Driving force control method and driving force control device

Abstract

A driving force control method. A step-corresponding control is performed to adjust the driving force of the front wheel motor and the driving force of the rear wheel motor when the vehicle passes through an undulating road surface. In the step-corresponding control, after the front wheel driving-on moment when the front wheel drives on the undulating road surface and before the rear wheel driving-on moment when the rear wheel drives on the undulating road surface, a first control mode is performed to regenerate the front wheel motor and operate the power of the rear wheel motor. After the first control mode is performed and before the rear wheel driving-on moment, a second control mode is performed to operate the power of the front wheel motor and regenerate the rear wheel motor.

Description

Technical Field

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

[0002] JP2006-69395A (Japan) proposes a driving force control method for creating a driving torque difference between the front wheels and the rear wheels according to the driving environment of the vehicle. In particular, in this driving force control method, when driving on bad road conditions, a driving force difference is created between the front wheels and the rear wheels to lift the vehicle body and improve the passability. Summary of the invention

[0003] It is believed that when driving on bad roads, the vibration caused by the vehicle crossing the uneven road surface will make the passengers feel uncomfortable. However, the control in JP2006-69395A (Japan) focuses on improving the passability, and does not provide any countermeasures for improving the vibration caused to the passengers.

[0004] Therefore, an object of the present invention is to provide a driving force control method and a driving force control device that can reduce vibrations imparted to a passenger when a vehicle passes over an uneven road surface.

[0005] According to a certain embodiment of the present invention, there is provided a driving force control method for controlling the front wheel driving force and the rear wheel driving force respectively by using a front wheel motor connected to the front wheel of the vehicle and a rear wheel motor connected to the rear wheel. The driving force control method performs a step-corresponding control for adjusting the driving force of the front wheel motor and the driving force of the rear wheel motor when the vehicle passes through an undulating road surface. Furthermore, in the step-corresponding control, after the front wheel driving-on moment when the front wheel drives onto the undulating road surface and before the rear wheel driving-on moment when the rear wheel drives onto the undulating road surface, a first control mode is performed to regenerate the front wheel motor and operate the power of the rear wheel motor. In addition, in the step-corresponding control, after the first control mode is executed and before the rear wheel drives on, a second control mode is performed to operate the power of the front wheel motor and regenerate the rear wheel motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 It is a diagram for explaining the structure of a vehicle that executes a driving force control method according to an embodiment of the present invention.

[0007] Figure 2 This is a diagram showing an overview of the structure of a chassis system of a vehicle.

[0008] Figure 3 It is a flowchart explaining the step correspondence control.

[0009] Figure 4A This is a diagram for explaining the effects of executing the step response control.

[0010] Figure 4B This is a diagram for explaining the effects of executing the step response control.

[0011] Figure 4C This is a diagram for explaining the effects of executing the step response control.

[0012] Figure 5 This is a timing chart showing an example of the result after executing the step-corresponding control.

[0013] Figure 6 : is a flowchart illustrating the tire diameter learning process. DETAILED DESCRIPTION

[0014] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0015] [First embodiment]

[0016] Figure 1 1 is a diagram for explaining the configuration of a vehicle 100 that executes the driving force control method according to the present embodiment.

[0017] It should be noted that the vehicle 100 of the present embodiment is assumed to be an electric vehicle or a hybrid vehicle that includes a drive motor 10 as a drive source and can travel using the drive force of the drive motor 10 .

[0018] The drive motor 10 includes a front wheel motor 10f provided at the front position (front wheel side) of the vehicle 100 and driving the front wheel 11f, and a rear wheel motor 10r provided at the rear position (rear wheel side) and driving the rear wheel 11r.

[0019] The front wheel motor 10f is configured as a three-phase AC motor. When the front wheel motor 10f is in power operation, it receives power supply from a vehicle-mounted battery (not shown) to generate driving force. The driving force generated by the front wheel motor 10f is transmitted to the front wheel 11f via the front wheel transmission 16f and the front wheel drive shaft 21f. On the other hand, when the front wheel motor 10f is in regeneration, the regenerative braking force of the front wheel 11f is converted into AC power and supplied to the vehicle-mounted battery.

