JP2019062705A - Drive force control device for vehicle - Google Patents

Abstract

To maintain traveling stability while hindering a sudden decrease of the total drive force of a vehicle when limiting output of one drive force.SOLUTION: A drive force control device 100 is mounted in a vehicle 1 having a front wheel motor 11 and a rear wheel motor 12, controls their operations, and comprises an EVCU 20. The EVCU 20 sets a permissible range DR for a distribution ratio R for distributing total drive force to the front wheel motor 11 and the rear wheel motor 12. In a case where output of the rear wheel motor 12 is limited when the front wheel motor 11 and the rear wheel motor 12 are driven with respective drive forces within respective permissible ranges DR at the distribution ratio R, the EVCU decreases output of the rear wheel motor 12 and, at the same time, increases output of the front wheel motor 11, thereby maintaining the total drive force. In a case where the distribution ratio R deviates from the permissible range DR as the output of the front wheel motor 11 increases, the EVCU maintains the lower limit of the permissible range DR of the rear wheel motor 12 and, at the same time, decreases the total drive force.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a driving force control device for a vehicle having a plurality of driving sources.

  Conventionally, in the field of electric vehicles or hybrid electric vehicles, vehicles (hereinafter referred to as independently driven vehicles) that travel by individually transmitting power from a plurality of drive sources to a plurality of wheels have been proposed. In such a vehicle, when outputting the required driving force or the required torque according to the driving operation, there is a degree of freedom in how to distribute the power to a plurality of driving sources.

In such an independently driven vehicle, when a motor or the like is employed as a drive source, it is necessary to limit the output of the drive source according to the state of heat generation (temperature) or the like.
At this time, if the output of one drive source whose output is limited is simply reduced, only the driving force to the wheel corresponding to this one drive source is limited, as shown by a solid arrow in FIG. The distribution ratio of the driving force to each wheel changes, and the running stability of the vehicle decreases.
On the other hand, if the output of one motor is reduced while maintaining the distribution ratio of the driving force in order to maintain the running stability of the vehicle, as shown by the broken arrow in FIG. The output of the driving source is also reduced, and the total driving force of the vehicle is significantly reduced.

  Therefore, for example, in the techniques described in Patent Documents 1 and 2, when reducing the output of one drive source whose output is limited, the output of the other drive source is increased by the reduced output, and The total driving force is maintained.

JP, 2009-247205, A JP, 2005-204436, A

  However, if the output of one drive source is simply reduced while maintaining the total driving force of the vehicle, the distribution ratio of the driving force is as shown in FIG. There is a risk of getting out of the obtainable range.

  The present invention has been made in view of the above circumstances, and in the case of limiting the output of one drive source, it is possible to maintain running stability while suppressing a sharp drop in the total driving force of the vehicle. An object of the present invention is to provide a driving force control device.

In order to achieve the above object, the invention according to claim 1 is
A driving force control device for a vehicle mounted on a vehicle including a plurality of driving sources for driving different driving systems and controlling operations of the plurality of driving sources,
Permission range setting means for setting a permission range of a distribution ratio to distribute the total driving force output to the plurality of driving sources to the plurality of driving sources;
In the case where the output of one of the plurality of drive sources is limited while the plurality of drive sources are driven by the respective drive forces within the permission range of the distribution ratio, the one drive source Driving force maintaining means for maintaining the total driving force by increasing the outputs of the other driving sources except the one driving source while decreasing the output;
When the distribution ratio deviates from the permission range as the output of the other drive source is increased by the driving force maintaining means, the total driving force is maintained while maintaining the lower limit of the permission range of the one drive source. Driving force reducing means for reducing
And the like.

According to a second aspect of the present invention, there is provided a driving force control apparatus for a vehicle according to the first aspect, wherein
The driving force reducing means gradually reduces the total driving force as the distribution ratio approaches the lower limit of the permission range after the distribution ratio reaches a predetermined range of the lower limit of the permission range. Do.

The invention according to claim 3 is the drive power control device for a vehicle according to claim 2.
The driving force reducing means is characterized in that the total driving force is reduced so that the time rate of change of the total driving force becomes substantially constant.

The invention according to claim 4 is the drive power control device for a vehicle according to any one of claims 1 to 3.
When limiting the output of the one drive source to a predetermined output upper limit value or less, the driving force maintaining means reduces the output of the one drive source to a value lower by a predetermined value than the output upper limit value. It features.

