Vehicle

Abstract

A vehicle 1 comprises a regenerative braking device (first braking device) that applies regenerative braking torque (first braking torque) to front wheels 21 and rear wheels, a friction braking device (second braking device) that applies friction braking torque (second braking torque) to the front wheels 21 and the rear wheels, and a control device that controls the regenerative braking device and the friction braking device to cooperatively output required braking torque that is required for braking. When vehicle behavior during turning has a prescribed US tendency, the control device adjusts the distribution ratio of the regenerative braking torque and the friction braking torque such that the load transfer amount ΔW1 between the left and right front wheels 21 decreases. When vehicle behavior during turning has a prescribed OS tendency, the control device adjusts the distribution ratio of the regenerative braking torque and the friction braking torque such that the load transfer amount ΔW2 between the left and right rear wheels 22 decreases.

Description

vehicle

[0001] The present invention relates to a vehicle that uses multiple braking devices to adjust vehicle behavior.

[0002] Conventionally, techniques for adjusting vehicle behavior using multiple braking devices have been known. For example, Patent Document 1 (Patent Document 1) describes a vehicle control device in which a driver performs a braking operation and changes the ratio of regenerative braking force and friction braking force when performing vehicle motion control. This vehicle control device prevents the in-wheel motor from exceeding its control range by, for example, reducing the ratio of regenerative braking force on the inner wheels when braking the vehicle while turning. This vehicle control device also increases the amount of recovered power and reduces friction loss by reducing the ratio of friction braking force on the outer wheels when braking the vehicle while turning.

[0003] JP 2017-77753 A

[0004] When a vehicle turns, vehicle behaviors such as understeer and oversteer tendencies occur. However, the device described in Patent Document 1 merely adjusts the distribution of braking force output from each braking device to prevent the in-wheel motor from exceeding its control range, increase recovered power, and reduce friction loss. Therefore, there is a risk that the understeer and oversteer tendencies cannot be appropriately adjusted during cornering braking of the vehicle.

[0005] The present invention has been made in view of the above-mentioned problems, and its object is to provide a vehicle that can more appropriately adjust the understeer and oversteer tendencies of the vehicle during cornering braking.

[0006] In order to achieve the above-mentioned object, the vehicle of the present invention comprises a first braking device mounted above the suspension device and applying a first braking torque to at least one of the front wheels and the rear wheels, a second braking device mounted below the suspension device and applying a second braking torque to at least one of the front wheels and the rear wheels to which the first braking torque is applied from the first braking device, and a control device that controls the first braking device and the second braking device so that they coordinate to output the required braking torque required for braking, wherein the control device adjusts the distribution ratio of the first braking torque and the second braking torque so that the amount of load transfer between the left and right front wheels is reduced when the vehicle behavior during cornering has a predetermined tendency toward understeer, and adjusts the distribution ratio of the first braking torque and the second braking torque so that the amount of load transfer between the left and right rear wheels is reduced when the vehicle behavior during cornering has a predetermined tendency toward oversteer.

[0007] According to the vehicle of the present invention, it is possible to more appropriately adjust the understeer or oversteer tendency of the vehicle during cornering braking.

[0008] Fig. 1 is a schematic configuration diagram showing a vehicle according to a first embodiment; Fig. 2 is an explanatory diagram schematically showing an anti angle and an anti force of a vehicle; Fig. 3 is an explanatory diagram showing an example of roll motion when braking a vehicle while turning; Fig. 4 is an explanatory diagram showing an example of roll motion when braking a vehicle while turning; Fig. 5 is an explanatory diagram showing the relationship between the wheel contact patch load and maximum lateral force; Fig. 6 is a flowchart showing an example of distribution ratio adjustment control; Fig. 7 is a schematic configuration diagram showing a vehicle according to a second embodiment;

