JP4182938B2 - Vehicle drive control device - Google Patents

Description

  The present invention relates to a vehicle drive control device in which at least one of front and rear wheels is driven by an internal combustion engine (engine) and the other is driven by an electric motor.

As a vehicle capable of driving the front wheels with the engine and driving the rear wheels with the output torque of the electric motor, there is one described in Patent Document 1, for example.
In this vehicle drive control device, the rear wheels can be driven by the output of the electric motor, the front wheels are driven by the output of the engine, and the generator is operated by a part of the output of the engine. The electric power generated by the machine is supplied to the electric motor. Then, from the start until the start completion speed is reached, the motor is driven in addition to the engine to enter the four-wheel drive state. Further, in order to solve the problem that an overload is applied to the drive system of the motor when it is detected that the motor is in a power generation state when the vehicle is started (the vehicle speed is near zero), At least one of the armature current or the field current supplied to is controlled to decrease.
Japanese Patent Laid-Open No. 2004-23887

In the above-mentioned Patent Document 1, when the vehicle rolls back (the vehicle moves backward regardless of the drive control state in the forward direction), the armature current or field current of the motor is obtained when the vehicle speed is near zero. Although it is disclosed to decrease, there is no disclosure of how to decrease.
However, since the motor is in the power generation state in the rollback state, the armature current of the motor may become excessive and exceed the allowable armature current allowed for the motor depending on the decrease in the command value. There is.

Moreover, if the control command to the motor is lowered too much during the rollback, the vehicle that is rolling back may not stop, or the acceleration during the rollback (decrease in moving speed backward) may be deteriorated. is there.
The present invention has been made paying attention to the above points, and it is an object of the present invention to provide a vehicle drive control device capable of appropriately suppressing rollback while suppressing an excessive current load on the electric motor. Yes.

In order to solve the above-described problems, the present invention provides an internal combustion engine that drives a main drive wheel, a generator that operates by a part of the output of the internal combustion engine, power that is generated by the generator, and a driven wheel. A drive control device for a vehicle that adjusts the armature current command value and the field current command value of the motor so as to be a target torque command value in a four-wheel drive state.
Rollback detection means for detecting rollback in which the electric motor is driven and controlled in the forward or reverse direction and the vehicle is moving in a direction opposite to the driving direction of the electric motor;
If it is determined that the vehicle is rolling back based on the detection of the rollback detecting means, the sum of the armature current generated by the motor and the armature current supplied from the generator is the maximum allowable from the performance of the motor. Field current limiting means for limiting the field current command value so as to be equal to or less than the armature current is provided.

  ADVANTAGE OF THE INVENTION According to this invention, the drive control apparatus of the vehicle which can suppress rollback appropriately can be provided, suppressing the load by the excessive electric current to an electric motor.

Next, a first embodiment according to 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). For example, the shift control unit has a shift shift schedule based on the vehicle speed and the accelerator opening as information such as a table, and if it determines that the shift point is passed based on the current vehicle speed and the accelerator opening, a shift command is sent to the transmission 30. Output.

  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 detected throttle opening 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 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 via the endless belt 6, so that the generator 7 has a rotational speed obtained by multiplying the rotational speed Ne of the engine 2 by the pulley ratio. Rotate at Nh.
As shown in FIGS. 2 and 3, the generator 7 includes a voltage regulator 22 (regulator) for adjusting the output voltage V, and a generator control command value from the generator control unit 8E in the 4WD controller 8. By adjusting the field current Ifh according to c1 (duty ratio), the power generation load on the engine 2 and the voltage V to be generated are controlled. That is, the voltage regulator 22 receives the generator control command c1 (duty ratio) from the generator control unit 8E, and adjusts the field current Ifh of the generator 7 to the duty ratio according to the generator control command c1. At the same time, the output voltage V of the generator 7 is 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.
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 (electric motor) 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 an armature current value Iat of power supplied from the generator 7 to the motor 4 and detects 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 9 is detected by the 4WD controller 8. Reference numeral 24 denotes a relay, and the cutoff and connection of the voltage (current) supplied to the motor 4 is controlled by a command from 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. 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.