The invention according to claim 5 is the drive power control device for a vehicle according to any one of claims 1 to 4,
A detection unit that detects the traveling state of the vehicle;
The permission range setting means sets the permission range as a range of the distribution ratio at which a required running stability can be obtained based on the traveling state.

The invention according to claim 6 relates to the driving force control device for a vehicle according to any one of claims 1 to 5,
The plurality of drive sources are characterized by comprising a front wheel motor generating motive power of front wheels and a rear wheel motor generating motive power of rear wheels.

According to the invention of claim 1, when limiting the output of one of the plurality of drive sources, the output of the one drive source is reduced while excluding the one of the one drive source. The output of the drive source is increased to maintain the total drive power. Then, if the drive power distribution ratio deviates from the allowable range with an increase in the output of another drive source at this time, the total drive power is reduced while the lower limit of the allowable range of one drive source is maintained. Ru.
Therefore, when limiting the output of one drive source, it is possible to maintain the running stability by maintaining the distribution ratio of the driving force within the permitted range while suppressing a sharp drop in the total driving force of the vehicle. .

According to the second aspect of the invention, when the total driving force is reduced while maintaining the lower limit of the allowable range of one drive source so that the allocation ratio does not deviate from the allowable range, the allocation ratio is permitted. After reaching the lower limit of the range, the total driving force is gradually reduced as the allocation ratio approaches the lower limit of the permission range.
As a result, it is possible to suppress a sharp drop (change) when reducing the total driving force of the vehicle, and to reduce the discomfort of the vehicle occupant.

According to the invention as set forth in claim 3, when the distribution ratio reaches within the predetermined range of the lower limit of the permission range and the total driving force is gradually decreased, the total driving force is made so that the time change rate becomes substantially constant. Be reduced.
Thus, it is possible to further suppress a sharp drop when reducing the total driving force of the vehicle.

According to the fourth aspect of the invention, when the output of one drive source is limited to a predetermined output upper limit value or less, the output of the one drive source is controlled to substantially match the output upper limit value. And is reduced to a value lower than the output upper limit value by a predetermined value.
As a result, the output of one drive source that limits the output can be suppressed as much as possible, and it is possible to suppress a further decrease in the output upper limit value caused by the heat generation of the one drive source.

  According to the fifth aspect of the invention, the permission range is set as the range of the distribution ratio at which the required traveling stability can be obtained based on the traveling state of the vehicle detected by the detection means. Driving stability can be more reliably maintained by keeping the permission range.

It is a block diagram which shows schematic structure of the vehicle in embodiment. It is a flow chart which shows a flow of driving power distribution processing in an embodiment. It is a graph which shows an example of the distribution ratio of the driving force in a driving force distribution process. It is a graph which shows an example of the distribution ratio of the driving force in a driving force distribution process. It is a graph which shows an example of the distribution ratio of the driving force in a driving force distribution process. It is a graph which shows the distribution ratio of the driving force in the conventional driving force distribution.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<Configuration>
First, the configuration of the vehicle 1 according to the present embodiment will be described. FIG. 1 is a configuration diagram showing a schematic configuration of a vehicle 1.

  As shown in this figure, the vehicle 1 is an electric vehicle (EV: Electric Vehicle) in which the front wheel 2 and the rear wheel 3 are motor-driven independently of each other. Specifically, the vehicle 1 includes left and right front wheels 2, left and right rear wheels 3, front wheel motor 11, rear wheel motor 12, front wheel transmission 13, rear wheel transmission 14, EVCU (Electric Vehicles Control Unit) 20, and sensor groups 31 to 39). Among these, the front wheel motor 11 and the rear wheel motor 12 correspond to an example of a plurality of drive sources according to the present invention. The front wheel 2 and the front wheel transmission 13 and the rear wheel 3 and the rear wheel transmission 14 correspond to an example of a plurality of drive systems according to the present invention.

  A driving force control device (hereinafter simply referred to as a “driving force control device”) 100 of the vehicle 1 according to the present embodiment is a device mounted on the vehicle 1 to control the operation of the front wheel motor 11 and the rear wheel motor 12 Particularly, even when one of the front wheel motor 11 and the rear wheel motor 12 is limited in output (when the output needs to be reduced), it is possible to suitably distribute the driving force. The driving force control device 100 corresponds to a portion including the EVCU 20 and the sensor group (31 to 39) in the configuration described above.

