JP7017895B2 - Vehicle driving force control device - Google Patents

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 an electric vehicle or a hybrid electric vehicle, a vehicle (hereinafter referred to as an independently driven vehicle) has been proposed in which power is individually transmitted from a plurality of drive sources to a plurality of wheels to travel. 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 adopted as a drive source, it becomes necessary to limit the output of the drive source according to a state such as heat generation (temperature) thereof.
Then, when returning one drive source from the output restricted state, it is necessary to release the restriction after the temperature has sufficiently dropped so that the output is not restricted again due to heat or the like after the restoration (for example, Patent Document). See 1 and 2).
Therefore, there is a problem that it takes time to recover the total driving force of the vehicle.

Japanese Unexamined Patent Publication No. 2009-247205 Japanese Unexamined Patent Publication No. 2005-204436

The present invention has been made in view of the above circumstances, and is a vehicle driving force control device capable of recovering the total driving force of a vehicle more quickly than before when the output limitation of one drive source is released. The purpose is to provide.

In order to achieve the above object, the invention according to claim 1 is
A vehicle driving force control device that is mounted on a vehicle having a plurality of drive sources for driving different drive systems and controls the operation of the plurality of drive sources.
A temperature acquisition means for acquiring temperature information of each of the plurality of drive sources,
An output upper limit setting means for setting an output upper limit value of each of the plurality of drive sources based on the temperature information of the drive source, and an output upper limit setting means.
A permission range setting means for setting a permission range of a distribution ratio for distributing the total driving force to be output to the plurality of drive sources to the plurality of drive sources.
A drive control means for driving the plurality of drive sources with each driving force within the permitted range of the distribution ratio and equal to or less than the output upper limit value.
Equipped with
The drive control means is
When the output of one of the plurality of drive sources is limited by the output upper limit value and the output of the one drive source is increased as the output upper limit value increases.
When the total driving force is less than the required driving force given to the vehicle and the temperature of the one driving source drops to the first temperature or lower , the output of the one driving source is increased. The first output control that increases the total driving force is carried out,
When the total driving force reaches the required driving force by the first output control and the temperature of the one driving source drops to the second temperature or less, which is lower than the first temperature, the one driving force is described. A second output control is performed to maintain the total driving force by increasing the output of the source and decreasing the output of the other driving sources other than the one driving source among the plurality of driving sources.
In the first output control, the output of the one drive source is increased in response to an increase in the output upper limit value, and in the second output control, the output of the one drive source is increased in response to an increase in the output upper limit value. It is characterized by delaying the increase of.

The invention according to claim 2 is the vehicle driving force control device according to claim 1.
In the first output control, the drive control means increases the output of the one drive source while setting the distribution ratio as the lower limit of the permitted range in the one drive source to increase the total drive force. It is characterized by.

The invention according to claim 3 is the vehicle driving force control device according to claim 1 or 2.
In the second output control, the drive control means sets the distribution ratio within the permitted range in the one drive source for a predetermined time after the total drive force reaches the required drive force by the first output control. It is characterized by keeping it at the lower limit.

The invention according to claim 4 is the vehicle driving force control device according to claim 1 or 2.
In the second output control, when the total driving force reaches the required driving force by the first output control, the drive control means maintains the total driving force and is in a range equal to or less than the output upper limit value. It is characterized in that the output of the one drive source is increased.

The invention according to claim 5 is the vehicle driving force control device according to claim 1 or 2.
In the second output control, the drive control means determines the distribution ratio based on the temperature information of the other drive source when the total drive force reaches the required drive force by the first output control. The output of the one drive source is maintained at the lower limit of the permitted range, or the output of the other drive source is decreased while increasing the output of the one drive source within the range equal to or less than the output upper limit value. It is characterized by selecting whether to maintain the total driving force.

The invention according to claim 6 is the vehicle driving force control device according to any one of claims 1 to 5.
A detection means for detecting the running state of the vehicle is provided.
The permission range setting means is characterized in that the permission range is set as a range of the distribution ratio from which the required running stability can be obtained, based on the running state.

The invention according to claim 7 is the vehicle driving force control device according to any one of claims 1 to 6.
The plurality of drive sources are characterized by including a front wheel motor that generates power for the front wheels and a rear wheel motor that generates power for the rear wheels.

The invention according to claim 8 is the vehicle driving force control device according to any one of claims 1 to 6.
The plurality of drive sources are characterized by including an engine that generates power for the front wheels and a motor that generates power for the rear wheels.