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

[0010] [First embodiment] Fig. 1 is a schematic diagram showing the configuration of a vehicle according to a first embodiment. The vehicle 1 is a four-wheel drive electric vehicle that travels by transmitting power from a front motor 101 as a power source to left and right front wheels 21 and transmitting power from a rear motor 102 as a power source to left and right rear wheels 22. Note that the vehicle 1 may be any vehicle that includes an electrified power source, such as a BEV (Battery Electric Vehicle), HEV (Hybrid Electric Vehicle), PHEV / PHV (Plug-in Hybrid Electric Vehicle / Plug-in Hybrid Vehicle), or FCEV / FCV (Fuel Cell Electric Vehicle / Fuel Cell Vehicle).

[0011] The front motor 101 outputs driving force to the left and right front wheels 21 via a transaxle 121, which includes a transmission and a differential gear, and left and right front axles 131. The rear motor 102 outputs driving force to the left and right rear wheels 22 via a transaxle 122, which includes a transmission and a differential gear, and left and right rear axles 132. 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, and 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 (not shown). The front motor 101 and the rear motor 102 are drive-controlled by a control device 16.

[0012] The vehicle 1 also includes a regenerative braking device 20 (first braking device) and a friction braking device 30 (second braking device) as braking devices that apply braking forces to the front wheels 21 and rear wheels 22. The regenerative braking device 20 includes a front motor 101 and a rear motor 102, a battery 14, and a power conversion device such as an inverter (not shown). When the vehicle 1 is decelerating with the accelerator released, the front motor 101 and the rear motor 102 are forcibly driven by the rotational forces of the front wheels 21 and the rear wheels 22 to generate regenerative power. This causes a regenerative braking torque T ＩＢ１(first braking torque), a regenerative braking torque T ＩＢ２ (First braking torque) is applied (FIG. 2). The regenerated electric power generated by the front motor 101 and the rear motor 102 is supplied to the battery 14.

[0013] The friction braking device 30 is a disc brake device that generates a friction force by pressing brake pads 30P, which are driven by an actuator (not shown), against disc rotors 30D provided corresponding to each front wheel 21 and each rear wheel 22 (each front axle 131 and each rear axle 132). As a result, the friction braking device 30 applies a friction braking torque T ＯＢ１ (second braking torque), and friction braking torque T ＯＢ２ (second braking torque) is applied (FIG. 2). The actuator may be either a hydraulic or electric type.

[0014] (Control Device) The control device 16 is configured to include input / output devices, storage devices (ROM, RAM, non-volatile RAM, etc.), a central processing unit (CPU), etc., and performs overall control of the vehicle 1. The control device 16 receives inputs of detected quantities and various operational information detected by various sensors (not shown), such as accelerator opening, brake depression amount, vehicle speed, and wheel speed. For example, the control device 16 receives input of the actual yaw rate of the vehicle 1 detected by a yaw rate detection sensor 15 mounted on the vehicle 1. Based on the input detected quantities and operational information, the control device 16 calculates information necessary for controlling the vehicle 1, such as the required driving torque and required braking torque required for the vehicle 1 to travel, and controls various devices of the vehicle 1 based on the calculated information.

[0015] In this embodiment, the control device 16 executes regenerative cooperative control, which outputs the required braking torque in a coordinated manner using regenerative braking torque and friction braking torque. That is, the control device 16 calculates the required braking force according to the amount of brake application by the driver, and determines the distribution ratio of the regenerative braking torque and the friction braking torque so that the total sum of the regenerative braking torque and the friction braking torque satisfies the required braking torque. The distribution ratio is, for example, such that the regenerative braking torque is output within the range of the upper limit of the amount of regenerative power generation, and the shortfall of the regenerative braking torque with respect to the required braking torque is output as friction braking torque. The upper limit of the amount of regenerative power generation is set according to the state of charge (SOC) and temperature of the battery 14, etc.