  The front wheel motor 11 and the rear wheel motor 12 individually drive the drive systems of the front and rear wheels based on a command from the EVCU 20. Specifically, the front wheel motor 11 drives the left and right front wheels 2 via the front wheel transmission 13, and the rear wheel motor 12 drives the left and right rear wheels 3 via the rear wheel transmission 14. More specifically, a drive circuit (not shown) corresponding to each of front wheel motor 11 and rear wheel motor 12 converts the electric power of the battery according to the command from EVCU 20 and outputs it to front wheel motor 11 and rear wheel motor 12 The motor 11 and the rear wheel motor 12 generate power based on this power.

  The EVCU 20 integrally controls the vehicle 1. Specifically, in the present embodiment, the EVCU 20 appropriately distributes the required driving force given to the vehicle 1 to the driving force of the left and right front wheels 2 and the driving force of the left and right rear wheels 3 Output a command. The required driving force is applied to the vehicle 1 by, for example, a driver's driving operation (for example, a sensor signal of an accelerator sensor 35 representing an accelerator operation amount). The EVCU 20 outputs a command of target output (target torque) to each of the front wheel motor 11 and the rear wheel motor 12 so that the distribution of the driving force is realized.

  The sensor group includes, for example, a longitudinal acceleration sensor 31, a lateral acceleration sensor 32, a yaw rate sensor 33, and a wheel speed sensor 34 as sensors for detecting the traveling state of the vehicle 1. The longitudinal acceleration sensor 31 detects an acceleration in the longitudinal direction of the vehicle 1. The left and right acceleration sensor 32 detects an acceleration in the left and right direction of the vehicle 1. The yaw rate sensor 33 detects the yaw rate of the vehicle 1. The wheel speed sensor 34 detects the wheel speeds (rotational speeds) of the left and right front wheels 2 and the left and right rear wheels 3.

The sensor group also includes an accelerator sensor 35, a steering angle sensor 36, and a brake sensor 37 as sensors for detecting the driver's driving operation. The accelerator sensor 35 detects an accelerator operation amount of the occupant. The steering angle sensor 36 detects the steering wheel operation amount of the occupant. The brake sensor 37 detects a brake operation amount of the occupant.
Further, as a sensor group for detecting the output limitation of the front wheel motor 11 and the rear wheel motor 12, the sensor group includes a thermometer 38 of the front wheel motor 11, a thermometer 39 of the rear wheel motor 12, and the wheel speed sensor 34 described above. Including.

<Driving force distribution processing>
Subsequently, a driving force distribution process in which the driving force control device 100 distributes the required driving force to the front wheel motor 11 and the rear wheel motor 12 will be described.
FIG. 2 is a flowchart showing the flow of the driving force distribution process, and FIGS. 3 to 5 are graphs showing an example of the distribution ratio of the driving force to the front wheel motor 11 and the rear wheel motor 12 in the driving force distribution process. is there.

The driving power distribution process is repeatedly performed in a short cycle such as several milliseconds when the vehicle 1 is in the traveling mode.
When this driving force distribution process is started, as shown in FIG. 2, first, the EVCU 20 acquires each sensor value of the sensor group (31 to 39) (step S1). Among these, for example, a sensor value of the accelerator sensor 35 is input as a required driving force which is a total of driving forces to be output by the front wheel motor 11 and the rear wheel motor 12.

  Next, the EVCU 20 determines a reference ratio as a reference of the distribution ratio of the required driving force (the ratio of distributing the required driving force to the front wheel motor 11 and the rear wheel motor 12) (step S2). The reference ratio is determined, for example, as a distribution ratio of the required driving power at which high traveling stability can be obtained, according to the traveling state of the vehicle 1.

Specifically, in step S2, the EVCU 20 first calculates a base reference ratio according to the load distribution of the vehicle 1. The base reference ratio is, for example, an ideal distribution ratio of driving power at which traveling stability is highest when traveling straight on a non-graded road. The load distribution of the vehicle 1 is calculated based on the longitudinal acceleration and the lateral acceleration among the plurality of acquired sensor values.
Next, the EVCU 20 calculates the amount of change of the reference ratio corresponding to the steering angle and the amount of change of the reference ratio corresponding to the road slope. The steering angle is acquired from the output value of the steering angle sensor 36, and the road gradient is estimated from, for example, the relationship between the accelerator operation amount and the change amount of the vehicle speed. The EVCU 20 stores in advance a data table indicating the relationship between each of the steering angle and the road gradient and the change in the reference ratio, and calculates the change in the reference ratio from the steering angle and the road gradient using these data tables. Do.
Then, the EVCU 20 integrates each change amount of the reference ratio corresponding to the steering angle and the road slope into the base reference ratio to calculate the reference ratio.