[0020] On the other hand, the rear wheel motor 10r is configured as a three-phase AC motor. When the rear wheel motor 10r is in power operation, it receives power supply from the vehicle-mounted battery to generate driving force. The driving force generated by the rear wheel motor 10r is transmitted to the rear wheel 11r via the rear wheel transmission 16r and the rear wheel drive shaft 21r. In addition, when the rear wheel motor 10r is in regeneration, the regenerative braking force of the rear wheel 11r is converted into AC power and supplied to the vehicle-mounted battery.

[0021] The inverter 12 includes a front wheel inverter 12f for adjusting the power supplied to the front wheel motor 10f (positive during power operation, negative during regeneration), and a rear wheel inverter 12r for adjusting the power supplied to the rear wheel motor 10r (positive during power operation, negative during regeneration).

[0022] The front wheel inverter 12f adjusts the power supplied to the front wheel motor 10f so as to achieve the total driving force required by the vehicle 100 (hereinafter also referred to as the “total required driving force F fr ”) and the driving force (hereinafter also referred to as “front wheel driving force F f On the other hand, the rear wheel inverter 12r adjusts the power supplied to the rear wheel motor 10r to achieve a power proportional to the total required driving force F fr The driving force (hereinafter also referred to as the rear wheel driving force F r ”).

[0023] In particular, the front wheel driving force F of this embodiment is determined f And the rear wheel drive force F r , so that the sum of the driving forces equals the total demand driving force F fr It should be noted that the total demand driving force F fr For example, it is determined based on the amount of operation of an accelerator pedal mounted on vehicle 100 (accelerator opening), or a command from a predetermined automatic driving system (automatic driving control device) such as ADAS (Advanced Driver Assistance Systems) or AD (Autonomous Driving).

[0024] In addition, the vehicle 100 is provided with a control system for controlling the front wheel driving force F f And the rear wheel drive force F r The controller 50 serves as a driving force control device.

[0025] The controller 50 is composed of a computer having 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 be able to perform various processes of vehicle control as described below. In particular, the functions of the controller 50 can be implemented by any on-board computer such as a vehicle controller (VCM: Vehicle Control Module), a vehicle motion control device (VMC: Vehicle Motion Controller), and a motor controller, and / or a computer installed outside the vehicle 100. It should be noted that the controller 50 can be implemented by using a single computer hardware, or by using a plurality of computer hardware to distribute various processes.

[0026] The controller 50 converts the total required driving force F fr , the detection values ​​of the vertical acceleration sensors 30fL and 30fR on the front wheel side, the detection values ​​of the vertical acceleration sensors 30rL and 30rR on the rear wheel side, and the detection value of the GPS vehicle speed sensor 32 are used as input information to calculate the front wheel driving force F f And the rear wheel drive force F r More specifically, the controller 50 controls the front wheel drive force F to achieve the desired front wheel drive force F. f And the rear wheel drive force F r , and issues instructions to the front wheel inverter 12f and the rear wheel inverter 12r.

[0027] In particular, in the present embodiment, the controller 50 performs any of the basic drive control and the step-corresponding control as control for regulating the distribution of the driving force when the vehicle 100 is traveling forward (particularly, when accelerating).

[0028] The controller 50 performs basic driving control during normal driving (except for the case of passing through an undulating road surface Bu described later in this embodiment). In the basic driving control, the controller 50 controls the front wheel driving force F f And the rear wheel drive force F r The predetermined basic front wheel driving force and the basic rear wheel driving force are set respectively.

[0029] Here, the basic front-wheel drive force and the basic rear-wheel drive force are values ​​determined by experiments or simulations in order to obtain the desired vehicle characteristics (especially power consumption performance) of the vehicle 100 corresponding to the driving scene. The specific values ​​of the basic front-wheel drive force and the basic rear-wheel drive force can be appropriately changed according to the specifications of the vehicle 100 and the driving scene. As an example, when driving straight on a flat paved road at a constant speed, the basic front-wheel drive force and the basic rear-wheel drive force can be set to the total required driving force F frThe distribution ratio of the basic front-wheel drive force to the basic rear-wheel drive force is determined to be 50:50.

[0030] On the other hand, the controller 50 performs the step-corresponding control for alleviating the vibration caused to the occupants of the vehicle 100 based on various input information when the vehicle 100 passes through a predetermined undulating road surface Bu under the execution of the above-mentioned basic driving control. In the step-corresponding control, the controller 50 sequentially executes the first control mode and the second control mode.