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 calculator 8A, a motor controller 8B, a relay controller 8C, a clutch controller 8D, a generator controller 8E, and a rollback detector 8F. It operates when the mode switch 39 is in the 4WD state.

The relay control unit 8C 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 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.
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 corresponding to the acceleration slip of the front wheels, and performs the following processing based on each input signal for each predetermined sampling time.
That is, as shown in FIG. 4, first, in step S10, the rear wheels 3L, from the wheel speeds of the front wheels 1L, 1R (main drive wheels) calculated based on the signals from the wheel speed sensors 27FL, 27FR, 27RL, 27RR, By subtracting the wheel speed of 3R (secondary drive wheel), the slip speed ΔVF which 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 accelerating and slipping, so the process proceeds to step S100, and after zero is substituted for Tm1, the process 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
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: Generator voltage
Ia: Armature current of the generator
Nh: Generator rotation speed
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. In the above processing, the first target motor torque Tm1 is calculated once the load torque Th at the generator 7 is obtained, but the acceleration slip amount of the front wheels 1L, 1R is directly multiplied by a predetermined gain. Then, the first target motor torque Tm1 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 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 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.

Here, it is considered that the characteristic value for calculating the second target motor torque Tm2 can be started on a road surface where the maximum value of the second target motor torque (CONST portion in FIG. 5) is normally assumed. The motor torque is set. Alternatively, the above characteristic value is the maximum value at which the maximum value of the second target motor torque (CONST portion in FIG. 5) is allowed in the motor characteristics so that the vehicle can start on a road surface with a large running resistance such as deep snow. Set to be.
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 control unit 8B.

Next, the process of the motor control 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 S300 and various types of two-wheel drive states such as a power generation stop (target power generation torque V = 0) signal are obtained. Outputs a signal and returns.

  In step S210, it is determined whether or not the shift is from the four-wheel drive state to the two-wheel drive state. If it is determined that the shift is to the two-wheel drive state, the process proceeds to step S300. It returns after performing a four-wheel drive end process such as outputting a clutch-off command and stopping power generation (target power generation torque V = 0). 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 S220.

In step S220, a clutch-on command is output to the clutch control unit 8D, and the process proceeds to step S230.
In step S230, it is determined whether or not the rollback flag RLB-FLG is ON, that is, in the rollback state. When it is determined that the rollback state is set, the process proceeds to step S240. Transition.

In step S240, it is determined whether or not the vehicle speed VWr is the rollback process start speed Vroll. If the vehicle speed VWr is equal to or higher than the rollback process start speed Vroll, the process proceeds to step S250, and if not, the process proceeds to step S245.
In addition, in this embodiment, it is an example in case the vehicle speed is estimated with the wheel speed of a rear wheel. The determination may be made by directly using the vehicle speed. In this case, the influence of the acceleration slip of the rear wheel can be suppressed.

  The rollback processing start speed Vroll is a value in the range of 2.5 to 4 km / h, for example. This rollback processing start speed Vroll is the maximum value of the rollback speed that a normal driver is assumed to allow rollback, and when the speed is higher than that, the steering stability deteriorates and the general driver Is the limit value of the reverse speed (movement speed) that will release the accelerator pedal and apply the brake.

In step S250, based on the following equation, the target motor torque Tm is reduced by an amount corresponding to the vehicle reverse speed (movement speed: also called rollback speed) at the time of rollback, and then the process proceeds to step S255.
Tm = Tm−f × VWr−α
Here, the vehicle speed at the time of rollback becomes the rollback speed. Further, f is a gain for converting to torque that reduces the rollback speed. Note that a map obtained in advance by experiments may be used.

Further, the loss α is a loss consisting of the sum of the torque due to the moment of inertia of the motor rotor and the loss due to friction, which occurs when a change in the motor rotation speed assumed during rollback occurs.
In step S245, the target motor torque Tm is reduced by the loss α based on the following equation, and then the process proceeds to step S255.

In step S255, 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 set to the target value of the motor field current, and then the process proceeds to step S270.
Here, step S255 is processing for calculating the target motor field current Ifm when the vehicle is in the rollback state.

