Driving force control method and driving force control device

Abstract

This invention provides a driving force control method in which front wheel driving force (Ff) and rear wheel driving force (Fr) are respectively controlled by a front wheel motor (10f) connected to front wheels (11f) of a vehicle (100) and a rear wheel motor (10r) connected to rear wheels (11r), a coordination process being executed to lift the body of the vehicle up or down by coordinating the adjustment of the front wheel driving force and / or the rear wheel driving force and the application of frictional braking force to the front wheels and / or the rear wheels.

Description

Technical Field

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

Background Art

[0002] In JP2007-118898A, when the effect of suspension cannot be sufficiently obtained in an in-wheel motor type vehicle, the pitch rate (pitch angular velocity) when passing through a step on the road surface is detected, and different driving forces are applied to the front and rear wheels so as to reduce the detected pitch rate (displacement in the pitch direction). A driving force control device has been proposed.

Summary of the Invention

[0003] Depending on the driving scene of the vehicle, there are cases where mainly the vertical displacement of the vehicle body (heave vibration) is large and control to suppress this is desired. However, in the control of applying different driving forces to the front and rear wheels to suppress the displacement in the pitch direction as described above, there is a problem that the suppression effect on the vertical displacement is limited.

[0004] Therefore, an object of the present invention is to provide a driving force control method and a driving force control device capable of further improving the suppression effect of the vertical displacement of the vehicle.

[0005] According to an aspect of the present invention, there is provided a driving force control method for controlling a front-wheel driving force and a rear-wheel driving force by a front-wheel motor connected to the front wheels of a vehicle and a rear-wheel motor connected to the rear wheels, respectively. In this driving force control method, a cooperative process is executed in which the adjustment of the distribution of the front-wheel driving force and the rear-wheel driving force and the application of a frictional braking force to at least one of the front wheels and the rear wheels are coordinated to lift up or lift down the vehicle body.

Brief Description of the Drawings

[0006]

Figure 1

Figure 2

Figure 3

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DETAILED DESCRIPTION OF THE INVENTION

[0007] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0008] FIG. 1 is a diagram for explaining the configuration of a vehicle 100 in which the driving force control method of the present embodiment is executed. Note that as the vehicle 100 of the present embodiment, an electric vehicle or a hybrid vehicle including a drive motor 10 as a drive source and capable of traveling by the driving force of the drive motor 10 is assumed.

[0009] The drive motor 10 is composed of a front wheel motor 10f provided at a position in front of the vehicle 100 (front wheel side) for driving the front wheels 11f and a rear wheel motor 10r provided at a rear position (rear wheel side) for driving the rear wheels 11r.

[0010] The front wheel motor 10f is configured as a three-phase AC motor. The front wheel motor 10f receives power supply from an in-vehicle battery (not shown) during power running to generate a driving force. The driving force generated by the front wheel motor 10f is transmitted to the front wheels 11f via the front wheel transmission 16f and the front wheel drive shaft 21f. On the other hand, the front wheel motor 10f converts the regenerative braking force of the front wheels 11f into AC power and supplies it to the in-vehicle battery during regeneration.

[0011] On the other hand, the rear-wheel motor 10r is configured as a three-phase AC motor. During power running, the rear-wheel motor 10r receives power supply from the in-vehicle battery and generates a driving force. The driving force generated by the rear-wheel motor 10r is transmitted to the rear wheel 11r via the rear-wheel transmission 16r and the rear-wheel drive shaft 21r. Also, during regeneration, the rear-wheel motor 10r converts the regenerative braking force of the rear wheel 11r into AC power and supplies it to the in-vehicle battery.

[0012] The inverter 12 includes a front-wheel inverter 12f that adjusts the supply power (positive during power running and negative during regeneration) to the front-wheel motor 10f, and a rear-wheel inverter 12r that adjusts the supply power (positive during power running and negative during regeneration) to the rear-wheel motor 10r.

[0013] The front-wheel inverter 12f adjusts the supply power to the front-wheel motor 10f so that a positive or negative driving force (hereinafter also referred to as "front-wheel driving force F fr ") defined with respect to the total driving force required for the vehicle 100 (hereinafter also referred to as "total required driving force F f ") is realized. On the other hand, the rear-wheel inverter 12r adjusts the supply power to the rear-wheel motor 10r so that a positive or negative driving force (hereinafter also referred to as "rear-wheel driving force F fr ") defined with respect to the total required driving force F r " is realized.

