JP2021027649A - Shift control method and shift control system - Google Patents

Abstract

To provide a shift control method and a shift control system capable of more quickly completing a shift at the time of braking a vehicle having a front wheel side transmission and a rear wheel side transmission.SOLUTION: A shift control method includes the steps of: if both of shift conditions of front-wheel down shift and shift conditions of rear wheel down shift are satisfied during friction braking performed when required braking force during braking of a vehicles 100 is a prescribed threshold value or more, executing the front wheel down shift and the rear wheel down shift in parallel; if both of the shift condition of the front wheel down shift and the shift condition of the rear wheel down shift are satisfied during regenerative braking executed when the required braking force is less than the prescribed threshold, executing the rear wheel down shift after completion of the front wheel down shift, or executing the front wheel down shift after completion of the rear wheel down shift; and compensating braking force loss of the front wheels during the front wheel down shift by regenerative braking force of the rear wheels, and compensating braking force loss of the rear wheels during the rear wheel down shift by regenerative braking force of the front wheels.SELECTED DRAWING: Figure 3

Description

The present invention relates to a shift control method and a shift control system.

Patent Document 1 proposes a transmission for a four-wheel drive vehicle including a plurality of dog clutches and a plurality of gear trains in which power transmission to and from the input shaft can be switched by displacing the dog clutch according to a desired gear ratio. ing.

In particular, the four-wheel drive vehicle of Patent Document 1 is provided with a transmission that adjusts the power transmitted from the drive source (engine or motor) to the front wheels and a transmission that adjusts the power transmitted to the rear wheels. There is. Therefore, in a state where the dog clutch does not mesh with the gear train during shifting of one of the transmissions (neutral state), the driving force is lost because the desired power is not transmitted to the driving wheels via the transmission.

On the other hand, in the shift control method proposed in Patent Document 1, in a scene where a drive force loss occurs during shifting of one transmission, the drive force of the other drive wheel is increased to compensate for the drive force loss. Processing (driving force compensation processing) is being performed.

Japanese Unexamined Patent Publication No. 2006-027383

However, in the shift control method proposed in Patent Document 1, when the conditions for downshift shifting are satisfied for both transmissions at almost the same time, such as when the vehicle is suddenly braked, the driving force of one transmission is lost ( It is necessary to compensate for the lack of braking force with the driving force (regenerative braking force) given to the other driving wheel. Therefore, it is necessary to shift the shift timing of both transmissions, and the shift time becomes long.

Therefore, another object of the present invention is to provide a shift control method and a shift control system capable of completing a shift more quickly when braking a vehicle having a front wheel side transmission and a rear wheel side transmission. ..

According to an aspect of the present invention, a front wheel drive system having a front wheel drive motor for driving the front wheels and a front wheel side transmission, and a rear wheel drive system having a rear wheel drive motor for driving the rear wheels and a rear wheel side transmission. In a vehicle equipped with, a front wheel down shift, which is a down shift by the front wheel side transmission, and a down shift by the rear wheel side transmission during execution of regenerative braking that regenerates at least one of the front wheel drive motor and the rear wheel drive motor. A shift control method for executing each of the rear wheel down shifts is provided. In this shift control method, when both the front wheel down shift condition and the rear wheel down shift condition are satisfied during friction braking executed when the required braking force at the time of braking the vehicle is equal to or more than a predetermined threshold value, the front wheels Down shifting and rear wheel down shifting are executed in parallel. Further, if both the front wheel down shifting condition and the rear wheel down shifting condition are satisfied during the regenerative braking executed when the required braking force is less than the above-mentioned predetermined threshold value, the rear wheel is down after the front wheel down shifting is completed. The shift is executed, or the front wheel down shift is executed after the rear wheel down shift is completed. Then, the loss of braking force of the front wheels during the front wheel down shift is compensated by the regenerative braking force of the rear wheels, and the loss of braking force of the rear wheels during the rear wheel down shift is compensated by the regenerative braking force of the front wheels.

According to the present invention, the shifting can be completed more quickly when braking a vehicle having a front wheel side transmission and a rear wheel side transmission.

FIG. 1 is a diagram illustrating a common electric vehicle configuration in which the shift control methods of the first and second embodiments are executed. FIG. 2 is a block diagram illustrating a control configuration for executing the shift control method of the first embodiment. FIG. 3 is a timing chart illustrating a shift during the sudden braking process according to the first embodiment. FIG. 4 is a timing chart illustrating a shift during the normal braking process according to the first embodiment. FIG. 5 is a timing chart illustrating a shift during the sudden braking process according to the second embodiment.

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

[First Embodiment]
Hereinafter, the first embodiment will be described.

(Vehicle configuration)
FIG. 1 is a diagram illustrating a main common configuration of a vehicle 100 in which the shift control method of each of the following embodiments is executed.

The vehicle 100 in FIG. 1 is a vehicle that includes a drive motor 10 as a drive source and can travel by the driving force of the drive motor 10, and includes an electric vehicle and a hybrid vehicle.

In particular, the vehicle 100 shown in FIG. 1 includes a front wheel drive system fds arranged at a position relatively forward (hereinafter referred to as "front wheel side") in the vehicle 100, and a position relatively rearward in the vehicle 100 (hereinafter referred to as "front wheel side"). Hereinafter, the rear wheel drive system rds arranged on the "rear wheel side") is mounted.

The front wheel drive system fds and the rear wheel drive system rds each include a front motor 10f as a front wheel side drive source and a rear motor 10r as a rear wheel side drive source. The front motor 10f and the rear motor 10r generate power to drive the front drive wheels 11f (left front drive wheels 11fL and right front drive wheels 11fR) and rear drive wheels 11r (left rear drive wheels 11rL and left rear drive wheels 11rR), respectively. To do.

That is, the vehicle 100 is configured as a four-wheel drive vehicle that transmits the power of the drive motor 10 to the front drive wheels 11f and the rear drive wheels 11r. Details of the front wheel drive system fds and the rear wheel drive system rds will be described.

The front wheel drive system fds includes a front inverter 14f and a front transmission 16f in addition to the front motor 10f and the front drive wheels 11f.

