JP2007245899A - Driving force controller for electric motor type four wheel drive vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To quickly switch two wheel drive to four wheel drive in the case of start so as to execute four wheel drive start with a high response, when a vehicle starts from a stopped state. <P>SOLUTION: When a selection operation from an N rage to a D range is performed at a t1, an electric motor is preliminarily excited by field currents Ifm1. This preliminary excitation is performed, only during a set time Δt1 for suppressing power consumption. After selecting N to D, a driver releases a brake pedal to make the brake inoperable (t2), and increases the engine revolution by stepping on an acceleration pedal (t3) for starting a vehicle. The electric motor is preliminarily excited by the field currents Ifm from the brake operation release time t2 prior to start; and the field currents Ifm of the electric motor are increased from the Ifm1, in response to the rising of the motor torque command value tTm from the start time t3, when the engine rotation is increased for driving the motor driving wheel; and the vehicle is started by four wheel drive based on this and the engine drive wheel. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  In the present invention, one of the front and rear wheels is driven by a main power source such as an internal combustion engine (engine), and the other wheel is driven by power from an electric motor that responds to power generated by a generator coupled to the main power source. In particular, when the vehicle starts, the electric motor drive wheels are driven via the electric motor by the electric power generated by applying a power generation load to the generator to start four-wheel drive. The present invention relates to a driving force control technique for an electric motor type four-wheel drive vehicle.

  In addition to main drive wheels driven by power from a main power source such as an internal combustion engine (engine), an electric motor driven by power from an electric motor that responds to power generated by a generator coupled to the main power source Conventionally, as an electric motor type four-wheel drive vehicle including a drive wheel, there are those described in Patent Document 1 and Patent Document 2, for example.

  This vehicle drives the front two wheels (or the rear two wheels) with an engine, and the rear two wheels (or the front two wheels) can be driven by an electric motor. To directly drive the electric motor.

  When controlling the generator and electric motor during four-wheel drive, the surplus torque that causes the drive slip of the main drive wheel is determined by comparing the road surface reaction force of the main drive wheel and the engine torque. The electric motor is driven by the electric power generated by applying the corresponding power generation load to the generator, and the corresponding wheel is driven by the electric motor under a situation where the main driving wheel is driven to slip. Let the four wheels run.

By the way, when starting the vehicle, since a large driving force is required and driving slip of the main driving wheel is likely to occur, there is also a meaning of improving the starting performance, the presence or absence of driving slip of the main driving wheel, that is, Regardless of the presence or absence of engine surplus torque, the electric motor is driven by the electric power generated by applying a power generation load to the generator, and the vehicle is started with four wheels: the electric motor drive wheel and the engine driven main drive wheel. Let
JP 2004-215499 A Japanese Patent Application Laid-Open No. 07-231508

  However, in the conventional electric motor type four-wheel drive vehicle described above, the driver switches the automatic transmission from the neutral (N) range to the traveling (D) range in a braking state where the brake pedal is depressed, After that, release the brake pedal to release the braking operation, and then apply a load to the generator from the time when the foot is moved to the accelerator pedal and depressed to increase the engine speed to a startable speed. Since the vehicle is started with four wheels by generating electric power and driving the electric motor with the electric power from now on, the following problems arise.

At the start of the above, the electric motor drive wheel starts rotating and the four-wheel drive is actually started.
When the generator is excited by energizing the field coil from the no-load state and generates power according to the generated load (when the accelerator pedal is depressed), the electric motor is moved from the no-load state to the field coil based on this generated power. Motor torque response delay until it is excited by energization to the motor and starts generating motor torque according to energization (excitation force) to the field coil,
The sum of the reduction gear transmission response delay from the start of the generation of the motor torque until the backlash of the reduction gear mechanism between the electric motor and the wheel driven by the electric motor (backlash due to the gap between the meshing teeth) is filled with the motor torque. Since the time corresponding to
There is a considerable response delay (four-wheel drive response delay when starting) until the electric motor-driven wheels actually start rotating and four-wheel drive is started.

  As a measure to improve the four-wheel drive response at the start, as shown in FIG. 5 and FIG. 7 with hatching, the electric motor or the By making the generator field pre-excited (pre-excitation motor torque command value is indicated by tTm1, pre-excitation motor field current is indicated by Ifm1, and pre-excitation generator field current is indicated by Ifh1). In this case, it is conceivable to improve the motor torque response delay and the reduction gear transmission response delay at the time t3 when the accelerator pedal is depressed last.