[0014] In particular, the front-wheel driving force F f and the rear-wheel driving force F r of the present embodiment are defined such that their sum matches the total required driving force F fr . Note that the total required driving force F fr is determined based on, for example, the operation amount (accelerator opening) of the accelerator pedal mounted on the vehicle 100, or a command from a predetermined automatic driving system (automatic driving control device) such as ADAS (Advanced Driver Assistance Systems) or AD (Autonomous Driving).

[0015] The brake actuator 14 is composed of a known mechanical brake that operates with hydraulic pressure or the like, and includes a front-wheel friction brake 14f that applies a frictional braking force (hereinafter also referred to as "front-wheel brake force B f ") to the front wheels 11f, and a rear-wheel friction brake 14r that applies a frictional braking force (hereinafter also referred to as "rear-wheel brake force B r ") to the rear wheels 11r.

[0016] Furthermore, the vehicle 100 is provided with a controller 50 as a driving force control device that controls the front-wheel driving force F f , the rear-wheel driving force F r , the front-wheel brake force B f , and the rear-wheel brake force B r .

[0017] The controller 50 is a computer equipped with a central processing unit (CPU), a read-only memory (ROM), a random access memory (RAM), and an input / output interface (I / O interface), and is programmed to execute each process in vehicle control described below. In particular, the functions of the controller 50 can be realized by an arbitrary in-vehicle computer such as a vehicle controller (VCM: Vehicle Control Module), a vehicle motion controller (VMC: Vehicle Motion Controller), and a motor controller, and / or a computer installed outside the vehicle 100. Note that the controller 50 may be realized by a single computer hardware, or may be realized by distributing various processes among a plurality of computer hardwares. The controller 50 uses the total required driving force F

[0018] , 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 suspension stroke amount S fr detected by a sensor (not shown) as input information, and controls the front-wheel driving force F su , the rear-wheel driving force F f , the front-wheel brake force B r , and the rear-wheel brake force B f, and the rear wheel braking force B r is controlled. More specifically, the controller 50 controls the desired front wheel driving force F f , the rear wheel driving force F r , the front wheel braking force B f , and the rear wheel braking force B r so as to be realized, and issues commands to the front wheel inverter 12f, the rear wheel inverter 12r, the front wheel friction brake 14f, and the rear wheel friction brake 14r.

[0019] In particular, in the present embodiment, the controller 50 executes any one of basic drive control, cooperative processing, and non - cooperative processing as control for defining the drive force distribution during the forward running (especially during acceleration) of the vehicle 100.

[0020] During normal running (in this embodiment, especially in scenes other than running on a wavy road described later), the controller 50 executes basic drive control. In the basic drive control, the controller 50 sets the front wheel driving force F f and the rear wheel driving force F r to a predetermined basic front wheel driving force and a basic rear wheel driving force, respectively.

[0021] Here, the basic front wheel driving force and the basic rear wheel driving force are values determined by experiments or simulations so that the vehicle characteristics (especially power consumption performance) of the vehicle 100 take desired characteristics according to the running scene. The specific values of the basic front wheel driving force and the basic rear wheel driving force can be appropriately changed according to the specifications of the vehicle 100 and the running scene. As an example, when going straight at a constant speed on a flat paved road, the distribution ratio of the basic front wheel driving force to the basic rear wheel driving force with respect to the total required driving force F fr can be determined to be 50:50.

[0022] On the other hand, when the controller 50 detects a scene in which the vehicle 100 travels on a predetermined undulating road based on various input information, it executes either cooperative processing or non - cooperative processing according to the magnitude (amplitude) of the unevenness of the undulating road. In the present embodiment, the undulating road means a traveling road having unevenness over a certain distance in the traveling direction of the vehicle 100. Hereinafter, in particular, a portion protruding compared to the flat surface on the undulating road is referred to as a "hill", and a portion recessed compared to the flat surface is referred to as a "valley".

[0023] In the cooperative processing, when the controller 50 receives a request to lift up or lower the vehicle body, it executes either the first control mode or the second control mode.