The front motor 10f is configured as a three-phase AC motor. The front motor 10f is supplied with electric power from the battery 15 (see FIG. 2) as a power source to generate a driving force. The driving force generated by the front motor 10f is transmitted to the front drive wheels 11f via the front transmission 16f and the front drive shaft 21f.

Further, the front motor 10f converts the regenerative driving force generated when the vehicle 100 is driven by the front drive wheels 11f and rotates into AC power.

The front inverter 14f includes a switching circuit that performs switching for converting the electric power from the battery 15 into three-phase alternating current. Further, the front inverter 14f converts the AC power obtained based on the regenerative driving force of the front motor 10f described above into DC power by the switching and supplies the AC power to the battery 15.

The front transmission 16f is a device that executes a shift (hereinafter, also referred to as "front wheel shift") with respect to the transmission power between the front motor 10f and the front drive wheels 11f.

In particular, the front transmission 16f has a relatively low gear ratio in the power transmission path from the rotor shaft of the front motor 10f (hereinafter, also referred to as “input shaft 20f”) to the front drive shaft 21f as the front wheel shifting. It switches between two gears, a gear and a Low gear with a relatively high gear ratio. The configuration of the front transmission 16f will be described in more detail.

The front transmission 16f mainly includes a Low gear train 22f, a High gear train 24f, a dog clutch 26f, and a final gear 30f.

The Low gear train 22f includes a drive gear 40f and a driven gear 41f that mesh with each other. The drive gear 40f is rotatably provided on the input shaft 20f without being fixed. Further, the driven gear 41f is fixed to the output shaft 32f. Further, in the Low gear row 22f, the number of teeth of the driven gear 41f is larger than the number of teeth of the drive gear 40f. That is, the gear ratio γ (hereinafter, also referred to as _{“front gear ratio γ f} ”) when transmitted from the input shaft 20f to the output shaft 32f via the Low gear train 22f (when the shift stage Sh is Low) is 1. Become bigger.

The high gear train 24f includes a drive gear 42f and a driven gear 43f that mesh with each other. The drive gear 42f is rotatably provided on the input shaft 20f without being fixed. Further, the driven gear 43f is fixed to the output shaft 32f. Further, in the high gear train 24f, the number of teeth of the drive gear 42f and the number of teeth of the driven gear 43f are substantially equal. That is, when the transmission is transmitted from the input shaft 20f to the output shaft 32f via the high gear train 24f (when the shift stage Sh is High), the front gear ratio γ _f is approximately 1.

The dog clutch 26f is provided integrally with the shift fork 44f and the shift fork 44f that slide and move in the left-right direction of FIG. 1 between the low gear row 22f and the high gear row 24f based on a command from the shift controller 54 described later. It is composed of a selector gear 45f that can slide on the shaft 20f. The sliding movement of the dog clutch 26f can be performed by using a hydraulic system or a dedicated motor.

When the dog clutch 26f is positioned at the position where the selector gear 45f and the low gear train 22f are engaged, power is transmitted from the input shaft 20f to the output shaft 32f via the selector gear 45f and the low gear train 22f. ..

On the other hand, when the dog clutch 26f is positioned at the position where the selector gear 45f and the high gear train 24f are engaged, power is transmitted from the input shaft 20f to the output shaft 32f via the selector gear 45f and the high gear train 24f. Become.

When the dog clutch 26f is in a position where the selector gear 45f and the low gear row 22f or the high gear row 24f are not engaged, the neutral state is set.

Further, the final gear 30f has a gear structure for distributing the power of the output shaft 32f to the left front drive wheel 11fL and the right front drive wheel 11fR.

On the other hand, the rear wheel drive system rds includes a rear inverter 14r and a rear transmission 16r in addition to the rear motor 10r and the rear drive wheel 11r. Since the functions of each element of the rear wheel drive system rds are the same as the functions of each element of the front wheel drive system fds, detailed description thereof will be omitted.

Further, as a braking device, the vehicle 100 includes a mechanical friction brake 48 in addition to the regenerative brake realized by the regenerative operation of the drive motor 10.

(Control configuration of the first embodiment)
Hereinafter, regarding the common matters in each element of the front wheel drive system fds and each element of the rear wheel drive system rds, it is appropriately referred to as "f" indicating that it is the front such as "drive system ds" and the rear. A comprehensive description will be given using a code that omits characters such as "r".

FIG. 2 is a block diagram for explaining the control system of the vehicle 100. As shown in the figure, the control system of the vehicle 100 includes a dog clutch 26 that functions as a shift actuator and a controller 50 that controls an inverter 14 that functions as a motor actuator.

The controller 50 is composed of a computer having a central arithmetic unit (CPU), a read-only memory (ROM), a random access memory (RAM), and an input / output interface (I / O interface), particularly a microcomputer. The controller 50 is programmed to execute each process in the shift control and the motor control described below.

The controller 50 acquires the accelerator opening α (required driving force DF _req ), the vehicle speed V, the battery output possible power P _c , and the brake pedal operation amount (required braking force Bf _{req) as input information.} Then, based on these input information, the controller 50 determines the shift stage Sh (front shift stage Sh _f and rear shift stage Sh _{r ) of the transmission 16 and the motor torque T m} (front motor torque T _fm and rear motor) of the drive motor 10. Torque T _rm ) and friction braking force Bf of the friction brake 48 are determined.

In particular, the controller 50 acquires the detected value of the accelerator opening sensor 60 as the accelerator opening α. _{Further, the controller 50 calculates the motor rotation speed N m} (corresponding to the rotation speed of the input shaft 20) of the drive motor 10 acquired by a rotation speed sensor (not shown), and sets the current gear ratio γ to _{this motor rotation speed N m.} The vehicle speed V is calculated by multiplying the predetermined vehicle speed calculation gain Kv (= 2πR / γ) in consideration of the tire dynamic radius R. Instead of the mode in which the controller 50 calculates the vehicle speed V, a vehicle speed sensor may be provided and the detected value thereof may be acquired as the vehicle speed V.

