Driving force control method and driving force control device

Abstract

In the present invention, one of an in-phase mode in which positive / negative signs of output torque of each motor match each other, and an out-of-phase mode in which positive / negative signs of output torque of each motor match differ from other, is set as a control mode for deciding torque distribution of a vehicle. At a time of mutually transitioning the control mode between the in-phase mode and the out-of-phase mode, distribution adjustment control is executed in which torque distribution is adjusted. In the distribution adjustment control, during a coasting period of a first output torque in which positive / negative signs are reversed at the time of transitioning between control modes, adjustment is performed to bring a second output torque in which positive / negative signs are not reversed closer to a total requested torque.

Description

Technical Field

[0001] The present invention relates to a driving force control method and a driving force control device.

Background Art

[0002] In JP2013-85375A, a driving force control device is proposed that controls the behavior of a vehicle body by controlling the driving forces of the front wheels and the rear wheels respectively. In particular, in this driving force control device, from the viewpoint of obtaining a desired pitching behavior of the vehicle body, control is performed to reverse the directions of the driving forces of the front wheels and the rear wheels (one is for power running and the other is for regeneration).

[0003] In particular, in this driving force control device, during the free-running period (the period when the driving force is not transmitted due to the phase delay of the drive transmission system such as the backlash of the reduction gear) before and after the positive / negative of the output torque of one of the front-wheel motor and the rear-wheel motor is reversed, the output torque of the other is maintained constant.

Summary of the Invention

[0004] According to the driving force control of JP2013-85375A, since the combined output torque is also constant by making the output torque of the other constant during the free-running period of one output torque, the discomfort given to the occupant is suppressed.

[0005] However, when the total required driving force (total required torque) for the vehicle changes (when the vehicle accelerates or decelerates) during the control period including the free-running period in which the combined output torque is constant, there is a problem that a deviation occurs between the total required torque and the combined output torque at least during the free-running period, resulting in a step in the longitudinal acceleration of the vehicle.

[0006] Therefore, an object of the present invention is to provide a driving force control method and a driving force control device that can more reliably suppress the step in the longitudinal acceleration when reversing the positive / negative of the output torque of one of the front-wheel motor and the rear-wheel motor.

[0007] According to an aspect of the present invention, there is provided a driving force control method for controlling the torque distribution of each motor so as to satisfy the total required torque of the vehicle by the combined output torque of the front wheel motor that drives the front wheels and the rear wheel motor that drives the rear wheels. In this driving force control method, as a control mode for determining the torque distribution, either a in-phase mode in which the signs of the output torques of the respective motors match each other or an out-of-phase mode in which the signs of the output torques of the respective motors are different from each other is set. Then, when transitioning the control mode between the in-phase mode and the out-of-phase mode, distribution adjustment control for adjusting the torque distribution when transitioning between the in-phase mode and the out-of-phase mode is executed. In particular, in the distribution adjustment control, during the coasting period of the first output torque whose sign is reversed at the time of the transition of the control mode, the second output torque whose sign is not reversed is adjusted so as to approach the total required torque.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4A

Figure 4B

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0009] Hereinafter, each embodiment of the present invention will be described in detail with reference to the drawings.

[0010] [Premise Configuration] FIG. 1 is a diagram for explaining the premise configuration of a vehicle 100 in which the driving force control method of each embodiment is executed.

[0011] Note that as the vehicle 100, an electric vehicle or a hybrid vehicle equipped with a drive motor 10 as a drive source and capable of traveling by the driving force of the drive motor 10 is assumed.

[0012] The drive motor 10 is composed of a front-wheel motor 10f provided at a position in front of the vehicle 100 (front-wheel side) for driving the front wheels 11f and a rear-wheel motor 10r provided at a rear position (rear-wheel side) for driving the rear wheels 11r.

[0013] The front-wheel motor 10f is configured as a three-phase AC motor. During power running, the front-wheel motor 10f receives power supply from an in-vehicle battery (not shown) and generates a driving force. The driving force generated by the front-wheel motor 10f is transmitted to the front wheels 11f via the front-wheel transmission 16f and the front-wheel drive shaft 21f. On the other hand, during regeneration, the front-wheel motor 10f converts the regenerative braking force of the front wheels 11f into AC power and supplies it to the in-vehicle battery.