[0031] More specifically, the controller 50 executes the first control mode after detecting the moment when the front wheel 11f runs onto the uneven surface Bu (hereinafter also referred to as "front wheel running-on moment T1") and before the moment when the rear wheel 11r runs onto the uneven surface Bu (hereinafter also referred to as "rear wheel running-on moment T2").

[0032] In the first control mode, the controller 50 controls the front wheel driving force F f Set to a negative value and set the rear wheel drive force F r That is, the controller 50 causes the front wheel motor 10f to regenerate (responsibly brake the front wheel 11f), and causes the rear wheel motor 10r to power run (responsibly drive the rear wheel 11r).

[0033] On the other hand, the controller 50 executes the second control mode after executing the first control mode and before the rear wheels run onto the time T2.

[0034] In the second control mode, the controller 50 controls the front wheel driving force F f is set to a positive value, and the rear wheel drive force F r That is, the front wheel motor 10f is powered (the front wheel 11f is powered and driven), and the rear wheel motor 10r is regenerated (the rear wheel 11r is regeneratively braked).

[0035] It should be noted that the front wheel driving force F set in the first control mode or the second control mode f And the rear wheel drive force F r The specific value of is not limited to the specified value and can be adjusted appropriately according to the situation.

[0036] That is, in the present embodiment, in the scenario where the vehicle 100 passes through the undulating road surface Bu, the driving force control performed by the controller 50 is switched from the basic driving control to the step-corresponding control at an appropriate time. Furthermore, in the step-corresponding control, the driving force control is migrated in the order of the first control mode and the second control mode at an appropriate time.

[0037] Therefore, according to the front wheel driving force F f And the rear wheel drive force F rThe driving force distribution of the vehicle 100 is the force (pitch force F pi ) can be adjusted to alleviate the vibration when passing through the undulating road surface Bu. f And the rear wheel drive force F r The relationship between the adjustment of and the relaxation of vibration when passing through uneven road surfaces Bu will be described in more detail.

[0038] Figure 2 1 is a diagram showing the general structure of the chassis system of the vehicle 100 (particularly the general structure of the suspension geometry). f " represents the virtual rotation center (instantaneous rotation center) of the front part of the vehicle body in the pitch direction," r ” represents the virtual rotation center (instantaneous rotation center) of the rear part of the vehicle body in the pitch direction.

[0039] When the vehicle 100 is moving forward, a regenerative braking force (force in the opposite direction to the moving direction) is applied to the front wheel 11f and a powered driving force (force in the same direction as the moving direction) is applied to the rear wheel 11r. an On the other hand, when the power running driving force is applied to the front wheel 11f and the regenerative braking force is applied to the rear wheel 11r, a recoil force F acts on the vehicle body. sq (The force that causes the car body to sink).

[0040] Here, by adjusting the front wheel drive force F f And the rear wheel drive force F r The anti-recoil force F that can be achieved by the driving force distribution an or recoil F sq The size of depends on the size of the anti-squat angle θ corresponding to the suspension structure. Figure 2 As shown, the front anti-recoil angle θ is adopted in consideration of ride comfort and the diving feeling during braking. f Rear anti-squat angle θ r In the case of a small structure, the anti-recoil force F generated by adjusting the driving force distribution is greater than that of the front part of the vehicle body. an or recoil F sq Stronger effect on the rear of the vehicle.

[0041] Therefore, by providing the regenerative braking force to the front wheel 11f and the power running driving force to the rear wheel 11r during forward travel (by executing the above-mentioned first control mode), the rear part of the vehicle body can be lifted (the front of the vehicle body is facing downward). On the other hand, by providing the power running driving force to the front wheel 11f and the regenerative braking force to the rear wheel 11r (by executing the above-mentioned second control mode), the rear part of the vehicle body can be lowered (the front of the vehicle body is facing upward).

[0042] In view of the above, in this embodiment, by utilizing the step-corresponding control to switch the lifting and sinking of the rear part of the vehicle body at an appropriate time, the vibration suppression effect of the spring of the rear suspension 40r is improved, and the impact when the vehicle 100 passes over the uneven road surface Bu is reduced. The specific processing of the step-corresponding control is described below.

[0043] Figure 3 It is a flowchart for explaining the step-by-step control. It should be noted that the controller 50 repeatedly executes the step-by-step control at every predetermined calculation cycle while the vehicle 100 is traveling forward. Figure 3 Various treatments shown.