Further, as the motor rotation speed N _{m for calculating the vehicle speed V, either the front motor rotation speed N fm} , which is the rotation speed of the front motor 10f _{, or the rear motor rotation speed N rm} , which is the rotation speed of the rear motor 10r, can be used. Although good, it is preferable to use _{the motor rotation speed N m} of the drive motor 10 that drives the drive wheels 11 on the side where slip (idle) is less likely to occur, depending on the specifications of the vehicle 100 and the traveling scene.

(Shift control)
The controller 50 determines the shift stage Sh (front shift stage Sh _f and rear shift stage Sh _r ) based on a predetermined shift map based on the accelerator opening α (required driving force DF _{req) and the vehicle speed V.} Then, the controller 50 operates the dog clutch 26 so as to realize the predetermined shift stage Sh. Further, the controller 50 controls the progress of the front wheel shift and the rear wheel shift based on _{the battery output available power Pc and the braking command signal.}

_{In particular, the controller 50 switches the front transmission stage Sh f} from High to Low when the down shift condition of the front transmission 16f determined based on the above shift map is satisfied in a deceleration scene of the vehicle 100 such as during braking. Perform down shifting. Similarly, when the controller 50 is braking the vehicle 100 and satisfies the condition of down shifting of the rear transmission 16r determined based on the above shifting map, the rear wheel down that switches the _{rear shifting stage Sh r from High to Low.} Perform shifting.

(Motor control)
The controller 50 is the total of the total driving force required for the vehicle 100 based on the accelerator opening α and the shift stage Sh, that is, the total torque required for both the front motor 10f and the rear motor 10r as drive sources. _{Determine the} motor torque T frm.

Further, the controller 50 uses the _{front and rear driving force distribution gains appropriately determined from the above total motor torque T frm} from the viewpoint of suppressing slippage of the front drive wheels 11f and the rear drive wheels 11r, and uses the front motor torque basic value and the front motor torque basic value. Calculate the basic value of rear motor torque.

Further, the controller 50 corrects the front motor torque basic value with respect to the front motor torque basic value based on whether or not the rear transmission 16r is shifting (whether or not the rear wheel is shifting). Determine the front motor torque T _fm.

Further, the controller 50 corrects the rear motor torque basic value with respect to the rear motor torque basic value based on whether the front transmission 16f is shifting (whether the front wheel shifting is in progress). Determine the rear motor torque _rm.

In particular, when the accelerator opening α or the vehicle speed V crosses a predetermined front shift threshold value (when the shift condition of the front transmission 16f is satisfied), the controller 50 changes the front shift stage Sh _f from Low to High or Switch from High to Low.

The front shift threshold value that determines the shift condition of the front transmission 16f is appropriately set to an appropriate value determined from the viewpoint _{of optimizing the electricity cost of the vehicle 100 and realizing the required driving force DF req.} For example, the front shift threshold value can be set to a threshold vehicle speed at which the magnitude relationship between the regeneration efficiency when the _{front shift stage Sh f is set to High and the regeneration efficiency when the front shift stage Sh f is set to Low is interchanged.} By setting the front shift threshold value in this way, when the vehicle 100 is braked (during deceleration), when the vehicle speed decreases and the threshold vehicle speed is crossed, the front shift is performed so as to suitably maintain the regeneration efficiency. The stage Sh _f can be switched from High to Low.

Further, the front shift threshold value may be set to a vehicle speed at which the required regenerative braking force cannot be sufficiently exerted _{when the front shift stage Sh f is set to High when braking the vehicle 100.} Further, in the braking scene of the vehicle 100, when there is an acceleration request (increase in the accelerator pedal operation amount) for the vehicle 100, the maximum driving force on the power running side in the high gear is lower than the required driving force related to the acceleration request. It may be set to.

Further, in the following, the process of sliding the dog clutch 26f (that is, the process of cutting off the power transmission between the front motor 10f and the front drive wheels 11f) when switching the gear stage of the front transmission 16f is described as ". It is called "front wheel side power cutoff process".

Further, in the controller 50, in order to smoothly engage the dog clutch 26f to the gear of the shifting destination, the difference rotation speed between the input shaft 20f and the output shaft 32f is within a predetermined rotation speed corresponding _{to the front shifting ratio γ f of the shifting destination.} Correct the basic value of the front motor torque so as to. Hereinafter, this process is referred to as "front wheel side rotation speed synchronization".

Similarly, controller 50, High rear gear position Sh _r from Low when straddling the rear shift threshold accelerator position α or the vehicle speed V is the predetermined (if shift condition of the rear transmission 16r is satisfied) Or switch from High to Low. In the following, the process of sliding the dog clutch 26r (that is, the process of cutting off the power transmission between the rear motor 10r and the rear drive wheel 11r) when switching the gear stage of the rear transmission 16r is described as "rear." It is called "wheel side power cutoff process".

Further, in the controller 50, in order to smoothly engage the dog clutch 26r to the gear of the transmission destination, the difference rotation speed between the input shaft 20r and the output shaft 32r is within a predetermined rotation speed according _{to the rear gear ratio γ r of the transmission destination.} The rear motor torque basic value is corrected so as to. Hereinafter, this process is referred to as "rear wheel side rotation speed synchronization".

Further, the controller 50 executes the driving force compensation process (braking force compensation process) during the rear wheel shifting (particularly when the dog clutch 26r is in the neutral state). More specifically, the controller 50 compensates for the loss of driving force (loss of braking force) of the rear drive wheels 11r caused by the interruption of the transmission of the driving force (braking force) between the rear motor 10r and the rear drive wheels 11r. _{As described above, the front motor torque T fm} is determined by correcting the basic value of the front motor torque to the increasing side (during power running) or the decreasing side (during regeneration). That is, the corrected portion of the front motor torque T _fm becomes the supplementary driving force (compensated braking force) during the rear wheel shifting.