  The reference ratio thus determined is an ideal distribution ratio that achieves high traveling stability, corresponding to the load distribution of the vehicle and the individual correction parameters (steering angle and road slope) representing the traveling state. However, the correction parameter representing the traveling state is not limited to the steering angle and the road slope, and other parameters may be used to perform the same correction processing as long as the parameters affect the ideal distribution ratio of the driving force. Good.

  Next, the EVCU 20 sets the permission range of the distribution ratio of the required driving force based on the traveling state of the vehicle 1 (step S3). The permission range indicates a range of ratios that can be selected as the distribution ratio of the required driving force, and is set as a range of distribution ratios that does not interfere with the traveling stability of the vehicle.

Specifically, in step S3, first, the EVCU 20 calculates values of a plurality of parameters representing the traveling state of the vehicle 1 based on the plurality of acquired sensor values. The plurality of parameters include, for example, vehicle speed, slip ratio, longitudinal acceleration, lateral acceleration, understeer degree, oversteer degree, brake operation amount and the like. These multiple parameters are parameters that affect the need for running stability.
Next, the EVCU 20 calculates the width lengths of the upper limit allowable width and the lower limit allowable width individually corresponding to the calculated values of the plurality of parameters. Here, the upper limit side allowable width is an allowable range in which the distribution ratio of the driving force to the front wheels 2 can be increased within the range that does not interfere with the traveling stability, and the lower limit side allowable range does not interfere with the traveling stability. This is an allowable range in which the distribution ratio of the driving force to the rear wheel 3 can be increased. The relationship between the values of the individual parameters and the upper and lower allowable limits is stored in advance in the form of a data table or function in which these are associated with one another. These relationships are correspondence relationships in which the tolerance range decreases as the need for running stability increases, and the tolerance range increases as the need for running stability decreases. The EVCU 20 uses the data table or the function to calculate the upper limit side allowable width and the lower limit side allowable width for each of the plurality of parameters.
In the traveling state in which the behavior of the vehicle 1 is not disturbed, the upper limit side allowable width and the lower limit side allowable width have the same size. However, in the traveling state in which the behavior of the vehicle 1 is disturbed during the understeer tendency or the oversteer tendency, the upper limit side allowable width and the lower limit side allowable width are not the same size. For example, when the understeer tendency appears weak, increasing the ratio of the driving force of the front wheel 2 promotes the understeer tendency. Therefore, the allowable range in which the distribution ratio of the driving force to the front wheels 2 can be increased is smaller than the allowable range in which the distribution ratio of the driving forces to the rear wheels 3 can be increased. Therefore, the upper limit side allowable width corresponding to the understeer degree is set smaller than the lower limit side allowable width. On the other hand, the upper limit side allowable width according to the oversteer degree is set larger than the lower limit side allowable width, contrary to the case of the understeer degree.

  After calculating the plurality of upper limit side allowable widths and the plurality of lower limit side allowable widths corresponding to each of the plurality of parameters, EVCU 20 extracts the minimum upper limit side allowable width and the minimum lower limit side allowable width from among them. Do. Then, the EVCU 20 adds the minimum upper limit side allowable width and the lower limit side allowable width to the reference ratio to calculate the permission range of the distribution ratio. In this way, it is possible to determine the allowable range of the distribution ratio for obtaining the required running stability for all of the plurality of parameters.

Next, the EVCU 20 distributes the driving force to the front wheel motor 11 and the rear wheel motor 12 within the permission range of the distribution ratio (step S4). In the present embodiment, as shown in FIG. 3, the distribution ratio R is set to a predetermined ideal distribution ratio DRi (for example, the above-mentioned reference ratio) within the permission range DR from the upper limit side allowable limit PL1 to the lower limit side allowable limit PL2. Shall be
In the present embodiment, at this point in time, it is assumed that neither the front wheel motor 11 nor the rear wheel motor 12 has its output limited. When one of the front wheel motor 11 and the rear wheel motor 12 receives output restriction, and the output upper limit value is set, the distribution ratio R is set in the range equal to or less than the output upper limit value.