[0024] In the first control mode, the controller 50 sets the front - wheel braking force B f to a positive value, the front - wheel driving force F f to a negative value, and the rear - wheel driving force F r to a positive value respectively. That is, the controller 50 regenerates the front - wheel motor 10f (performs regenerative braking on the front wheels 11f), drives the rear - wheel motor 10r (performs power running on the rear wheels 11r), and then applies frictional braking force to the front wheels 11f. Also, in the second control mode, the controller 50 sets the front - wheel driving force F f to a positive value, the rear - wheel driving force F r to a negative value, and the rear - wheel braking force B r to a positive value respectively. That is, the controller 50 drives the front - wheel motor 10f while performing power running (performs power running on the front wheels 11f), regenerates the rear - wheel motor 10r (performs regenerative braking on the rear wheels 11r), and then applies frictional braking force to the rear wheels 11r.

[0025] On the other hand, in the non - cooperative processing, when the controller 50 receives a request to lift up or lower the vehicle body, it executes either the third control mode or the fourth control mode.

[0026] In the third control mode, the controller 50 does not apply the front - wheel braking force B f and sets the front - wheel driving force F fis set to a negative value, and the rear-wheel driving force F r is set to a positive value. Also, in the fourth control mode, the controller 50 applies no rear-wheel braking force B r and sets the front-wheel driving force F f to a positive value while setting the rear-wheel driving force F r to a negative value.

[0027] The relationship between the adjustment of the front-wheel driving force F f , rear-wheel driving force F r , front-wheel braking force B f , and rear-wheel braking force B r in cooperative and non-cooperative processes and the suppression of the vertical displacement of the vehicle body will be described more specifically.

[0028] FIG. 2 is a diagram showing the schematic structure of the chassis system of the vehicle 100 (particularly the schematic of the suspension geometry). In the figure, "O f " represents the virtual rotation center (instantaneous rotation center) in the pitch direction at the front of the vehicle body, and "O r " represents the virtual rotation center (instantaneous rotation center) in the pitch direction at the rear of the vehicle body.

[0029] When the vehicle 100 is moving forward and a regenerative braking force (a force opposite to the traveling direction) is applied to the front wheels 11f and a tractive driving force (a force in the same direction as the traveling direction) is applied to the rear wheels 11r, an anti-squat force F an (a force that lifts the vehicle body) acts on the vehicle body. On the other hand, when a tractive driving force is applied to the front wheels 11f and a regenerative braking force is applied to the rear wheels 11r, a squat force F sq (a force that sinks the vehicle body) acts on the vehicle body.

[0030] Therefore, theoretically, in a scene where the vehicle 100 is traveling on a wavy road, by adjusting the distribution of the driving forces of the front wheels 11f and the rear wheels 11r to perform pitch adjustment (i.e., the above-mentioned non-cooperative process), it is possible to appropriately lift or lower the vehicle body to suppress the vertical displacement (heave vibration) of the vehicle body.

[0031] On the other hand, the anti-squat force F obtained by non-coordinated processing an or the squat force F sq is dependent on the magnitude of the anti-squat angle θ (front anti-squat angle θ f and rear anti-squat angle θ r ) of the suspension 40 (front suspension 40f and rear suspension 40r) of the vehicle 100.

[0032] More specifically, the front-wheel driving force F generated by the front-wheel motor 10f f and the rear-wheel driving force F generated by the rear-wheel motor 10r r are transmitted to the front wheels 11f and rear wheels 11r with the front-wheel drive shaft 21 and the rear-wheel drive shaft 21r as the points of action, respectively.

[0033] Therefore, the vertical component of the pitching force (i.e., the magnitude of the anti-squat force F an or the squat force F sq ) defined by adjusting the drive force distribution, the anti-squat angle θ f , θ r is determined as the angle formed by the horizontal line, the virtual rotation center O f , O r defined by the structure of the suspensions 40f, 40r, and the straight line connecting the above points of action.

[0034] For this reason, due to the structure of the suspensions 40f, 40r, when the anti-squat angle θ f , θ r cannot be increased (when the virtual rotation center O f , O r is at a relatively low position), the range of the anti-squat force F an or the squat force F sq obtained by adjusting the drive force distribution is limited.

[0035] In particular, like the vehicle 100 of the present embodiment shown in FIG. 2, considering the ride comfort and the nose-dive feeling during braking, the front anti-squat angle θ fWhen a relatively small suspension structure is adopted, there is a problem that even if non-coordinated processing is executed, a sufficient effect of suppressing the vertical displacement of the vehicle body cannot be obtained.