On the other hand, the controller 50 executes the driving force compensation process (braking force compensation process) during the front wheel shifting (particularly when the dog clutch 26f is in the neutral state). More specifically, the controller 50 compensates for the loss of driving force (loss of braking force) of the front drive wheels 11f caused by the interruption of the transmission of the driving force (braking force) between the front motor 10f and the front drive wheels 11f. Therefore, the rear motor torque basic value is corrected to the increasing side (during power running) or the decreasing side (during regeneration) to determine the rear motor torque _Tr . That is, the corrected portion of the rear motor torque _Trm becomes the supplementary driving force (compensated braking force) during the front wheel shifting.

Then, the motor controller 52 executes a switching operation on the front inverter 14f and the rear inverter 14r so that the actual torques of the front motor 10f and the rear motor 10r become the predetermined front motor torque T _fm and the rear motor torque T _rm. To do.

(Brake control)
When the controller 50 detects a decrease in the accelerator opening α or an operation on the brake pedal, the controller 50 executes braking of the vehicle 100.

In particular, the controller 50 uses the friction brake 48 when the brake pedal operation amount or the rate of change thereof is equal to or higher than a certain value, that is, when the required braking force Bf _{req is equal to} or higher than a predetermined threshold value Bf req_th. Performs sudden braking processing by friction braking. On the other hand, when the required braking force Bf _req is less than the predetermined threshold value Bf _{req_th} , the normal braking process by regenerative braking using the drive motor 10 is executed. Here, the predetermined threshold value Bf _{req_th} is appropriately set from the viewpoint of whether the amount of brake pedal operation is large enough to determine that the driver intends to suddenly decelerate the vehicle 100 in an emergency or the like.

In particular, the predetermined threshold value Bf _{req_th} is the maximum value of the braking force due _{to the motor torque T m} that can compensate for all the braking force loss of the drive wheels 11 in the braking force compensation process executed during the front wheel shifting or the rear wheel shifting. Is set as.

That is, the predetermined threshold value Bf _{req_th} cannot compensate for all the braking force loss of the drive wheels 11 in the braking force compensation process, and cannot _{satisfy the required braking force Bf req} of the vehicle 100 during shifting, so that before and after shifting. It is set from the viewpoint of whether or not the _{required braking force Bf req} is large enough to fluctuate the deceleration of the vehicle 100.

As will be described in detail later, in the normal braking process in the present embodiment, the rear wheel shift is executed after the front wheel shift is executed. Therefore, in the normal braking process, the braking force estimated to stop the vehicle 100 before the rear wheel shift is completed under the regenerative braking can be set to the _{predetermined threshold value Bf req_th.}

In the sudden braking process, the controller 50 suddenly decelerates the vehicle 100 by performing frictional braking using the friction brake 48 so as to satisfy _{the required braking force Bf req.} On the other hand, the controller 50 decelerates the vehicle 100 by performing regenerative braking using the drive motor 10 so as to satisfy _{the required braking force Bf req in the normal braking process.} Depending on the braking scene of the vehicle 100, frictional braking using the friction brake 48 and regenerative braking using the drive motor 10 can be used together. In this case, the controller 50 controls each actuator so that the sum of the friction braking force related to friction braking and the regenerative braking force related to regenerative braking _{approaches the required braking force Bf req while setting the desired ratio.}

Hereinafter, the shift control method of the present embodiment, particularly the shift during the sudden braking process and the shift during the normal braking process will be described in more detail.

FIG. 3 is a timing chart for explaining the shift during the sudden braking process in the present embodiment.

As shown in the figure, when the controller 50 detects the operation on the brake pedal and determines that the brake pedal operation amount is equal to or more than a certain value (that is, the required braking force Bf _{req is equal to} or more than the predetermined threshold value Bf req_th), the sudden braking process is performed. Friction braking for this is started (time t1). In the sudden braking process of the present embodiment, the required braking force Bf _req (see the alternate long and short dash line in the figure) is entirely covered by the friction braking force (see the alternate long and short dash line in the figure).

Next, after the start of the friction braking, the controller 50 relates to the shifting conditions relating to the shift from High to Low of the front transmission 16f and the shifting from High to Low of the rear transmission 16r by reducing the vehicle speed V. When it is detected that both of the shifting conditions are satisfied, the front wheel down shifting and the rear wheel down shifting are started at the same time (time t2).

Then, the controller 50 completes switching the front wheel side shift position (position of the dog clutch 26f) and the rear wheel side shift position (position of the dog clutch 26r) from High to Low through the respective processes of the front wheel down shift and the rear wheel down shift. Then, the front wheel down shift and the rear wheel down shift are completed (time t3).

After that, when the controller 50 detects that the operation amount of the brake pedal has decreased and the required braking force Bf _req has become substantially 0, the braking state by the friction brake 48 is released and the sudden braking process is completed (time t4). ..

On the other hand, FIG. 4 is a timing chart for explaining the shift during the normal braking process in the present embodiment.

As shown in the figure, when the controller 50 detects a decrease in the accelerator opening α, it starts regenerative braking by a regenerative braking force according to the magnitude of the accelerator opening α (time t1). In the sudden braking process of the present embodiment, the required braking force Bf _req (see the alternate long and short dash line in the figure) is entirely covered by the regenerative braking force.

Next, the controller 50 starts the regenerative braking and as a result of the auxiliary friction braking, the vehicle speed V decreases, so that the shifting conditions related to the shift from High to Low of the front transmission 16f and the high of the rear transmission 16r When it is detected that both of the shifting conditions related to the shifting to Low are satisfied, the front wheel down shifting is first started (time t2).

Here, since the braking force of the front drive wheels 11f is released during the front wheel downshift, the regenerative torque required for regenerative braking is mainly _{increased by increasing the rear motor torque rm} to the minus side to rear drive wheels 11r. Will be compensated by.

Then, the controller 50 switches the front wheel side shift position (position of the dog clutch 26f) from High to Low through the process of front wheel down shifting, and when the braking force compensation process by the _{rear motor torque rm is completed, the front wheel down shifting is performed.} Complete (time t3).

Further, the controller 50 starts the rear wheel down shifting substantially at the same time as or immediately after the completion of the front wheel down shifting.

Here, since the braking force of the rear drive wheel 11r is released during the rear wheel downshift, the regenerative torque required for regenerative braking is mainly _{increased by increasing the front motor torque T fm} to the minus side to drive the front drive wheel. It is supplemented from 11f.

