Vehicle control device

Abstract

A control device 10 uses the driving forces Fdf, Fdr and regenerative braking forces Fgf, Fgr from a front motor 101 and a rear motor 102 mounted on a sprung part of a vehicle 1 and / or the friction braking forces Fbf, Fbr from friction braking devices 30 mounted on an unsprung part of the vehicle 1 to generate a driving force difference or a braking force difference between inner wheels and outer wheels when the vehicle turns and thereby adjust the yaw moment of the vehicle 1. The control device 10 preferentially outputs, to the left and right front wheels 21 and / or the left and right rear wheels 22, that among the driving forces Fdf, Fdr and regenerative braking forces Fgf, Fgr from the sprung part of the vehicle 1 and the friction braking forces Fbf, Fbr from the unsprung part of the vehicle 1 which suppresses a rolling motion generated in the vehicle 1 (steps ST6 to ST8).

Description

Vehicle control device

[0001] The present invention relates to a vehicle control device that adjusts the yaw moment of a vehicle by generating a difference in driving force or braking force between left and right wheels.

[0002] Conventionally, there has been known a technique for adjusting the yaw moment of a vehicle by generating a difference in driving force or braking force between left and right wheels. For example, Patent Document 1 describes a vehicle in which a target yaw angular velocity is calculated based on the sideslip angle of the front wheels and the vehicle speed, and the operation of a torque distribution control device is controlled to obtain a yaw moment corresponding to the target yaw angular velocity.

[0003] JP 2010-025272 A

[0004] However, the control device as described in Patent Document 1 cannot suppress the roll motion that occurs in the vehicle body when the vehicle turns, which may affect the riding comfort of the driver.

[0005] The present invention has been made in consideration of such problems, and its purpose is to provide a vehicle control device that can achieve both adjustment of the vehicle's turning attitude and suppression of roll motion.

[0006] In order to achieve the above-mentioned object, the vehicle control device of the present invention is a vehicle control device that uses at least one of a force from a drive unit mounted on the sprung portion of the vehicle and a force from a braking unit mounted on the unsprung portion of the vehicle to create a driving force difference or a braking force difference between the inner and outer wheels when the vehicle turns, thereby adjusting the yaw moment of the vehicle, and preferentially outputs, to at least one of the left and right front wheels and the left and right rear wheels, the force from the sprung portion and the force from the unsprung portion that suppresses the roll motion generated in the vehicle.

[0007] In the vehicle control device of the present invention, among the forces used to adjust the yaw moment, those that suppress roll motion are adjusted preferentially, so it is possible to achieve both adjustment of the vehicle's turning posture and suppression of roll motion.

[0008] FIG. 1 is a schematic configuration diagram showing a vehicle equipped with a vehicle control device according to an embodiment. FIG. 2 is an explanatory diagram showing an anti-force acting on the vehicle during driving. FIG. 3 is an explanatory diagram showing an anti-force acting on the vehicle during braking. FIG. 4 is a flowchart showing an example of yaw control according to an embodiment. FIG. 5 is an explanatory diagram showing a case where the turning attitude of the vehicle tends to understeer. FIG. 6 is an explanatory diagram showing a case where the turning attitude of the vehicle tends to oversteer. FIG. 7 is an explanatory diagram showing forces acting on the vehicle in a first case. FIG. 8 is an explanatory diagram showing forces acting on the vehicle in a second case. FIG. 9 is an explanatory diagram showing forces acting on the vehicle in a third case. FIG. 10 is an explanatory diagram showing forces acting on the vehicle in a fourth case. FIG. 11 is an explanatory diagram showing forces acting on the vehicle in a fifth case. FIG. 12 is an explanatory diagram showing forces acting on the vehicle in a sixth case. FIG. 13 is an explanatory diagram showing forces acting on the vehicle in a seventh case. FIG. 14 is an explanatory diagram showing forces acting on the vehicle in an eighth case. FIG. 15 is a flowchart showing another example of yaw control according to an embodiment.

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

[0010] (Vehicle) Fig. 1 is a schematic diagram showing the configuration of a vehicle equipped with a vehicle control device according to an embodiment. The vehicle 1 is a four-wheel drive electric vehicle that travels by transmitting power from front motors 101R, 101L as a power source for traveling to left and right front wheels 21, and transmitting power from rear motors 102R, 102L as a power source for traveling to left and right rear wheels 22. Hereinafter, unless there is a need to distinguish between them, the front motors 101R, 101L will be referred to as the "front motor 101" and the rear motors 102R, 102L will be referred to as the "rear motor 102."