[0036] In contrast, the inventor of the present invention uses the front wheel braking force B f or the rear wheel braking force B r to adjust the net driving force distribution applied to the front wheels 11f and the rear wheels 11r beyond the adjustment range by the above non-coordinated processing, so that even in a vehicle 100 equipped with a suspension structure with a relatively small anti-skid angle θ, a high effect of suppressing the vertical displacement of the vehicle body can be obtained.

[0037] FIG. 3 is a diagram for explaining the operational effects by executing coordinated processing. In the following, the operational effects of the coordinated processing will be particularly described focusing on the first control mode (applying the front wheel braking force B f , performing regenerative braking on the front wheels 11f, and performing power running drive on the rear wheels 11r). On the other hand, the following explanation also applies similarly to the second control mode (performing power running drive on the front wheels 11f, applying the rear wheel braking force B r , and performing regenerative braking on the rear wheels 11r).

[0038] As shown in the figure, when the first control mode is executed during the forward running of the vehicle 100, the acting point of the front wheel braking force B f is the outer peripheral portion of the front wheels 11f. Therefore, the anti-skid angle θ f defined as the angle formed by the horizontal line, the straight line connecting the virtual rotation center O f on the front wheel side and the acting point of the front wheel braking force B Bf becomes larger than the anti-skid angle θ f in the above non-coordinated processing. Therefore, when the first control mode of the coordinated processing is executed, the effect of suppressing the vertical displacement of the vehicle body can be enhanced more than when the third control mode of the non-coordinated processing is executed.

[0039] On the other hand, the coordinated processing is control for operating the mechanical brake actuator 14. Therefore, in terms of control responsiveness, the non-coordinated processing, which is an electric control not involving the operation of the mechanical actuator, is superior.

[0040] Therefore, in the following, in the scene where the vehicle 100 travels on a wavy road, the situation where suppressing the vertical displacement of the vehicle body should be prioritized according to the magnitude of the unevenness of the driving road surface, and the situation where the control responsiveness should be prioritized will be distinguished, and an example of executing either coordinated processing or uncoordinated processing as appropriate will be described.

[0041] FIG. 4 is a flowchart for explaining the driving force control method of the present embodiment. Each process shown in FIG. 4 is executed based on information such as the driving road surface provided by a predetermined internal sensor or an external server mounted on the vehicle 100 by the controller 50 at the timing when it is determined that the vehicle 100 is traveling on a wavy road. In particular, the controller 50 repeatedly executes each process shown in FIG. 4 at a predetermined calculation cycle in this scene.

[0042] In steps S110 and S120, the controller 50 determines whether the pitch rate ω pi and the vertical acceleration a G respectively exceed the pitch rate threshold ω piTH and the vertical acceleration threshold a GTH .

[0043] Here, the pitch rate ω pi is a parameter defined as the time derivative of the pitch angle θ pi (i.e., the pitch angular velocity). Further, the pitch angle θ pi is defined as the displacement angle in the pitch direction with respect to the horizontal direction around the center of gravity G of the vehicle 100 (see FIG. 2). Note that the sign of the pitch angle θ pi is set such that the direction in which the front wheels 11f of the vehicle 100 are lifted (nose-up direction) is positive, and the direction in which the rear wheels 11r are lifted (nose-down direction) is negative. Furthermore, the vertical acceleration a G is the acceleration in the vertical displacement of the vehicle 100 (the center of gravity G of the vehicle 100). Note that the pitch rate ω pi , the pitch angle θ pi , and the vertical acceleration a Gcan be calculated by a known method based on 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 other necessary parameters.

[0044] Pitch rate ω pi and vertical acceleration a G both represent the magnitude of the vertical displacement of the actual vehicle 100 when driving on a wavy road. That is, they are parameters that suggest the magnitude of the unevenness of the wavy road (unevenness parameter).

[0045] Also, the pitch rate threshold ω piTH and the vertical acceleration threshold a GTH are determined as values that appropriately distinguish which of the vertical displacement suppression effect and high control responsiveness of the vehicle 100 should be prioritized. More specifically, the pitch rate threshold ω piTH and the vertical acceleration threshold a GTH are determined such that cooperative processing is executed when the unevenness of the wavy road is relatively large (when high control responsiveness is not required while a high vertical displacement suppression effect is required). Conversely, the pitch rate threshold ω piTH and the vertical acceleration threshold a GTH are determined such that non - cooperative processing is executed when the unevenness of the wavy road is relatively small (when high control responsiveness is required while the required vertical displacement suppression effect is small).

