JPH11125129A - Vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To put a rotary condition of a first driving wheel in an always optimal condition by the driving of a second driving wheel by discriminating a rotary condition of the first driving wheel, and controlling output torque of the second driving wheel according to its result. SOLUTION: A wheel condition of front wheels is classified into two conditions of requiring/non-requiring an assist by rear wheel drive by a car body speed and a slip rate (105), and a wheel condition of rear wheels is classified into three conditions, and the left and right are separately judged (106). When the system of the rear wheel drive is put in a standby condition, and a parking brake is released (107), and also a brake pedal is released (108), an operation is performed on torque applied to left and right rear wheels (109). When it is not more than a preset value by comparing the car body speed with a prescribed preset value (110), a wheel motor is driven so as to become operation toque (109) performed on torque output to the left and right rear wheels. Therefore, rear wheel torque is adjusted in a desirable form, and front wheels can be effectively assisted by the rear wheels at starting time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle having a first drive wheel driven by an internal combustion engine and a second drive wheel driven by an electric motor.

[0002]

2. Description of the Related Art Vehicles having a first drive wheel driven by an internal combustion engine and a second drive wheel driven by an electric motor are not well known at present. On the other hand, a so-called electric vehicle in which wheels are driven only by an electric motor (motor) is well known, and a control device thereof is disclosed in, for example, JP-A-5-17648.

In this prior art electric vehicle, a plurality of wheel driving motors are provided. A control device sets a motor speed command value based on an accelerator operation amount and a brake operation amount, and also sets a speed command value and a speed command value. A torque command value is determined and controlled based on the difference from the motor speed of each wheel.

[0004]

On the other hand, a vehicle to which the present invention is directed has a first drive wheel driven by an internal combustion engine and a second drive wheel driven by an electric motor. It is necessary to control the device in a well-balanced manner according to the purpose. A control technique that satisfies such a demand is, of course, not disclosed in the above-mentioned prior art.
In particular, no desirable control has been disclosed at all when the first drive wheel is a main drive wheel and the second drive wheel is an auxiliary drive wheel.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve such problems, and one of them is as follows.
A vehicle that includes a first drive wheel driven by an internal combustion engine and a second drive wheel driven by an electric motor, and that determines the rotation state of the first drive wheel in a vehicle that controls driving of the first drive wheel by operating an accelerator. A first determining means; and a control means for controlling an output torque of the second drive wheel in accordance with a determination result of the first determining means.

Since the output torque of the second drive wheel is adjusted according to the rotation state of the first drive wheel, the rotation state of the first drive wheel always becomes optimal by driving the second drive wheel.

It is desirable that the state of rotation of the first drive wheel be determined based on the slip ratio of the first drive wheel and the vehicle speed. The driving force of the first driving wheel can be obtained from the slip ratio and the vehicle speed, and the output torque of the second driving wheel can be controlled so that the driving force of the first driving wheel becomes maximum.

[0008] The control of the output torque of the second drive wheel is further performed by the second drive wheel based on the slip ratio of the second drive wheel and the vehicle speed.
It is desirable to take into account the rotational state of the drive wheels. By detecting the rotational state of the second drive wheel, unnecessary assist of the second drive wheel with respect to the first drive wheel is suppressed, and optimal assist within the possible range in the rotational state of the second drive wheel at that time is provided. The output torque is adjusted so that

Further, the present invention includes a first driving wheel driven by an internal combustion engine and second driving wheels provided on the left and right driven by an electric motor, and controls driving of the first driving wheel by operating an accelerator. In the vehicle, the second speed is determined based on the wheel speed of the first drive wheel and the wheel speed of the second drive wheel.
Control means for controlling the output torque of the drive wheels is provided. The control means prohibits the left and right second drive wheels from being driven simultaneously, and the continuous drive state of one of the second drive wheels has passed a predetermined time. At this time, or when the speed difference between the left and right second drive wheels becomes equal to or more than a predetermined value, control for switching the drive of the second drive wheels to the other is performed. Second
The drive wheels are alternately driven within a range where the left and right wheel speeds are not so far apart. And, the wheel speed of the second drive wheel is the first
If this alternate driving is performed so as to approach the wheel speed of the driving wheel, the second driving wheel can achieve driving assistance for the first driving wheel so that the driving force of the first driving wheel increases as a result. In addition, since one of the second drive wheels is always in a rolling state, it is easy to accurately estimate the vehicle body speed from the wheel speed in the rolling state without using an acceleration sensor or the like.