[0011] The front motor 101R outputs a driving force Fdf (FIG. 2) to the right front wheel 21 via the transaxle 121R and the front axle 131. The front motor 101L outputs a driving force Fdf (FIG. 2) to the left front wheel 21 via the transaxle 121L and the front axle 131. The rear motor 102R outputs a driving force Fdr (FIG. 2) to the right rear wheel 22 via the transaxle 122R and the rear axle 132. The rear motor 102L outputs a driving force Fdr (FIG. 2) to the left rear wheel 22 via the transaxle 122L and the rear axle 132.

[0012] The vehicle 1 is equipped with a battery 14 serving as a power source, which is configured as a secondary battery such as a lithium-ion battery. Power from the battery 14 is supplied to the front motor 101 and the rear motor 102 via a power conversion device such as an inverter, thereby outputting driving forces Fdf and Fdr. Furthermore, when the vehicle 1 is decelerating with the accelerator released, the front motor 101 and the rear motor 102 regenerate power using the rotational forces of the front wheels 21 and the rear wheels 22, thereby generating regenerative braking forces Fgf and Fgr ( FIG. 3 ). The regenerated power generated by the front motor 101 and the rear motor 102 is supplied to the battery 14. As described above, the front motor 101 and the rear motor 102 function as drive devices that apply driving force and regenerative braking force to the respective wheels, and are controlled by a control device (vehicle control device) 10 installed in the vehicle 1.

[0013] The vehicle 1 also includes a friction braking device 30 that applies braking force to the front wheels 21 and the rear wheels 22. The friction braking device 30 generates friction force by pressing brake pads 30P driven by an actuator (not shown) against disc rotors 30D provided corresponding to each of the front wheels 21 and each of the rear wheels 22. As a result, the friction braking device 30 applies a friction braking force Fbf ( FIG. 3 ) to each of the front wheels 21 and a friction braking force Fbr ( FIG. 3 ) to each of the rear wheels 22. The friction braking device 30 may include either a hydraulic actuator or an electric actuator. The friction braking device 30 is controlled by the control device 10.

[0014] The control device 10 is configured to include input / output devices, storage devices (ROM, RAM, non-volatile RAM, etc.), a central processing unit (CPU), etc. The control device 10 acquires detected quantities detected by various sensors of the vehicle 1 and operation information of various devices, calculates values ​​such as the required braking / driving force required for the vehicle 1 to travel, and controls each device of the vehicle 1 based on the calculated values. For example, the control device 10 acquires the vehicle speed of the vehicle 1 detected by a vehicle speed sensor 15, the steering angle of the vehicle 1 detected by a steering angle sensor 16, and the actual yaw rate γ of the vehicle 1 detected by a yaw rate detection sensor 17 (FIGS. 5 and 6), and performs yaw control, which will be described later, based on the acquired values.

[0015] (Anti-force) Next, the anti-force acting on the vehicle 1 will be described. FIG. 2 is an explanatory diagram showing the anti-force acting on the vehicle 1 when driving. FIG. 3 is an explanatory diagram showing the anti-force acting on the vehicle 1 when braking. Suspension devices 11 that suspend the front wheels 21 and the rear wheels 22 from the vehicle body are provided between the front wheels 21 and the rear wheels 22 of the vehicle 1 and the vehicle body. The front motor 101 and the rear motor 102 are mounted in sprung portions (inboard portions) above the suspension devices 11 of the vehicle 1, and the friction braking device 30 is mounted in unsprung portions (outboard portions) below the suspension devices 11 of the vehicle 1. Therefore, when the vehicle 1 is driven, driving forces Fdf and Fdr output from the sprung portions act on the front wheels 21 and the rear wheels 22. Furthermore, when braking the vehicle 1, regenerative braking forces Fgf, Fgr output from the sprung portions or friction braking forces Fbf, Fbr output from the unsprung portions act on the front wheels 21 and rear wheels 22.