[0046] And when the determination results in both step S110 and step S120 are affirmative, the controller 50 executes the process of step S130, and otherwise, executes non - cooperative processing (step S160).

[0047] In step S130, the controller 50 determines whether the suspension stroke amount S su exceeds the first stroke amount threshold S suTH1 .

[0048] Note that the suspension stroke amount S su is also the pitch rate ωpi and the vertical acceleration a G Similarly, it is an unevenness parameter representing the magnitude of the vertical displacement of the actual vehicle 100 when traveling on a wavy road. Further, the first stroke amount threshold S suTH1 also depends on the front wheel braking force B f or the rear wheel braking force B r is determined to be a suitable value from the viewpoint of determining whether the unevenness of the wavy road is large enough that suppression of the vertical displacement of the vehicle 100 by cooperative processing using it is desired.

[0049] And when the determination result in step S130 is affirmative, the controller 50 executes cooperative processing (step S140), and when it is not, non - cooperative processing is executed (step S160).

[0050] As a specific example of the cooperative processing, in a scene where a force in the lift - down direction is generated on the vehicle body because the vehicle 100 is traveling on the valley portion of the wavy road, the controller 50 executes the first control mode (lifting up the vehicle body) so as to cancel this. On the other hand, in a scene where a force in the lift - up direction is generated on the vehicle body because the vehicle 100 is traveling on the hill of the wavy road, the controller 50 executes the second control mode (lifting down the vehicle body) so as to cancel this.

[0051] Also, as an example of the non - cooperative processing, in a scene where a force in the lift - down direction is generated on the vehicle body because the vehicle 100 is traveling on the valley portion of the wavy road, the controller 50 executes the third control mode (lifting up the vehicle body) so as to cancel this. On the other hand, in a scene where a force in the lift - up direction is generated on the vehicle body because the vehicle 100 is traveling on the hill of the wavy road, the controller 50 executes the fourth control mode (lifting down the vehicle body) so as to cancel this.

[0052] Note that the modes of selecting the first control mode or the second control mode in the above-described cooperative processing, and the modes of selecting the third control mode or the fourth control mode in the non-cooperative processing are merely examples and are not limited thereto. Further, the front-wheel driving force F f , the rear-wheel driving force F r , the front-wheel braking force B f , and the rear-wheel braking force B r set in the cooperative processing or the non-cooperative processing are not limited to specific numerical values and can be appropriately adjusted according to the situation.

[0053] Furthermore, during the execution of the cooperative processing, the controller 50 determines whether or not the suspension stroke amount S su is less than the second stroke amount threshold S suTH2 (step S150).

[0054] The second stroke amount threshold S suTH2 is set to an appropriate value from the viewpoint of determining whether or not the unevenness of the undulating road has become small to such an extent that it can be determined that the control should be switched from the cooperative processing to the non-cooperative processing in consideration of the control responsiveness.

[0055] Then, when the controller 50 determines that the suspension stroke amount S su is less than the second stroke amount threshold S suTH2 , the control is switched from the cooperative processing to the non-cooperative processing (step S160) and this routine is terminated.

[0056] Note that in consideration of the low control responsiveness in the above-described cooperative processing, a configuration may be adopted in which the switching from the cooperative processing to the non-cooperative processing is executed when the suspension stroke amount S su is less than the second stroke amount threshold S suTH2 a plurality of times. In particular, it takes a certain amount of time from the start of the cooperative processing according to the result of the determination in step S130 until the effect of suppressing the vertical displacement of the vehicle body is actually obtained. Considering this, at the immediate start of the cooperative processing or the like, the front-wheel braking force B f or the rear-wheel braking force B rEven though it has not yet followed the command, the temporary suspension stroke amount S su is detected to be in a reduced state, and it is possible to prevent a situation where the control switches to non-cooperative processing. Further, in the determination in step S150 (determination of whether to switch from cooperative processing to non-cooperative processing), the pitch rate ω pi and / or the vertical acceleration a G may adopt a configuration that refers to the comparison result of the magnitude with the respectively determined threshold values.