[0044] In step S110, the controller 50 determines the detection values ​​of the vertical acceleration sensors 30fL and 30fR on the front wheel side (hereinafter, each also referred to as “front fL vertical G fl ” and “Front fR up and down G fr ”) Whether both parties have exceeded the specified rough road surface determination threshold G bu .

[0045] It should be noted that this determination is a preliminary process for detecting a scene in which the step-corresponding control (steps S120 to S170) should be executed. Here, from the perspective of determining whether the undulation of the undulating road surface Bu will cause vibrations that make the occupants of the vehicle 100 uncomfortable when the wheels drive on it, the undulating road surface determination threshold G is set to bu A more appropriate value is determined in advance through experiments, simulations, etc.

[0046] Then, the controller 50 determines the upper and lower G of the front fL fl And the front fR up and down G fr Both parties exceed the rough road judgment threshold G bu In this case, execute the step corresponding control after step S120. If it is judged that it is not the above result, end this program.

[0047] That is, in both wheels ( Figure 1When the left front wheel 11fL and the right front wheel 11fR shown in the figure drive on the undulating surface Bu, step corresponding control is performed. When at least one of the left front wheel 11fL and the right front wheel 11fR (only one side wheel) does not drive on the undulating surface Bu, step corresponding control is not performed, but basic driving control is maintained.

[0048] Next, in step S120, the controller 50 uses the time when the front wheel 11f is detected to have driven onto the uneven road surface Bu in step S110 (i.e., the time when the front wheel drives onto the uneven road surface Bu) as a base point and starts measuring the elapsed time ΔT. co .

[0049] Furthermore, in step S130, the controller 50 determines the elapsed time ΔT co Is it the first switching determination time ΔT? up above.

[0050] From the perspective of defining the switching timing from the basic drive control to the first control mode, the first switching determination time ΔT up is set to an appropriate value. In particular, the first switching determination time ΔT up It is determined that the control mode is switched to the second control mode when the rear wheel 11r runs on the uneven surface Bu, based on the basic drive control that continues to achieve the preferred vehicle characteristics (optimal power consumption, etc.) as long as possible even after the front wheel 11f runs on the uneven surface Bu.

[0051] More specifically, the controller 50 first uses the time T1 at which the front wheel has come up as a base point and calculates an estimated value of the distance traveled by the vehicle 100 thereafter (hereinafter also referred to as “estimated travel distance D T≥T1 ”). In particular, the estimated driving distance D T≥T1 The detected value of vehicle speed V (such as GPS vehicle speed V GPS ) or estimated value and wheel speed w (or wheel rotation number N w ), as the elapsed time ΔT co function to determine.

[0052] In addition, the controller 50 obtains the calculated estimated travel distance D T≥T1 The first scheduled switching time T is equal to the time obtained by subtracting the margin α from the distance between the front wheel 11f and the rear wheel 11r. a Then, the controller 50 will change the time from the front wheel driving up to the first scheduled switching time T1. a The time is determined as the first switching determination time ΔT up .

[0053] It should be noted that the margin α is set to an appropriate value that can maintain the basic drive control for realizing the preferred vehicle characteristics as long as possible after the front wheel runs on time T1 and complete the switch from the first control mode to the second control mode before the rear wheel runs on time T2.

[0054] Then, when the controller 50 determines that the time ΔT has elapsed co is the first switching determination time ΔT up In the above case, the process of step S140 is executed.

[0055] In step S140, the controller 50 executes the first control mode. More specifically, the controller 50 controls the driving force from the front wheel driving force F f And the rear wheel drive force F r The basic drive control is switched to the front wheel drive force F f Set to negative and rear wheel drive force F r Set to positive first control mode.

[0056] Next, in step S150, the controller 50 determines the elapsed time ΔT co Is it the prescribed second switching determination time ΔT? do above.

[0057] From the perspective of defining the switching time from the first control mode to the second control mode, the second switching determination time ΔT do is set to an appropriate value. In particular, the second switching determination time ΔT do is set to an appropriate value so that the time for which the first control mode is continued (from the front wheel driving-on time T1 to the first scheduled switching time T a The time interval) is ensured to be greater than a constant value, and at the time T2 when the rear wheel runs on, the control mode is switched to the second control mode.