Next, the EVCU 20 determines whether or not the output of either the front wheel motor 11 or the rear wheel motor 12 is limited, and the current output value of the motor needs to be reduced accordingly (step S5). .
Here, motor temperature, a vehicle speed, etc. are mentioned as an output restriction factor of front wheel motor 11 and rear wheel motor 12, for example. For example, when the motor temperature is equal to or higher than a predetermined threshold value, the output of the motor is limited to the limit value or less corresponding to the motor temperature. Further, with regard to the vehicle speed, the maximum torque of the motor may be limited when the vehicle speed exceeds a predetermined value.
Therefore, the EVCU 20 acquires the output upper limit value of each of the plurality of sensor values acquired in step S1 based on the respective temperatures of the front wheel motor 11 and the rear wheel motor 12, the vehicle speed, etc. And it is determined whether the output value of the rear wheel motor 12 needs to be reduced.

  If it is determined in step S5 that the output value of neither the front wheel motor 11 nor the rear wheel motor 12 needs to be decreased (step S5; No), the EVCU 20 shifts the process to step S1 described above.

  On the other hand, when it is determined in step S5 that the output value of either the front wheel motor 11 or the rear wheel motor 12 needs to be decreased (step S5; Yes), the EVCU 20 selects one of the motors that needs an output decrease. The output value of is decreased according to the output upper limit value, and the output value of the other motor is increased to maintain the total driving force (the total output of the front wheel motor 11 and the rear wheel motor 12) (step S6).

Hereinafter, in the present embodiment, it is assumed that the output of the rear wheel motor 12 is limited.
In this case, in step S6, as shown in FIG. 4A, the EVCU 20 decreases the output value of the rear wheel motor 12 corresponding to the output upper limit value F of the rear wheel motor 12 and reduces the same. By increasing the output value of the front wheel motor 11 by an amount, the total driving force is maintained.
Thus, unlike the case where only the output of the rear wheel motor 12 is simply reduced according to the decrease of the output upper limit value F, it is possible to suppress the rapid decrease of the total driving force.

  At this time, the output value of the rear wheel motor 12 may be made substantially equal to the output upper limit F, or, as shown in FIG. 4B, even if the output upper limit F is lower than the output upper limit F by a predetermined value. Good. When the output value is lower than the output upper limit value F, the heat generation of the rear wheel motor 12 is further suppressed, so that the further decrease in the output upper limit value F is suppressed.

Next, the EVCU 20 determines whether the distribution ratio R is out of the permission range DR in accordance with the change of the distribution ratio R in step S6 described above (step S7). That is, whether or not the output upper limit F of one motor whose output is limited falls below the limit output value of the permission range DR when the output value of the one motor is decreased while maintaining the total driving force. Is determined.
That is, in the present embodiment, for example, in the graph showing the distribution ratio R as shown in FIG. 5A, the total drive when the output upper limit F of the rear wheel motor 12 decreases the output value of the rear wheel motor 12 It is determined whether or not it falls below the point of intersection of the force constant line (shown by an alternate long and short dash line) and the upper limit side allowable limit PL1 (the lower limit of the permission range DR of the rear wheel motor 12).
Then, if it is determined that the allocation ratio R does not deviate from within the permission range DR (step S7; No), the EVCU 20 shifts the process to the above-described step S1.

On the other hand, when it is determined in step S7 that the allocation ratio R is out of the permission range DR (step S7; Yes), the EVCU 20 decreases the total driving force while maintaining the allowable limit of the allocation ratio R (step S7). S8).
In the present embodiment, as shown in FIG. 5A, by changing the distribution ratio R in step S6 described above, the total driving force is maintained while the distribution ratio R is at the upper limit tolerance PL1 (in the rear wheel motor 12). The lower limit of the permission range DR is reached. Thereafter, while the upper limit side allowable limit PL1 is maintained, the outputs of both the front wheel motor 11 and the rear wheel motor 12 are reduced to reduce the total driving force.
Thus, the output value of the rear wheel motor 12 can be reduced corresponding to the output upper limit F while maintaining the distribution ratio R within the permission range DR and maintaining the traveling stability of the vehicle 1.