It is desirable that the drive switching of the second drive wheel is performed after a state in which neither the left or right second drive wheel is driven. In this way, when one of the wheels transitions from the rolling state to the driving state, the other wheel transitions from the driving state to the rolling state and a predetermined time has elapsed, so the stable rolling state It has become. Therefore, the use of the rolling wheel speed makes it possible to more accurately estimate the vehicle speed.

[0011]

FIG. 1 is a system diagram showing a configuration of a vehicle according to an embodiment of the present invention. This vehicle is a two-drive system vehicle in which front wheels are driven by a gasoline engine, which is an internal combustion engine, and rear wheels are driven by a wheel motor, which is an electric motor. The wheel motor mentioned here has been proposed to increase the driving efficiency when driving the wheels with an electric motor, and all or a part of the motor is housed in the wheel of the wheel. Is transmitted directly to the wheels, and there is an advantage that energy loss in the driving force transmission path is small. In the vehicle of this embodiment, a wheel motor can be selectively mounted. Hereinafter, the configuration of the vehicle will be described in detail.

The left and right front wheels 3 and 4 are rotatably driven by a gasoline engine 11 which is a main power source, and the right and left rear wheels 7 and 9 are driven by detachable wheel motors 15 and 17, respectively. It is designed to rotate. As a result, the vehicle can run with four-wheel drive. The wheel motors 15 and 17 can be removed by the user, and the rear wheels 7 and 9 can be driven by two-wheel drive using only a gasoline engine by using normal driven wheels (rolling wheels). is there.

The output of the engine 11 is controlled by adjusting the opening of a throttle valve 13 and the like, as in the case of an engine mounted on a normal gasoline engine vehicle. Electronic control unit (EC) of the electronically controlled fuel injection system (EFI)
U) It is controlled by a command from 27.

The driving force of the wheel motors 15 and 17 is used for assistance, and is used here to assist the driving of the front wheels when starting. Such wheel motors 15 and 16 are mounted together with the wheels 7 and 9 on a wheel support mounted on a suspension arm, and the respective rotating shafts of the wheel motors 15 and 16 and the respective axle hubs of the wheels 7 and 9 And coaxially rotate together.

The wheel motors 15 and 17 are driven and controlled by power supply from an electronic control unit (ECU) 31 for performing drive control of the whole wheels including drive adjustment of front and rear wheels. The vehicle control ECU 31 includes a vehicle control unit 33, motor control units 35 and 37, and an inverter 3
9 and 41 are provided. Motor control unit 35 and inverter 39
Are for supplying controlled power to the left wheel motor 15, respectively, and the motor control unit 37 and the inverter 41 are for supplying controlled power to the right wheel motor 17, respectively.

The vehicle control unit 33 is connected to an electronic control unit (ECU) 29 of an antilock brake system (ABS) for controlling the operation of the brake and an ECU 27 of the EFI via connectors 73 and 71, respectively. Further, the vehicle control unit 33 is connected to various sensors via a connector 67 via a connector.

The various sensors include a steering angle sensor 53 for detecting a steering angle of a front wheel which is a steered wheel, an accelerator sensor 55 for detecting an amount of depression of an accelerator pedal, that is, an accelerator opening, and whether or not a brake pedal is being depressed. , A shift position switch 59 for detecting the gear shift position of the transmission of the engine drive system, a yaw rate sensor 61 for detecting the turning angular velocity of the vehicle, a lateral acceleration sensor 63 for detecting the lateral acceleration of the vehicle, A longitudinal acceleration sensor 65 for detecting longitudinal acceleration, a PKB sensor 77 for detecting the on / off state of the parking brake, and a wheel speed sensor 1 for independently detecting the speeds of the four front, rear, right and left wheels
9, 21, 23, 24 and the like.