The invention according to claim 9 is the vehicle driving force control device according to claim 7 or 8.
The output upper limit setting means is an MCU that sets an output upper limit value of the motor .
The drive control means is an EVCU that drives and controls a motor based on the output upper limit value output from the output upper limit setting means.

According to the first aspect of the present invention, when the output of one drive source is limited and the output of the one drive source is increased as the upper limit of the output increases, the total drive of the vehicle is increased. When the force is less than the required driving force, the first output control is carried out to increase the output of one driving source to increase the total driving force. Then, when the total driving force reaches the required driving force by this first output control, the second output control that increases the output of one driving source and decreases the output of the other driving source to maintain the total driving force is performed. Will be implemented. At this time, in the first output control, the output of one drive source is increased according to the increase in the output upper limit value, and in the second output control, the output of one drive source is increased in response to the increase in the output upper limit value. Delay.
In this way, by gradually releasing the output limit so as to preferentially recover the total driving force, it is quicker than in the past where the output limit was temporarily released after simply confirming a sufficient temperature drop. The total driving force of the vehicle can be restored.

According to the second aspect of the present invention, when the output of one drive source is increased to increase the total drive force, the distribution ratio is set to the lower limit of the permitted range in one drive source, so that one drive is used. The total driving force of the vehicle can be restored while suppressing the output of the source as much as possible.

According to the third aspect of the invention, when the increased total driving force reaches the required driving force, the distribution ratio is maintained at the lower limit of the permitted range in one driving source for a predetermined time.
As a result, the output of one drive source can be suppressed as much as possible, and the temperature drop of the one drive source can be promoted.

According to the invention of claim 4, when the increased total driving force reaches the required driving force, the output of one driving source is output within the range of the output upper limit value or less while maintaining the total driving force. Is increased.
As a result, the allocation ratio can be brought closer to the ideal allocation at an early stage, and the running stability can be quickly restored.

According to the invention of claim 5, when the increased total driving force reaches the required driving force, it is based on the temperature information of the other driving sources excluding one of the plurality of driving sources. , The distribution ratio is maintained at the lower limit of the permitted range in one drive source, or the output of one drive source is increased and the output of another drive source is decreased within the range below the upper limit of the output to reduce the total drive. It is selected whether to maintain the force.
Thereby, for example, when it is desired to suppress the temperature of another drive source, the latter process can be selected to control the temperature of the other drive source.

According to the invention of claim 6, since the permitted range is set as the range of the distribution ratio at which the required running stability can be obtained based on the running state of the vehicle detected by the detection means, the distribution ratio is set. By keeping it within the permitted range, running stability can be maintained more reliably.

It is a block diagram which shows the schematic structure of the vehicle in an embodiment. It is a flowchart which shows the flow of the driving force distribution processing in an embodiment. It is a graph which shows an example of the distribution ratio of the driving force in the driving force distribution processing. This is an example of a temperature chart of a rear wheel motor in a driving force distribution process. It is a graph which shows an example of the distribution ratio of the driving force in the driving force distribution processing. It is a graph which shows an example of the distribution ratio of the driving force in the driving force distribution processing. It is a graph which shows an example of the distribution ratio of the driving force in the driving force distribution processing. This is an example of a time chart of the total driving force, each motor driving force, and the driving force distribution rate in the driving force distribution process. It is a block diagram which shows one modification of the schematic structure of the vehicle in an embodiment.

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

<Structure>
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) in which the front wheels 2 and the rear wheels 3 are driven by motors 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, radiator 15, EVCU (Electric Vehicles Control Unit) 20, and A group of sensors (31 to 39) is provided. Of 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. Further, 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.

The driving force control device (hereinafter, simply referred to as “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. In particular, when one of the front wheel motor 11 and the rear wheel motor 12 has a limited output, the driving force can be preferably restored due to the release of the limitation. The driving force control device 100 corresponds to a portion of the above-mentioned configuration including the EVCU 20 and the sensor group (31 to 39).

The front wheel motor 11 and the rear wheel motor 12 individually drive the drive systems of the front and rear wheels based on the 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 the front wheel motor 11 and the rear wheel motor 12 converts the electric power of the battery in response to a command from the EVCU 20 and outputs the power to the front wheel motor 11 and the rear wheel motor 12 to output the front wheels. The motor 11 and the rear wheel motor 12 generate electric power based on this electric power.