However, the driver may not perform the starting operation of releasing the brake pedal and depressing the accelerator pedal for a considerable time after the N → D selection operation, and during this time, the electric motor and generator If the magnet is in a pre-excited state, heat generation of the electric motor and power consumption of the battery become problems.
Therefore, it is common sense to stop the pre-excitation control for setting the fields of the electric motor and the generator to the pre-excitation state when the set time as indicated by Δt1 in FIGS. 5 and 7 elapses.

Therefore, as shown in FIGS. 5 and 7, when the brake pedal is released after the set time Δt1 has elapsed (instantaneous t2) and then the accelerator pedal is depressed (instantaneous t3), the starting operation is performed. It will be a start without encouragement,
Although the speed reducer transmission response delay described above has been eliminated by pre-excitation during the set time Δt1, the motor torque response delay described above cannot be avoided, and a corresponding four-wheel drive response delay occurs when starting.

  An object of the present invention is to propose a driving force control device for an electric motor type four-wheel drive vehicle capable of improving the response of the four-wheel drive at the time of starting.

For this purpose, the driving force control apparatus for an electric motor type four-wheel drive vehicle according to the present invention has the following configuration as described in claim 1.
First of all, the premise of the electric motor type four-wheel drive vehicle is
A main drive wheel driven by power from a main power source;
An electric motor drive wheel driven by power from an electric motor that responds to power generated by a generator coupled to the main power source,
When the vehicle starts, four-wheel drive is performed by driving electric motor drive wheels via the electric motor with electric power generated by applying a power generation load to the generator.

The driving force control device of the present invention is such an electric motor type four-wheel drive vehicle,
Of the release of the brake operation and the rotation increase operation of the main power source that are sequentially performed at the time of starting, the configuration is such that at least one of the field of the generator and the electric motor is kept in a pre-excited state from when the brake operation is released. It is characterized by that.

According to the driving force control apparatus of the present invention,
In order to keep at least one of the field of the generator and the electric motor in a pre-excited state from when the brake operation is released,
There is a request to switch from the two-wheel drive state to the four-wheel drive state due to the start by the rotation increase operation of the main power source performed after the brake operation is released, and this excitation is pre-excited when exciting the field of the generator and the electric motor. From the state, the electric motor generates the motor torque corresponding to the energization (excitation force) to the field coil from the rotation increase operation of the main power source (from the start operation end). The motor torque response delay until the start can be reduced,
By the above pre-excitation, the backlash of the speed reduction gear mechanism that is indispensable between the electric motor and the electric motor drive wheel is packed, so there is no delay in the speed reducer transmission response,
The four-wheel drive response delay at start, which is the sum of the motor torque response delay and the reduction gear transmission response delay, can be reduced to improve the four-wheel drive response at start.

In addition, since the pre-entrainment is executed from the time of release of the brake operation, and when starting, the rotation increase operation of the main power source performed after the release of the brake operation is performed immediately after the release of the brake operation.
In addition, the above-described motor torque response improvement effect and reduction gear transmission response improvement effect during the main power source rotation increasing operation by the pre-excitation can be surely enjoyed, and as a result, the above-described four-wheel drive response improvement effect at start-up is ensured. Can be made.

Hereinafter, embodiments of the present invention will be described in detail based on examples shown in the drawings.
FIG. 1 schematically shows a drive system of an electric motor type four-wheel drive vehicle including a drive force control device according to an embodiment of the present invention.
In this embodiment, this vehicle is a front engine / front wheel drive vehicle (F / F vehicle) driven by an engine (internal combustion engine) 2 with the left and right front wheels 1L and 1R as the main power source, and the left and right rears. A so-called electric motor type four-wheel drive vehicle in which the wheels 3L and 3R can be driven by a rear wheel drive motor 4, which is an electric motor, as required.

As usual, the engine 2 is assumed to increase its output according to the degree to which the driver depresses an accelerator pedal (not shown).
The engine 2 is drivably coupled to the left and right front wheels (main drive wheels) 1L and 1R via a transaxle in which the automatic transmission 5 and the differential gear device 6 are configured as an integral unit. It is assumed that the vehicle is transmitted to the left and right front wheels 1L and 1R via the differential gear device 6 and used for traveling of the vehicle.