  The value of the target motor field current Ifm at the time of rollback will be described. As shown in FIGS. 7 and 8, the target motor field current Ifm at the time of rollback is limited according to the reverse speed of the vehicle. The speed gradually decreases until 1 reverse speed Vr1 (the lower limit value of the predetermined reverse speed range), and in the range of the first reverse speed Vr1 to the second reverse speed Vr2 (predetermined reverse speed range), a constant field current is obtained. It is maintained and is set to gradually decrease above the second reverse speed Vr2 (the upper limit value of the range of the predetermined reverse speed).

When the first reverse speed Vr1 is fixed to a field current equal to the target motor field current “A” when the reverse speed is zero (vehicle speed zero), the armature current value generated by the power generation of the motor 4 is The reverse speed (point A) is equal to the target armature current value determined from the target motor torque and the field current value.
Further, when the second reverse speed Vr2 is fixed to the field current “I” when the field is held constant, the armature current value generated by the motor 4 generates the target motor torque Tm and the field magnet. The reverse speed (point B) is equal to the target armature current value determined from the current value.

Further, in the present embodiment, the second reverse speed Vr2 is set to be equal to the rollback processing start speed Vroll.
Next, in step S260, 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 After setting the magnetic current Ifm to the target value of the motor field current, the process proceeds to step S270. 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. 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.

Next, in step S270, the corresponding target armature current Ia is obtained based on a map or the like using the target motor torque Tm and the target motor field current Ifm as variables, and the process proceeds to step S280.
In step S280, based on the target armature current Ia, a target generated voltage V (= Ia × R + E: E is an induced voltage of the motor 4 and R is a 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. Note that E is a negative value during rollback.
The generator control unit 8E calculates a generator control command value c1 that is the target generated voltage V while inputting the current generated voltage, and the generator control command value c1 through the voltage regulator 22. The output voltage of the generator 7 is controlled by adjusting the field current Ifh of the generator 7 to a value according to the above.

Next, the processing of the rollback detection unit 8F will be described with reference to FIG.
The rollback detection unit 8F operates at predetermined sampling times. First, in step S400, it is determined whether or not the shift of the transmission 30 is in the forward drive range. If the forward drive range is determined, step S410 is performed. Otherwise, the process proceeds to step S460.
In step S410, it is determined whether or not the accelerator opening indicating the acceleration instruction amount is equal to or greater than a predetermined opening. If it is determined that the accelerator opening is equal to or greater than the predetermined opening, the process proceeds to step S420. When it is less than the predetermined accelerator opening, the routine proceeds to step S460. The predetermined accelerator opening is a lower limit value of the accelerator opening that is only considered to have an intention to accelerate the vehicle.

In step S420, it is determined whether or not the parking brake PKB is off. If the parking brake PKB is off, the process proceeds to step S430, and if the parking brake PKB is on, the process proceeds to step S460.
In step S430, it is determined whether or not the brake is operating based on the amount of depression of the brake pedal 34. If it is determined that the brake is not operating, the process proceeds to step S440. If it is determined that the brake is operating, step S460 is performed. Migrate to

In step S440, it is determined whether or not the motor 4 is in a power generation state. If it is determined that the motor 4 is in a power generation state, the process proceeds to step S450. If it is determined that the motor 4 is not in a power generation state, the process proceeds to step S460.
Here, the determination as to whether or not the vehicle is in the power generation state is made based on whether or not the counter electromotive force generated by the motor 4 rotating in the direction opposite to the vehicle forward direction is generated.
In step S450, the rollback flag RLB-FLG indicating the rollback state is turned on, and the process ends.
In step S460, the rollback flag RLB-FLG is turned off and the process is terminated.

Next, processing of the engine controller 18 will be described.
In the engine controller 18, processing as shown in FIG. 10 is performed based on each input signal for every predetermined sampling time.
That is, first, in step S500, 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 S510 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 S550. 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 S520. The target slip amount Tslip is set to, for example, about 10% in terms of slip rate.