[0016] (Anti-angle and anti-force) Figure 2 is an explanatory diagram that schematically shows the anti-angle and anti-force of the vehicle 1. Between each front wheel 21 and each rear wheel 22 of the vehicle 1 and the vehicle body, there is provided a suspension device 11 that has anti-dive and anti-lift geometry and suspends each front wheel 21 and each rear wheel 22 relative to the vehicle body. In the following description, the sprung portion of the vehicle 1 above the suspension device 11 will be referred to as the "inboard portion," and the unsprung portion below the suspension device 11 will be referred to as the "outboard portion." The regenerative braking device 20 described above is mounted on the inboard portion, and the friction braking device 30 is mounted on the outboard portion. Therefore, the front wheels 21 and rear wheels 22 of the vehicle 1 are subjected to a regenerative braking force F output from the inboard portion. ＩＢ１ , F ＩＢ２ and the friction braking force F output from the outboard section ＯＢ１ , F ＯＢ２ This works as follows (Figure 2).

[0017] The vehicle 1 is supplied with a regenerative braking force F ＩＢ１ , F ＩＢ２ The anti-force corresponding to the friction braking force F ＯＢ１ , F ＯＢ２ The anti-angle is determined by the geometry of the suspension device 11. In this embodiment, the anti-angle θ ＩＢ１ , θ ＯＢ１ , θ ＩＢ２ , θ ＯＢ２ Including anti-angle θ ＩＢ１, anti-angle θ ＩＢ２ is the angle formed by a straight line connecting the center of each wheel and the attachment point of the suspension link 11L, which connects the suspension device 11 to the body (inboard portion), with respect to the horizontal direction. ＯＢ１ , anti-angle θ ＯＢ２ is the angle formed by a line connecting the center of the ground contact surface of each wheel and the attachment point of the suspension link 11L to the body with respect to the horizontal direction. ＩＢ１ In general suspension geometry, this corresponds to the anti-nose-up angle that acts as an anti-nose-up force when the vehicle is driven, and the anti-angle θ ＩＢ２ corresponds to the anti-squat angle that applies the anti-squat force when the vehicle is driven. ＯＢ１ is the anti-nose dive angle in a typical suspension geometry, and the anti-angle θ ＯＢ２ is the anti-tail lift angle. Anti-angle θ ＯＢ１ is the anti-angle θ ＩＢ１ Larger than the anti-angle θ ＯＢ２ is the anti-angle θ ＩＢ２ is greater than.

[0018] As a result, the regenerative braking force F ＩＢ１ The upward component of the anti-force Z ＩＢ１ is the anti-angle θ ＩＢ１ The regenerative braking force F ＩＢ２ The downward component of the anti-force Z ＩＢ２ is the anti-angle θ ＩＢ２ In response to the frictional braking force F ＯＢ１ The upward component of the anti-force Z ＯＢ１ is the anti-angle θ ＯＢ１ In response to the frictional braking force F ＯＢ２ The anti-force Z as a component of the vertical downward force ＯＢ２ is the anti-angle θ ＯＢ２ Each reaction force Z acts on the attachment point of the suspension link 11L on the rear side of the vehicle 1 in accordance with the ＩＢ１ , ZＩＢ２ , Z ＯＢ１ , Z ＯＢ２ is expressed by the formulas (1) to (4), where “R” is the radius of the front wheel 21 and the rear wheel 22.

[0019]

[0020]

[0021]

[0022]

[0023] 3 and 4 are explanatory diagrams showing an example of roll motion during braking when turning the vehicle 1. FIG. 3 shows a schematic view of the front axle 131 side of the vehicle 1, and FIG. 4 shows a schematic view of the rear axle 132 side of the vehicle 1, as viewed from the rear side in the vehicle longitudinal direction. As shown in the figures, when the vehicle 1 is turning left by steering, an inertial force G ｙ acts on the center of gravity CG of the vehicle 1. As a result, as shown schematically by the dashed lines in the figure, the inboard portion of the vehicle 1 changes its posture in a clockwise rotational direction around the roll center rc1 on the front axle 131 side and the roll center rc2 on the rear axle 132 side.