  Next, a rear wheel drive system by the electric motor 4 will be described. This includes a dedicated generator 8 driven via an endless belt 7 by a part of the output torque of the engine 2, and the generator 8 The engine is driven at a rotational speed obtained by multiplying the rotational speed of 2 by the belt pulley ratio, and a load is applied to the engine 2 in accordance with the field current Ifh applied to the field current line 8a adjusted by the four-wheel drive controller 9. Electric power is generated according to the torque.

The electric power generated by the generator 8 is supplied to the rear wheel drive motor 4 through the relay 11 through the power line 10.
The relay 11 is also controlled by the command from the controller 9 when the power line 10 is cut off when the generator 8 becomes poorly controlled, or when the rear wheel drive is unnecessary and the controller 9 does not apply a power generation load to the generator 8. Since there is some power generation by the permanent magnet, the power line 10 is cut off so as not to be supplied to the motor 4.

  The drive shaft of the rear wheel drive motor 4 is coupled to the differential gear device 14 of the left and right rear wheels (electric motor drive wheels) 3L and 3R via the speed reducer 12 and the 4WD clutch 13 incorporated therein, and the output of the motor 4 If the torque is increased by the gear ratio by the speed reducer 12 and the 4WD clutch 13 is engaged by the electric power from the clutch engagement power line 13a, this increased torque is distributed and output to the left and right rear wheels 3L, 3R by the differential gear device 14. To be done.

The four-wheel drive controller 9 also controls the engagement / release of the 4WD clutch 13 and the rotation direction / drive torque of the electric motor 4.
In controlling the electric motor 4, the controller 9 obtains the motor torque command value of the electric motor 4 corresponding to the target driving force of the left and right rear wheels (electric motor driving wheels) 3L, 3R determined according to the vehicle operating state, and calculates the field current. By adjusting the field current Ifm from the line 4a to the electric motor 4, the motor drive torque is controlled to coincide with this command value, and the motor rotation direction is controlled by the direction of the field current Ifm.

In order to perform the above-described control of the electric motor 4, the generator 8, the relay 11, and the 4WD clutch 13, in addition to inputting the signal from the four-wheel drive switch 21 to the four-wheel drive controller 9,
Signals from the wheel speed sensor group 22 for individually detecting the wheel speeds (front wheel speeds) V _WFL and V _WFR of the left and right front wheels 1L and 1R and the wheel speeds (rear wheel speeds) V _WRL and V _WRR of the left and right rear wheels 3L and 3R When,
A signal from the motor rotation sensor 23 for detecting the rotational speed Nm of the rear wheel drive motor 4,
A signal from the inhibitor switch 24 for detecting a selection range for determining the transmission form of the automatic transmission 5,
A signal from the accelerator opening sensor 25 that detects the accelerator pedal depression amount (accelerator opening) APO,
Input a signal from the brake switch 26 that turns ON when the brake pedal is depressed (during brake operation).

The four-wheel drive controller 9 determines whether the four-wheel drive is necessary and automatically performs the motor four-wheel drive while the driver is turning on the four-wheel drive switch 21 as described later.
While the driver is turning off the four-wheel drive switch 21, the two-wheel drive by only the engine drive of the front two wheels is continuously performed.

However, at the time of starting, the four-wheel drive controller 9 does not make the above-mentioned determination of the four-wheel drive on the condition that the driver turns on the four-wheel drive switch 21 and unconditionally engages the 4WD clutch 13. It is assumed that motor four-wheel drive is performed.
As shown in FIG. 5 and FIG. 7, when the four-wheel drive is started, the four-wheel drive controller 9 releases the brake operation by depressing the brake pedal (t2) and then the engine speed increasing operation is performed by depressing the accelerator pedal. From (t3), the motor torque command value tTm = tTm2 of the electric motor 4 corresponding to the target driving force of the left and right rear wheels (electric motor driving wheels) 3L, 3R determined according to the accelerator opening APO is obtained, and the field current line By adjusting the field current Ifm from 4a to the electric motor 4, the motor drive torque is controlled to coincide with this command value tTm = tTm2, and the field current line is generated so that the generator 8 generates the necessary power at this time. A field current Ifh to 8a is determined, and a power generation load corresponding to the field current Ifh is applied to the engine 2 to generate the necessary power.