In step S520, 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 S530.
In step S530, 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 S540.
In step S540, 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 S560.
ΔTe = TeN−Te

On the other hand, in step S550, 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 S560.
In step S560, 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.
At the time of starting, before the acceleration slip occurs on the front wheels, the motor 4 and the generator 7 are controlled based on the target motor torque Tm2 corresponding to the accelerator opening. Further, 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 target motor torque Tm1 corresponding to the accelerated slip is calculated. The target motor torque and the target motor torque corresponding to the accelerator opening are selected high, and the motor 4 and the generator 7 are controlled based on the larger target motor torque Tm. This improves the acceleration of the vehicle at the start.

  In addition, when the front wheel is performing an acceleration slip, if the target motor torque Tm1 corresponding to the acceleration slip amount is larger than the target motor torque Tm2 corresponding to the accelerator opening, the acceleration slip amount depends on the acceleration slip amount. However, in this case, the motor 4 is driven by the power generation output corresponding to the surplus torque exceeding the road surface reaction force limit torque of the front wheels, so that the energy efficiency of the entire vehicle is good.

  Then, when the vehicle starts moving uphill on the hill and is determined to be in the rollback state, the target motor torque Tm of the motor 4 is reduced by the loss α until the reverse speed reaches the rollback processing start speed Vroll. To do. Further, if the driver intends to start by stepping on the accelerator even when the reverse speed exceeds the rollback processing start speed Vroll, the target motor torque Tm of the motor 4 is further reduced by an amount corresponding to the reverse speed. Thus, the target motor torque Tm is suppressed. FIG. 11 shows a conceptual diagram of a change in the target motor torque Tm that is a control command value of the motor 4 with respect to the vehicle speed in the rollback state.

Since the energization direction and the actual rotation direction are reversed during rollback, as shown in FIG. 12, even if the vehicle speed is the same, the torque transmission system from the motor 4 to the rear wheels is loaded compared to the normal direction. Torque increases. Since the torque transmission system includes low-strength parts such as a clutch and a drive shaft, it is desired to prevent an excessive torque load on the torque transmission system.
In the present embodiment, in the rollback state, excessive torque generation to the torque transmission system can be suppressed by suppressing the absolute value of the vehicle speed to be smaller than the target motor torque Tm at the time of forward traveling.

  At this time, when the reverse speed at the time of rollback is small, the amount of torque that increases due to the reverse of the energization direction and the actual rotation direction is small. Therefore, in this embodiment, the reverse speed is equal to or higher than the rollback processing start speed Vroll. Then, by suppressing the torque corresponding to the reverse speed, the 4WD performance (climbing performance) is ensured while suppressing excessive torque generation.

  Further, in the rollback state, the motor rotation shaft rotates in the direction opposite to the driving direction of the motor 4 and the motor 4 is in the power generation state. Therefore, the armature current of the motor 4 is the armature current generated by the power generation of the motor 4. And the total current supplied from the generator 7. For this reason, if the field current value is kept as high as when starting the vehicle, the target motor torque Tm cannot be controlled. Therefore, in this embodiment, as shown in FIG. By limiting or reducing the field current value, the armature current value of the motor 4 is increased, the increase in the motor torque due to the increase in the energization current to the motor 4 is suppressed, and the target motor torque Tm can be controlled.

  Here, when the target motor torque Tm is constant when the reverse speed is equal to or less than the rollback processing start speed Vroll, the armature current generated by the motor 4 is limited to a value that does not exceed the target armature current. The reason why the constant field current is controlled in principle is that the difference between the armature current generated by the motor 4 and the target armature current may be supplied by the generator 7, so that the armature current This is because the target motor torque can be controlled while suppressing the overcurrent.

  However, immediately after the rise of the motor torque and in the vicinity of the vehicle speed 0, the armature current generated by the power generation of the motor 4 is very small, and the rise of the power generation capability of the generator 7 is delayed. With respect to the magnetic current, the target field current at a vehicle speed of zero is set to be large, and the target field current is reduced toward the constant field current according to the reverse speed. This makes it possible to earn the required motor torque even if there is a delay until the current supplied from the generator 7 approaches the target armature current, such as immediately after the rise of the motor torque.