[0016] Here, the anti-angles θdf, θdr, θbf, and θbr of the suspension unit 11 are determined by its geometry. The anti-angle θdf is the angle formed with the horizontal by a line connecting the center of the front wheel 21 and the attachment point of the suspension link 11L, which connects the suspension unit 11 to the body (sprung portion), and is the so-called anti-nose-up angle. The anti-angle θdr is the angle formed with the horizontal by a line connecting the center of the rear wheel 22 and the attachment point of the suspension link 11L to the body, and is the so-called anti-squat angle. The anti-angle θbf is the angle formed with the horizontal by a line connecting the center of the ground contact patch of the front wheel 21 and the attachment point of the suspension link 11L to the body, and is the so-called anti-nose-dive angle. The anti-angle θbr is the angle formed with the horizontal by a line connecting the center of the ground contact patch of the rear wheel 22 and the attachment point of the suspension link 11L to the body, and is the so-called anti-tail-lift angle. The anti angle θbf is larger than the anti angle θdf, and the anti angle θbr is larger than the anti angle θdr. Also, the anti angle θbr is larger than the anti angle θbf.

[0017] As a result, when the vehicle 1 is driven, as shown in FIG. 2, a downward anti-force Zdf acts on the front side of the vehicle 1 as a component of the driving force Fdf in accordance with the anti-angle θdf. Furthermore, an upward anti-force Zdr acts on the rear side of the vehicle 1 as a component of the driving force Fdr in accordance with the anti-angle θdr. Furthermore, when the vehicle 1 is braking, as shown in FIG. 3, an upward anti-force Zgf acts on the front side of the vehicle 1 in accordance with the anti-angle θdf as a component of the regenerative braking force Fgf. Furthermore, a downward anti-force Zgr acts on the rear side of the vehicle 1 in accordance with the anti-angle θdr as a component of the regenerative braking force Fgr. Furthermore, an upward anti-force Zbf acts on the front side of the vehicle 1 in accordance with the anti-angle θbf as a component of the frictional braking force Fbf. Furthermore, a downward anti-force Zbr acts on the rear side of the vehicle 1 in accordance with the anti-angle θbr as a component of the frictional braking force Fbr. The anti-forces Zdf, Zdr, Zgf, Zgr, Zbf, and Zbr are expressed by the following equations (1) to (6).

[0018] Zdf=Fdf・tan(θdf)…(1) Zdr=Fdr・tan(θdr)…(2) Zgf=Fgf・tan(θdf)…(3) Zgr=Fgr・tan(θdr)…(4) Zbf=Fbf・tan(θbf)…(5) Zbr=Fbr・tan(θbr)…(6)

[0019] (Yaw Control) Next, yaw control will be described. Yaw control is a control for adjusting the yaw moment of the vehicle 1 by generating a driving force difference or a braking force difference between the inner and outer wheels during cornering while satisfying the required braking / driving force required for the vehicle 1 to travel. In this embodiment, at least one of the driving forces Fdf and Fdr output from the sprung portion, the regenerative braking forces Fgf and Fgr output from the sprung portion, and the frictional braking forces Fbf and Fbr output from the unsprung portion is applied to at least one of the left and right front wheels 21 and the left and right rear wheels 22. FIG. 4 is a flowchart showing an example of yaw control according to this embodiment. The process shown in FIG. 4 is repeatedly executed by the control device 10 every unit time (e.g., every few milliseconds) while the vehicle 1 is traveling in a corner.

[0020] The control device 10 acquires the vehicle speed, steering angle, and actual yaw rate γ of the vehicle 1 (step ST1), and calculates a target yaw rate γt, which is a target value of the yaw rate during turning, based on the acquired vehicle speed and steering angle (step ST2). The target yaw rate γt is calculated using a well-known method. Next, the control device 10 calculates a yaw rate deviation Δγ, which is the deviation between the actual yaw rate γ and the target yaw rate γt (step ST3), and calculates a target yaw moment My, which is a target value of the yaw moment to be applied to the vehicle 1, based on the calculated yaw rate deviation Δγ (step ST4).

[0021] The target yaw moment My will now be described. FIG. 5 is an explanatory diagram showing a case where the turning attitude of the vehicle 1 tends to understeer. As shown in the figure, when the absolute value of the target yaw rate γt is small relative to the absolute value of the actual yaw rate γ of the vehicle 1 and the turning desired by the driver is not being performed, this state is called an understeer tendency (hereinafter referred to as a "US tendency"). In this case, a target yaw moment My that further promotes the turning of the vehicle 1 is set. On the other hand, FIG. 6 is an explanatory diagram showing a case where the turning attitude of the vehicle 1 tends to oversteer. As shown in the figure, when the absolute value of the target yaw rate γt is large relative to the absolute value of the actual yaw rate γ of the vehicle 1 and the vehicle is turning more than desired by the driver, this state is called an oversteer tendency (hereinafter referred to as an "OS tendency"). In this case, a target yaw moment My that suppresses the turning of the vehicle 1 is set. The target yaw moment My is set by well-known feedback control or the like so that the yaw rate deviation Δγ approaches the value 0.