The radiator 15 is for cooling various devices of the vehicle 1, and in the present embodiment, the front wheel motor 11 and the rear wheel motor 12 are cooled. The radiator 15, the front wheel motor 11 and the rear wheel motor 12 are connected to each other via a pipe provided with a circulation pump (not shown), and the front wheel motor 11 and the rear wheel motor 12 are connected by circulating cooling water through the pipe. Is water-cooled.

The EVCU 20 is for integrated control of 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 given to the vehicle 1 by, for example, an occupant's driving operation (for example, a sensor signal of an accelerator sensor 35 representing an accelerator operation amount). The EVCU 20 outputs a target output (target torque) command 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 front-rear acceleration sensor 31, a left-right 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 front-back acceleration sensor 31 detects the front-back acceleration of the vehicle 1. The left-right acceleration sensor 32 detects the left-right acceleration 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.

Further, the sensor group includes an accelerator sensor 35, a steering angle sensor 36, and a brake sensor 37 as sensors for detecting the driving operation of the occupant. The accelerator sensor 35 detects the amount of accelerator operation by the occupant. The steering angle sensor 36 detects the amount of steering wheel operation by the occupant. The brake sensor 37 detects the amount of brake operation by the occupant.
Further, 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 as sensors for detecting the output limitation of the front wheel motor 11 and the rear wheel motor 12. include.

<Driving force distribution processing>
Subsequently, the driving force distribution process in which the driving force control device 100 distributes the 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 and 5 to 7 show an example of the driving force distribution ratio to the front wheel motor 11 and the rear wheel motor 12 in the driving force distribution process. FIG. 4 is an example of a temperature chart of the rear wheel motor temperature Trm in the driving force distribution process. Further, FIG. 8 is an example of a time chart of the total driving force, each motor driving force, and the driving force distribution rate in the driving force distribution process.

The driving force distribution process is repeatedly executed 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, the EVCU 20 first acquires each sensor value of the sensor group (31 to 39) including the front wheel motor thermometer 38 and the rear wheel motor thermometer 39. (Step S1). Of these, for example, the sensor value of the accelerator sensor 35 is input as the required driving force, which is the total driving force to be output by the front wheel motor 11 and the rear wheel motor 12.

Next, the EVCU 20 determines a reference ratio that serves as a reference for the required driving force distribution ratio (the ratio of the required driving force distributed to the front wheel motor 11 and the rear wheel motor 12) (step S2). The reference ratio is determined as, for example, the distribution ratio of the required driving force that can obtain high running stability according to the running state of the vehicle 1.

Specifically, in this step S2, the EVCU 20 first calculates the base reference ratio according to the load distribution of the vehicle 1. The base reference ratio is an ideal driving force distribution ratio that maximizes driving stability when traveling straight on a road with no slope, for example. The load distribution of the vehicle 1 is calculated based on the values of the front-rear acceleration and the left-right acceleration among the acquired plurality of sensor values.
Next, the EVCU 20 calculates the amount of change in the reference ratio corresponding to the steering angle and the amount of change in the reference ratio corresponding to the road gradient. 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 showing the relationship between each of the steering angle and the road gradient and the change amount of the reference ratio, and calculates the change amount of the reference ratio from the steering angle and the road gradient using these data tables. do.
Then, the EVCU 20 calculates the reference ratio by integrating each change amount of the reference ratio corresponding to the steering angle and the road gradient into the base reference ratio.

The reference ratio thus obtained is an ideal distribution ratio that realizes high driving stability in accordance with the load distribution of the vehicle and the individual correction parameters (steering angle and road gradient) representing the driving state. However, the correction parameters that represent the driving condition are not limited to the steering angle and the road gradient, and if the parameters affect the ideal driving force distribution ratio, the same correction processing can be performed using other parameters. good.

Next, the EVCU 20 sets a permitted range of the required driving force distribution ratio based on the traveling state of the vehicle 1 (step S3). The permitted 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 do not interfere with the running stability of the vehicle.