[0024] At this time, the spring 11L on the inner wheel side (here, the left side) of the suspension device 11 expands during turning, and the spring 11R on the outer wheel side (here, the right side) of the suspension device 11 contracts during turning. As a result, the suspension device 11 generates a rotational moment M ｓａ１ A rotational moment M in the opposite direction to the roll motion is generated around the roll center rc2 on the rear axle 132 side. ｓａ２ Generates.

[0025] (Anti-force during cornering braking) Next, the anti-force when a braking force is applied to the vehicle 1 when the vehicle 1 is cornering will be described. As described above, when the spring 11L on the inner wheel side expands and the spring 11R on the outer wheel side contracts due to cornering, the anti-angles on the inner wheel side become larger than those on the outer wheel side, and as a result, the anti-force on the inner wheel side becomes larger than that on the outer wheel side. As a result, the rotational moment M about the roll centers rc1 and rc2 ａｐ１ , M ａｐ２ will occur.

[0026] Specifically, as shown in FIG. 3, the front axle 131 has an inner wheel side anti-force Z ＩＢ１ , Z ＯＢ１ The sum of the anti-force Z on the outer ring side ＩＢ１ , Z ＯＢ１ The rotational moment M in the same direction as the roll motion (clockwise in this case) becomes larger than the sum of ａｐ１ On the other hand, as shown in FIG. 4, an anti-force Z ＩＢ２ , Z ＯＢ２ The sum of the anti-force Z on the outer ring side ＩＢ２ , Z ＯＢ２ The rotational moment M in the opposite direction to the roll motion (counterclockwise in this case) becomes larger than the sum of ａｐ２ The rotational moment M ａｐ１ , M ａｐ２ is expressed by the formulas (5) and (6) based on the formulas (1) to (4). ＩＢＲ１ " is the anti-angle θ on the right side (outer ring side) ＩＢ１ , "θ ＩＢL１ " is the anti-angle θ on the left side (inner wheel side) ＩＢ１ , "θ ＩＢＲ２ " is the right anti-angle θ ＩＢ２ , "θ ＩＢL２ " is the left anti-angle θ ＩＢ２ , "θ ＯＢＲ１ " is the right anti-angle θ ＯＢ１ , "θ ＯＢL１ " is the left anti-angle θ ＯＢ１ , "θ ＯＢＲ２ " is the right anti-angle θ ＯＢ２ , "θ ＯＢL２ " is the left anti-angle θ ＯＢ２ Also, "d ｌｉｎｋ" is the distance between the left and right attachment points of the suspension link that transmits the anti-force to the inboard part.

[0027]

[0028]

[0029] (Left and right load shift amount during cornering braking) Next, the shift amount of the ground contact load occurring between the left and right front wheels 21 and between the rear wheels 22 during cornering braking of the vehicle 1 will be described. Hereinafter, the shift amount of the ground contact load occurring between the left and right front wheels 21 will be referred to as the "load shift amount ΔW １ ", and the amount of shift of the ground contact load occurring between the left and right rear wheels 22 is referred to as "load shift amount ΔW ２ " and the load movement amount ΔW １ , ΔW ２ When no distinction is made between the load and the load, the term "load movement amount ΔW" is used.

[0030] First, the balance of the rotational moment acting on the inboard portion of the vehicle 1 is expressed by equation (7). The balance of the rotational moment acting on the outboard portion on the front axle 131 side is expressed by equation (8), and the balance of the rotational moment acting on the outboard portion on the rear axle 132 side is expressed by equation (9). ｃｇ " is the height of the center of gravity CG, "h ｒｃ１ " is the height of the roll center rc1, "h ｒｃ２ " is the height of the roll center rc2, "h ｒｃ " is the height of the intersection of the line connecting the roll center rc1 and the roll center rc2 with the vertical line passing through the center of gravity CG, "m" is the weight of the vehicle 1, "T" is the tread (the distance between the centers of the left and right wheel contact surfaces), "Y １ " is the lateral force acting on the front wheel 21 during cornering braking, "Y ２ " is the lateral force acting on the rear wheel 22 during cornering braking.