[0058] More specifically, the controller 50 obtains the estimated travel distance D calculated in step S130. T≥T1 The second scheduled switching time T is the time when the distance between the front wheel 11f and the rear wheel 11r becomes equal. b In addition, the controller 50 sets the time from the front wheel driving up to the second scheduled switching time T1. b The time is determined as the second switching determination time ΔT do That is, the second switching determination time ΔT do The second scheduled switching time T b It should be noted that the second scheduled switching time T may be set to be substantially the same as the rear wheel running-on time T2 in consideration of control delay, etc. b The second switching determination time ΔT is determined before the rear wheel running-on time T2do .

[0059] Then, when the controller 50 determines that the time ΔT has elapsed co is the second switching determination time ΔT do In the above case, the process of step S160 is executed.

[0060] In step S160, the controller 50 executes the second control mode. More specifically, the driving force control is changed from the front wheel driving force F f Set to negative and rear wheel drive force F r The first control mode set to positive switches to the front wheel drive force F f Set to positive and rear wheel drive force F r Set to negative second control mode.

[0061] Then, in step S170, when the controller 50 determines that the time ΔT has elapsed co is the specified control duration ΔT end When the control duration time T is reached end When the control mode is changed from the second control mode to the basic drive control, the program ends.

[0062] Figure 4A to Figure 4C This is a diagram for explaining the effects of executing the step response control.

[0063] By executing the above-mentioned step-corresponding control, when the front wheel 11f drives onto the undulating road surface Bu, the front wheel reaches the time T1 ( Figure 4A ) After the first switching determination time ΔT up When the control mode is switched from the basic drive control to the first control mode, the anti-recoil force F an Acting on the vehicle 100, the rear part of the vehicle body is lifted ( Figure 4B ). As a result, the rear suspension 40r is further extended compared to the case where the driving force distribution is set under the basic driving control.

[0064] After that, before the rear wheel 11r reaches the bumpy road surface Bu at the rear wheel reaching time T2 (from the front wheel reaching time T1 ( Figure 4A ) after the first switching determination time ΔTup), the control mode is switched from the first control mode to the second control mode, and the recoil force F sq Acting on the vehicle 100, the rear part of the vehicle body settles ( Figure 4C ) As a result, a force in a contraction direction (more specifically, a downward force) acts on the rear suspension 40r in the extended state in the first control mode.

[0065] Therefore, through the first control mode (anti-recoil force F an) and the compression force of the rear suspension 40r extended by the second control mode (recoil force F sq ) and the downward forces acting on the rear suspension 40r interact with each other, and the damping force (resistance) of the rear suspension 40r observed from the vehicle body structure portion (including the interior of the vehicle cabin) above the rear suspension 40r is reduced (the rear suspension 40r becomes softer). Therefore, the vibration in the vehicle cabin when the rear wheel 11r drives on the uneven road surface Bu is reduced, and the riding comfort of the occupants is further improved.

[0066] Figure 5 : is a timing chart showing an example of the control result of the step response control. As shown in the figure, in this embodiment, the vertical force F input from the rear suspension 40r to the upper body structure sus (see the solid line) is smaller than that of the comparative example (see the dotted line) in which the step-corresponding control is not executed (the basic driving control is maintained even when traveling on the uneven road surface Bu).

[0067] Next, the structure and effects of the above-mentioned embodiment will be summarized and described.

[0068] In this embodiment, a driving force control method is provided, which uses a front wheel motor 10f connected to a front wheel 11f of a vehicle 100 and a rear wheel motor 10r connected to a rear wheel 11r to control the front wheel driving force F f And the rear wheel drive force F r .

[0069] In this driving force control method, when the vehicle 100 passes over an uneven road surface Bu, the front wheel driving force F f And the rear wheel drive force F r The step-corresponding control (steps S120 to S170) is performed to adjust the step-corresponding control. In addition, in the step-corresponding control, after the front wheel 11f drives onto the undulating surface Bu at the front wheel driving-on time T1 and before the rear wheel driving-on time T2 when the rear wheel 11r drives onto the undulating surface Bu, the first control mode (steps S120 to S140) is executed to make the front wheel motor 10f regenerate and the rear wheel motor 10r run with power, and after the first control mode is executed and before the rear wheel driving-on time T2 (before or at the rear wheel driving-on time T2), the second control mode (steps S150 to S170) is executed to make the front wheel motor 10f run with power and the rear wheel motor 10r regenerate.