The inverter sections 39 and 41 are connected to the DC / DC converter 43 by connectors 69 and 79, respectively.
Battery 45 with a voltage of 12 volts (V) via
To the connector. In addition, the inverter units 39, 4
1 is connected to the wheel motors 15 and 17 via a connector 69 and power supply lines 83 and 85.

The vehicle control unit 33 controls the driving of the entire vehicle based on the outputs of the sensors described above. Therefore, of course, the wheel motors 15 and 17
Is also controlled. That is, the outputs of the inverters 39 and 41 are adjusted based on the outputs from various sensors including the wheel speed sensors 19, 21, 23 and 25 and the accelerator sensor 55 in accordance with a preset algorithm, and the wheel motors 15 and 17 are controlled. Control the drive.

The vehicle control unit 33 also has a function of controlling the wheel driving devices, that is, the wheel motors 15, 17 and the engine 11, and also has a function of performing a self-diagnosis as to whether normal wheel driving by the wheel motor is possible. Have.
Since the wheel motors 15 and 17 are detachable, which can be selectively attached as needed, it is checked at least before running whether or not the wheels can be driven by the wheel motors and whether or not the vehicle can be driven by four wheels. The vehicle control unit 3
3 itself needs to know.

How to control the driving of the wheel motors 15 and 17 may be determined by the algorithm of the vehicle control unit 33 based on the design concept for the vehicle.
Here, it is determined to assist the driving of the front wheels, which is the main driving force at the time of starting.

Of course, it can be used for other purposes, for example, as an alternative power when an engine trouble occurs, and can also be used for attitude control during turning.

FIG. 2 is a general flowchart showing the rear wheel drive control performed by the vehicle control unit 33, which aims at optimally assisting front wheel drive when starting.

First, in step 101, the front left wheel speed VwFL, the front right wheel speed VwFR,
The left rear wheel speed VwRL and the right rear wheel speed VwRR are calculated.

Next, the routine proceeds to step 102, where the vehicle speed Vso is estimated from these wheel speeds. There are various methods of estimating the vehicle body speed. For example, in the case of two-wheel drive, a method of estimating the wheel speed of the rolling wheel as the vehicle speed is often used. However, in this embodiment, since all four wheels may be driven, here, the smallest one of the above four wheel speeds is represented by the vehicle speed Vs.
o.

Next, at step 103, the slip ratio SlipF of the front wheels, ie, the wheels driven by the engine,
Ask for. For each of the left and right wheels, the slip ratio, that is, the ratio of the wheel speed to the vehicle speed, is determined, and the larger one is set as the representative value of the front wheel slip ratio.

Since the left and right front wheels are connected via a differential gear, the left and right wheel speeds have a negative correlation with each other. In an extreme case, if one of the wheels runs idle, the other wheel will not rotate. A situation occurs in which no power is transmitted at all. However, even in such a case, the slip state of the front wheels is not overlooked by setting the larger one of the left and right slip ratios as the representative value of the front wheel slip ratio.

Next, the routine proceeds to step 104, where the rear wheel slip ratio is calculated. The rear wheel slip ratio is calculated for the left and right wheels, and the left rear wheel slip ratio SlipRL and the right rear wheel slip ratio SlipR are used as they are.
Let it be R. The formula for calculating the slip ratio is obtained by dividing the wheel speed Vw by the vehicle speed Vso as in the case of the front wheels.

Next, the routine proceeds to step 105, where the state of the front wheels is determined. Here, the wheel state is divided into two states according to the vehicle body speed and the slip ratio. The graph drawn in the frame of step 105 is obtained by taking the slip rate SlipF on the horizontal axis and the vehicle speed Vso on the vertical axis, with the solid line a as the boundary, the right side in the first state, and the left side in the second state. And The first state is a state in which the front wheels cannot exert sufficient driving force because the front wheel slip ratio is too large, and is a state in which assistance by rear wheel driving is required. Conversely, in the second state, the front wheel slip ratio is in an appropriate range,
This is a state in which the front wheels can exert a sufficient driving force, and a state in which assist by rear wheel driving is unnecessary. This step 10
A flag F-slipF is set based on the determination result in step 5, and the content of this flag is used in a torque calculation process in step 109 described later.