[0031]

[0032]

[0033]

[0034] In addition, the roll rigidity of the suspension device 11 on the front axle 131 side is set to "K ｒ１", and the roll rigidity of the suspension device 11 on the rear axle 132 side is set to "K ｒ２ ", and the roll angle of the vehicle 1 is "φ", the rotational moment M ｓａ１ , M ｓａ２ are expressed by equations (10) and (11). Substituting equations (10) and (11) into equation (7) and rearranging, the roll angle φ is expressed by equation (12). Therefore, the load shift amount ΔW １ is expressed by equation (13) from equations (8) and (12), and the load shift amount ΔW ２ is expressed by equations (9), (12) to (14).

[0035]

[0036]

[0037]

[0038]

[0039]

[0040] (Relationship between Load Transfer Amount and Lateral Force) Here, Figure 5 is an explanatory diagram showing the relationship between the wheel contact patch load and maximum lateral force. As shown in the figure, for example, assume that the absolute value of the load transfer amount ΔWa between the inner wheel ai and the outer wheel ao during a certain turning braking is smaller than the absolute value of the load transfer amount ΔWb between the inner wheel bi and the outer wheel bo during another turning braking. In this case, the maximum lateral force Ya acting on the inner wheel ai and the outer wheel ao (the average value of the maximum lateral forces acting on each wheel) is greater than the maximum lateral force Yb ​​acting on the inner wheel bi and the outer wheel bo. In this way, the smaller the absolute value of the load transfer amount ΔW, the greater the lateral force acting on the wheel.

[0041] Therefore, the load shift amount ΔW calculated by the formula (13) １ The smaller the absolute value of the lateral force Y acting on the front wheel 21, １ becomes larger, and the understeer tendency of the vehicle 1 (hereinafter referred to as "US tendency") can be suppressed. ２ The smaller the absolute value of the lateral force Y acting on the rear wheel 22, the greater the ２Therefore, in order to adjust the US tendency and the OS tendency of the vehicle 1, the control device 16 of the present embodiment adjusts the regenerative braking torque T ＩＢ１ , T ＩＢ２ , friction braking torque T ＯＢ１ , T ＯＢ２ In the following description, the load shift amount ΔW １ , ΔW ２ "is small" means "the load movement amount ΔW １ , ΔW ２ The absolute value of "load movement amount ΔW １ , ΔW ２ "The load shift amount ΔW １ , ΔW ２ The absolute value of "is large" is used to mean that

[0042] (Distribution Ratio Adjustment Control) Fig. 6 is a flowchart showing an example of distribution ratio adjustment control. The process shown in Fig. 6 is repeatedly executed by the control device 16 at predetermined time intervals (for example, several msec) while the vehicle 1 is turning, and the regenerative braking torque T ＩＢ１ , T ＩＢ２ , friction braking torque T ＯＢ１ , T ＯＢ２ is output during braking.

[0043] The control device 16 first acquires the actual yaw rate γ and the estimated yaw rate γref(δ) of the vehicle 1 (step ST1). The actual yaw rate γ is detected by the yaw rate detection sensor 15 (FIG. 1). The estimated yaw rate γref(δ) is calculated based on the steering angle δ acquired from a sensor (not shown) that detects the steering amount of the steering wheel. Next, the control device 16 calculates the yaw rate deviation Δγ (=γref(δ)-γ), which is the difference between the estimated yaw rate γref(δ) and the actual yaw rate γ (step ST2).