[0014] On the other hand, the rear-wheel motor 10r is configured as a three-phase AC motor. During power running, the rear-wheel motor 10r receives power supply from the in-vehicle battery and generates a driving force. The driving force generated by the rear-wheel motor 10r is transmitted to the rear wheels 11r via the rear-wheel transmission 16r and the rear-wheel drive shaft 21r. Also, during regeneration, the rear-wheel motor 10r converts the regenerative braking force of the rear wheels 11r into AC power and supplies it to the in-vehicle battery.

[0015] The inverter 12 includes a front-wheel inverter 12f that adjusts the supply power to the front-wheel motor 10f (positive during power running and negative during regeneration) and a rear-wheel inverter 12r that adjusts the supply power to the rear-wheel motor 10r (positive during power running and negative during regeneration).

[0016] The front wheel inverter 12f generates a total required torque T sum Front torque T according to f The power supplied to the front wheel motor 10f is adjusted so that the front torque T f is the output torque of the front wheel motor 10f, which corresponds to the driving force (or regenerative braking force) output by the front wheel motor 10f. On the other hand, the rear wheel inverter 12r is sum Rear torque T according to r The power supplied to the rear wheel motor 10r is adjusted so that the rear torque T r is the output torque of the rear wheel motor 10r, which corresponds to the driving force (or regenerative braking force) output by the rear wheel motor 10r.

[0017] In particular, the total required torque T sum Front torque T according to f and rear torque T r The torque distribution of the is basically the sum of these (hereinafter referred to as "total torque T f+r ") is the total required torque T sum The total required torque T sum is determined, for example, based on the amount of operation of the accelerator pedal by an occupant of the vehicle 100 (accelerator opening APO), or based on a command from a predetermined autonomous driving system (autonomous driving control device) such as ADAS (Advanced Driver Assistance Systems) or AD (Autonomous Driving).

[0018] Furthermore, the vehicle 100 is provided with a controller 50 as a driving force control device that controls torque distribution. The controller 50 is composed of a computer equipped with a central processing unit (CPU), a read-only memory (ROM), a random access memory (RAM), and an input / output interface (I / O interface), and is programmed to execute each process in vehicle control described below. In particular, the functions of the controller 50 can be realized by an in-vehicle computer such as a vehicle control module (VCM), a vehicle motion controller (VMC), a motor controller, etc. and / or a computer installed outside the vehicle 100. Note that the controller 50 may be realized by a single computer hardware, or may be realized by distributing various processes among a plurality of computer hardwares.

[0019] The controller 50 takes the total required torque T sum , and the detection results of various sensors (not shown) as input information, and determines a command value of the front torque T f according to a desired torque distribution (hereinafter also referred to as "command front torque T * f ") and a command value of the rear torque T r (hereinafter also referred to as "command rear torque T * r "). Then, the controller 50 commands the front-wheel inverter 12f and the rear-wheel inverter 12r so that the actual value of the front torque T f (hereinafter also referred to as "actual front torque T f_re ") and the actual value of the rear torque T r (hereinafter also referred to as "actual rear torque T r_re ") follow the command front torque T * f and the command rear torque T * r .

[0020] In particular, in each of the embodiments described below, the controller 50, as a control mode for determining torque distribution, includes a front torque T f and a rear torque T r either sets a in-phase mode in which the positive and negative signs of these match each other or a out-of-phase mode in which the positive and negative signs of these are different from each other.

[0021] The in-phase mode is a control mode that defines torque distribution so that the vehicle characteristics take on desired characteristics during acceleration and deceleration of the vehicle 100. In particular, in the in-phase mode during acceleration, the distribution ratio κ of the front torque T f and the rear torque T r is set to a basic distribution ratio (for example, 50:50) that realizes favorable vehicle characteristics during acceleration within the range of 0 to 100:100 to 0. On the other hand, in the in-phase mode during deceleration, the distribution ratio κ of the front torque T f and the rear torque T r is set to a basic distribution ratio (for example, -50:-50) that realizes favorable vehicle characteristics during deceleration within the range of -100 to 0:0 to -100. Hereinafter, in the in-phase mode during acceleration or deceleration, the torque distribution based on the basic distribution ratio that realizes favorable vehicle characteristics is also referred to as the "in-phase basic distribution". Note that the basic distribution ratio in the in-phase basic distribution may be a fixed value or a variable value that changes within the above range.