[0022] To apply the target yaw moment My to the vehicle 1, a driving force difference or a braking force difference may be generated between the left and right wheels. For example, in the US trend shown in FIG. 5 , the driving force difference may be set so that the total driving force on the outer wheels is greater than the total driving force on the inner wheels, or the total braking force difference may be set so that the total braking force on the inner wheels is greater than the total braking force on the outer wheels. On the other hand, in the OS trend shown in FIG. 6 , the driving force difference may be set so that the total driving force on the inner wheels is greater than the total driving force on the outer wheels, or the braking force difference may be set so that the total braking force on the outer wheels is greater than the total braking force on the inner wheels. To determine such a distribution of the braking and driving forces, the control device 10 of this embodiment executes the processing of the following steps ST5 to ST8.

[0023] The control device 10 determines whether the turning attitude of the vehicle 1 has a US tendency or an OS tendency (step ST5). Whether the turning attitude of the vehicle 1 has a US tendency or an OS tendency can be determined from the relationship between the actual yaw rate γ and the target yaw rate γt, as described above. If the control device 10 determines that the turning attitude of the vehicle 1 has a US tendency, it prioritizes the allocation of the braking / driving forces to favor the US tendency, as described below (step ST6). On the other hand, if the control device 10 determines in step ST5 that the turning attitude of the vehicle 1 has an OS tendency, it prioritizes the allocation of the braking / driving forces to favor the OS tendency, as described below (step ST7). The control device 10 then sets and outputs the braking / driving forces for generating the target yaw moment My in accordance with the priority setting in step ST6 or step ST7 (step ST8), and executes this routine again from the beginning.

[0024] (Priority Setting in US Tendency) The above priority setting will be explained in detail. First, in the case of step ST6 (US tendency), in order to obtain the target yaw moment My, it is necessary to set a driving force difference so that the driving force on the outer wheel is greater than the driving force on the inner wheel, or to set a braking force difference so that the braking force on the inner wheel is less than the braking force on the outer wheel. Here, the following cases (A) to (D) will be considered as examples. (A) First case: A driving force Fdf is applied to the right front wheel 21. (B) Second case: A regenerative braking force Fgf or a friction braking force Fbf is applied to the left front wheel 21. (C) Third case: A driving force Fdr is applied to the right rear wheel 22. (D) Fourth case: A regenerative braking force Fgr or a friction braking force Fbr is applied to the left rear wheel 22.

[0025] FIG. 7 is an explanatory diagram showing forces acting on the vehicle 1 in a first case. FIG. 8 is an explanatory diagram showing forces acting on the vehicle 1 in a second case. FIG. 9 is an explanatory diagram showing forces acting on the vehicle 1 in a third case. FIG. 10 is an explanatory diagram showing forces acting on the vehicle 1 in a fourth case. FIGS. 7 to 10 are schematic diagrams of the vehicle 1 as viewed from the rear in the vehicle's longitudinal direction. FIGS. 7 and 8 are diagrams focusing on the front wheel 21 side, and FIGS. 9 and 10 are diagrams focusing on the rear wheel 22 side. As shown in the figures, when the vehicle 1 is turning left, an inertial force acting outward in the vehicle width direction acts on the center of gravity CG of the vehicle 1. As a result, as shown by the dashed line in the figure, the sprung portion of the vehicle 1 rolls so as to rotate clockwise around the roll center Rc. This causes a change in the vehicle 1's posture in the roll direction by a roll angle φ. The roll angle φ may be calculated based on detection values ​​of well-known sensors mounted on the vehicle 1.

[0026] As shown in Fig. 7A, when a driving force Fdf is applied to the right front wheel 21, a downward anti-force Zdf causes a clockwise rotational moment M1 in the figure to act on the vehicle 1 about the roll center Rc. Also, as shown in Fig. 8B, when a regenerative braking force Fgf or a frictional braking force Fbf is applied to the left front wheel 21, an upward anti-force Zgf or Zbf causes a clockwise rotational moment M2 in the figure to act on the vehicle 1 about the roll center Rc. Thus, in the first case (A) and the second case (B), the rotational moments M1 and M2 increase the roll motion.