[0044] Next, the control device 16 determines whether the vehicle behavior during the turn is in a predetermined US tendency (a US tendency of a predetermined degree or more) or a predetermined OS tendency (an OS tendency of a predetermined degree or more) based on the yaw rate deviation Δγ (step ST3). Specifically, when the estimated yaw rate γref(δ) is positive, the control device 16 determines that the vehicle behavior is in a predetermined US tendency if the yaw rate deviation Δγ is greater than a predetermined positive threshold, and that the vehicle behavior is in a predetermined OS tendency if the yaw rate deviation Δγ is smaller than a predetermined negative threshold. Furthermore, when the estimated yaw rate γref(δ) is negative, the control device 16 determines that the vehicle behavior is in a predetermined US tendency if the yaw rate deviation Δγ is greater than a predetermined negative threshold, and that the vehicle behavior is in a predetermined OS tendency if the yaw rate deviation Δγ is smaller than a predetermined positive threshold. Furthermore, when the yaw rate deviation Δγ is equal to or less than the positive threshold or equal to or greater than the negative threshold, the control device 16 determines that the vehicle behavior is neither in a state of a predetermined US tendency nor a predetermined OS tendency. The threshold value may be set in consideration of the stability of the behavior desired when braking the vehicle 1 during cornering.

[0045] If the control device 16 determines in step ST3 that the vehicle behavior has a predetermined US tendency, it adjusts the distribution ratio of the braking torque for the US tendency (step ST4) and executes this routine from the beginning. On the other hand, if the control device 16 determines in step ST3 that the vehicle behavior has a predetermined OS tendency, it adjusts the distribution ratio of the braking torque for the OS tendency (step ST5) and executes this routine from the beginning. Also, if the control device 16 determines in step ST3 that the vehicle behavior has neither a US tendency nor an OS tendency, it executes this routine from the beginning. Specific examples of the distribution ratio adjustment in steps ST4 and ST5 will be described later, but in this embodiment, the adjustment amount of the distribution ratio is set to increase as the yaw rate deviation Δγ calculated in step ST2 increases, i.e., as the degree of the US tendency or OS tendency increases.

[0046] (Specific Example of Distribution Ratio Adjustment) Next, a specific example of distribution ratio adjustment will be described. In all cases (including the second embodiment), the sum of all braking torques (i.e., required braking torque), the regenerative braking torque T applied to the front wheels 21, ＩＢ１and friction braking torque T ＯＢ１ , the regenerative braking torque T applied to the rear wheels 22 ＩＢ２ and friction braking torque T ＯＢ２ In all the following cases (including the second embodiment), the load shift amount ΔW １ , ΔW ２ Specific details for reducing the load shift amount ΔW will be described. １ , ΔW ２ can be made smaller.

[0047] (Distribution Ratio Adjustment for US Tendency) An example of adjusting the distribution ratio of the braking torque in step ST4 for the US tendency will be described. １ The smaller the lateral force Y acting on the front wheel 21, １ becomes larger and the tendency for US to be suppressed. １ (Here, it is assumed to be a positive value when turning left) in order to reduce the rotational moment M ａｐ１ The rotational moment M ａｐ１ In the calculation formula (5), "T ＩＢ１ ", "T ＯＢ１ ", "tanθ ＩＢＲ１ -tanθ ＩＢＬ１ ", "tanθ ＯＢＲ１ -tanθ ＯＢＬ１ " are all negative. Also, the length of the suspension link 11L is the height H from the wheel center to the attachment point of the suspension link 11L to the body. Ｌ (Figure 2. Including the case where it changes during turning) In a typical vehicle configuration, "tanθ ＯＢＲ１ -tanθ ＯＢＬ１ The absolute value of " is "tan θ ＩＢＲ１ -tanθ ＩＢＬ１ ” is larger than the absolute value of the regenerative braking torque T ＩＢ１ is small, and the friction braking torque T ＯＢ１ If the rotational moment M ａｐ１ It can be seen that becomes smaller.