Hereinafter, the four-wheel drive control other than the basic start performed by the four-wheel drive controller 9 will be described.
First, by the process shown in FIG. 2, surplus torque of the engine 2 that causes the driving (acceleration) slip of the front wheels 1L and 1R that are the main driving wheels (engine driving wheels) is calculated.
In step S1, from the average front wheel speed Vwf that can be obtained from the front wheel speeds V _WFL and V _WFR detected by the wheel speed sensor group 22, the average after that that can be obtained from the rear wheel speeds V _WRL and V _WRR that are also detected by the wheel speed sensor group 22 By subtracting the wheel speed Vwr, the driving (acceleration) slip amount ΔVf of the left and right front wheels 1L and 1R as the main driving wheels is obtained.

In the next step S2, it is determined whether or not a driving slip has occurred depending on whether or not the driving slip amount ΔVf of the left and right front wheels 1L and 1R is a predetermined value, for example, 3 km / h or more.
When it is determined that the drive slip amount ΔVf is less than 3 km / h, the drive slip is not generated and the control is terminated as it is because there is no surplus of engine output.

When a drive slip is generated in step S2, where the drive slip amount ΔVf is determined to be 3 km / h or more, it is necessary to suppress the excess torque of the engine that generates the drive slip of the front wheels 1L, 1R, that is, the drive slip in step S3. The absorption torque T (ΔVf) is calculated by T (ΔVf) = K1 × ΔVf.
K1 is a gain obtained through experiments or the like.

In the next step S4, the current load torque Tg of the generator 8 is obtained. In step S5, the current generator load torque Tg and the surplus torque T (ΔVf) are added together to obtain the target power generation load of the generator 8. Find the torque Th.
In step S6, the motor speed VSP that can be obtained from the wheel speeds V _WFL , V _WFR , V _WRL , V _WRR is a motor overspeed vehicle speed that is a lower limit value of the vehicle speed range in which the motor 4 is overrotated when the 4WD clutch 13 is engaged ( For example, check whether it is less than 30km / h).

If the vehicle speed VSP is equal to or higher than the motor overspeed vehicle speed, the motor 4 is overrotated and its durability is lowered. Therefore, the control is terminated as it is so that the four-wheel drive is not performed, but the vehicle speed VSP is less than the motor overspeed vehicle speed. Then, in step S7, the maximum load torque Thmax of the generator 8 is obtained.
Next, in step S8, it is checked whether or not the target power generation load torque Th (step S5) of the generator 8 is greater than or equal to the maximum load torque Thmax, and if so, the limit in which the target power generation load torque Th can be realized by setting Th = Thmax in step S9. If Th <Thmax, the control is terminated and the target power generation load torque Th is set to the value as obtained in step S5.

In FIG. 2, the method of obtaining the target power generation load torque Th of the generator 8 only when the engine drive wheels 1L and 1R generate a drive slip has been described.
Even if the engine drive wheels 1L and 1R may cause a drive slip or when the engine drive wheels 1L and 1R are in a low speed state below a predetermined level, the target power generation load torque Th of the generator 8 is driven in order to realize the four-wheel drive of the electric motor. According to

The four-wheel drive controller 9 controls the generator 8 and the electric motor 4 by the control program of FIG. 3 based on the target power generation load torque Th of the generator 8 obtained as described above.
In step S11, it is checked whether or not there is a power generation request depending on whether or not the target power generation load torque Th of the generator 8 is positive.
If there is no power generation request, the control is terminated, so that the power generation load of the generator 8 is not applied to the engine 2, and the 4WD clutch 13 is in a released state.
If there is a power generation request, in step S12, the target motor field current Ifm is calculated from the motor rotation speed Nm based on the scheduled map.
Although not shown, at the same time, when the input / output rotational speeds of the 4WD clutch 13 coincide with each other, the 4WD clutch 13 is engaged so that the rotation of the motor 4 can be transmitted to the rear wheels 3L and 3R.

Here, as shown in step S12, the target motor field current Ifm with respect to the rotational speed Nm of the motor 4 is set to a constant predetermined current value when the motor rotational speed Nm is equal to or smaller than the predetermined rotational speed, and the motor rotational speed beyond that is determined. When the number is reached, the field current Ifm of the motor 4 is reduced by a known field weakening control method.
The reason for this is that when the motor 4 rotates at a high speed, the motor torque decreases due to the increase of the motor back electromotive force E. Therefore, when the motor rotation speed Nm exceeds a predetermined value, the field current Ifm of the motor 4 is decreased and reversed. This is because the current flowing through the motor 4 is increased by reducing the electromotive voltage E so that the required motor torque Tm can be obtained.