Specifically, in this step S3, the EVCU 20 first calculates the values of a plurality of parameters representing the traveling state of the vehicle 1 based on the acquired plurality of sensor values. The plurality of parameters include, for example, vehicle speed, slip ratio, front-rear acceleration, lateral acceleration, degree of understeer, degree of oversteer, amount of brake operation, and the like. These plurality of parameters are parameters that affect the degree of running stability.
Next, the EVCU 20 calculates the width length of the upper limit side allowable width and the lower limit side allowable width individually corresponding to each value of the calculated plurality of parameters. Here, the upper limit side allowable width is a permissible width that can increase the distribution ratio of the driving force to the front wheels 2 within a range that does not hinder the running stability, and the lower limit side permissible width is a range that does not hinder the running stability. It is an allowable range that can increase the distribution ratio of the driving force to the rear wheels 3. The relationship between the value of each parameter and the upper limit side allowable width and the lower limit side allowable width is stored in advance in the form of a data table or function in which they are associated with each other. These relationships are such that the permissible width becomes smaller as the necessity of running stability becomes higher, and the permissible width becomes larger as the necessity of running stability becomes lower. The EVCU 20 uses these data tables or functions to calculate the upper limit side allowable width and the lower limit side allowable width for each of the plurality of parameters.
In a traveling state where the behavior of the vehicle 1 is not disturbed, the upper limit side allowable width and the lower limit side allowable width are the same size. However, in a traveling state in which the behavior of the vehicle 1 is disturbed, such as when there is a tendency for understeer or when there is a tendency for oversteer, the upper limit side allowable width and the lower limit side allowable width do not become the same size. For example, when the understeer tendency appears weakly, increasing the ratio of the driving force of the front wheels 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 force to the rear wheels 3 can be increased. Therefore, the upper limit side allowable width according to the degree of understeer is set smaller than the lower limit side allowable width. On the other hand, the upper limit side allowable width according to the degree of oversteer is set to be 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 these. do. Then, the EVCU 20 adds these minimum upper limit side allowable widths and lower limit side allowable widths to the reference ratio to calculate the allowable range of the distribution ratio. As a result, it is possible to obtain an allowable range of distribution ratios that can obtain the required running stability for all of the plurality of parameters.

Next, the EVCU 20 determines each of the front wheel motor 11 and the rear wheel motor 12 based on the temperatures, vehicle speeds, etc. of the front wheel motor 11 and the rear wheel motor 12 acquired from the front wheel motor thermometer 38 and the rear wheel motor thermometer 39. The output upper limit value is set (step S4).

Next, the EVCU 20 distributes the driving force to the front wheel motor 11 and the rear wheel motor 12 so that the driving force is within the permitted range of the distribution ratio and equal to or less than the output upper limit value (step S5).

Next, the EVCU 20 determines whether or not the output of either the front wheel motor 11 or the rear wheel motor 12 is restricted (step S6).
In the present embodiment, as shown in FIGS. 3 and 4, the rear wheel motor temperature Trm rises to exceed the output limit temperature Ts of the rear wheel motor 12 in the normal state (when the output is not limited). (F1 in FIG. 4), it is assumed that the output upper limit value F of the rear wheel motor 12 is lowered and the output of the rear wheel motor 12 is limited. Then, the output value of the rear wheel motor 12 is reduced and the output value of the front wheel motor 11 is slightly reduced in accordance with the decrease in the output upper limit value F, and the distribution ratio R is a predetermined ideal distribution ratio DRi (for example, the above-mentioned reference). It is assumed that the ratio) has been changed to the upper limit side allowable limit PL1. However, the distribution ratio R at this time may be within the permission range DR and may not be on the upper limit side allowable limit PL1. Here, the upper limit side allowable limit PL1 is the one with the higher distribution ratio of the driving force to the front wheels 2 among the allowable limits of the distribution ratio R in the permission range DR, and the lower limit side allowable limit PL2 is the rear wheel 3 The ratio of the driving force to the vehicle is higher.
By reducing the output value of the rear wheel motor 12 in this way, the rear wheel motor temperature Trm decreases, and the output upper limit value F increases accordingly.

If it is determined in step S6 that neither the front wheel motor 11 nor the rear wheel motor 12 has output limitation (step S6; No), EVCU 20 shifts the process to step S1 described above.

On the other hand, if it is determined in step S6 that either the front wheel motor 11 or the rear wheel motor 12 has the output restricted (step S6; Yes), the EVCU 20 determines the total driving force of the vehicle 1 (front wheel motor 11). And whether or not the total output of the rear wheel motor 12) is less than the required driving force (step S7).
Then, when the total driving force has reached the required driving force (step S7; No), the EVCU 20 shifts the process to step S9 described later. Here, it is assumed that the total driving force does not exceed the required driving force.