Then, the controller 50 switches the rear wheel side shift position (position of the dog clutch 26r) from High to Low through the process of rear wheel down shifting, and completes the braking force compensation process by the _{front motor torque T fm.} The down shift is completed (time t4).

After that, when the controller 50 detects that the accelerator opening α has increased or the brake pedal operation amount has become substantially 0, the controller 50 completes the regenerative braking (time t5).

In this embodiment, an example will be described in which the rear wheel down shift is started after the front wheel down shift is started when the shift conditions of both the front transmission 16f and the rear transmission 16r are satisfied during the normal braking process. did. However, when the front wheel down shift is started after the rear wheel down shift is started according to the driving scene or specifications of the vehicle 100, the process related to the front wheel down shift and the process related to the rear wheel down shift can be appropriately exchanged. The above-mentioned normal braking process can be applied in the same manner.

If the timing of satisfying the shifting condition of the front transmission 16f and the timing of satisfying the shifting condition of the rear transmission 16r during regenerative braking deviate from each other, downshifting by the transmission 16 for which the shifting condition is satisfied is started. , The normal braking process of the present embodiment described above can be applied.

The action and effect of the configuration of the present embodiment described above will be described in more detail.

The shift control method of the present embodiment includes a front wheel drive system fds having a front wheel drive motor (front motor 10f) for driving the front wheels (front drive wheels 11f) and a front wheel side transmission (front transmission 16f), and rear wheels (rear). In a vehicle 100 equipped with a rear wheel drive system rds having a rear wheel drive motor (rear motor 10r) for driving the drive wheels 11r) and a rear wheel side transmission (rear transmission 16r), the front motor 10f and the rear motor 10r During the regenerative braking that regenerates at least one of them, the front wheel down shift, which is a down shift by the front transmission 16f, and the rear wheel down shift, which is a down shift by the rear transmission 16r, are executed.

Then, in the shift control method of the present embodiment, the front wheels are subjected to friction braking (time t1 to time t4 in FIG. 3) executed _{when the required braking force Bf req} at the time of braking the vehicle 100 is equal to or greater than a predetermined threshold value Bf _{req_th.} When both the down shift condition and the rear wheel down shift condition are satisfied (time t2), the front wheel down shift and the rear wheel down shift are executed in parallel (time t2 to time t3).

Further, in the shift control method of the present embodiment, the shift condition of the front wheel down shift and the shift condition of the front wheel down shift during regenerative braking (time t1 to time t5 in FIG. 4) executed when _{the required braking force Bf req} is less than the predetermined threshold value Bf _{req_th.} When both of the shift conditions for the rear wheel down shift are satisfied (time t2), the rear wheel down shift is executed after the front wheel down shift is completed (time t2 to time t4).

Then, the brake force loss of the front drive wheels 11f during the front wheel down shift and the braking force loss of the rear drive wheels 11r during the rear wheel down shift are compensated by the regenerative braking force of the rear drive wheels 11r and the regenerative braking force of the front drive wheels 11f, respectively. To do.

As described above, in the vehicle 100 having the transmissions 16 on both the front wheel side and the rear wheel side, when the shifting conditions of both the front wheel shifting and the rear wheel shifting are satisfied at the time of sudden braking (during sudden deceleration), the main Unlike normal braking, which performs regenerative braking, the entire shifting process consisting of front wheel down shifting and rear wheel down shifting is quickly completed by executing front wheel down shifting and rear wheel down shifting in parallel. Can be made to.

Therefore, when the braking request is later released and the acceleration request is made again, it is possible to suppress the occurrence of insufficient driving force due to the fact that the shifting process is not completed. That is, since the responsiveness of the driving force at the time of re-acceleration is improved, it is possible to reduce the discomfort given to the occupants of the vehicle 100 due to the insufficient driving force.

As described above, by executing the front wheel down shift and the rear wheel down shift in parallel during sudden braking, the braking force of the front drive wheels 11f is released during the front wheel down shift and the rear drive wheels during the rear wheel down shift. It is assumed that the braking force of 11r is released at the same time. As described above, when the braking force is released from both drive wheels 11, it becomes impossible to execute the braking force compensation process for compensating the regenerative braking force of the other drive wheel 11 by the one drive wheel 11 described above. However, in the case of sudden braking, even in a scene where such braking force compensation processing cannot be executed, it is preferable to release the braking force of both the front drive wheels 11f and the rear drive wheels 11r by the friction braking force of the friction brake 48. Can be supplemented to.

That is, according to the shift control method of the present embodiment, the shift process can be completed quickly while preferably realizing _{the required braking force Bf req of the vehicle 100 during the shift during sudden braking.}

Further, in the shift control method of the present embodiment, _{during regenerative braking (during normal braking processing) executed when the required braking force Bf req} is less than the predetermined threshold value Bf _{req_th} , the rear wheels are down after the front wheel down shift is completed. Perform a shift.

That is, in the normal braking process that does not require sudden deceleration of the vehicle 100, the rear wheel downshift is executed after the front wheel downshift is completed, and the braking force compensation process is performed during each shift.

As a result, during the normal braking process, the timing of the braking force compensation process is shifted in each drive wheel 11f. Therefore, it is preferable to release the braking force of each drive wheel 11 during both the front wheel down shift and the rear wheel down shift. It can be suppressed. Further, by shifting the execution timings of the front wheel downshift and the rear wheel downshift, the timing of _{the peak of the front motor torque T fm} (the peak between time t2 and time t3 in FIG. 4) for synchronizing the front wheel side rotation speed and the timing , it is possible to prevent the timing of the rear wheel rotational speed synchronous rear motor torque T _rm peak for (peak between times t3~ time t4 in FIG. 4) overlap.

Therefore, it is possible to prevent a significant increase in the required power of the front motor 10f and the rear motor 10r due to the overlapping of the peaks of the driving power.

Further, in the present embodiment, a shift control system S for executing the shift control method is provided.