  At this time, as shown in FIG. 5 (b), after the distribution ratio R reaches near the allowable limit (upper limit allowable limit PL1), the total driving force is calculated as the allocation ratio R approaches the allowable limit. You may make it decrease gradually (slowly). In this case, it is preferable to reduce the total driving force so that the temporal change rate of the total driving force is substantially constant. As a result, it is possible to suppress the sudden decrease of the total driving force and reduce the discomfort of the user (the occupant of the vehicle 1).

Next, the EVCU 20 determines whether or not to end the driving power distribution process (step S9), and when it is determined not to end (step S9; No), shifts the process to step S1 described above. Then, the detection of the traveling state of the vehicle 1 and the distribution of the driving force based thereon are sequentially repeated.
On the other hand, if it is determined that the driving power distribution processing is to be ended due to, for example, the vehicle 1 stopping (step S9; Yes), the EVCU 20 ends the driving power distribution processing.

<Effect>
As described above, according to the driving force control device 100 of the present embodiment, when the output of the rear wheel motor 12 is limited, first, the output of the front wheel motor 11 is increased while the output of the rear wheel motor 12 is decreased. Total driving force is maintained. Then, when the distribution ratio R of the driving force deviates from within the permission range DR with the increase of the output of the front wheel motor 11 at this time, the upper limit side allowable limit PL1 which is the lower limit of the permission range DR in the rear wheel motor 12 The total driving force is reduced while being maintained.
Therefore, when limiting the output of one drive source, the drive power distribution ratio R is held within the permission range DR while maintaining the running stability while suppressing a sharp drop in the total drive force of the vehicle 1 be able to.

Further, when the total driving force is decreased while maintaining the upper limit side allowable limit PL1 so that the allocation ratio R does not deviate from within the permission range DR, the distribution rate R reaches within the predetermined range of the upper limit side allowable limit PL1. After that, it is preferable to gradually reduce the total driving force as the allocation ratio R approaches the upper limit side allowable limit PL1.
As a result, it is possible to suppress a sharp drop (change) when the total driving force of the vehicle 1 is reduced, and to reduce the discomfort of the occupant of the vehicle 1.

Further, when the distribution ratio R reaches a predetermined range of the upper limit side allowable limit PL1 and the total driving force is gradually decreased, it is preferable to reduce the total driving force so that the time change rate becomes substantially constant.
As a result, it is possible to further suppress a sharp drop when reducing the total driving force of the vehicle 1.

When the output of the rear wheel motor 12 is limited to the output upper limit F or less, the output of the rear wheel motor 12 is not controlled to substantially match the output upper limit F, but the output upper limit F It is reduced to a value lower than the predetermined value.
As a result, the output of the rear wheel motor 12 that limits the output can be suppressed as much as possible, and a further decrease in the output upper limit F associated with the heat generation of the rear wheel motor 12 can be suppressed.

  Further, based on the traveling state of the vehicle 1 detected by the sensor group, the permission range DR is set as the range of the distribution ratio R in which the required traveling stability can be obtained, so the distribution ratio R falls within the permission range DR. By holding it, traveling stability can be more reliably maintained.

<Modification>
The embodiment to which the present invention can be applied is not limited to the above-described embodiment, and can be appropriately changed without departing from the spirit of the present invention.

  For example, in the said embodiment, the example which applied the front wheel motor 11 and the rear wheel motor 12 as a some drive source was shown. However, the plurality of drive sources are not limited to the motor, and may include an engine such as an engine (internal combustion engine) generating motive power of front wheels and a motor generating motive power of rear wheels. That is, the vehicle may be an electric vehicle (EV: electric vehicle), a hybrid vehicle (HV: hybrid vehicle), a hybrid electric vehicle (HEV: hybrid electric vehicle), or a fuel cell vehicle (FCV: fuel cell vehicle).

Moreover, in the said embodiment, the example which distributes driving force by the front wheel 2 and the rear wheel 3 was shown. However, the combination of the wheels to which the driving force is distributed, such as each pair of front and rear, left and right wheels, or two sets of two rear wheels, left front wheel and right front wheel, can be changed as appropriate.
Furthermore, the combination of the number of drive sources corresponding to a plurality of drive systems is not particularly limited. For example, one front wheel motor 11 and two rear wheel motors 12 may be used.

  In the above embodiment, the drive system includes the front wheel transmission 13 and the rear wheel transmission 14. However, the transmission may not be provided. For example, a power transmission mechanism may be provided instead of the transmission.