Next, at step S13, the back electromotive force E of the motor 4 is calculated from the target motor field current Ifm and the rotation speed Nm of the motor 4 obtained as described above, based on a predetermined map.
Further, in step S14, a corresponding motor torque command value tTm is calculated based on the power generation load torque Th, and a target motor field current Ifm corresponding to the motor torque command value tTm is commanded to the electric motor 4, so that the electric motor 4 outputs a torque corresponding to the motor torque command value tTm.

In step S15, a target armature current Ia that is a function of the motor torque command value tTm and the target motor field current Ifm is calculated.
Thereafter, in step S16, the target voltage V of the generator 8 is obtained from the target armature current Ia, the total resistance R, and the counter electromotive voltage E by calculation of V = Ia × R + E.
The controller 9 feedback-controls the field current Ifh of the generator 8 so that the generated voltage of the generator 8 becomes the target voltage V thus obtained.

In addition to the control of the generator 8 and the electric motor 4, the four-wheel drive controller 9 executes the control program of FIGS. 4 and 6 to start pre-excitation control of the electric motor 4 and the generator 8 as follows. By performing the above, it is assumed that the effect of improving the four-wheel drive response at the start of the present invention is achieved.
First, to explain the pre-excitation control at the start of the electric motor 4 shown in FIG.
In step S21, it is checked whether or not the selected range of the automatic transmission 5 is the forward travel (D) range.
In step S22, it is checked whether or not the accelerator pedal is depressed with the accelerator pedal depressed from the accelerator opening APO.
In step S23, a check is made as to whether or not the brake is being depressed with the brake pedal depressed.

  In step S21, it is determined that the vehicle is in the forward travel (D) range. In step S22, it is determined that the accelerator pedal is not depressed and the brake pedal is not depressed in step S23. When starting in the driving (D) range, the brake operation is released, but when it is determined that the accelerator pedal is not yet depressed (the accelerator is not in the ON state) (instant t2 in FIG. 5), in step S24, as shown in FIG. Thus, even if the motor torque command value tTm is 0 before the accelerator ON instant t3, ifm1 for pre-excitation is given as the motor field current Ifm, and the electric motor 4 is pre-excited from t2 when the brake operation is released. .

  After reaching the accelerator ON instant t3 in FIG. 5, the motor torque command value tTm is set to the value tTm2 corresponding to the accelerator opening APO because the accelerator is ON, so the motor field current Ifm is set to the motor torque command. As a value corresponding to the value tTm = tTm2, four-wheel drive start using the electric motor 4 is also performed.

  When it is determined in step S21 that the vehicle is not in the forward travel (D) range, it is already determined in step S22 that the accelerator is on (after starting), or in step S23, the brake operation state is still determined. Since the pre-relief is not necessary or is still too early, the control is terminated without executing step S24.

Next, to explain the pre-excitation control at the start of the generator 8 shown in FIG.
In step S21 to step S23, the same check as in the step indicated by the same reference numeral in FIG. 4 is performed. In step S21, it is determined that the vehicle is in the forward travel (D) range, and the accelerator pedal is not depressed in step S22 yet. When it is determined that the brake pedal is not depressed in step S23, that is, when the vehicle starts moving in the forward travel (D) range, the brake operation is released, but the accelerator pedal is not depressed yet (accelerator ON state). 7 (instantaneous t2 in FIG. 7), in step S25, the motor torque command value tTm is before the accelerator ON instant t3 as shown in FIG. Ifh1 for pre-compulsion is given, and the generator 8 is pre-excited from t2 when the brake operation is released.

  After reaching the accelerator ON instant t3 in FIG. 7, since the motor torque command value tTm is set to the value tTm2 corresponding to the accelerator opening APO after the accelerator is ON, the generator field current Ifh is set to the motor torque. As a value corresponding to the command value tTm = tTm2, four-wheel drive start using the electric motor 4 described above is made possible.