[0057] FIG. 5 is a timing chart showing an example of the time-series change of each control parameter when the control of the present embodiment is executed in a wavy road driving scene. In the timing chart of FIG. 5, the pitch angle θ pi and the pitch rate ω pi are positive in the nose-up direction of the vehicle 100, the vertical acceleration a G is positive in the upward direction with respect to the vehicle 100, and the suspension stroke amount S su is positive in the compression direction of the suspension 40.

[0058] As shown in the figure, in a section where any of the pitch rate ω pi , the vertical acceleration a G , and the suspension stroke amount S su is below each threshold value (time t < t1), that is, in a scene where it is estimated that the unevenness of the wavy road is relatively small, non-cooperative processing is executed with priority given to control responsiveness.

[0059] And when all of the pitch rate ω pi , the vertical acceleration a G , and the suspension stroke amount S s u (in FIG. 5, particularly the suspension stroke amount S su ) on the rear wheel side exceed their respective threshold values (time t = t1), that is, when it is estimated that the vehicle has entered a section with relatively large unevenness of the wavy road, from the viewpoint of improving the suppression effect of the vertical displacement of the vehicle body, the control switches from non-cooperative processing to cooperative processing.

[0060] After that, the suspension stroke amount S su (In FIG. 5, the suspension stroke amounts S for both the front wheel side and the rear wheel side su ) is less than the second stroke amount threshold S suTH2 , that is, when it is estimated that the vehicle has entered a section with relatively small undulations of the undulating road, the control switches from the cooperative process to the non - cooperative process again.

[0061] FIG. 6 is a diagram for explaining the operational effects obtained by executing the control described in the timing chart of FIG. 5. As shown in the figure, in the control of the present embodiment, the pitch rate ω, which is a parameter indicating the magnitude of the vertical displacement, pi , the vertical acceleration a G and the suspension stroke amount S su (see the dashed line) are reduced compared to those of the comparative example (see the solid line) that maintains the basic drive control even during traveling on an undulating road.

[0062] Hereinafter, the configuration of the present embodiment described above and its operational effects will be collectively described.

[0063] In the present embodiment, a driving force control method is provided in which the front - wheel driving force F f connected to the front wheels 11f of the vehicle 100 and the rear - wheel driving force F r connected to the rear wheels 11r are respectively controlled by the front - wheel motor 10f and the rear - wheel motor 10r.

[0064] In this driving force control method, an adjustment for at least one of the front - wheel driving force F f and the rear - wheel driving force F r , and the application of a frictional braking force (the front - wheel braking force B f or the rear - wheel braking force B r ) to at least one of the front wheels 11f and the rear wheels 11r are coordinated to perform a cooperative process (step S140) of lifting up or lifting down the vehicle body.

[0065] As a result, the front - wheel driving force F f and the rear - wheel driving force F rCompared with the case of lifting up or lifting down the vehicle body by the control that only adjusts [the relevant factor], the effect of suppressing the vertical displacement (heave vibration) of the vehicle 100 can be enhanced more effectively.

[0066] In particular, the cooperative process (step S140) includes a first control mode for lifting up the vehicle body and a second control mode for lifting down the vehicle body. In the first control mode, a frictional braking force (front wheel braking force B f ) is applied to the front wheels 11f to make the rear wheel motor 10r perform power running. In the second control mode, the front wheel motor 10f performs power running, and a frictional braking force (rear wheel braking force B r ) is applied to the rear wheels 11r.

[0067] Thereby, when the vehicle 100 is moving forward, a more specific control mode for lifting up or lifting down the vehicle body in the cooperative process is realized.

[0068] In addition, the driving force control method of this embodiment further executes a non - cooperative process (step S160) of lifting up or lifting down the vehicle body only by adjusting the front - wheel driving force F f and the rear - wheel driving force F r . The non - cooperative process includes a third control mode in which the front - wheel motor 10f is regenerated and the rear - wheel motor 10r performs power running, and a fourth control mode in which the front - wheel motor 10f performs power running and the rear wheels 11r are regenerated.

