging, the generator and the motor are connected. The vehicle driving force control device is characterized in that, after the current supplied to the battery is reduced to zero or small, the connection between the generator and the battery is cut off. A generator driven by an internal combustion engine, a motor driven by the generator, a battery charged by the generator, a first relay for connecting / disconnecting the generator and the motor, and power generation A second relay for connecting / disconnecting the machine and the battery,
When a motor drive command is input while the battery is being charged by the generator, the vehicle driving force control device is characterized in that the first relay is set in a connected state and then the second relay is set in a disconnected state.   The vehicle driving force control device according to claim 2, wherein the second relay is cut off when it is determined that the voltage of the generator has become equal to or lower than the battery voltage.   4. The vehicle driving force control device according to claim 3, further comprising field adjusting means for adjusting a voltage of the generator toward a battery voltage or less by adjusting a field current of the motor.   The vehicle driving force control device according to any one of claims 1 to 4, further comprising backflow prevention means for preventing backflow of current from the battery to the motor side.

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