  Further, if the reverse speed exceeds the rollback processing start speed Vroll, the target armature current cannot be controlled by the current from the generator 7 as it is, so the field current is decreased in accordance with the increase of the reverse speed and the generator The target armature current can be controlled by the current from 7. In accordance with this, the target motor torque Tm is reduced to prevent the armature current from exceeding the allowable armature current defined by the motor performance.

FIG. 13 shows the above relationship.
Here, in the above embodiment, the target motor torque Tm is described to be reduced by an amount corresponding to the reverse speed only when the reverse speed is equal to or higher than the rollback processing start speed Vroll. Then, even if it is less than the rollback processing start speed Vroll, the target motor torque Tm may be reduced by an amount corresponding to the reverse speed.

In the present embodiment, the target motor torque Tm is reduced by the loss α in addition to the amount corresponding to the reverse speed. This is due to the following reason.
That is, since the torque transmission system shaft between the motor 4 and the rear wheel has a predetermined spring constant, when the accelerator 4 is stepped on and the motor 4 outputs torque, the torque transmission system shaft As a result of the twisting, as shown in FIG. 12, the rotational speed of the motor 4 is decelerated relative to the vehicle speed and then accelerated, and the transmission torque increases by the rotational inertia. In consideration of this increase, in this embodiment, the target motor torque Tm at the time of rollback is reduced by a loss α.

It should be noted that the loss α may be ignored as long as the loss α is acceptable. Further, since the loss α is generally input within a predetermined time range from the start of motor torque generation, the loss α may be reduced only within a predetermined time range from the detection of rollback.
Further, in the above embodiment, when the front wheel accelerates and slips at the time of starting, the actual target motor torque Tm value is determined by taking into account the target motor torque Tm value corresponding to the acceleration slip, but only based on the accelerator opening. You may make it determine the target motor torque Tm value at the time of start.

  In the above embodiment, the characteristics of the target motor torque Tm at the start and the characteristics of the target motor torque Tm during the travel after the start are set to be the same, but the characteristics of the target motor torque Tm at the start and during the travel are set. May be set to be different. In the above description, the rollback at the time of starting is exemplified, but the control command is also suppressed when the rollback is performed while the torque is reduced during traveling.

In the above embodiment, the target motor torque Tm at the time of start is calculated based on at least the accelerator opening, but an apparatus for determining the target motor torque Tm at the start regardless of the accelerator opening. Even if it is a structure, this invention is applicable.
The motor 4 may be an AC motor instead of a DC motor.

  Here, as the target motor torque Tm at the time of vehicle start, the second target motor torque Tm2 calculated from a map as shown in FIG. 5 is usually adopted, and the output of the motor 4 at the start is allowed by the motor characteristics. The maximum torque is calculated. However, since there may be a difference between the vehicle speed equivalent to the vehicle speed and the vehicle speed as described above, when calculating the second target motor torque Tm2, the vehicle speed, that is, the wheel as described above. The second target motor torque Tm2 obtained from the map shown in FIG. 5 using the speed and the second target motor torque Tm2 obtained from the map shown in FIG. 5 using the rotation speed corresponding to the vehicle speed of the motor rotation speed. It is preferable to perform a select low and calculate the actual second target motor torque Tm2 to ensure that the second target motor torque Tm2 does not exceed the maximum torque allowed by the motor characteristics.

Further, at this time, in order to prevent an adverse effect due to signal noise or the like, a filter process may be performed on the detected vehicle speed or motor rotation speed to limit the amount of change. Also, the target motor torque command value itself may be filtered to limit the amount of change.
When such filter processing is performed, the start of reduction of the control command value corresponding to the reverse speed is delayed by an amount delayed by the filter processing. Therefore, the roll processing start speed Vroll is reduced by the start delay amount ΔVroll (Vroll = Vroll−ΔVroll) to suppress an excessive control command value due to the delay caused by the filter processing. preferable. Note that the roll processing start speed Vroll may be reduced by the start delay ΔVroll only when the deviation between the actual detection value and the value after the filter processing is greater than or equal to a predetermined deviation.