[0022] Note that the concept of vehicle characteristics assumed in each embodiment includes, for example, characteristics related to energy efficiency (electricity consumption performance) consumed in operations such as running of the vehicle 100, characteristics related to the difficulty of slipping in the front wheels 11f or the rear wheels 11r (slip performance), and the followability of the actual longitudinal acceleration with respect to the total required torque T sum and the like.

[0023] On the other hand, the out-of-phase mode is a control mode that defines the torque distribution required in the control to achieve specific vehicle behavior according to various driving scenarios during acceleration and deceleration of the vehicle 100. Note that the control to achieve this specific vehicle behavior includes, for example, control to adjust the pitch behavior of the vehicle body (so-called pitch control) to reduce the vibration transmitted to the occupants in a scene of driving over a step or unevenness, or control to enhance the running performance of the vehicle 100 under the situation of driving on a special road surface. In the following, in the out-of-phase mode during acceleration or deceleration, the torque distribution based on the preferable basic distribution ratio from the viewpoint of achieving the desired vehicle behavior is also referred to as "out-of-phase basic distribution".

[0024] In particular, the out-of-phase basic distribution includes the front-wheel regeneration distribution and the rear-wheel regeneration distribution according to the target vehicle behavior.

[0025] In the front-wheel regeneration distribution, the commanded front torque T * f is set to a negative value, and the commanded rear torque T * r is set to a positive value. That is, while regenerating the front-wheel motor 10f (while performing regenerative braking on the front wheel 11f), the rear-wheel motor 10r is made to perform power running (the rear wheel 11r is driven by power running).

[0026] In the rear-wheel regeneration distribution, the commanded front torque T * f is set to a positive value, and the commanded rear torque T * r is set to a negative value. That is, while making the front-wheel motor 10f perform power running (while driving the front wheel 11f by power running), the rear-wheel motor 10r is regenerated (the rear wheel 11r is regeneratively braked).

[0027] In particular, in the driving force control method of each embodiment, when transitioning between the in-phase mode and the out-of-phase mode, during the free-running period caused by backlash resulting from one of the actual front torque T f_re or the actual rear torque T r_re crossing zero, the total combined torque T sum with respect to the total required torque T f+r (more specifically, the actual combined torque Tf+r_re ) deviation is suppressed. The distribution adjustment control will be described below.

[0028] In this specification, the "coasting period" means a period during which the driving force actually transmitted to the driving wheels cannot sufficiently follow the command value of the output torque of the motor due to the phase delay of the driving force transmission system from the motor to the driving wheels (for example, backlash in a speed reduction mechanism, etc.) when the positive and negative of the output torque of the motor are reversed. Hereinafter, in particular, the coasting period generated due to the driving force transmission system between the front wheel motor 10f and the front wheel 11f is referred to as the "front coasting period", and the coasting period generated due to the driving force transmission system between the rear wheel motor 10r and the rear wheel 11r is referred to as the "rear coasting period". Also, the actual front torque T f_re and the actual rear torque T r_re The terms respectively mean torques corresponding to the driving forces actually transmitted to the front wheels 11f and the rear wheels 11r transmitted through each driving force transmission system.

[0029] [Distribution Adjustment Control] FIG. 2 is a flowchart for explaining the control logic of the distribution adjustment control common to each embodiment. The controller 50 repeatedly executes each process shown in FIG. 2 at a predetermined calculation cycle when the vehicle 100 is accelerating or decelerating.

[0030] In step S110, the controller 50 determines whether a request to transition the control mode between the out-of-phase mode and the in-phase mode has occurred. For example, the controller 50 makes this determination based on input information acquired from various sensors mounted on the vehicle 100 and / or a predetermined external server.

[0031] Next, in step S120, the controller 50 sets the torque adjustment start timing. Specifically, the controller 50 determines a suitable timing to start adjusting the command torque before the coasting period in which the positive and negative of the torque are reversed.