[0027] On the other hand, as shown in Figure 9, when (C) a driving force Fdr is applied to the right rear wheel 22, an upward anti-force Zdr causes a counterclockwise rotational moment M3 in the figure to act on the vehicle 1. Also, as shown in Figure 10, when (D) a regenerative braking force Fgr or a frictional braking force Fbr is applied to the left rear wheel 22, a downward anti-force Zgr or Zbr causes a counterclockwise rotational moment M4 in the figure to act on the vehicle 1. Thus, in the (C) third case and the (D) first case, roll motion is suppressed by the rotational moments M3 and M4.

[0028] Therefore, in step ST6, the control device 10 performs a setting to adjust the driving force difference or braking force difference preferentially on the rear wheels 22 side over the front wheels 21 side. That is, on the rear wheels 22 side, the driving force Fdr of the outer wheels is output greater than the driving force Fdr of the inner wheels to generate the rotational moment M3, or the sum of the regenerative braking force Fgr and frictional braking force Fbr of the inner wheels is output greater than the sum of the regenerative braking force Fgr and frictional braking force Fbr of the outer wheels to generate the rotational moment M4. This makes it possible to generate the target yaw moment My while suppressing roll motion.

[0029] As described above, the anti-angle θbr is greater than the anti-angle θdr ( FIG. 3 ). Therefore, of the anti-forces Zdr, Zgr, and Zbr, the anti-force Zbr tends to be the largest, which tends to increase the rotational moment M4. Therefore, the control device 10 preferentially outputs the frictional braking force Fbr to the inner rear wheels 22 as the roll angle φ increases. This allows the largest anti-force Zbr to be utilized to generate a large rotational moment M4, thereby more effectively suppressing roll motion. The control device 10 may output the driving force Fdr, the regenerative braking force Fgr, and the frictional braking force Fbr so that the anti-force that suppresses roll motion acts more strongly as the roll angle φ increases.

[0030] However, upper limits for the driving force difference and braking force difference are set according to vehicle specifications such as the grip limits of each wheel, the output limits of each motor, and the regenerative power generation limits. When the target yaw moment My cannot be obtained even when the driving force difference or braking force difference of the rear wheels 22 reaches its upper limit, the control device 10 generates a driving force difference or braking force difference at the front wheels 21 to obtain the target yaw moment My, as in (A) Case 1 or (B) Case 2 indicated by the dashed arrows in FIG. 5 . This allows for more reliable control of the yaw rate. Note that, in order to prevent roll motion from increasing, it is preferable to control the anti-forces Zdf, Zgf, and Zbf generated at the front wheels 21 to act in order from smallest to largest.

[0031] (Priority Setting for OS Tendency) Next, in the case of step ST7 (OS tendency), in order to obtain the target yaw moment My, it is necessary to set a driving force difference so that the driving force on the inner wheel is greater than the driving force on the outer wheel, or to set a braking force difference so that the braking force on the outer wheel is less than the braking force on the inner wheel. Here, the following cases (E) to (H) are considered as examples. (E) Fifth Case: A driving force Fdf is applied to the left front wheel 21. (F) Sixth Case: A regenerative braking force Fgf or a friction braking force Fbf is applied to the right front wheel 21. (G) Seventh Case: A driving force Fdr is applied to the left rear wheel 22. (H) Eighth Case: A regenerative braking force Fgr or a friction braking force Fbr is applied to the right rear wheel 22.

[0032] FIG. 11 is an explanatory diagram showing forces acting on the vehicle 1 in the fifth case. FIG. 12 is an explanatory diagram showing forces acting on the vehicle 1 in the sixth case. FIG. 13 is an explanatory diagram showing forces acting on the vehicle 1 in the seventh case. FIG. 14 is an explanatory diagram showing forces acting on the vehicle 1 in the eighth case. FIGS. 11 to 14 are schematic diagrams of the vehicle 1 viewed from the rear in the vehicle longitudinal direction. Also, FIGS. 11 and 12 are diagrams focusing on the front wheel 21 side, and FIGS. 13 and 14 are diagrams focusing on the rear wheel 22 side. Note that the direction of roll motion in the case of an OS tendency is the same as in the case of a US tendency.