The reason why the solid line a is an upward-sloping curve that smoothly curves is based on the fact that as the vehicle speed increases, the slip ratio required to obtain a desired driving force can be increased to a large value. Things.

Next, at step 106, the state of the rear wheels is determined separately for the left and right wheels. Here, the wheel state is divided into three states according to the vehicle speed and the slip ratio. The graph drawn in the frame of step 106 relates to the left rear wheel, and the horizontal axis represents the slip ratio Slip of the left rear wheel.
RL, and the vertical axis represents the vehicle speed Vso. State A, state A, and state C are in order from right to left with two solid lines b and c as boundaries. State a is a state in which the motor torque is excessive and the slip ratio of the left rear wheel is unnecessarily large. State A indicates that the motor torque is appropriate. State C has insufficient slip,
If the motor torque is increased to increase the slip ratio, the driving force can be further improved.

FIG. 3 is a flowchart showing the details of the determination processing in step 106, and FIG.
6 is an enlarged view of a graph for rear wheel state determination displayed in a frame 6. The determination process of step 106 will be described with reference to FIGS.

In step 301, intersections X (Vso, x) and Y (Vso, y) between the curves b and c and the straight line d indicating the vehicle speed Vso obtained in step 102 are obtained.

Next, the routine proceeds to step 302, where the left rear wheel slip ratio SlipRL determined at step 104 is compared with x determined at step 301. If SlipRL is equal to or greater than x, the routine further proceeds to step 304. , Sli
The pRL is compared with y obtained in step 301. By the judgment processing of steps 302 and 304, the slip
If RL is smaller than x, the state of the left rear wheel is state c (step 303). If RL is not less than x and smaller than y, the state is state a (step 305). If RL is not less than y, state a (step 306). Is determined.

Based on the result of this determination, the flag F-sli
pRL is set, and the content of this flag is used in the torque calculation processing in step 109 described later.

The rotation state of the right rear wheel is similarly determined based on the same determination criterion, and a flag F-slipRR is set based on the determination result.

When the determination of the wheel condition of the rear wheels is completed in step 106, the data necessary for the rear wheel drive control has been completed, and the torque control of the rear wheels is subsequently executed in step 107 and subsequent steps. become.

First, at step 107, it is determined whether the system is in a standby state, and whether the parking brake P
A determination is made as to whether the KB has been released. System standby is a check to determine whether the system used for rear wheel drive is ready, that is, whether the connection for driving the wheel motor is normal and whether there is any abnormality in the inverter. Means that they are normal.

If the system is in the standby state and the parking brake PKB has been released, the routine proceeds to step 108. If either or both are denied, the rear wheel drive control is not executed through steps 112 and 113. Steps 112 and 113 will be described later.

In step 108, it is determined whether or not the brake lamp is off, that is, whether or not the driver has released the brake pedal. If the brake pedal is released, the process proceeds to step 109 to calculate the torque to be applied to the left and right rear wheels. If the brake pedal is depressed, the rear wheel drive control is executed through steps 112 and 113. It ends without being done.

The details of the arithmetic processing in step 109 are shown in FIG.
Is shown in the flowchart of FIG. First, step 105 in FIG.
It is determined in step 5 whether the state of the front wheel determined in step 1 is the first state.
01 is determined. If the result is negative, that is, if the vehicle is in the second state, the routine proceeds to step 515, where the torque TqRL applied to the left rear wheel and the torque TqRR applied to the right rear wheel are both set to zero, and this subroutine ends. Let it.

When it is determined in step 501 that the front wheel state is the first state, the flow shifts to step 502 to determine whether the front wheel state determined last time was the first state. If the previous front wheel state is the first state, the process directly proceeds to step 504, and if not, the step 503 is performed.
Step 504 sets the count values of the control counters provided separately for the left and right rear wheels to 0.
Move to The count value of the control counter is the torque Tq.
Is determined, and is increased, decreased, or held in the subsequent processing. Step 112 described above is a process for setting the count value to 0.