[0032] Incidentally, hereinafter, when adjusting the front torque T f (command front torque T * f ) at the time of transition of the control mode, the timing at which the adjustment starts is also referred to as "t at the start of front torque adjustment f_s ". On the other hand, when adjusting the rear torque T r (command rear torque T * r ), the timing at which the adjustment starts is also referred to as "t at the start of rear torque adjustment r_s ".

[0033] And in step S130, the controller 50 sets the torque adjustment end timing. Specifically, the controller 50 determines a suitable timing for ending the torque adjustment after the coasting period in which the sign of the torque reverses.

[0034] Incidentally, hereinafter, when adjusting the command front torque T * f at the time of transition of the control mode, the timing at which the adjustment ends is also referred to as "t at the end of front torque adjustment f_e ". On the other hand, when adjusting the command rear torque T * r , the timing at which the adjustment ends is also referred to as "t at the end of rear torque adjustment r_e ".

[0035] Furthermore, in step S140, the controller 50 executes the torque adjustment. Specifically, the controller 50 switches the command torque from the value corresponding to the basic distribution of the control mode of the transition source to a value closer to the total required torque T sum from the start timing of the adjustment determined in step S120 to the end timing of the adjustment determined in step S130.

[0036] And in step S150, the controller 50 ends the torque adjustment. Specifically, the controller 50 returns the command torque to the value corresponding to the basic distribution of the control mode of the transition destination based on the above adjustment end timing.

[0037] In each of the following embodiments, an example of applying the distribution adjustment control shown in FIG. 2 to a more specific scenario will be described.

[0038] [First Embodiment] In this embodiment, the distribution adjustment control applied to a scene where the control mode transitions from the out-of-phase mode (front-wheel regeneration and rear-wheel power running) to the in-phase mode (front-wheel power running and rear-wheel power running) during the acceleration of the vehicle 100 will be described. That is, in this embodiment, when the front torque T f reverses from negative to positive, the command rear torque T * r is adjusted during the front-wheel free-running period.

[0039] Specifically, in this embodiment, in step S120 of FIG. 2, the start time t r_s of rear torque adjustment is determined to be the timing when the commanded front torque T * f (more specifically, the commanded front torque T * f corresponding to the out-of-phase basic distribution) coincides with the front torque threshold T f_th .

[0040] Here, the front torque threshold T f_th is determined by experiment or simulation as the value that the commanded front torque T * f reaches a predetermined time before the point in time when it enters the front-wheel free-running period (i.e., when the commanded front torque T * f becomes zero). Specifically, the front torque threshold T f_th is determined such that the change in the actual rear torque T r_s following the adjusted commanded rear torque T * r during the period from the start time t r_re of rear torque adjustment to the point in time when it enters the front-wheel free-running period is within a predetermined allowable upper limit. The allowable upper limit of the change in the actual rear torque T r_re isr_re It is determined such that changes in r_re do not cause fluctuations in longitudinal acceleration (longitudinal G fluctuations) that give discomfort to the occupants of the vehicle 100 before and after the change.

[0041] Also, in the present embodiment, in step S130 of FIG. 2, at the end time t of rear torque adjustment r_e is set to coincide with the time when the front free-running period ends (the time when the rotational play is clogged). Note that the end time of the front free-running period can be determined in advance by experiments or simulations according to the characteristics of the driving force transmission system on the front wheel side of the vehicle 100.

[0042] FIG. 3 is a timing chart showing an example of the control result by the distribution adjustment control of the present embodiment.

[0043] As shown in the figure, after the time t when the acceleration of the vehicle 100 starts 1 the actual front torque T f_re and the actual rear torque T r_re respectively change following the commanded front torque T * f (<0) and the commanded rear torque T * r (>0) defined in the different-phase mode which is the mode transition source.

[0044] Then, when the rear torque adjustment start time t r_s is reached, the adjustment of the commanded rear torque T * r is started. As a result, the actual rear torque T r_re gently increases so as to coincide with the total required torque T sum at the time of entering the subsequent front free-running period.