[0069] Thereby, according to the driving scene of the vehicle 100, etc., it is possible to appropriately execute the lifting up or lifting down of the vehicle body by the non - cooperative process with high control responsiveness instead of the cooperative process. In this specification, the phrase "only the adjustment of the front - wheel driving force F f and the rear - wheel driving force F r " means that the operation amounts for the control of lifting up or lifting down the vehicle body are the front - wheel driving force F f and the rear - wheel driving force F rThis means that it is included but the frictional braking force is not. Therefore, the above statement does not intend to exclude from the technical scope of the present invention a form in which control logic using an operation amount other than the frictional braking force for assisting the operation of lifting up or down the vehicle body is included in the non-coordinated process.

[0070] Furthermore, in the driving force control method of the present embodiment, when the vehicle 100 is traveling on a wavy road, an unevenness degree parameter (pitch rate ω pi , vertical acceleration a G , and suspension stroke amount S su ) indicating the magnitude of the unevenness of the wavy road is acquired. Then, during the execution of the non-coordinated process, when the unevenness degree parameter exceeds a predetermined first threshold value (pitch rate threshold value ω piTH , vertical acceleration threshold value a GTH , and / or first stroke amount threshold value S suTH1 ), the non-coordinated process is switched to the coordinated process (steps S110 to S130, and step S140).

[0071] Thereby, according to the magnitude of the unevenness of the wavy road of the vehicle 100, it is possible to appropriately select between the suppression effect of vertical displacement and the non-coordinated process with high control responsiveness.

[0072] In particular, in the present embodiment, during the execution of the coordinated process, when the unevenness degree parameter (particularly the suspension stroke amount S su ) is below a predetermined second threshold value (second stroke amount threshold value S suTH2 ), the coordinated process is switched to the non-coordinated process.

[0073] Thereby, according to the degree of the magnitude of the unevenness of the wavy road of the vehicle 100, it is possible to more appropriately select between the suppression effect of vertical displacement and the non-coordinated process with high control responsiveness.

[0074] Furthermore, in the present embodiment, a controller 50 is provided that functions as a driving force control device for executing the above driving force control method. The controller 50 controls the front-wheel driving force F f and the rear-wheel driving force F r by a front-wheel motor 10f connected to the front wheels 11f of the vehicle 100 and a rear-wheel motor 10r connected to the rear wheels 11r, respectively.

[0075] In particular, the controller 50 has a cooperative processing unit (step S140) that cooperatively performs adjustment of at least one of the front-wheel driving force F f and the rear-wheel driving force F r and application of a frictional braking force (front-wheel braking force B f or rear-wheel braking force B r ) to at least one of the front wheels 11f and the rear wheels 11r to lift up or lift down the vehicle body.

[0076] Thereby, a configuration of a control device suitable for executing the above driving force control method is realized.

[0077] As described above, the embodiments of the present invention have been described. However, the above embodiments merely show a part of the application examples of the present invention, and are not intended to limit the technical scope of the present invention to the specific configurations of the above embodiments.

[0078] For example, in the above embodiment, an example in which either non-cooperative processing or cooperative processing is executed according to the magnitude of unevenness in a scene where the vehicle 100 is traveling on a wavy road has been described. However, the present invention is not limited to this, and the same control can be executed in other traveling scenes where suppression of the vertical displacement of the vehicle 100 is assumed.

[0079] Furthermore, the specific embodiments of the above unevenness degree parameter are not limited to those described in the above embodiments. For example, any Using in-vehicle sensors to obtain information about the unevenness of undulating roads, a value directly estimated for the magnitude of the unevenness from the information may be used as a parameter for the degree of unevenness. Furthermore, the parameters used for the switching determination from non-cooperative processing to cooperative processing are not limited to the above-described parameters for the degree of unevenness. For example, based on information obtained from in-vehicle or off-vehicle servers, etc., a parameter indicating the length of the period of the valleys and ridges of the unevenness of undulating roads is obtained, and a configuration may be adopted to determine whether to switch from non-cooperative processing to cooperative processing based on the parameter.

[0080] Also, in the above embodiment, an example was described in which, in both the first control mode (lift-up control) and the second control mode (lift-down control) of cooperative processing, the adjustment of the driving force distribution (pitch adjustment) for each driving wheel and the application of frictional braking force are coordinated. However, it is not limited to this, and in cooperative processing, a control mode may be adopted in which frictional braking force is applied only to either one of the first control mode and the second control mode. For example, in the first control mode (lift-up control) of cooperative processing, the front wheel braking force B f is applied, while in the second control mode (lift-down control), the rear wheel braking force B r is not applied. This control logic, as shown in FIG. 2, is particularly preferably applied to a vehicle body structure in which the anti-dive angle θ f on the front side is relatively small, while the anti-dive angle θ r on the rear side is relatively large, and for the rear side, a sufficient lift-up / down amount can be ensured only by adjusting the driving force distribution.