Further, in step S7, when the total driving force is less than the required driving force (step S7; Yes), the EVCU 20 restores (increases) the output of the output of one of the motors whose output is limited. The first output control is carried out to increase the total driving force to the required driving force (step S8).
In the present embodiment, when the rear wheel motor temperature Trm drops to the first temperature T1 or less (f2 in FIG. 4), the EVCU 20 increases with the increase in the output upper limit value F as shown in FIGS. 5 and 8. While increasing the output of the rear wheel motor 12, the output of the front wheel motor 11 is also increased ((I) in FIG. 8). Then, the EVCU 20 increases the total driving force to the required driving force while maintaining the distribution ratio R above the upper limit side allowable limit PL1 (the lower limit of the permitted range DR in the rear wheel motor 12). Here, the first temperature T1 is not particularly limited, but for example, even when a predetermined load (for example, maximum output for a certain period of time) is applied to one of the motors in the state of the first temperature T1. The temperature is such that the temperature of one of the motors does not exceed the output limit temperature Ts (see the two-dot chain line in FIG. 4). The first temperature T1 is preset based on the cooling capacity of the radiator 15 for cooling the one motor and the like.
As a result, the total driving force can be preferentially recovered while suppressing the output of the rear wheel motor 12 as much as possible within the range in which the running stability can be maintained.
However, at this time, the total driving force may be increased while increasing the output of the rear wheel motor 12 within the range of the output upper limit value F or less, and the distribution ratio R may not be maintained above the upper limit side allowable limit PL1.

When the total driving force reaches the required driving force, the EVCU 20 increases the output of one motor whose output is limited and decreases the output of the other motor whose output is not limited to maintain the total driving force. 2 Output control is performed (step S9).
In the present embodiment, when the rear wheel motor temperature Trm drops to the second temperature T2 or less (f3 in FIG. 4), the EVCU 20 further releases the output limitation of the rear wheel motor 12 as shown in FIG. The output is increased while maintaining the total driving force, and the distribution ratio R is returned to the ideal distribution ratio DRi. Here, the second temperature T2 is a temperature lower than the first temperature T1, and is a temperature at which it can be determined that, for example, one of the motors has been sufficiently cooled to the extent that the output limitation can be completely released. The second temperature T2 is preset based on the cooling capacity of the radiator 15 for cooling the one motor and the like.

In the second output control in step S9, the EVCU 20 delays the increase in the output of one of the motors with respect to the increase in the upper limit value of the output. The delay mode in this case is not particularly limited.
For example, as shown in FIGS. 7 (a) and 8 (FIG. 8), after the total driving force reaches the required driving force, the distribution ratio R may be maintained at the upper limit side allowable limit PL1 for a predetermined time (FIG. 8). (II)-(III)). As a result, the output of the rear wheel motor 12 can be suppressed and its cooling can be promoted.
However, in this case, as shown in FIG. 7B, the output of the rear wheel motor 12 is increased within the range of the output upper limit value F or less while maintaining the required driving force, and the distribution ratio R is set to the ideal distribution ratio. It may be brought closer to DRi. As a result, it is possible to recover the running stability as well as the recovery of the total driving force.
Which of these processes is selected is not particularly limited, but may be determined based on the motor temperature of the front wheel motor 11 (that is, the other motor whose output is not limited). For example, when the motor temperature of the front wheel motor 11 has not risen so much, the former process shown in FIG. 7A is selected, and when the motor temperature of the front wheel motor 11 rises, it is shown in FIG. 7B. The latter process may be switched to suppress the output of the front wheel motor 11.

Next, the EVCU 20 determines whether or not to end the driving force distribution process (step S10), and if it is determined not to end (step S10; No), the process shifts to the above-mentioned step S1. Then, the detection of the traveling state of the vehicle 1 and the distribution of the driving force based on the detection are sequentially repeated.
On the other hand, when it is determined that the driving force distribution process is terminated due to, for example, the vehicle 1 being stopped (step S10; Yes), the EVCU 20 terminates the driving force distribution process.