[0070] Thus, the front wheel driving force F can be adjusted before and after the rear wheel 11r runs on the uneven road surface Bu. f And the rear wheel drive force F rThe driving force distribution is optimized to achieve the vertical displacement of the vehicle 100 with the damping force of the rear suspension 40r reduced. Therefore, the vibration transmitted to the vehicle cabin when the vehicle 100 passes over the uneven road surface Bu can be reduced, and the riding comfort of the occupants can be further improved.

[0071] In the present embodiment, when a predetermined first switching determination time ΔT has elapsed since the front wheel has driven onto the vehicle T1, up , the first control mode starts (steps S130 and S140).

[0072] Thus, it is possible to realize a specific control logic for switching to the first control mode while maintaining the basic driving control for realizing the preferred vehicle characteristics (optimal power consumption, etc.) as long as possible. In particular, by determining the first switching determination time ΔT according to the vehicle speed V up , it is possible to execute the switch from the basic drive control to the first control mode at a more appropriate time.

[0073] In the present embodiment, when a time period longer than the first switching determination time ΔT has passed since the front wheel came up at the time T1, up Long second switching determination time ΔT do , the second control mode starts (steps S150 and S160).

[0074] Thus, a specific control logic for performing the first control mode and the second control mode before the rear wheel 11r runs onto the uneven road surface Bu can be realized. do , it is possible to execute the switch from the first control mode to the second control mode at a more appropriate time.

[0075] Furthermore, the driving force control method of the present embodiment executes a rough road surface determination process (step S110 ) for determining whether the vehicle 100 passes over the rough road surface Bu.

[0076] Furthermore, in the undulating road surface determination process, when both wheels of the front wheel 11f (the left front wheel 11fL and the right front wheel 11fR) are detected to have crossed the undulating road surface Bu, it is determined that the vehicle 100 has passed the undulating road surface Bu. On the other hand, when at least one wheel is not detected to have crossed the undulating road surface Bu, it is determined that the vehicle 100 has not passed the undulating road surface Bu.

[0077] If it is determined that the vehicle 100 has passed through the undulating road surface Bu, the step-corresponding control is executed (Yes in step S110). On the other hand, if it is determined that the vehicle 100 has not passed through the undulating road surface Bu, the front wheel driving force F f And the rear wheel drive force F rThe basic drive control is performed in which each of the predetermined basic drive forces (basic front-wheel drive force and basic rear-wheel drive force) is set (No in step S110).

[0078] Therefore, because the front wheel 11f drives onto the undulating surface Bu while the rear wheel 11r does not drive onto the undulating surface Bu, it is possible to determine a scenario where step-corresponding control is not required (for example, when the vehicle 100 turns, etc., where only one side of the front wheel 11f drives onto the undulating surface Bu), thereby maintaining the basic driving force distribution that achieves appropriate vehicle characteristics in this scenario.

[0079] In addition, in the present embodiment, a controller 50 is provided, which functions as a driving force control device for executing the above-mentioned driving force control method. The controller 50 uses a front wheel motor 10f connected to the front wheel 11f of the vehicle 100 and a rear wheel motor 10r connected to the rear wheel 11r to control the front wheel driving force F f And the rear wheel drive force F r .

[0080] In particular, the controller 50 has a function to control the front wheel driving force F when the vehicle 100 passes over an uneven road surface Bu. f And the rear wheel drive force F r The step corresponding control unit for adjustment ( Figure 3 ). Furthermore, the step-corresponding control unit executes a first control mode (steps S110 to S140) for regenerating the front wheel motor 10f and powering the rear wheel motor 10r after the front wheel running-on time T1 when the front wheel 11f runs on the undulating surface Bu and before the rear wheel running-on time T2 when the rear wheel 11r runs on the undulating surface Bu, and executes a second control mode (steps S150 to S170) for powering the front wheel motor 10f and regenerating the rear wheel motor 10r after the first control mode is executed and before the rear wheel running-on time T2 (before the rear wheel running-on time T2 or at the same time).

[0081] Thereby, it is possible to realize a structure of a control device suitable for executing the above-mentioned driving force control method.

[0082] [Second Embodiment]

[0083] Next, the second embodiment will be described. It should be noted that the same reference numerals are used for the main components that are the same as those in the first embodiment, and their descriptions are omitted. In particular, in this embodiment, with respect to the tire diameter R that changes due to aging or the like, a learning value after adding the change (hereinafter also referred to as "tire diameter learning value R") is obtained. L ”) tire diameter learning process.