  When it is determined in step S21 that the vehicle is not in the forward travel (D) range, it is already determined in step S22 that the accelerator is on (after starting), or in step S23, the brake operation state is still determined. Since the above pre-excitation is unnecessary or is still too early, the control is terminated without executing step S25.

By the way, in this embodiment, as shown in FIG. 5 and FIG.
In order to keep the fields of the generator 8 and the electric motor 4 in the pre-excited state from t2 when the release of the brake pedal (release of the brake operation), which is performed immediately before raising the engine speed by depressing the accelerator pedal at the start,
Because of the start by depressing the accelerator pedal (engine rotation increasing operation) after releasing the brake operation (instant t3), there is a request to switch from the two-wheel drive state to the four-wheel drive state, and the field of the generator 8 and the electric motor 4 When this is excited, it is promptly completed because the excitation is from the pre-excitation state, and the electric motor 4 energizes the field coil (excitation force) from the engine rotation increasing operation (from the start operation end). ) Until the start of generating the motor torque according to the motor torque response delay,
With the pre-excitation between t2 and t3 above, the backlash of the reduction gear mechanism 12 between the electric motor 4 and the electric motor drive wheels 3L, 3R is packed, so there is no delay in the reduction gear transmission response,
The four-wheel drive response delay at start, which is the sum of the motor torque response delay and the reduction gear transmission response delay, can be reduced to improve the four-wheel drive response at start.

Moreover, in order to execute the pre-compression from the time t2 when the brake operation is released, the engine rotation increasing operation through the depression of the accelerator pedal that is performed after the brake operation is released at the time of starting is performed immediately after the brake operation is released. Because there is
In addition, the motor torque response improvement effect and the reduction gear transmission response improvement effect due to the pre-excitation can be surely enjoyed, and as a result, the above-described four-wheel drive response improvement effect at start can be ensured.

  The generator 8 and the electric motor 4 may be pre-excited with electric power from the battery, but the electric motor 4 is pre-excited with the electric power generated by the pre-excitation of the generator 8. By doing so, it is not necessary to cover the pre-excitation energy of the electric motor 4 with the battery, and it is possible to suppress a decrease in the battery storage state, which is advantageous.

This requirement can be realized by configuring the control circuit for the generator 8 and the electric motor 4 as shown in FIG.
In FIG. 8, parts that function in the same manner as in FIG.
Reference numeral 16 denotes an in-vehicle battery mainly for vehicle electrical components 17 (air conditioners, wipers, lamps, etc.), and the vehicle electrical components 17 are connected to the in-vehicle battery 16 via an operation switch (not shown).
Then, the electromagnetic coil of the rear wheel drive motor 4 is connected to the connection point between the in-vehicle battery 16 and the vehicle electrical component 17 via the relay switch 31 and the inverter 4b, and the electromagnetic coil of the generator 8 via the relay switch 31. Connect.
The relay switch 31 is turned off when the four-wheel drive switch 21 (see FIG. 1) is turned on and the motor four-wheel drive is desired, but is turned on when the generated voltage of the generator 8 is less than 14V under the same conditions. When the four-wheel drive switch 21 (see FIG. 1) is OFF and motor four-wheel drive is not desired, it is turned ON.

On the other hand, the field coil of the rear wheel drive motor 4 is connected to the battery 16 via the field current line 4a, and the field coil of the generator 8 is connected to the battery 16 via the field current line 8a and the power line 18 Then, the power line 10 is connected between the electromagnetic coils of the generator 8 and the motor 4.
One end of the electromagnetic coil of the 4WD clutch 13 is connected to the battery 16 by the clutch engagement power line 13a and the other end is connected to the 4WD controller 9.
Further, the 4WD controller 9 is not used to determine whether or not the field current Ifh is applied to the field coil of the generator 8, and the terminal for that purpose is used as the control terminal of the switching transistor on the ground side of the generator field coil. Connecting.

In FIG. 8, when the four-wheel drive switch 21 (see FIG. 1) is ON, motor four-wheel drive is desired, and if the power generation voltage of the generator 8 is 14V or higher, the relay switch 31 is turned OFF and the following Four-wheel drive driving is possible with the rear wheel drive by the motor 4.
At this time, the four-wheel drive controller 9 puts the field current Ifh into the field coil of the generator 8 and engages the 4WD clutch 13.