[0045] When entering the front free-running period, the control mode transitions from the first different-phase mode to the in-phase mode. Along with this, the commanded front torque T * fmaintains the basic distribution (more specifically, follows the switching from the out-of-phase basic distribution before mode transition to the in-phase basic distribution after transition). In contrast, the actual front torque T f_re cannot follow the change in the commanded front torque T * f due to the occurrence of rotational backlash caused by the phase delay of the driving force transmission during the front coasting period and is maintained in a substantially zero state. On the other hand, the actual rear torque T r_re is adjusted based on the commanded rear torque T r_s regulated with the start time t * r as a reference point, changes following the commanded rear torque T sum and coincides with the total required torque T

[0046] from the entry point to the end point of the front coasting period. r_e ) to a value corresponding to the basic distribution defined in the transition destination in-phase mode. And at time t2 after a certain period, both the actual front torque T * r and the actual rear torque T f_re and the actual rear torque T r_re converge to the steady basic distribution ratio in the in-phase mode during acceleration.

[0047] Next, the effects of the control according to the present embodiment will be described while comparing with a comparative example.

[0048] FIG. 4A is a timing chart for explaining the result of the control of the comparative example, and FIG. 4B is a timing chart for explaining the effect of the control of the example (the control of the present embodiment). Note that the comparative example shown in FIG. 4A assumes a control (a control that does not execute the correction of the commanded rear torque T 1 ~t 2 ) that maintains the basic torque distribution defined in the first out-of-phase mode or in-phase mode during the entire control period (t = t * r ).

[0049] As shown in FIG. 4A, in the control of the comparative example, during the front free-running period in which the actual front torque T f_re is maintained at zero without following the commanded front torque T * f , a step (front-rear G step) of the actual combined torque T f+r_re occurs (see the circled part in the figure).

[0050] On the other hand, in the control of the embodiment shown in FIG. 4B, during the front free-running period, the actual rear torque T r_re changes to follow the corrected commanded rear torque T * r so as to match the total required torque T sum . Therefore, the front-rear G step during the front free-running period is suppressed.

[0051] Hereinafter, the configuration of the present embodiment described above and its operation and effects will be collectively described.

[0052] In the present embodiment, the torque distribution of each of the front motor 10f that drives the front wheels 11f of the vehicle 100 and the rear motor 10r that drives the rear wheels 11r is controlled so as to satisfy the total required torque T f+r of the vehicle 100 by the combined output torque (combined torque T sum ) of the motors 10f and 10r.

[0053] In this driving force control method, either a in-phase mode in which the signs of the output torques (front torque T f and rear torque T r ) of each of the motors 10f and 10r match each other, or an out-of-phase mode in which the signs of the output torques of each of the motors 10f and 10r are different from each other is set. In particular, in this driving force control method, distribution adjustment control for adjusting the torque distribution when transitioning the control mode between the in-phase mode and the out-of-phase mode is executed.

[0054] And in this distribution adjustment control, during the free-running period (front free-running period) of the first output torque (front torque T f ) whose sign is reversed when the control mode is transitioned, the second output torque (rear torque Tr ) to adjust so as to approach the total required torque T sum .

[0055] Thereby, even during the front free-running period in which the front torque T f is not transmitted as the actual driving force of the front wheels 11f, by correcting the rear torque T r , the deviation of the combined torque T sum with respect to the total required torque T f+r can be suitably compensated. As a result, even in a scene passing through the front free-running period in a situation where the total required torque T sum changes, the occurrence of an unintended front-rear G difference can be suppressed, and the shock given to the occupants can be reduced.

[0056] In particular, in the present embodiment, the control mode is changed from the out-of-phase mode to the in-phase mode when the vehicle 100 is accelerating. In the distribution adjustment control, the command value of the rear torque T r (command rear torque T r_re sum r ) is adjusted so that the actual value of the rear torque T r (actual rear torque T * r ) coincides with the total required torque T

[0057] Thereby, more specific control logic for compensating the deviation of the combined torque T sum with respect to the total required torque T f+r is realized during the front free-running period.

[0058] Also, in the present embodiment, when the command value of the front torque T f (command front torque T * f ) coincides with a predetermined torque threshold value (front torque threshold value T f_th ), the adjustment of the command rear torque T * r is started. Also, in accordance with the end of the front free-running period, the adjustment of the command rear torque T * r is ended.

[0059] As a result, during the front coasting period, the actual rear torque T r_re is made to suitably follow the total required torque T sum and, after the end of the front coasting period, the torque distribution can be quickly returned to the basic distribution (torque distribution for realizing good vehicle characteristics) defined in the in-phase mode after the transition.