<Effect>
As described above, according to the driving force control device 100 of the present embodiment, the output of the rear wheel motor 12 is increased as the output upper limit value F increases from the state where the output of the rear wheel motor 12 is restricted. If the total driving force of the vehicle 1 is less than the required driving force, the first output control is performed to increase the output of the rear wheel motor 12 to increase the total driving force. Then, when the total driving force reaches the required driving force by this first output control, the second output control is carried out in which the output of the front wheel motor 11 is decreased while increasing the output of the rear wheel motor 12 to maintain the total driving force. Will be done. At this time, in the first output control, the output of the rear wheel motor 12 is increased according to the increase in the output upper limit value F, and in the second output control, the output of the rear wheel motor 12 is increased in response to the increase in the output upper limit value F. Delay the increase.
In this way, by gradually releasing the output limit so as to preferentially recover the total driving force, it is quicker than in the past where the output limit was temporarily released after simply confirming a sufficient temperature drop. The total driving force of the vehicle 1 can be restored.

Further, when the output of the rear wheel motor 12 is increased to increase the total driving force, the distribution ratio R is set to the upper limit side allowable limit PL1 (that is, the lower limit of the permitted range DR in the rear wheel motor 12). The total driving force of the vehicle 1 can be recovered while suppressing the output of the motor 12 as much as possible.

Further, when the total driving force reaches the required driving force, the distribution ratio R may be maintained at the upper limit side allowable limit PL1 for a predetermined time.
As a result, the output of the rear wheel motor 12 can be suppressed as much as possible, and the temperature drop of the rear wheel motor 12 can be promoted.

Further, when the total driving force reaches the required driving force, the output of the rear wheel motor 12 may be increased within the range of the output upper limit value F or less while maintaining the total driving force.
As a result, the allocation ratio R can be brought closer to the ideal allocation ratio DRi at an early stage, and eventually the running stability can be quickly restored.

Further, in this case, the distribution ratio R is maintained at the upper limit side allowable limit PL1 based on the temperature of the front wheel motor 11, or the output of the rear wheel motor 12 is increased within the range of the output upper limit value F or less. You may choose whether to reduce the output of the front wheel motor 11 to maintain the total driving force.
Thereby, for example, when it is desired to suppress the temperature of the front wheel motor 11, the temperature of the front wheel motor 11 can be controlled by selecting the latter process.

Further, since the permitted range DR is set as the range of the distributed ratio R in which the required running stability can be obtained based on the running state of the vehicle 1 detected by the sensor group, the distributed ratio R is set within the permitted range DR. By holding it, running stability can be maintained more reliably.

<Modification example>
The embodiment to which the present invention is applicable 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 above embodiment, an example in which the front wheel motor 11 and the rear wheel motor 12 are applied as a plurality of drive sources is shown. However, the plurality of drive sources are not limited to the motor, and may include an engine, for example, the engine (internal combustion engine) generates the power of the front wheels and the motor generates the power of the 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).

Further, in the above embodiment, an example in which the driving force is distributed between the front wheels 2 and the rear wheels 3 is shown. However, the combination of wheels that distribute driving force can be appropriately changed, such as for each of the front, rear, left, and right wheels, or for each of the two rear wheels, and for each of the three sets of wheels, the left front wheel and the right front wheel.
Further, 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.

Further, in the above embodiment, the drive system including the front wheel transmission 13 and the rear wheel transmission 14 is shown, but the transmission may not be provided, and for example, a power transmission mechanism may be provided instead of the transmission.

Further, in the above embodiment, the front wheel motor thermometer 38 and the rear wheel motor thermometer 39 detect the motor temperatures of the front wheel motor 11 and the rear wheel motor 12, and the motor temperature is used to set the output upper limit value and the like. I decided to control it.
However, the parameters used for these various controls do not have to be the motor temperatures themselves as long as they have information on the motor temperatures of the front wheel motor 11 and the rear wheel motor 12. For example, a thermometer that detects the temperature of the cooling water that cools the front wheel motor 11 and the rear wheel motor 12 is provided, and various controls are performed using the cooling water temperature, or the motor temperature is indirectly acquired from the cooling water temperature. It may be done.

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 states may be included. Further, in the above embodiment, parameters such as vehicle speed, slip ratio, front-rear acceleration, etc. are shown as a plurality of types of parameters that affect the allowable width of the permitted range, but even if parameters representing other driving conditions are included. good. Further, the function value obtained by combining two of these parameters may be treated as one parameter.

Further, in the above embodiment, an example in which the permission range DR of the driving force distribution ratio R is calculated by adding the allowable range to the reference ratio is shown, but 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 running stability is improved according to the running state may be directly obtained as the permitted range.