[0048] In addition, when turning left, the load shift amount ΔW１ To reduce the rotational moment M ａｐ２ The rotational moment M ａｐ２ In the calculation formula (6), "T ＩＢ２ ", "T ＯＢ２ ", "tanθ ＩＢＲ２ -tanθ ＩＢＬ２ ", "tanθ ＯＢＲ２ -tanθ ＯＢＬ２ " are all negative. In addition, in the above general vehicle configuration, "tanθ ＯＢＲ２ -tanθ ＯＢＬ２ The absolute value of " is "tan θ ＩＢＲ２ -tanθ ＩＢＬ２ ” is larger than the absolute value of the regenerative braking torque T ＩＢ２ is small, and the friction braking torque T ＯＢ２ If the rotational moment M ａｐ２ It can be seen that becomes larger.

[0049] Therefore, the control device 16 adjusts the regenerative braking torque T ＩＢ１ and reduce the friction braking torque T ＯＢ１ In addition, the control device 16 performs a first front-side adjustment to increase the regenerative braking torque T ＩＢ２ is reduced, and the friction braking torque T ＯＢ２ As a result, the lateral force Y acting on the front wheel 21 is increased. １ It is possible to suppress the US tendency of the vehicle 1 by increasing the value of

[0050]

[0051] (Distribution Ratio Adjustment for OS Tendency) An example of adjusting the distribution ratio of the braking torque for OS tendencies in step ST5 will be described. ２ The smaller the lateral force Y acting on the rear wheel 22, the greater the ２ The load shift amount ΔW ２ (Here, it is assumed to be a positive value when turning left) in order to reduce the rotational moment M ａｐ１ From equation (5), the regenerative braking torque T ＩＢ１is large, and the friction braking torque T ＯＢ１ If becomes smaller, the rotational moment M ａｐ１ It can be seen that the load shift amount ΔW becomes larger when turning left. ２ To reduce the rotational moment M ａｐ２ From equation (6), the regenerative braking torque T ＩＢ２ is large, and the friction braking torque T ＯＢ２ If becomes smaller, the rotational moment M ａｐ２ It can be seen that becomes larger.

[0052] Therefore, the control device 16 adjusts the regenerative braking torque T ＩＢ１ and the friction braking torque T ＯＢ１ In addition, the control device 16 performs a second front adjustment to reduce the regenerative braking torque T ＩＢ２ and the friction braking torque T ＯＢ２ As a result, the lateral force Y acting on the rear wheel 22 is reduced. ２ It is possible to suppress the OS tendency of the vehicle 1 by increasing the value.

[0053]

[0054] As described above, the vehicle 1 of the first embodiment applies a regenerative braking torque T ＩＢ１ , T ＩＢ２ a regenerative braking device 20 (first braking device) that applies a friction braking torque T ＯＢ１ , T ＯＢ２ The vehicle is equipped with a friction braking device 30 (second braking device) that applies a regenerative braking device 20 (second braking torque) to the left and right front wheels 21, and a control device 16 that controls the regenerative braking device 20 and the friction braking device 30 so that they cooperatively output a required braking torque required for braking. The control device 16 calculates a load shift amount ΔW between the left and right front wheels 21 when the vehicle behavior during cornering has a predetermined US tendency. １ The regenerative braking torque T ＩＢ１ , T ＩＢ２ (first braking torque) and friction braking torque T ＯＢ１ , T ＯＢ２In addition, when the vehicle behavior during cornering has a predetermined OS tendency, the control device 16 adjusts the distribution ratio of the load shift amount ΔW between the left and right rear wheels 22. ２ The regenerative braking torque T ＩＢ１ , T ＩＢ２ and friction braking torque T ＯＢ１ , T ＯＢ２ This configuration makes it possible to more appropriately adjust the US tendency and OS tendency of the vehicle during cornering braking.