[0060] Furthermore, in the present embodiment, a controller 50 that functions as a driving force control device for executing the above driving force control method is provided.

[0061] The controller 50 controls the torque distribution of each of the front motor 10f that drives the front wheels 11f of the vehicle 100 and the rear motor 10r that drives the rear wheels 11r so as to satisfy the total required torque T f+r of the vehicle 100 by the combined output torque (combined torque T sum ) of the motors 10f and 10r.

[0062] The controller 50 sets either an in-phase mode in which the signs of the output torques (front torque T f and rear torque T r ) of each of the motors 10f and 10r match each other, or an out-of-phase mode in which the signs of the output torques of each of the motors 10f and 10r are different from each other. Further, the controller 50 executes distribution adjustment control for adjusting the torque distribution when transitioning the control mode between the in-phase mode and the out-of-phase mode.

[0063] Then, in the distribution adjustment control, during the coasting period (front coasting period) of the first output torque (front torque T f ) whose sign is inverted at the time of transition of the control mode, the second output torque (rear torque T r ) whose sign is not inverted is adjusted so as to approach the total required torque T sum .

[0064] As a result, a configuration of a control device suitable for executing the above driving force control method is realized.

[0065] [Second Embodiment] Hereinafter, a second embodiment will be described. Elements similar to those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

[0066] In the driving force control method of the present embodiment, based on the distribution adjustment control described in the first embodiment, an example of executing a zero torque command for maintaining the commanded front torque T * f at zero during the front coasting period will be described.

[0067] In FIG. 5, an example of the control result by the distribution adjustment control of the present embodiment is shown. As shown in the figure, in the present embodiment, the controller 50 determines that the commanded front torque T * f is equal to a predetermined processing start threshold value T f_th1 (<0), and starts the zero torque command. Further, the controller 50 starts adjusting the commanded rear torque T * r described in the first embodiment in accordance with the start of the zero torque command.

[0068] Note that the processing start threshold value T f_th1 is determined to be an appropriate value from the viewpoint of keeping within a range that does not cause a front-rear G variation that gives discomfort to the occupants of the vehicle 100 due to the change in the commanded rear torque T * f caused by executing the zero torque command and the change in the commanded front torque T * r (actual rear torque T r_re ).

[0069] Further, when the commanded front torque T * f is equal to a predetermined processing end threshold value T f_th2 , the controller 50 ends the zero torque command. Furthermore, the controller 50 ends the adjustment of the commanded rear torque T * r in accordance with the end of the zero torque command. Note that the processing end threshold value T f_th2is determined to be an appropriate value from the viewpoint of promptly returning the torque distribution after the end of the zero torque command to the basic distribution defined in the in-phase mode after the transition.

[0070] According to the driving force control method of the present embodiment described above, by executing the zero torque command, the front-rear G variation caused by backlash during the front free-running period is suppressed, and the commanded rear torque T * r is adjusted to make the actual rear torque T r_re closely follow the total required torque T sum to suppress the occurrence of the front-rear G step difference.

[0071] Also, in accordance with the start and end timings of the zero torque command, the adjustment of the commanded rear torque T * r is started and ended, so that after the zero torque command, the torque distribution can be promptly returned to the basic distribution (particularly, the basic distribution in the in-phase mode) that defines the preferable vehicle characteristics.

[0072] [Third Embodiment] Hereinafter, the third embodiment will be described. Note that the same reference numerals are given to the same elements as those in the first embodiment or the second embodiment, and the description thereof will be omitted. In particular, in this embodiment, during deceleration of the vehicle 100, in each of the scene where the control mode is first transitioned (hereinafter, also referred to as "front half transition"), and the scene where the control mode is next transitioned (hereinafter, also referred to as "rear half transition"), an example of applying the distribution adjustment control will be described.

[0073] In particular, in this embodiment, during the front half transition during deceleration, the control mode is transitioned from the in-phase mode (front wheel power running and rear wheel power running) to the out-of-phase mode (front wheel power running and rear wheel regeneration). On the other hand, during the rear half transition, the control mode is transitioned from the out-of-phase mode (front wheel power running and rear wheel regeneration) to the in-phase mode (front wheel regeneration and rear wheel regeneration).