[0081] Furthermore, in the above-described embodiment, as an uncoordinated process, an example of a control mode in which only the drive force distribution of the vehicle 100 is adjusted to adjust the pitch displacement has been described. However, instead of this, as an uncoordinated process, a control mode may be adopted in which an arbitrary drive force distribution (for example, basic drive control for determining the drive force distribution during normal driving) performed for purposes other than adjusting the pitch displacement is used. For example, by setting the uncoordinated process as the basic drive control, direct switching (switching not via pitch adjustment by adjusting the drive force distribution) between the basic drive control and the coordinated process can be appropriately realized according to the conditions of the driving road surface such as the magnitude of the unevenness of the undulating road, and such a control mode is also included in the technical scope of the present invention.

Claims

1. A driving force control method for controlling the front-wheel driving force and the rear-wheel driving force respectively by a front-wheel motor connected to the front wheels of a vehicle and a rear-wheel motor connected to the rear wheels, comprising: acquiring a pitch rate, a vertical acceleration, and a suspension stroke amount of the vehicle as unevenness degree parameters indicating vertical displacement of the vehicle according to the magnitude of unevenness of a driving road surface of the vehicle; judging the level of a requirement for suppressing the vertical displacement with reference to the unevenness degree parameter; mutually switching and executing cooperative processing and non-cooperative processing according to a judgment result of the level of the requirement; in the cooperative processing, adjusting at least one of the front-wheel driving force and the rear-wheel driving force and applying a frictional braking force to at least one of the front wheels and the rear wheels in cooperation to lift up or lift down a vehicle body; in the non-cooperative processing, lifting up or lifting down the vehicle body only by adjusting the front-wheel driving force and the rear-wheel driving force; A driving force control method.

2. The driving force control method according to claim 1, wherein: the cooperative processing includes a first control mode for lifting up the vehicle body and a second control mode for lifting down the vehicle body; in the first control mode, applying a frictional braking force to the front wheels and making the rear-wheel motor perform a power running; in the second control mode, making the front-wheel motor perform a power running and applying a frictional braking force to the rear wheels or regenerating the rear wheels. A driving force control method.

3. The driving force control method according to claim 1 or 2, wherein: the non-cooperative processing includes a third control mode for regenerating the front-wheel motor and making the rear-wheel motor perform a power running and a fourth control mode for making the front-wheel motor perform a power running and regenerating the rear-wheel motor. A driving force control method.

4. The driving force control method according to claim 3, wherein: when the vehicle is traveling on a wavy road, acquiring the unevenness degree parameter; during execution of the non-cooperative processing, when the unevenness degree parameter exceeds a predetermined first threshold value, switching the non-cooperative processing to the cooperative processing. A driving force control method.

5. The driving force control method according to claim 4, wherein: during execution of the cooperative processing, when the unevenness degree parameter is lower than a predetermined second threshold value, switching the cooperative processing to the non-cooperative processing. A driving force control method.

6. A driving force control device that controls the front-wheel driving force and the rear-wheel driving force respectively by a front-wheel motor connected to the front wheels of a vehicle and a rear-wheel motor connected to the rear wheels, As a roughness parameter indicating the vertical displacement of the vehicle according to the magnitude of the unevenness of the traveling road surface of the vehicle, the pitch rate, the vertical acceleration, and the suspension stroke amount of the vehicle are acquired, Referring to the roughness parameter, the level of the requirement for suppressing the vertical displacement is judged, Cooperative processing and non-cooperative processing are mutually switched and executed according to the judgment result of the level of the requirement, In the cooperative processing, Adjustment of at least one of the front-wheel driving force and the rear-wheel driving force and application of frictional braking force to at least one of the front wheels and the rear wheels are coordinated to lift up or lift down the vehicle body, In the non-cooperative processing, the vehicle body is lifted up or lifted down only by adjusting the front-wheel driving force and the rear-wheel driving force, Driving force control device.

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