Further, in the above embodiment, the EVCU 20 performs various controls, but the control subject is not limited to the EVCU. For example, another ECU (Electric Control Unit) may perform various controls, or the output from the sensor group may be input to the other ECU and the other ECU may output the sensor value to the EVCU 20. good.
Specifically, as shown in FIG. 9, the MCU (Motor Control Unit) 21 is based on the temperatures of the front wheel motor 11 and the rear wheel motor 12 acquired from the front wheel motor thermometer 38 and the rear wheel motor thermometer 39. Alternatively, the output upper limit values of the front wheel motor 11 and the rear wheel motor 12 may be set. Then, the EVCU 20 may drive and control each motor based on the output upper limit value of each motor output from the MCU 21.

1 Vehicle 2 Front wheels 3 Rear wheels 11 Front wheel motors 12 Rear wheel motors 20 EVCU
21 MCU
38 Front wheel motor thermometer 39 Rear wheel motor thermometer 100 Driving force control device R Distribution ratio DR Allowed range DRi Ideal distribution ratio PL1 Upper limit side allowable limit PL2 Lower limit side allowable limit F Output upper limit value

Claims (9)

A vehicle driving force control device that is mounted on a vehicle having a plurality of drive sources for driving different drive systems and controls the operation of the plurality of drive sources.
A temperature acquisition means for acquiring temperature information of each of the plurality of drive sources,
An output upper limit setting means for setting an output upper limit value of each of the plurality of drive sources based on the temperature information of the drive source, and an output upper limit setting means.
A permission range setting means for setting a permission range of a distribution ratio for distributing the total driving force to be output to the plurality of drive sources to the plurality of drive sources.
A drive control means for driving the plurality of drive sources with each driving force within the permitted range of the distribution ratio and equal to or less than the output upper limit value.
Equipped with
The drive control means is
When the output of one of the plurality of drive sources is limited by the output upper limit value and the output of the one drive source is increased as the output upper limit value increases.
When the total driving force is less than the required driving force given to the vehicle and the temperature of the one driving source drops to the first temperature or lower , the output of the one driving source is increased. The first output control that increases the total driving force is carried out,
When the total driving force reaches the required driving force by the first output control and the temperature of the one driving source drops to the second temperature or less, which is lower than the first temperature, the one driving force is described. A second output control is performed to maintain the total driving force by increasing the output of the source and decreasing the output of the other driving sources other than the one driving source among the plurality of driving sources.
In the first output control, the output of the one drive source is increased according to the increase of the output upper limit value, and in the second output control, the output of the one drive source is increased with respect to the increase of the output upper limit value. A vehicle driving force control device characterized by delaying the increase in. In the first output control, the drive control means increases the output of the one drive source while setting the distribution ratio as the lower limit of the allowable range in the one drive source to increase the total drive force. The vehicle driving force control device according to claim 1. In the second output control, the drive control means sets the distribution ratio within the permitted range in the one drive source for a predetermined time after the total drive force reaches the required drive force by the first output control. The vehicle driving force control device according to claim 1 or 2, wherein the vehicle is maintained at a lower limit. In the second output control, when the total driving force reaches the required driving force by the first output control, the drive control means maintains the total driving force and is in a range equal to or less than the output upper limit value. The vehicle driving force control device according to claim 1 or 2, wherein the output of the one driving source is increased. In the second output control, the drive control means determines the distribution ratio based on the temperature information of the other drive source when the total drive force reaches the required drive force by the first output control. The output of the one drive source is maintained at the lower limit of the permitted range, or the output of the other drive source is decreased while increasing the output of the one drive source within the range equal to or less than the output upper limit value. The driving force control device for a vehicle according to claim 1 or 2, wherein the driver selects whether to maintain the total driving force. A detection means for detecting the running state of the vehicle is provided.
The one according to any one of claims 1 to 5, wherein the permission range setting means sets the permission range as a range of the distribution ratio from which the required running stability can be obtained. The vehicle driving force control device described. The invention according to any one of claims 1 to 6, wherein the plurality of drive sources are composed of a front wheel motor that generates power for the front wheels and a rear wheel motor that generates power for the rear wheels. Vehicle driving force control device. The vehicle according to any one of claims 1 to 6, wherein the plurality of drive sources are composed of an engine that generates power of the front wheels and a motor that generates power of the rear wheels. Driving force control device. The output upper limit setting means is an MCU that sets an output upper limit value of the motor .
The vehicle driving force control device according to claim 7 or 8, wherein the drive control means is an EVCU that drives and controls a motor based on the output upper limit value output from the output upper limit setting means.

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