[0074] FIG. 6 shows an example of the control result by the distribution adjustment control of this embodiment. As shown in the figure, in the distribution adjustment control during the front half transition, the commanded front torque T during the rear free-running period* f Perform the adjustment. Note that the commanded front torque T * f Regarding the specific method for adjusting, except that the adjustment target is the front torque T r instead of the rear torque T f and the point that it becomes the front torque T, it is the same as the adjustment of the commanded rear torque T * r described in the first embodiment.

[0075] On the other hand, in the distribution adjustment control in the latter half transition, the commanded rear torque T * r is adjusted during the front coasting period. Note that regarding the specific method for adjusting the commanded rear torque T * r except that the direction in which the sign of the front torque T f transitions is different, it is the same as the adjustment of the commanded rear torque T * r described in the first embodiment.

[0076] That is, in this embodiment, when the vehicle 100 decelerates, the first half transition for transitioning the control mode from the in-phase mode to the out-of-phase mode and the second half transition for transitioning the control mode from the out-of-phase mode to the in-phase mode are executed in sequence.

[0077] And in each distribution adjustment control, the command value of the second output torque is adjusted so that the actual value of the second output torque matches the total required torque T sum . More specifically, in the distribution adjustment control in the first half transition, the commanded front torque T f_re is adjusted so that the actual front torque T sum during the rear coasting period matches the total required torque T * f . On the other hand, in the distribution adjustment control in the second half transition, the commanded rear torque T r_re is adjusted so that the actual rear torque T sum during the front coasting period matches the total required torque T * r .

[0078] Accordingly, when the vehicle 100 decelerates and the control mode transitions multiple times, during the rear coasting period and the front coasting period at each transition, the actual front torque T f_re and the actual rear torque T r_re can be suitably matched to the total required torque T sum As a result, even when the vehicle 100 decelerates, the occurrence of an unintended front-rear G difference can be suppressed, and the shock applied to the passengers can be reduced.

[0079] In particular, in the present embodiment, in the distribution adjustment control at the time of the latter half transition, by determining the adjustment start / end timing of the commanded rear torque T * r with the same control logic as in the first embodiment, after the adjustment of the commanded rear torque T * r at the time of the latter half transition, the torque distribution of the vehicle 100 can be quickly restored to the basic distribution (distribution that realizes good vehicle characteristics during deceleration) in the in-phase mode of the transition destination.

[0080] [Fourth Embodiment] Hereinafter, the fourth embodiment will be described. Note that the same reference numerals are given to the same elements as in any of the first to third embodiments, and the description thereof will be omitted.

[0081] In the present embodiment, based on the respective distribution adjustment controls executed in the first half transition and the second half transition described in the third embodiment, an example of executing the zero torque command described in the second embodiment in each scene will be described.

[0082] In FIG. 7, an example of the control result by the distribution adjustment control of the present embodiment is shown. As shown in the figure, in the present embodiment, in the zero torque command in the first half transition, the commanded rear torque T * r is maintained at zero. On the other hand, in the zero torque command in the second half transition, the commanded front torque T * fMaintain it at zero. Note that the specific control logic of the zero torque command (start and end timings, and the relationship with the start and end timings of each command torque) is the same as that of the second embodiment.

[0083] In this way, by executing the adjustment of the zero torque command and the command torque in the first half transition and the second half transition during the deceleration of the vehicle 100, respectively, it is possible to suppress the fluctuations and steps of the longitudinal G in both the first half transition and the second half transition.

[0084] As described above, the embodiments of the present invention have been described. However, the above embodiments merely show a part of the application examples of the present invention, and are not intended to limit the technical scope of the present invention to the specific configurations of the above embodiments.

[0085] In particular, the specific control logic for determining the timing to start / end the adjustment of the command rear torque T * r or the command front torque T * f is not limited to that shown in each of the above embodiments, and can be appropriately changed in consideration of the balance between the suppression effect of the longitudinal G step and the prompt return to the basic distribution after the adjustment of the command torque.