  In the above-described embodiment, the first reverse speed Vr1 is set to a reverse speed at which the armature current generated by the motor 4 is the target armature current with a field current equal to the field current at the vehicle speed of zero. However, with a predetermined margin, the armature current generated by the motor 4 is set to the reverse speed at which the current value is slightly smaller than the target armature current, that is, the reverse speed is set to be slightly smaller than the reverse speed. Also good.

Similarly, the second reverse speed Vr 2 is set to a reverse speed at which the armature current generated by the motor 4 becomes the target armature current with a field current equal to the field current when the field is constant. Even if the armature current generated by the power generation of the motor 4 is set to a reverse speed at which the current value is slightly smaller than the target armature current, that is, the reverse speed is set to be slightly smaller than the reverse speed. good.

  In the above embodiment, the second reverse speed Vr2 and the roll processing start speed Vroll are made to coincide with each other, but the sum of the armature current generated by the motor 4 and the current from the generator 7 is allowed by the motor 4. The second reverse speed Vr2 may be a reverse speed shifted from the roll processing start speed Vroll within a range not exceeding the maximum armature current.

In the above description, as shown in FIG. 9, the process of the rollback detection unit 8F of the present embodiment is determined as to whether or not it is in the forward drive range, and then the accelerator opening state, the parking brake on / off, Although it is determined based on the depression amount of the brake pedal 34 and the power generation state of the motor 4 whether or not it is in the rollback state, the rollback may be detected by performing a process as shown in FIG. That is, in step S600, it is determined whether or not the shift of the changing machine 30 is the forward drive range. If it is determined that the shift range is the forward drive range, the process proceeds to step S610, and if not, the process proceeds to step S630. In step S610, it is determined whether the induced voltage Er of the motor 4 is smaller than a predetermined rollback determination value ErTH (for example, 0.6 V). First, based on the motor voltage Vm, the motor armature current Ia, and the motor resistance R, the induced voltage Er is calculated based on the following equation.
Er = V−Ia × R

  When the induced voltage Er calculated in this way is smaller than the rollback determination value ErTH, the process proceeds to step S620 and the rollback flag RLB-FLG indicating that the vehicle is in the rollback state is turned ON and the process is ended. To do. On the other hand, when the induced voltage Er is equal to or higher than the rollback determination value ErTH, the process proceeds to step S630.

In step S630, the rollback flag RLB-FLG is turned OFF and the process is terminated.
Here, whether or not the vehicle is in the rollback state can be determined based on whether or not the induced voltage Er is smaller than a predetermined rollback determination value ErTH, for example, in the same direction as the motor rotates when the vehicle moves forward. If it is set so that the induced voltage Er is output in the positive direction when the motor rotates in the direction, the induced voltage Er becomes a negative value when rotated in the reverse direction. In the calculation, when the induced voltage Er is a negative value, if the process of “0” is performed, the induced voltage Er is equal to the wheel speed being higher than the predetermined value (the wheel is rotating). Since it is “0”, it is smaller than the rollback determination value ErTH, and the rollback state can be detected on the assumption that the motor is rotating in the reverse direction to the case of rotating in the forward direction.

  In the present embodiment, the rollback state is described as a state in which the shifter shifts backward when the shifter is in the forward drive range. However, the present invention is not limited to this, and the shift of the transmission is not limited to this. A state in which the vehicle moves forward when it is in the reverse drive range can also be a rollback state. In this case, it is determined whether or not the shift of the transmission is in the reverse range, and the rollback is performed when it is determined that the shift of the transmission is in the reverse drive range and the motor is rotating in the vehicle forward direction. It can be determined that it is in a state.

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, vehicle speed, and the 2nd target motor torque. It is a figure which shows the motor control part which concerns on embodiment based on this invention. It is a figure which shows the state of the target field current at the time of the rollback which concerns on embodiment based on this invention. It is a figure explaining the example of how to determine the target field current at the time of the rollback which concerns on embodiment based on this invention. It is a figure explaining the process of the rollback detection 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 schematic diagram which shows the change of the target motor torque which is a control command value at the time of the rollback which concerns on embodiment based on this invention. It is a schematic diagram which shows the change of the target field current and target armature current at the time of the rollback which concerns on embodiment based on this invention. It is a figure explaining the torque fluctuation accompanying the fluctuation | variation of a motor rotation speed. It is a figure explaining the process of the rollback detection part which concerns on other embodiment based on this invention.