Therefore, the generator 8 driven by the engine generates power corresponding to the power generation load determined by the field current Ifh, and directs the power to the electromagnetic coil of the rear wheel drive motor 4 via the inverter 4b through the power line 10.
At this time, the inverter 4b can drive the motor 4 to output torque and rotation in a direction according to the field current Ifm, and can drive the vehicle in four-wheel drive by rear wheel drive by the motor 4.

During the four-wheel drive traveling, when the motor overspeed exceeds the target speed, the motor 4 is brought into a braking state by a three-phase short circuit of the motor 4 by the inverter 4b.
The motor 4 generates electric power (voltage Viv) by such regenerative braking, and this electric power generated by the motor 4 is supplied to the field coil of the generator 8 through the power line 18 to cause the generator 8 to generate electric power.
If the voltage of the generated power is less than 14V, the relay switch 31 is turned on to go to the battery 16 to be charged.

By the way, in this embodiment, during the pre-excitation of the generator 8 by the field current Ifh, the generated power generated by this pre-excitation is indicated by the wavy arrow α, the power line 10, the closed relay switch 31, and the field The field current Ifm is supplied to the field coil of the electric motor 4 through the current line 4a, so that the electric motor 4 can be pre-excited.
Therefore, the electric motor 4 can be pre-excited with the generated power generated by the pre-excitation of the generator 8, and it is not necessary to cover the pre-excitation energy of the electric motor 4 with the battery, thereby suppressing the decrease in the battery storage state. In addition, it is possible to suppress heat generation due to pre-excitation of the generator 8.

  In each of the above-described embodiments, the description has been given assuming that both the electric motor 4 and the generator 8 are pre-excited. However, even if only one of the electric motor 4 and the generator 8 is pre-excited, there is a difference in degree. However, it goes without saying that the same four-wheel drive response improvement effect at the start can be expected as described above.

1 is a schematic diagram showing a drive control system of an electric motor type four-wheel drive vehicle including a drive force control device according to an embodiment of the present invention. It is a flowchart which shows the engine surplus torque calculation program which the four-wheel drive controller in the drive control system of the motor four-wheel drive vehicle performs. It is a flowchart which shows the control program of the generator and electric motor which the same 4 wheel drive controller performs. It is a flowchart which shows the pre-excitation control program at the time of starting of the electric motor which the same 4 wheel drive controller performs. FIG. 5 is an operation time chart by the pre-excitation control at the start of the electric motor shown in FIG. 2 is a flowchart showing a generator pre-excitation control program executed by the four-wheel drive controller of FIG. FIG. 7 is an operation time chart by the pre-excitation control at the start of the generator shown in FIG. 6. FIG. It is a control circuit diagram of a generator and an electric motor when pre-exciting the electric motor with the electric power generated by the pre-excitation of the generator.

Explanation of symbols

1L front left wheel (main drive wheel)
1R right front wheel (main drive wheel)
2 Engine (Main power source)
3L left rear wheel (electric motor drive wheel)
3R right rear wheel (electric motor drive wheel)
4 Rear wheel drive motor (electric motor)
5 Automatic transmission 6 Differential gear device 7 Endless belt 8 Generator 9 Four-wheel drive controller
10 Power line
11 Relay
12 Reducer
13 4WD clutch
14 Differential gear unit
21 Four-wheel drive switch
22 Wheel speed sensors
23 Motor rotation sensor
24 Inhibitor switch
25 Accelerator position sensor
26 Brake switch

Claims (2)

A main drive wheel driven by power from a main power source;
An electric motor drive wheel driven by power from an electric motor that responds to power generated by a generator coupled to the main power source,
In an electric motor type four-wheel drive vehicle configured to drive an electric motor drive wheel through the electric motor with electric power generated by applying a power generation load to the generator at the start of the vehicle, and to perform four-wheel drive,
Of the release of the brake operation and the rotation increase operation of the main power source that are sequentially performed at the time of starting, the configuration is such that at least one of the field of the generator and the electric motor is kept in a pre-excited state from when the brake operation is released. A driving force control apparatus for an electric motor type four-wheel drive vehicle. The drive of an electric motor type four-wheel drive vehicle according to claim 1, wherein both the field of the generator and the electric motor are kept in a pre-excited state from when the brake operation for starting the vehicle is released. In the force control device,
A driving force control device for an electric motor type four-wheel drive vehicle, wherein the electric motor is pre-excited by electric power generated by pre-excitation of the generator.

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