In steps 504 and 505, it is determined whether the state of the left rear wheel determined in step 106 of FIG. 2 is A, B or C. If the state is a, the count value of the left rear wheel control counter is decremented by 1 in step 507, and then, in step 508.
Move to If the state is A, the process proceeds to step 508 without performing any processing on the control counter, that is, while keeping the count value. If the state is c, the count value of the left rear wheel control counter is incremented by 1 in step 505, and then, in step 508.
Move to

In step 508, the torque TqRL to be applied to the left rear wheel is calculated based on the count value of the left rear wheel control counter.
Ask for. A map indicating the relationship between the count value of the left rear wheel control counter and the torque TqRL to be applied to the left rear wheel is set in advance. The relationship between the two is determined by step 508 in FIG.
When the count value is plotted on the horizontal axis and the torque TqRL is plotted on the vertical axis, the curve is a monotonically increasing curve that is convex upward.

As can be seen from the characteristic diagram, the torque TqRL increases as the count value increases, and conversely, the torque TqRL decreases as the count value decreases. Therefore, when the process proceeds to step 508 after step 505, a larger torque TqRL than the previous time is obtained,
If the process proceeds to step 508 via step 507, a smaller torque TqRL than the previous time is obtained. If the process directly proceeds from step 506 to step 508, the previous torque is held.

The left rear wheel torque T obtained as described above
qRL is equal to the torque limit value T-l in step 509.
If the value is equal to or greater than the torque limit value, the process proceeds to step 510 and the left rear wheel torque TqRL
Is replaced by the torque limit value T-limit.
The torque limit value is a value that changes in accordance with the state of charge of the battery 45, and monitors the balance between the power consumption and the charge power in the battery 45. The higher the size, the higher. This prevents an excessive load on the battery 45 and an alternator (not shown) for charging the battery 45, thereby protecting the vehicle power supply system.

Here, the calculation process of the torque limit value will be described with reference to the flowchart of FIG. A voltage / current monitoring sensor is provided at the output end of the alternator.
1, the voltage V0 and the current A0 measured by this sensor
Is time-integrated (added) to obtain the production-side power W0. On the other hand, a voltage / current monitoring sensor is similarly provided at the input terminals of the inverter units 39 and 41, and in step 602, the product of the voltage V1 and the current A1 measured by this sensor is integrated over time (added) to the consumption side. The power W1 is obtained.

Subsequently, the flow shifts to step 603 to perform an operation for obtaining the ratio of the production-side power W0 to the consumption-side power W1, that is, the power balance γ. Where the power balance γ is 100%
If so, it means that the production-side power and the consumption-side power are balanced, and if it is smaller than 100%, it means that the consumption is excessive. When the power balance γ drops significantly, it is necessary to determine that there is a possibility of a system down due to a shortage of supplied power, and to reduce the torque limit value to suppress power consumption.

Therefore, in the next step 604, the amount of drop of the power balance γ from 100% is set to a predetermined value P
It is determined whether it is larger than 1 (for example, 20%). If it is larger, a torque limit value according to the power balance γ at that time is obtained in step 606.

In step 606, a torque limit value corresponding to the power balance γ is obtained from a map defining the relationship between the power balance γ and the torque limit value. A graph showing the relationship between the power balance γ and the torque limit value is shown in the frame of Step 606. This graph has the power balance γ on the horizontal axis and the torque limit value on the vertical axis, and is a graph that smoothly increases monotonically. Therefore, the smaller the power balance γ, the smaller the torque limit value.

If the result in step 604 is negative, it is determined that there is enough power to supply, and the flow shifts to step 605 to maximize the torque limit value. Then, the torque limit value thus determined is applied to steps 509 and 510 in FIG.

The routine 550 composed of steps 504 to 510 described above is a torque calculation for the left rear wheel. The same torque calculation is similarly performed for the right rear wheel in the routine 551, and the right rear wheel is executed. Torque TqRR
Is required.