The shift control system S includes a front wheel drive system fds having a front wheel drive motor (front motor 10f) for driving the front wheels (front drive wheels 11f) of the vehicle 100 and a front wheel side transmission (front transmission 16f), and the vehicle 100. A rear wheel drive system rds having a rear wheel drive motor (rear motor 10r) for driving the rear wheels (rear drive wheel 11r) and a rear wheel side transmission (rear transmission 16r), and at least one of the front motor 10f and the rear motor 10r. It has a controller 50 as a shift control device that executes a front wheel down shift, which is a down shift by the front transmission 16f, and a rear wheel down shift, which is a down shift by the rear transmission 16r, during regenerative braking to be regenerated.

Then, the controller 50 as a shift control device has front wheels during friction braking (time t1 to time t4 in FIG. 3) that is executed _{when the required braking force Bf req} at the time of braking the vehicle 100 is equal to or greater than a predetermined threshold value Bf _{req_th.} When both the down shift condition and the rear wheel down shift condition are satisfied (time t2), the sudden braking shift control unit (time t2 to time t3) that executes the front wheel down shift and the rear wheel down shift in parallel. Functions as.

Further, the controller 50 determines the shifting conditions for front wheel down shifting and rear wheel down shifting during regenerative braking (time t1 to time t5 in FIG. 4), which is executed when _{the required braking force Bf req} is less than the predetermined threshold value Bf _{req_th.} When both shift conditions are satisfied (time t2), it functions as a regenerative braking shift control unit (time t2 to time t4) that executes rear wheel down shift after the front wheel down shift is completed.

The controller 50, which functions as a shift control unit during regenerative braking, regenerates the rear drive wheels 11r to release the braking force of the front drive wheels 11f during the front wheel down shift and the braking force of the rear drive wheels 11r during the rear wheel down shift. It is compensated by the braking force and the regenerative braking force of the front drive wheels 11f.

As a result, a system configuration suitable for executing the shift control method is realized.

In the example shown in FIG. 3, the example in which the front wheel down shift and the rear wheel down shift during the sudden braking process are started and completed at substantially the same timing has been described. However, the present invention is not limited to this, and if the front wheel down shift and the rear wheel down shift overlap for a certain period of time or more, their start timing and completion timing may be deviated.

That is, if the front wheel down shift and the rear wheel down shift during the sudden braking process overlap for a certain period of time or more, at least the front wheel down shift and the rear wheel down shift are executed without overlapping in time. It is possible to exert a certain effect of shortening the shift time.

Further, in the present embodiment, an example in which the rear wheel downshift is started after the front wheel downshift is completed in the normal braking process has been described. However, the shift control of the present embodiment can be similarly applied even when the front wheel downshift is started after the rear wheel downshift is completed in the normal braking process according to the specifications of the vehicle 100 and the like.

Further, as in the present embodiment, in addition to executing the front wheel down shift and the rear wheel down shift substantially at the same time when the vehicle 100 is suddenly braked, for example, when the vehicle 100 is Fehling downhill, a request is made. When the driving force DF _req becomes a negative value and both the front wheel down shift and the rear wheel down shift conditions are satisfied, the front wheel down shift and the rear wheel down shift are executed substantially simultaneously in the same manner. Is also good.

[Second Embodiment]
Hereinafter, the second embodiment will be described. The same elements as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted.

FIG. 5 is a timing chart illustrating a shift during the sudden braking process of the present embodiment.

In the present embodiment, as shown in FIG. 5 (A), the controller 50, so as to shift the front-wheel-side rotation speed synchronization start timing t _sf1 and the rear wheel-side rotation speed synchronization start timing t _sr1 in sudden braking process Control. In particular, setting the start timing t _sr1 the rear wheel rotational speed synchronization from the front wheel side speed synchronization start timing t _sf1 after a synchronization offset time tau.

Here, the synchronization offset time τ is the maximum value of the total driving power, which is the sum of the driving power of the front motor 10f for synchronizing the front wheel side rotation speed and the driving power of the rear motor 10r for synchronizing the rear wheel side rotation speed. , The battery 15 is set to be equal to or less than the battery outputable power Pc, which is the maximum power that can be output.

That is, the synchronous offset time τ of the present embodiment is such that the peak of the drive power of the front motor 10f and the peak of the drive power of the rear motor 10r do not overlap and the total drive power exceeds the battery output possible power Pc. , It is set from the viewpoint of shifting the degree of mutual progress of the front wheel side rotation speed synchronization and the rear wheel side rotation speed synchronization.

More specifically, in the present embodiment, the synchronization offset time τ is set so that the average value of the total drive power per total rotation speed synchronization time ΔTs substantially matches the battery output available power Pc. That is, the synchronization offset time τ is determined from the viewpoint of setting the total drive power as large as possible while satisfying the limitation by the battery output possible power Pc.

The effect of the control of this embodiment will be described.

As a comparative example, figure 5 (B), shows a schematic timing chart when simultaneously controlling the front-wheel-side rotation speed synchronization start timing t _sf1 and the rear wheel-side rotation speed synchronization start timing t _sr1 in sudden braking process.

In the control of this comparative example, the front wheel side rotation speed synchronization and the rear wheel side rotation speed synchronization proceed at substantially the same degree of progress from the _{start timings t sf1} and t _sr1. Therefore, the peaks of the drive powers of the front motor 10f and the rear motor 10r for synchronizing the rotation speeds substantially overlap, and the total drive power is greatly increased. On the other hand, due to the limitation based on the battery output available power Pc, a state in which the increased total drive power cannot be satisfied at least momentarily occurs, and sufficient front motor torque T _fm and rear motor torque T _rm cannot be secured. The processing time related to the total rotation speed synchronization becomes long.

On the other hand, in the control of the present embodiment shown in FIG. 5A, since the start timings of the front wheel side rotation speed synchronization and the rear wheel side rotation speed synchronization are different, the front for the rotation speed synchronization The peaks of the drive powers of the motor 10f and the rear motor 10r can be shifted. As a result, the peak of the total drive power for the rotation speed synchronization can be reduced as compared with the case of the above comparative example.