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 controller 8C Relay control Part 8D clutch control part 8E generator control part 8F rollback detection part 9 electric wire 10 junction box 11 speed reducer 12 clutch 14 intake pipe 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 rotation 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 Tm Target motor torque Tm1 First target motor torque Tm2 Second target motor torque RLB-FLG Rollback detection flag Tslip Target slip amount Ifh Generator field current V Generator voltage Nh Power generation Machine speed Ia Target armature current Ifm Target motor field current E Motor induced voltage Nm Motor speed (rotation speed)
Th Generator load torque Te Engine output torque Vr1 First reverse speed (lower limit)
Vr2 Second reverse speed (lower limit)

Claims (11)

A four-wheel drive system comprising an internal combustion engine that drives main drive wheels, a generator that operates with a portion of the output of the internal combustion engine, and an electric motor that is supplied with power generated by the generator and that can drive the driven wheels In the state, in the vehicle drive control device that adjusts the armature current command value and the field current command value of the motor so as to become the target torque command value,
Rollback detection means for detecting rollback in which the electric motor is driven and controlled in the forward or reverse direction and the vehicle is moving in a direction opposite to the driving direction of the electric motor;
If it is determined that the vehicle is rolling back based on the detection of the rollback detecting means, the sum of the armature current generated by the motor and the armature current supplied from the generator is the maximum allowable from the performance of the motor. A vehicle drive control device comprising: a field current limiting means for limiting the field current command value so as to be equal to or less than an armature current.   2. The field current limiting unit according to claim 1, wherein the field current command value decreases continuously or stepwise as the moving speed of the vehicle in the rollback state increases. Vehicle drive control device. The field current command value when the moving speed of the vehicle is zero is set higher than the field current command value when the moving speed of the vehicle in the rollback state is positive. The vehicle drive control device according to claim 2.   The field current limiting means keeps the field current command value constant in a predetermined moving speed range, and the upper limit value of the field constant moving speed range is the motor current at the constant field current command value. 4. The moving speed at which the armature current generated by power generation is equal to the armature current command value or a value that is lower than the armature current command by a predetermined current value. The vehicle drive control device described in the item.   The lower limit value of the moving speed range is a moving speed at which the armature current generated by the motor is equal to the armature current command value with a field current command value equal to the field current command value when the moving speed of the vehicle is zero. The drive control apparatus for a vehicle according to claim 4.   6. The field current command means according to claim 1, wherein the field current limiting means limits the field current command value according to the moving speed only when the moving speed of the vehicle in the rollback state is equal to or higher than a predetermined value. A drive control device for a vehicle according to any one of the preceding claims.   The vehicle drive according to any one of claims 1 to 6, further comprising target torque reduction means for reducing the target torque command value by an amount corresponding to a moving speed of the vehicle in a rollback state. Control device. 8. The vehicle drive control apparatus according to claim 7 , wherein the target torque reducing means further suppresses the target torque command value by an amount corresponding to the rotational inertia caused by the acceleration / deceleration change of the rotation speed of the electric motor.   9. The vehicle according to claim 7, wherein the target torque reduction unit performs suppression according to the movement speed of the target torque command value only when the movement speed is equal to or higher than a predetermined speed. Drive control device.   The field current limiting means keeps the field current command value constant in a predetermined moving speed range, and the upper limit value of the field constant moving speed range is the motor current at the constant field current command value. The armature current generated by power generation is equal to the armature current command value or a moving speed that is lower than the armature current command by a predetermined current value, and the moving speed that is the upper limit value is equal to the predetermined speed. The vehicle drive control device according to claim 9. The vehicle drive control device according to any one of claims 1 to 10, wherein a moving speed of the vehicle in a rollback state is estimated from a motor rotational speed.

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