Claims

1. A driving force control method for controlling the torque distribution of each motor so as to satisfy the total required torque of the vehicle by the combined output torque of a front-wheel motor that drives the front wheels and a rear-wheel motor that drives the rear wheels, As a control mode for determining the torque distribution, either a in-phase mode in which the signs of the output torques of the respective motors match each other or an out-of-phase mode in which the signs of the output torques of the respective motors are different from each other is set, When the control mode is mutually transitioned between the in-phase mode and the out-of-phase mode, distribution adjustment control for adjusting the torque distribution is executed, In the distribution adjustment control, The entry point and the end point of the coasting period of the first output torque whose sign is reversed at the time of the transition of the control mode are specified, The entry point is the timing at which the command value of the first output torque corresponding to the basic torque distribution before the transition becomes zero, A predetermined adjustment start timing earlier than the entry point is set, At least during the period from the adjustment start timing to the entry point, while maintaining the command value of the first output torque at a value corresponding to the basic torque distribution before the transition, the command value of the second output torque whose sign is not reversed is switched from a value corresponding to the basic torque distribution before the transition to a value closer to the total required torque, The command value of the second output torque after the switching is determined so that the actual value of the second output torque matches the total required torque from the entry point to the end point, The adjustment start timing is determined so that the change in the actual value of the second output torque during the period from the adjustment start timing to the entry point is equal to or less than an allowable upper limit that suppresses the fluctuation of the longitudinal acceleration of the vehicle during the period, Driving force control method.

2. The driving force control method according to claim 1, When the vehicle is accelerating, the control mode is transitioned from the out-of-phase mode to the in-phase mode, In the distribution adjustment control, The command value of the second output torque is adjusted so that the actual value of the second output torque during the coasting period matches the total required torque. Driving force control method.

3. The driving force control method according to claim 1, When the vehicle is decelerating, the first half transition of transitioning the control mode from the in-phase mode to the out-of-phase mode and the second half transition of transitioning the control mode from the out-of-phase mode to the in-phase mode are sequentially executed, The distribution adjustment control is executed in both the first half transition and the second half transition. In each of the above distribution adjustment controls, a method for controlling driving force, wherein a command value of the second output torque is adjusted so that an actual value of the second output torque matches the total required torque. Driving force control method. **Claim 4** A driving force control method according to claim 1, wherein the adjustment start timing is determined as a timing at which a command value of the first output torque, which changes according to the basic torque distribution before transition, matches a predetermined torque threshold different from zero, and in the distribution adjustment control, when the command value of the first output torque matches the torque threshold, adjustment of the command value of the second output torque is started, and the adjustment of the command value of the second output torque is terminated in accordance with the end of the free-running period. Driving force control method. **Claim 5** A driving force control method according to claim 1, wherein in the distribution adjustment control, the command value of the first output torque is maintained at a value according to the basic torque distribution before transition during a period from the adjustment start timing to the point of entry, and is maintained at zero during the free-running period. Driving force control method. **Claim 6** A driving force control device that controls the torque distribution of each motor so that the total required torque of the vehicle is satisfied by the combined output torque of a front-wheel motor that drives the front wheels and a rear-wheel motor that drives the rear wheels, wherein, as a control mode for determining the torque distribution, either a in-phase mode in which the signs of the output torques of the respective motors match each other or an out-of-phase mode in which the signs of the output torques of the respective motors are different from each other is set, distribution adjustment control for adjusting the torque distribution is executed when the control mode is mutually transitioned between the in-phase mode and the out-of-phase mode, and in the distribution adjustment control, the entry point and the end point of the free-running period of the first output torque, whose sign is reversed during the transition of the control mode, are specified, the entry point is the timing at which the command value of the first output torque according to the torque distribution before transition becomes zero, a predetermined adjustment start timing before the entry point is set, at least during a period from the adjustment start timing to the entry point, while maintaining the command value of the first output torque at a value according to the torque distribution before transition, the command value of the second output torque, whose sign does not reverse, is switched from a value according to the torque distribution before transition to a value closer to the total required torque, and the command value of the second output torque after the switching is determined so that the actual value of the second output torque matches the total required torque from the entry point to the end point. The adjustment start timing is determined such that a change in the actual value of the second output torque in the period from the adjustment start timing to the entry timing is equal to or less than an allowable upper limit for suppressing fluctuations in the longitudinal acceleration of the vehicle. Drive force control device.

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