[0084] In particular, in the tire diameter learning process, a scenario in which the vehicle 100 passes over an undulating road surface Bu is assumed similar to the step-corresponding control described above, and a basic driving control is set to measure the time from the time when the front wheel 11f drives onto the undulating road surface Bu to the time when the rear wheel 11r drives onto the undulating road surface Bu, and the tire diameter learning value R is determined based on the time. L .

[0085] It should be noted that, for the sake of convenience in the following description, the same reference numerals are used for the same parameters as the control parameters described in the step-corresponding control of the first embodiment.

[0086] Figure 6 This is a flowchart for explaining the tire diameter learning process of this embodiment. It should be noted that the controller 50 executes the tire diameter learning process when starting the vehicle system (a system for realizing the driving of the vehicle 100 and other auxiliary functions). Figure 6 Various treatments shown.

[0087] As shown in the figure, in step S210, the controller 50 determines whether a system activation command for the vehicle 100 is detected. Here, the system activation command of the present embodiment refers to a signal generated in response to an operation of the occupant requesting activation of the vehicle system (eg, an operation of turning on the ignition switch).

[0088] Then, the controller 50 executes the processing after step S220 when the system start command is detected, and terminates the tire diameter learning processing when the system start command is not detected.

[0089] Next, in step S220, the controller 50 sets the step-corresponding control prohibition flag. The step-corresponding control prohibition flag is a flag that prohibits execution of the step-corresponding control. Figure 3 The step corresponding control (step S120 to step S170) is a flag. That is, in this embodiment, the controller 50 is configured to start Figure 3 Before the various processing shown (or before starting the processing of step S120), the step-corresponding control prohibition flag is referred to, and the step-corresponding control is not performed when the flag is set.

[0090] In step S230, the controller 50 determines the front fL up and down G fl And the front fR up and down G fr Have both parties exceeded the bumpy road determination threshold G? bu It should be noted that this judgment is consistent with Figure 3 The controller 50 is similar to step S120, which is executed for the purpose of detecting the state of the front wheel 11f running on the undulating road surface Bu. Then, the controller 50 determines the state of the front wheel 11f running on the undulating road surface Bu. fl And the front fR up and down G fr Both parties exceed the rough road judgment threshold Gbu In this case, execute the processing after step S240.

[0091] Next, in step S240, the controller 50 starts measuring the elapsed time ΔT based on the time when the front wheel 11f has driven onto the uneven road surface Bu detected in step S230. co .

[0092] In step S250, the controller 50 determines the detection value of the rear rL vertical acceleration sensor 30rL (hereinafter also referred to as “rear rL vertical G rl ”) and the detection value of the rear rR up and down acceleration sensor 30rR (hereinafter also referred to as “rear rR up and down G rr ”) Whether both parties exceed the rough road surface determination threshold G bu It should be noted that this determination is performed for the purpose of detecting the state in which the rear wheel 11r is running on the uneven road surface Bu.

[0093] Then, the controller 50 determines the following rL up and down G rl And then rR up and down G rr Both parties exceed the rough road judgment threshold G bu In this case, execute the processing after step S260.

[0094] Next, in step S260, the controller 50 stops measuring the elapsed time ΔT at the time when the affirmative determination is made in step S250 (the time when the rear wheel 11r runs onto the uneven road surface Bu). co , and store the elapsed time ΔT co That is, the elapsed time ΔT co It is equivalent to the period from when the front wheel 11f drives onto the uneven road surface Bu to when the rear wheel 11r drives onto the uneven road surface Bu. It should be noted that for the convenience of explanation, it is also referred to as the "front and rear wheel driving time ΔT" below. f→r ”.

[0095] In step S270, the controller 50 calculates the vehicle body speed V based on the GPS vehicle body speed V input from a sensor (not shown) or the like. GPS , number of wheel rotations N w , and the time ΔT for the front and rear wheels to drive on f→r According to the following formula (1), the tire diameter learning value R L Perform calculations.

[0096] [Number 1]

[0097]

[0098] In step S280, the controller 50 calculates the tire diameter learning value R LThe step-corresponding control prohibition flag set in step S220 is stored, and the tire diameter learning process is terminated. It should be noted that by terminating the tire diameter learning process with the step-corresponding control prohibition flag canceled, the controller 50 is allowed to perform subsequent step-corresponding control.