When both the left rear wheel torque TqRL and the right rear wheel torque TqRR are obtained, the routine proceeds to step 511, where the left and right torques are compared. As described above, since the torques of the left and right rear wheels are obtained independently in the routines 550 and 551, both may be significantly different depending on the road surface condition. For example, one of the rear wheels is on a road surface having a high road friction resistance, and the other is on a road surface having a low road friction resistance. However, even in such a case, if the torques of the right and left rear wheels are largely different, the vehicle body may be deflected, which is not preferable.
Adjustments are made according to 11-514.

In step 511, the rear left wheel torque T
If the absolute value of the difference between qRL and the right rear wheel torque TqRR is not equal to or greater than the predetermined set value A, the left rear wheel torque TqRL and the right rear wheel torque TqRR obtained in the routines 550 and 551 are determined as they are in the current calculation Value. If the absolute value of the difference between the left rear wheel torque TqRL and the right rear wheel torque TqRR is greater than or equal to the set value A, the process proceeds to step 512, where it is determined whether the left or right torque is greater. If the left rear wheel torque TqRL is larger than the right rear wheel torque TqRR, the process proceeds to step 513, where the left rear wheel torque TqRL is obtained by adding a correction value ΔTq to the right rear wheel torque TqRR. If a negative determination is made in step 512, the process proceeds to step 314, where the right rear wheel torque TqRR is obtained by adding the correction value ΔTq to the left rear wheel torque TqRL. That is, when the torque difference between the left and right rear wheels is equal to or greater than the set value A, the smaller torque value is left as it is, and the larger torque value is replaced by a value obtained by adding the correction value ΔTq to the smaller torque value. Thus, the calculation of the torque of the rear wheels in FIG. 5 is completed.

Next, step 11 of the general flow
The process proceeds to 0, and the vehicle speed SPD is compared with a preset value B. Since this rear wheel drive system is a start assist, it becomes unnecessary when the vehicle speed increases to some extent. Therefore, the vehicle speed SPD is equal to the set value B.
If it becomes greater than (e.g., 20 km / h), the routine proceeds to step 112 and step 113, where the count value of the control counter is set to zero, and the torque outputs TqoutRL and TqoutRR of the left and right rear wheels are set to zero. This control is ended without performing the rear wheel drive by (17) and (17).

Conversely, when the vehicle speed SPD falls below the set value B, the torque output Tqout for the left and right rear wheels
The wheel motors 15 and 16 are driven such that RL and TqoutRR become the left and right rear wheel torque values TqRL and TqRR calculated in step 109.

Thus, one cycle of the rear wheel drive processing is completed. By repeating this cycle, the rear wheel torque is adjusted in a preferable manner, and effective assist at the time of starting by the rear wheels is achieved.

Next, a second embodiment of the present invention will be described with reference to the flowchart of FIG. In this embodiment, similarly to the first embodiment, in the vehicle shown in FIG. 1, drive control of rear wheels driven by a motor is performed so as to assist the front wheels driven by the engine when starting. However, it is different from the first embodiment in that the rear wheels are alternately driven. By alternately driving, one of the rear wheels is always rolling even during the rear wheel drive control, and the wheel speed of the rolling wheel can be used as a control parameter.

First, at step 701, it is determined whether or not the vehicle speed is lower than a set value, for example, 20 km / h. If the vehicle speed is equal to or higher than the set value, the rear wheel drive is not required for the purpose of assisting at the time of starting. Therefore, the flow is ended only by clearing the counter in step 713. The significance of this counter will be described later.

If the vehicle speed is lower than the set value, the process proceeds to step 702, where it is determined whether the system is in a standby state, whether the parking brake PKB is released, and whether the brake lamp is off. A decision is made. The meanings of the system standby, the PKB release, and the non-lighting of the brake lamp are the same as those in the first embodiment, and when all of them are satisfied, effective rear wheel drive control is permitted.

Therefore, if any one of these three conditions is not satisfied, the counter is cleared in step 713 and this flow is terminated. When all three conditions are satisfied, the process proceeds to step 703, the system flag is changed from standby to active, and the process further proceeds to step 704.