  Further, in the above embodiment, the steering angle and the road gradient are shown as a plurality of types of parameters that affect the reference ratio, but the present invention is not limited to these, and parameters representing other traveling conditions may be included. In the above embodiment, the vehicle speed, the slip ratio, the longitudinal acceleration, etc. are shown as a plurality of types of parameters that affect the allowable range of the permission range, but parameters representing other traveling states may be included. Good. Moreover, you may treat the function value which put together two parameters among these as one parameter.

In the above embodiment, the permission range DR of the distribution ratio R of the driving force is calculated by adding the allowable range to the reference ratio. However, the method of calculating the permission range is not limited to this method.
For example, the range of the distribution ratio R in which the traveling stability is increased according to the traveling state may be directly obtained as the permission range. Specifically, when the vehicle speed or the like is a predetermined condition, it is conceivable to set the ratio of the front wheel driving force to the rear wheel driving force within the range of 9: 1 to 1: 9, for example, as the permission range DR. Further, the allowable range DR may be changed by setting the upper limit side allowable limit PL1 and the lower limit side allowable limit PL2 as the reference and changing them based on the traveling state such as the vehicle speed.

  In the above embodiment, when either the front wheel motor 11 or the rear wheel motor 12 receives output limitation, the output upper limit value is set. However, the output upper limit value may be the temperature of each motor It may be always set based on the vehicle speed or the like.

Further, although the EVCU 20 performs various controls in the above embodiment, this control subject is not limited to the EVCU. For example, another ECU (Electric Control Unit) may perform various controls, or an output from a sensor group may be input to another ECU and the other ECU may output a sensor value to EVCU 20. Good.
Specifically, based on the temperatures of front wheel motor 11 and rear wheel motor 12 acquired from front wheel motor thermometer 38 and rear wheel motor thermometer 39 by the MCU (Motor Control Unit), front wheel motor 11 and rear wheel 12 are obtained. The output upper limit value of each motor 12 may be set. The EVCU 20 may drive and control each motor based on the output upper limit value of each motor output from the MCU.

1 vehicle 2 front wheel 3 rear wheel 11 front wheel motor 12 rear wheel motor 20 EVCU
38 front wheel motor thermometer 39 rear wheel motor thermometer 100 driving force control device R distribution ratio DR permission range PL1 upper limit side allowable limit PL2 lower limit side allowable limit F output upper limit value

Claims (6)

A driving force control device for a vehicle mounted on a vehicle including a plurality of driving sources for driving different driving systems and controlling operations of the plurality of driving sources,
Permission range setting means for setting a permission range of a distribution ratio to distribute the total driving force output to the plurality of driving sources to the plurality of driving sources;
In the case where the output of one of the plurality of drive sources is limited while the plurality of drive sources are driven by the respective drive forces within the permission range of the distribution ratio, the one drive source Driving force maintaining means for maintaining the total driving force by increasing the outputs of the other driving sources except the one driving source while decreasing the output;
When the distribution ratio deviates from the permission range as the output of the other drive source is increased by the driving force maintaining means, the total driving force is maintained while maintaining the lower limit of the permission range of the one drive source. Driving force reducing means for reducing
A driving force control device for a vehicle, comprising:   The driving force reducing means gradually reduces the total driving force as the distribution ratio approaches the lower limit of the permission range after the distribution ratio reaches a predetermined range of the lower limit of the permission range. The driving force control device of a vehicle according to claim 1.   3. The driving force control apparatus according to claim 2, wherein the driving force reducing means decreases the total driving force such that a time change rate of the total driving force becomes substantially constant.   When limiting the output of the one drive source to a predetermined output upper limit value or less, the driving force maintaining means reduces the output of the one drive source to a value lower by a predetermined value than the output upper limit value. The driving force control device for a vehicle according to any one of claims 1 to 3, characterized by the above. A detection unit that detects the traveling state of the vehicle;
The permission range setting means sets the permission range as a range of the distribution ratio at which a required running stability can be obtained, based on the traveling state. Driving force control device for a vehicle as described.   The plurality of drive sources according to any one of claims 1 to 5, wherein the plurality of drive sources are constituted by a front wheel motor generating motive power of front wheels and a rear wheel motor generating motive power of rear wheels. Driving force control device for vehicles.

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