[0099] Then, the controller 50 uses the tire diameter learning value R obtained by the tire diameter learning process in the subsequent step-corresponding control (particularly step S130 and step S150). L In order to obtain the first switching determination time ΔT up and the second switching determination time ΔT do The calculation is performed using the vehicle speed V. That is, the first switching determination time ΔT up and the second switching determination time ΔT do Set to the tire diameter learning value R L The variable value corresponding to the vehicle speed V.

[0100] Next, the structure and effects of the above-mentioned embodiment will be summarized and described.

[0101] In the driving force control method of the present embodiment, a learning value of the tire diameter R (tire diameter learning value R L ) tire diameter learning process. And, in the step response control ( Figure 3 ) is compared with the tire diameter learning value R obtained through the tire diameter learning process. L The determined vehicle speed V corresponds to the first switching determination time ΔT up and the second switching determination time ΔT do Set to a variable value.

[0102] Thus, in the step-by-step control, the first switching determination time ΔT that specifies the start time of the first control mode can be determined based on the change in the vehicle speed V caused by the change in the tire diameter R due to aging. up and a second switching determination time ΔT that specifies the start time of the second control mode. do Therefore, in the step-by-step response control, the switching timing between the power running and the regeneration of the front wheels 11f and the rear wheels 11r can be determined with high accuracy, and the effect of alleviating the vibration felt by the occupants can be more reliably exerted.

[0103] Although the embodiments of the present invention have been described above, the above embodiments merely represent a part of application examples of the present invention and are not intended to limit the technical scope of the present invention to the specific structures of the above embodiments.

Claims

1. A driving force control method, using a front wheel motor connected to a front wheel of a vehicle and a rear wheel motor connected to a rear wheel to control the front wheel driving force and the rear wheel driving force respectively, wherein the driving force control method is characterized in that: performing step response control for reducing vibration transmitted to the vehicle cabin when the rear wheels run over the uneven road surface by adjusting the driving force of the front wheel motor and the driving force of the rear wheel motor when the vehicle passes over the uneven road surface, In the step-by-step control, The control mode for adjusting the driving force distribution is shifted in the order of a first control mode in which the front wheel motor is regenerated and the rear wheel motor is powered, and a second control mode in which the front wheel motor is powered and the rear wheel motor is regenerated. detecting the front wheel driving-on moment when the front wheel drives onto the undulating road surface, When a predetermined first switching determination time has elapsed from the time when the front wheel drives up, the first control mode is started, When a second switching determination time longer than the first switching determination time elapses from the front wheel running-on timing, the second control mode is started.

2. The driving force control method according to claim 1, characterized in that: Furthermore, a tire diameter learning process is performed to obtain a learned value of the tire diameter. In the step-by-step control, The first switching determination time and the second switching determination time are set to variable values ​​in accordance with a vehicle speed determined based on the learned value obtained by the tire diameter learning process.

3. The driving force control method according to claim 1 or 2, characterized in that: Further, performing an undulating road surface determination process to determine whether the vehicle passes through the undulating road surface, In the rough road surface determination process, When it is detected that both wheels of the front wheels have crossed the uneven road surface, it is determined that the vehicle has passed the uneven road surface. When at least one of the wheels is not detected to have crossed the uneven road surface, it is determined that the vehicle has not passed the uneven road surface, When it is determined that the vehicle passes through the undulating road surface, the step-corresponding control is executed. When it is determined that the vehicle has not passed through the uneven road surface, basic drive control is executed to set each drive force of the front wheel motor and the rear wheel motor to a predetermined basic drive force.

4. A driving force control device, which uses a front wheel motor connected to the front wheel of the vehicle and a rear wheel motor connected to the rear wheel to control the front wheel driving force and the rear wheel driving force respectively, wherein the driving force control device is characterized in that: The invention has a step-corresponding control unit, which adjusts the driving force of the front wheel motor and the driving force of the rear wheel motor when the vehicle passes through an undulating road surface, thereby reducing the vibration transmitted to the vehicle cabin when the rear wheel drives on the undulating road surface. The control mode for adjusting the driving force distribution is shifted in the order of a first control mode in which the front wheel motor is regenerated and the rear wheel motor is powered, and a second control mode in which the front wheel motor is powered and the rear wheel motor is regenerated, and a front wheel driving-on timing when the front wheel drives onto the uneven road surface is detected. When a predetermined first switching determination time has elapsed from the time when the front wheel drives up, the first control mode is started, When a second switching determination time longer than the first switching determination time elapses from the front wheel running-on timing, the second control mode is started.

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