In step 704, it is determined whether the average wheel speed of the left and right front wheels is higher than the average wheel speed of the left and right rear wheels by a predetermined value x0 or more. The time when the average wheel speed of the front wheels is higher than the average wheel speed of the rear wheels is when the front wheels are slipping and when the assist by the rear wheels is required. Conversely, when the average wheel speed of the front wheels is lower than the average wheel speed of the rear wheels, or when the difference is smaller than a predetermined value, the front wheels are not slipping, or the slip assists rear wheel assist. Since it can be estimated that the slip is not necessary, in this case, the process proceeds to step 713 to end this processing without performing the rear wheel drive.

The predetermined value x0 at this time can be changed to a value according to the environment by a command from the separately provided environment information determining unit 750. The environment information determination unit 750 determines the environment from the intake air temperature sensor, the hill-climbing angle sensor, and the like, and obtains a predetermined value x0 according to the environment.

When the determination in step 704 is affirmative, and it is determined that the front wheels are slipping, the process proceeds to step 705 to determine whether the last rear wheel drive is other than left wheel drive. This is a decision to alternately drive the left and right wheels,
If the last drive was the left rear wheel, the process proceeds to step 706, where the subsequent drive control is performed on the right wheel, and the left wheel speed is set to be used for the vehicle speed. Conversely, if it is determined in step 705 that the left wheel was not driven last time,
The process proceeds to step 707, where the subsequent drive control is performed for the left wheel, and the right wheel speed is set to be used for the vehicle speed.

Subsequently, the process proceeds to step 708 to obtain an optimum drive torque and execute torque output with the obtained drive torque value. The value of the drive torque is uniquely determined by the count value of the drive control counter. An example of the relationship between the drive torque and the count value of the drive control counter is shown in the graph in the frame of step 708. The value of the counter is to be incremented in a later step 709.
While continuously outputting the torque by repeating 711,
Continue to increase. As can be seen from the graph shown in the frame of step 708, as the count value increases, the torque increases and the rate of increase gradually decreases. Note that the counter clearing process in step 713 is a process for setting the counter value to 0.

The time during which torque is output to one of the right and left rear wheels by repeating steps 708 to 711 is monitored by a drive timer, and when the predetermined time has expired, the flow proceeds from step 710 to step 712. The torque output to that wheel is terminated.

When the wheel speed of the rear wheel being driven becomes larger than the wheel speed of the other rear wheel, that is, the rolling wheel, by a predetermined value x1 or more during the repetition of steps 708 to 711, the steps from step 711 to step 711 are repeated. 712
Then, the torque output is terminated. In the determination of step 711, the case where the wheel speed of the driving rear wheel is higher than the wheel speed of the rolling rear wheel by a predetermined value x1 or more means that the slip of the driving rear wheel is larger than necessary. I have. Therefore, when this state is reached, the torque output is stopped even before the predetermined time has expired,
The body is not deflected.

In step 712, steps 708-7
The predetermined value n is subtracted from the final value of the count value of the counter that has increased while repeating step 11. By this processing, the first drive torque value for the other rear wheel to be performed next becomes a value slightly smaller than the torque value at the end of the current rear wheel drive. This makes it possible to gradually increase the torque of the drive wheels after the left and right wheels are changed from a value slightly smaller than the optimum torque value to the optimum torque value. If this process is not performed, step 711 may be satisfied immediately after the drive wheels are changed. In such a case, only the drive time of one rear wheel is extremely shortened, and the alternate drive is performed. May be unstable. However, if this process is performed, the drive will continue to some extent after the drive wheels are replaced, and stable alternate drive can be achieved.

After the processing in step 712 is completed, in step 714, in order to secure time until the next drive,
The time is maintained for t1 hours. While the driving is completed, the rear wheel next becomes a rolling wheel, and the wheel speed is used as the vehicle body speed. If the process returns to step 701 without waiting for the holding time t1, the wheel that should be the rolling wheel will be used. May not come out of the slip state due to inertia force or the like. If the wheel speed in this state is set as the vehicle speed, erroneous drive control is performed.
It is to be held for about a second.

When the time holding in step 714 is completed,
The process moves to step 701 again, and the above-described processing is repeated. By this repetition, the rear wheels are alternately driven at the time of starting to assist the front wheels.