_{As a result, the total rotation speed synchronization time ΔTs, which is the time from the start timing t sf1} of the front wheel side rotation speed synchronization to the completion timing t _sr2 of the rear wheel side rotation speed synchronization in the present embodiment, is the total rotation speed synchronization time in the comparative example. It is shorter than ΔTs'.

The action and effect of the configuration of the present embodiment described above will be described in more detail.

In the shift control method of the present embodiment, the front wheel down shift is performed by the front wheel side power cutoff process that cuts off the power transmission between the front motor 10f and the front drive wheel 11f, and the front transmission 16f during the front wheel side power cutoff process. It includes front wheel side rotation speed synchronization in which the adjustment of the input / output difference rotation speed is performed by using the driving force of the front motor 10f. Further, in the rear wheel down shift, the difference rotation between the input and output of the rear transmission 16r during the rear wheel side power cutoff process that cuts off the power transmission between the rear motor 10r and the rear drive wheel 11r and the rear wheel side power cutoff process. It includes rear wheel side rotation speed synchronization in which the number is adjusted by using the driving force of the rear motor 10r. Further, the drive power of the front motor 10f required for the front wheel side rotation speed synchronization and the drive power of the rear motor 10r required for the rear wheel side rotation speed synchronization are supplied from the same battery 15.

Then, when running in parallel front downshift and rear wheels downshift in the friction braking, shifting the start timing t _sr1 the rear wheel rotational speed synchronized with the front-wheel-side rotation speed synchronization start timing t _sf1.

As a result, even when the front wheel down shift and the rear wheel down shift are executed in parallel during the sudden braking process, the process from the start to the completion of the front wheel side rotation speed synchronization and the rear wheel side rotation speed synchronization can be completed. It is possible to avoid a situation in which they match in time. Therefore, even when the front wheel down shift and the rear wheel down shift are performed in parallel, the peaks of the drive powers of the front motor 10f and the rear motor 10r in the front wheel side rotation speed synchronization and the rear wheel side rotation speed synchronization are shifted. Can be done. _{As a result, the front motor torque T fm} and the rear motor torque T _rm required for front wheel shifting and rear wheel shifting can be more preferably realized even under the limitation of the battery output available power Pc of the same battery 15. Can be done.

Further, the synchronization offset time τ as the time difference between the start timings of the front wheel side rotation speed synchronization and the rear wheel side rotation speed synchronization is set, and the maximum value of the total drive power of the front motor 10f and the rear motor 10r is the output power of the battery 15. Set so that the outputable power is Pc or less.

As a result, in the scene where the front wheel down shift and the rear wheel down shift are executed in parallel during the sudden braking process, the maximum electric power assumed by the parallel shift processes of both shifts can be obtained from the battery 15 which is a common power source. It can be adjusted below the output upper limit of. That is, it is possible to more reliably prevent the situation in which the total drive power reaches the battery output possible power Pc during the sudden braking process.

In particular, in the shift control method of the present embodiment, the synchronization offset time τ is such that the average of the total drive power of the front motor 10f and the rear motor 10r per total rotation speed synchronization time ΔTs substantially matches the battery output available power Pc. Set.

As a result, the front wheel side rotation speed synchronization and the rear wheel side rotation speed synchronization can be completed more quickly within the range of the battery output possible power Pc. As a result, it contributes to further shortening of the shift time.

Hereinafter, a modified example of the second embodiment will be described. In the following modification, another mode for setting the synchronization offset time τ so that the maximum value of the total drive power of the front motor 10f and the rear motor 10r is equal to or less than the battery output possible power Pc is provided. ..

(Modification example)
In this modification, as described above, in the case of setting before the start timing t _sr1 the rear wheel speed-synchronizing a front wheel-side rotation speed synchronization start timing t _sf1, front-wheel-side rotating said synchronization offset time τ It is set based on the drive power of the front motor 10f for number synchronization.

More specifically, the synchronization offset time τ is _set from the start timing t sf1 of the front wheel side rotation speed synchronization until the drive power of the front motor 10f starts to decrease as the synchronization progresses (to the peak of the _{front motor torque T fm).} Set as the time between (to reach). That is, in this case, the rear wheel side rotation speed synchronization is started substantially at the same time as the reduction start timing of the drive power of the front motor 10f.

By setting the synchronization offset time τ in this way, the rear wheel side rotation speed synchronization is started at least after the peak of the drive power of the front motor 10f during the front wheel side rotation speed synchronization. Therefore, since it is possible to suppress the occurrence of an excessively high peak (maximum value) of the total drive power, the maximum value of the total drive power can be preferably adjusted to the battery output possible power Pc or less.

In the second embodiment and the present modification, the synchronization offset time τ is stored in a memory (not shown) which is predetermined by an experiment or the like, and the controller 50 appropriately stores the synchronization in the memory during the sudden braking process. A configuration that refers to the offset time τ can be adopted.

On the other hand, instead of the configuration in which the synchronization offset time τ is stored in the memory in advance, a configuration in which the controller 50 calculates the synchronization offset time τ from various detected values in real time may be adopted. _{For example, the controller 50 detects the} above-mentioned event (such as the drive power of the front motor 10f starting to decrease) that triggers the passage of the synchronization offset time τ from the start timing t sf1 of the front wheel side rotation speed synchronization, and the start timing. A configuration (program) may be adopted in which the time difference between t _sf1 and the detection timing is calculated in real time and this is set to the synchronization offset time τ.

In this modification, if both the front wheels down shift and rear wheels downshift during sudden braking process is established, starting front wheel rotational speed synchronization start timing t _sf1 of the rear wheel-side rotation speed synchronization timing t _sr1 It is assumed that it will be set before. However, the start timing t _sr1 the rear wheel rotational speed synchronization set earlier than the front wheel speed-synchronizing the start timing t _sf1, a method of setting the synchronization offset time τ in Modification 1 or 2, "front-wheel-side rotation It is possible to replace the "number synchronization start timing t _sf1 " with the "rear wheel side rotation speed synchronization start timing t _sf1 " and the "front motor 10f drive power" with the "rear motor 10r drive power". ..