[0033] As shown in Fig. 11, when (E) a driving force Fdf is applied to the left front wheel 21, a downward anti-force Zdf causes a counterclockwise rotational moment M5 in the figure to act on the vehicle 1. Also, as shown in Fig. 12, when (F) a regenerative braking force Fgf or a frictional braking force Fbf is applied to the right front wheel 21, an upward anti-force Zgf or an upward anti-force Zbf causes a counterclockwise rotational moment M6 in the figure to act on the vehicle 1. In this way, in the (E) fifth case and the (F) sixth case, the roll motion is suppressed by the rotational moments M5 and M6.

[0034] On the other hand, as shown in Figure 13, when a driving force Fdr is applied to the left rear wheel 22 (G), an upward anti-force Zdr causes a clockwise rotational moment M7 to act on the vehicle 1. Also, as shown in Figure 14, when a regenerative braking force Fgr or a frictional braking force Fbr is applied to the right rear wheel 22 (H), a downward anti-force Zgr or Zbr causes a clockwise rotational moment M8 to act on the vehicle 1. Thus, in the (G) seventh case and the (H) eighth case, the roll motion is increased by the rotational moments M7 and M8.

[0035] Therefore, in step ST7, the control device 10 performs a setting to adjust the driving force difference or braking force difference preferentially on the front wheels 21 side over the rear wheels 22 side. That is, on the front wheels 21 side, the driving force Fdr of the inner wheels is output greater than the driving force Fdr of the outer wheels to generate the rotational moment M5, or the sum of the regenerative braking force Fgr and frictional braking force Fbr of the outer wheels is output greater than the sum of the regenerative braking force Fgr and frictional braking force Fbr of the inner wheels to generate the rotational moment M6. This makes it possible to generate the target yaw moment My while suppressing roll motion.

[0036] As described above, the anti-angle θbf is greater than the anti-angle θdf ( FIG. 3 ). Therefore, of the anti-forces Zdf, Zgf, and Zbf, the anti-force Zbf tends to be the largest, which tends to increase the rotational moment M6. Therefore, the control device 10 preferentially outputs the frictional braking force Fbf at the outer wheel of the front wheels 21 as the roll angle φ increases. This allows the largest anti-force Zbf to be utilized to generate a large rotational moment M6, thereby achieving better roll suppression. The control device 10 may output the driving force Fdf, the regenerative braking force Fgf, and the frictional braking force Fbf so that the anti-force that suppresses roll motion acts more strongly as the roll angle φ increases.

[0037] As in step ST6, if the target yaw moment My cannot be obtained even when the driving force difference or braking force difference at the front wheels 21 reaches its upper limit, the control device 10 also generates a driving force difference or braking force difference at the rear wheels 22, as in the seventh case (G) or the eighth case (H) indicated by the dashed arrows in Figure 6. This allows for more reliable control of the yaw rate. Note that, in order to prevent the roll motion from becoming too large, it is preferable to control the anti-forces Zdr, Zgr, and Zbr generated at the rear wheels 22 to act in order from smallest to largest.

[0038] Effect of the embodiment As described above, the control device (vehicle control device) 10 of the embodiment uses at least one of the driving forces Fdf, Fdr and regenerative braking forces Fgf, Fgr from the front motor (drive device) 101 and the rear motor (drive device) 102 mounted in the sprung portion of the vehicle 1, and the friction braking forces Fbf, Fbr from the friction braking device (brake device) 30 mounted in the unsprung portion of the vehicle 1, to generate a driving force difference or a braking force difference between the inner wheel and the outer wheel when the vehicle is turning, thereby adjusting the yaw moment of the vehicle 1. The control device 10 preferentially outputs, to at least one of the left and right front wheels 21 and the left and right rear wheels 22, the driving forces Fdf, Fdr, the regenerative braking forces Fgf, Fgr from the sprung portion of the vehicle 1, and the friction braking forces Fbf, Fbr from the unsprung portion of the vehicle 1, which suppress the roll motion generated in the vehicle 1 (steps ST6 to ST8).

[0039] With this configuration, as described above, the driving forces Fdf, Fdr for adjusting the yaw moment, the regenerative braking forces Fgf, Fgr, and the friction braking forces Fbf, Fbr that suppress roll motion are adjusted preferentially, making it possible to achieve both adjustment of the turning posture of the vehicle 1 and suppression of roll motion.