The set value in step 701, the table showing the relationship between the drive torque in step 708 and the count value of the control counter, and the predetermined value x1 in step 711 are as follows:
Similarly to the predetermined value x0 in step 704, the environment information determination unit 7
It is changed according to the environment by a command from 50.

In the first and second embodiments,
Although the front wheels are first drive wheels driven by the internal combustion engine and the rear wheels are second drive wheels driven by an electric motor, the front wheels may be replaced with second drive wheels and the rear wheels may be replaced with first drive wheels.

[0073]

As described above, according to the vehicle of the present invention, the first drive wheels driven by the internal combustion engine are the main drive wheels, and the second drive wheels driven by the electric motor are the auxiliary drive wheels. In this case, the second drive wheel can be efficiently used as assist when starting.

[Brief description of the drawings]

FIG. 1 is a system diagram showing a configuration of a vehicle applied to first and second embodiments of the present invention.

FIG. 2 is a flowchart showing rear wheel drive control according to the first embodiment of the present invention.

FIG. 3 is a flowchart showing a subroutine in the flowchart shown in FIG. 2;

FIG. 4 is a graph for explaining a wheel state of a rear wheel.

FIG. 5 is a flowchart showing a subroutine in the flowchart shown in FIG. 2;

FIG. 6 is a flowchart for deriving a torque limit value used in the flowchart shown in FIG. 2;

FIG. 7 is a flowchart illustrating rear wheel drive control according to the first embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Body, 3, 5, 7, 9 ... Wheels, 11 ... Engine, 1
5, 17: wheel motor, 31: vehicle control ECU, 3
3: vehicle control unit, 35, 37: motor control unit, 39, 4
DESCRIPTION OF SYMBOLS 1 ... Inverter, 55 ... Accelerator sensor, 57 ... Brake sensor, 67, 69, 71, 73 ... Connector, 43 ...
DC / DC converter, 45 ... battery, 83, 85 ...
Power supply wiring.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kiyoshi Iga 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation

Claims (7)

[Claims] 1. A vehicle having a first drive wheel driven by an internal combustion engine and a second drive wheel driven by an electric motor, wherein the drive of the first drive wheel is controlled by an accelerator operation. A vehicle comprising: first determination means for determining a rotation state; and control means for controlling output torque of a second drive wheel in accordance with a determination result of the first determination means. 2. The vehicle according to claim 1, wherein the first determination unit determines a rotation state of the first drive wheel based on a slip ratio of the first drive wheel and a vehicle speed. 3. The vehicle according to claim 1, further comprising: a second determining unit configured to determine a rotation state of the second driving wheel based on a slip ratio of the second driving wheel and a vehicle speed. In consideration of the determination result of the second determination means, the second
The vehicle according to claim 2, wherein the output torque of the driving wheel is controlled. 4. The system according to claim 3, wherein driving of the second drive wheel by the electric motor is permitted when a brake pedal is released and an accelerator pedal is depressed. Vehicle. 5. A charging device for a battery, which is a driving power source for the second driving wheel, wherein an integrated value of driving power of the second driving wheel exceeds an integrated value of charging power of the battery than a predetermined value. 2. The vehicle according to claim 1, wherein when the vehicle speed exceeds the upper limit, the upper limit of the output torque value of the second drive wheel is reduced in accordance with the amount of the increase. 6. A vehicle comprising: a first drive wheel driven by an internal combustion engine; and left and right second drive wheels driven by an electric motor, wherein the drive of the first drive wheel is controlled by an accelerator operation. Control means for controlling the output torque of the second drive wheel based on the wheel speed of the first drive wheel and the wheel speed of the second drive wheel, wherein the control means simultaneously controls the left and right second drive wheels Driving is prohibited, and when the continuous driving state of one of the second driving wheels exceeds a predetermined time,
A vehicle that performs control to switch the driving of a second driving wheel to the other when the speed difference between the driving wheels becomes equal to or greater than a predetermined value. 7. The vehicle according to claim 6, wherein the control unit switches the drive of the second drive wheel after a state in which neither of the left and right second drive wheels is driven.