Although the embodiments of the present invention have been described above, the above embodiments are only a part of the application examples of the present invention, and the technical scope of the present invention is limited to the specific configurations of the above embodiments. Absent.

In each of the above embodiments, an example in which one controller 50 is used as a control device for executing various controls has been described. However, a plurality of controllers 50 may be installed to distribute the processing in various controls. For example, as the controller 50, a motor controller that executes a process related to motor control, a shift controller that executes a process related to shift control, and an integrated controller that executes other controls while supervising the motor control and shift control are provided. Is also good.

Further, in each of the above embodiments, for the sake of simplification of the description, it is assumed that the specifications (characteristics) of the front motor 10f and the specifications (characteristics) of the rear motor 10r are substantially the same as each other. However, these may be different from each other as long as they do not interfere with the execution of the shift control method of each of the above embodiments.

10 Drive motor 10f Front motor 10r Rear motor 11 Drive wheel 11f Front drive wheel 11r Rear drive wheel 14 Inverter 14f Front inverter 14r Rear inverter 15 Battery 16 Transmission 16f Front transmission 16r Rear transmission 48 Friction brake 50 Controller 100 Vehicle

Claims (6)

In a vehicle equipped with a front wheel drive system having a front wheel drive motor for driving the front wheels and a front wheel side derailleur, and a rear wheel drive system having a rear wheel drive motor for driving the rear wheels and a rear wheel side derailleur, the front wheels During regenerative braking that regenerates at least one of the drive motor and the rear wheel drive motor, the front wheel down shift, which is a down shift by the front wheel side transmission, and the rear wheel down shift, which is a down shift by the rear wheel side transmission, are performed. It is a shift control method to be executed,
When both the front wheel down shifting condition and the rear wheel down shifting condition are satisfied during friction braking executed when the required braking force at the time of braking the vehicle is equal to or higher than a predetermined threshold value, the front wheel down shifting and the front wheel down shifting are performed. The rear wheel down shift is executed in parallel,
When both the shift condition of the front wheel down shift and the shift condition of the rear wheel down shift are satisfied during the regenerative braking executed when the required braking force is less than the predetermined threshold value,
The rear wheel down shift is executed after the front wheel down shift is completed, or the front wheel down shift is executed after the rear wheel down shift is completed.
The regenerative braking force of the rear wheels compensates for the loss of braking force of the front wheels during the downshifting of the front wheels.
The regenerative braking force of the front wheels compensates for the loss of braking force of the rear wheels during the rear wheel down shifting.
Shift control method. The shift control method according to claim 1.
The front wheel down shift is the difference rotation speed between the input and output of the front wheel side transmission during the front wheel side power cutoff process that cuts off the power transmission between the front wheel drive motor and the front wheel. Including front wheel side rotation speed synchronization in which adjustment is performed using the driving force of the front wheel drive motor.
The rear wheel down shift includes a rear wheel side power cutoff process that cuts off power transmission between the rear wheel drive motor and the rear wheel, and an onset of the rear wheel side transmission during the rear wheel side power cutoff process. Including the rear wheel side rotation speed synchronization in which the adjustment of the output difference rotation speed is performed by using the driving force of the rear wheel drive motor.
The drive power of the front wheel drive motor required in the front wheel side rotation speed synchronization and the drive power of the rear wheel drive motor required in the rear wheel side rotation speed synchronization are supplied from the same battery.
When the front wheel down shift and the rear wheel down shift are executed in parallel during the friction braking, the start timing of the front wheel side rotation speed synchronization and the start timing of the rear wheel side rotation speed synchronization are shifted.
Shift control method. The shift control method according to claim 2.
The time difference between the start timings of the front wheel side rotation speed synchronization and the rear wheel side rotation speed synchronization
The maximum value of the total drive power of the front wheel drive motor and the rear wheel drive motor is set to be equal to or less than the outputable power of the battery.
Shift control method. The shift control method according to claim 3.
The time difference
The average value of the total drive power of the front wheel drive motor and the rear wheel drive motor per total rotation speed synchronization time is set so as to substantially match the output power of the battery.
Shift control method. The shift control method according to claim 3.
When the start timing of the front wheel side rotation speed synchronization is set earlier than the start timing of the rear wheel side rotation speed synchronization,
The time difference is set to the time from the start timing of the front wheel side rotation speed synchronization to the time when the drive power of the front wheel drive motor starts to decrease as the front wheel side rotation speed synchronization progresses.
When the start timing of the rear wheel side rotation speed synchronization is set earlier than the start timing of the front wheel side rotation speed synchronization,
The time difference is set to the time from the start timing of the rear wheel side rotation speed synchronization to the time when the drive power of the rear wheel drive motor starts to decrease as the rear wheel side rotation speed synchronization progresses.
Shift control method. A front-wheel drive system with a front-wheel drive motor that drives the front wheels of the vehicle and a front-wheel side transmission,
A rear wheel drive system having a rear wheel drive motor for driving the rear wheels of the vehicle and a rear wheel side transmission,
During execution of regenerative braking that regenerates at least one of the front wheel drive motor and the rear wheel drive motor, the front wheel down shift is a down shift by the front wheel side transmission and the rear wheel down is a down shift by the rear wheel side transmission. A shift control system including a shift control device that executes a shift.
The shift control device is
When both the front wheel down shifting condition and the rear wheel down shifting condition are satisfied during friction braking executed when the required braking force during braking of the vehicle is equal to or higher than a predetermined threshold value, the front wheel down shifting condition is satisfied. And the shift control unit during sudden braking that executes the rear wheel down shift in parallel,
If both the front wheel down shift condition and the rear wheel down shift condition are satisfied during the regenerative braking executed when the required braking force is less than the predetermined threshold value, after the front wheel down shift is completed. It has a regenerative braking shift control unit that executes the rear wheel down shift or executes the front wheel down shift after the rear wheel down shift is completed.
The shift control unit during regenerative braking
The regenerative braking force of the rear wheels compensates for the loss of braking force of the front wheels during the downshifting of the front wheels.
The regenerative braking force of the front wheels compensates for the loss of braking force of the rear wheels during the rear wheel down shifting.
Shift control system.

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