[0040] Furthermore, when the turning posture of the vehicle 1 tends to US, the control device 10 outputs the driving forces Fdf, Fdr, regenerative braking forces Fgf, Fgr, and friction braking forces Fbf, Fbr that suppress roll motion preferentially on the rear wheel 22 side over the front wheel 21 side (steps ST6, ST8), and when the turning posture of the vehicle 1 tends to OS, the control device 10 outputs the driving forces Fdf, Fdr, regenerative braking forces Fgf, Fgr, and friction braking forces Fbf, Fbr that suppress roll motion preferentially on the front wheel 21 side over the rear wheel 22 side (steps ST7, ST8). With this configuration, it is possible to generate a target yaw moment My while appropriately suppressing roll motion according to the turning posture of the vehicle 1.

[0041] Furthermore, the control device 10 prioritizes output of the friction braking forces Fbf and Fbr from the friction braking device 30 as the roll angle φ increases (steps ST6 to ST8). This configuration allows for the use of relatively large anti-forces Zbf and Zbr due to the friction braking forces Fbf and Fbr, thereby more effectively suppressing the roll motion of the vehicle 1. However, depending on the vehicle specifications, the anti-force due to the friction braking forces may not be maximized. For example, in the sixth case (F) shown in FIG. 12 , the spring of the suspension device 11 on the outer wheel side compresses during cornering, causing the anti-angle θbf on the outer wheel side to become smaller than the anti-angle θbf on the inner wheel side, resulting in a smaller anti-force Zbf on the outer wheel side than when traveling straight. Therefore, the control device 10 may prioritize output of the braking / driving force that maximizes the anti-force, rather than the friction braking forces Fbf and Fbr.

[0042] Furthermore, when the target yaw moment My cannot be obtained even if the driving force difference or braking force difference at either the front wheels 21 or the rear wheels 22 reaches an upper limit value according to the vehicle specifications, the control device 10 outputs any one of the driving forces Fdf, Fdr, regenerative braking forces Fgf, Fgr, and friction braking forces Fbf, Fbr that do not suppress roll motion. This makes it possible to more reliably control the yaw rate as described above.

[0043] Furthermore, the control device 10 may change the priority setting according to, for example, the control mode of the vehicle 1. Fig. 15 is a flowchart showing another example of yaw control according to the embodiment. Of the processing shown in Fig. 15, the processing of steps ST11 to ST17 and ST20 is the same as steps ST1 to ST8 in Fig. 4, and therefore description thereof will be omitted.

[0044] In the example shown in FIG. 15 , after processing step ST16 or step ST17, the control device 10 determines whether the control mode of the vehicle 1 is set to the eco mode (step ST18). As shown in FIG. 1 , the vehicle 1 is provided with a mode setting switch 19 that can set the control mode. The mode setting switch 19 is provided inside the vehicle cabin so that it can be operated by the driver. The control modes include, for example, an eco mode that places more importance on improving the energy consumption efficiency of the vehicle 1 than the normal mode, and a comfort mode that places more importance on the ride comfort of the vehicle 1 than the normal mode. Note that the normal mode is a state in which neither the eco mode nor the comfort mode is set. Here, a case in which either the eco mode or the comfort mode is set will be described as an example.

[0045] If the control device 10 determines in step ST18 that the control mode is the eco mode (Yes in step ST18), it resets the settings in step ST16 or step ST17 so that adjustment of the driving forces Fdf, Fdr or the regenerative braking forces Fgf, Fgr takes priority over adjustment of the frictional braking forces Fbf, Fbr (step ST19). Then, the control device 10 sets and outputs the braking / driving forces in accordance with the priority settings (step ST20), and executes this routine again from the beginning. That is, the control device 10 prioritizes output of the driving forces Fdf, Fdr or the regenerative braking forces Fgf, Fgr over the frictional braking forces Fbf, Fbr. This minimizes the activation of the frictional braking device 30, thereby reducing energy consumption and improving the energy consumption efficiency of the vehicle 1. It is more preferable that the control device 10 not set the frictional braking forces Fbf, Fbr so as not to activate the frictional braking device 30.

[0046] On the other hand, if the control device 10 determines in step ST18 that the control mode is not the eco mode, that is, that the comfort mode is set (No in step ST18), it resets the control mode so that adjustment of the frictional braking forces Fbf and Fbr takes priority over adjustment of the driving forces Fdf and Fdr or the regenerative braking forces Fgf and Fgr (step ST21). Then, the control device 10 sets and outputs the braking and driving forces in accordance with the priority setting (step ST20), and executes this routine again from the beginning. That is, the control device 10 prioritizes output of the frictional braking forces Fbf and Fbr over the driving forces Fdf and Fdr or the regenerative braking forces Fgf and Fgr. This utilizes the relatively large antiforces Zbf and Zbr to further suppress roll motion and improve the ride comfort of the vehicle 1.

[0047] Furthermore, when ride comfort of the vehicle 1 is emphasized, such as in the comfort mode described above, the control device 10 may generate a driving force difference or braking force difference between all of the inner and outer wheels that tends to suppress roll motion. In the case of the US tendency shown in FIG. 5 , if the driving force difference or braking force difference at the rear wheels 22 can maintain the direction of the target yaw moment My, a force may be applied to the front wheels 21 in the direction opposite to the dashed arrow in the figure. That is, a driving force Fdr may be applied to the left front wheel 21, or a regenerative braking force Fgr or a frictional braking force Fbr may be applied to the right front wheel 21. In the case of the OS tendency shown in FIG. 6 , if the driving force difference or braking force difference at the front wheels 21 can maintain the direction of the target yaw moment My, a force may be applied to the rear wheels 22 in the direction opposite to the dashed arrow in the figure. That is, a driving force Fdr may be applied to the right rear wheel 22, or a regenerative braking force Fgr or a frictional braking force Fbr may be applied to the left rear wheel 22. As a result, the tendency for the actual yaw rate γ to approach the target yaw rate γt is maintained, while the roll motion is more strongly suppressed, and the ride comfort of the vehicle 1 can be improved.

[0048] Although the description of the embodiment has been completed above, aspects of the present invention are not limited to this embodiment. For example, in this embodiment, the present invention is applied to a vehicle 1 that is a four-wheel drive electric vehicle. However, the present invention may be applied to other vehicles as long as it is possible to generate a driving force difference and a braking force difference between the left and right front wheels 21 and the left and right rear wheels 22. For example, the present invention may be applied to an electronically controlled on-demand four-wheel drive vehicle that uses an internal combustion engine mounted in the sprung portion as a drive source.

[0049] 1 Vehicle 10 Control device (vehicle control device) 11 Suspension device 21 Front wheels 22 Rear wheels 30 Friction braking device (brake device) 101, 101R, 101L Front motor (drive device) 102, 102R, 102L Rear motor (drive device) Fbf, Fbr Friction braking force (force from brake device) Fdf, Fdr Drive force (force from drive device) Fgf, Fgr Regenerative braking force (force from drive device) My Target yaw moment Zdf, Zdr, Zgf, Zgr, Zbf, Zbr Anti-force γ Actual yaw rate γt Target yaw rate Δγ Yaw rate deviation θdf, θdr, θbf, θbr Anti-angle

Claims

1. A vehicle control device that adjusts the yaw moment of a vehicle by generating a difference in driving force or braking force between the inner and outer wheels when the vehicle is turning, using at least one of a force from a drive unit mounted on the sprung portion of the vehicle and a force from a braking unit mounted on the unsprung portion of the vehicle, and that preferentially outputs, to at least one of the left and right front wheels and the left and right rear wheels, the force from the sprung portion or the force from the unsprung portion that suppresses the roll motion generated in the vehicle.

2. A vehicle control device as described in claim 1, wherein, when the turning posture of the vehicle tends to understeer, the force that suppresses the roll motion is output preferentially on the rear wheel side rather than the front wheel side, and when the turning posture of the vehicle tends to oversteer, the force that suppresses the roll motion is output preferentially on the front wheel side rather than the rear wheel side.

3. A vehicle control device according to claim 1 or 2, wherein the force output from the braking device is given priority as the roll angle of the vehicle increases.

4. A vehicle control device as described in claim 1 or 2, which includes outputting one of the forces that does not suppress the roll motion when the driving force difference or the braking force difference at either one of the front wheels or the rear wheels reaches an upper limit value corresponding to the vehicle specifications but the target yaw moment cannot be obtained.

5. A vehicle control device as described in claim 1 or 2, wherein when an eco mode is set that places more importance on improving the energy consumption efficiency of the vehicle than in the normal mode, the force from the drive device is output with priority over the force from the braking device, compared to the normal mode.

6. A vehicle control device as described in claim 1 or 2, wherein when a comfort mode is set that places more importance on the ride comfort of the vehicle than the normal mode, the force from the braking device is output with priority over the force from the drive device, compared to the normal mode.

7. A vehicle control device according to claim 1 or 2, wherein the driving force difference or the braking force difference that tends to suppress the roll motion is generated between all of the inner wheels and the outer wheels.

Images