[0055] More specifically, the control device 16 performs the first front adjustment and the first rear adjustment (Table 1) when the vehicle behavior tends to US, and performs the second front adjustment and the second rear adjustment (Table 2) when the vehicle behavior tends to OS. １ , ΔW ２ However, the control device 16 can adjust the load shift amount ΔW １ , ΔW ２ If it is possible to appropriately adjust the first front-side adjustment and the first rear-side adjustment, or only one of the second front-side adjustment and the second rear-side adjustment may be performed.

[0056] In particular, when the control device 16 performs only the first front adjustment, even if the vehicle 1 is a front-wheel drive vehicle that does not have a rear motor 102, the load movement amount ΔW １ This makes it possible to adjust the US tendency of the vehicle 1. In other words, when only the first front adjustment is performed, the first braking device and the second braking device only need to be braking devices that can apply at least the first braking torque and the second braking torque to the front wheels 21.

[0057] In addition, when the control device 16 performs only the second rear adjustment, even if the vehicle 1 is a rear-wheel drive vehicle that does not have a front motor 101, the load movement amount ΔW ２ It is possible to adjust the OS tendency of the vehicle 1 by reducing the braking torque. In other words, when only the second rear adjustment is performed, the first braking device and the second braking device only need to be braking devices that can apply at least the first braking torque and the second braking torque to the rear wheels 22.

[0058] Second Embodiment Fig. 7 is a schematic diagram showing the configuration of a vehicle according to a second embodiment. The vehicle 10 of the second embodiment includes rear motors 102R and 102L instead of the rear motor 102. The rear motor 102R outputs braking / driving force to the right rear wheel 22 via a right transaxle 122 and a rear axle 132. The rear motor 102L outputs braking / driving force to the left rear wheel 22 via a left transaxle 122 and a rear axle 132. The rear motors 102R and 102L are drive-controlled by a control device 16. The left and right transaxles 122 have the same configuration as in the first embodiment.

[0059] (Distribution Ratio Adjustment Control) In the second embodiment, the control device 16 executes the distribution ratio adjustment control shown in Fig. 6 in the same manner as in the first embodiment. １ By reducing the lateral force Y acting on the front wheel 21, １ is increased to suppress the US tendency, and in step ST5, the load transfer amount ΔW between the rear wheels 22 is ２ By reducing the lateral force Y acting on the rear wheel 22, ２ The point that the OS tendency is suppressed by increasing the value of the .times. ...

[0060] However, according to the configuration of the second embodiment, the rear motors 102R and 102L are used to generate separate regenerative braking torques T ＩＢ２ The friction braking device 30 can apply separate friction braking torques T ＯＢ２ Therefore, the control device 16 of the second embodiment adjusts the regenerative braking torque T ＩＢ２ , friction braking torque T ＯＢ２ and the regenerative braking torque T applied to the outer wheel. ＩＢ２ , friction braking torque T ＯＢ２ However, the regenerative braking torque T applied to the outer wheel is adjusted. ＩＢ２ and friction braking torque T ＯＢ２ The sum of the regenerative braking torque T applied to the inner wheel ＩＢ２ and friction braking torque T ＯＢ２ The sum of each shall be maintained.

[0061] (Adjustment of braking torque distribution ratio for US tendency) In order to suppress the US tendency, the load shift amount ΔW １ To reduce the rotational moment M ａｐ２ If the braking torques on the left and right are considered separately, the rotational moment M ａｐ２ is expressed by the formula (15). ＩＢＲ２ ” is the regenerative braking torque T applied to the right rear wheel 22 ＩＢ２ , "T ＯＢＲ２ ” is the friction braking torque T applied to the right rear wheel 22 ＯＢ２ , "T ＩＢＬ２ ″ is the regenerative braking torque T applied to the left rear wheel 22 ＩＢ２ , "T ＯＢＬ２ ” is the friction braking torque T applied to the left rear wheel 22 ＯＢ２ and all are positive. ＩＢＲ２ ", "tanθ ＯＢＲ２ ", "tanθ ＩＢＬ２ ", "tanθ ＯＢＬ２ " are all positive, and tanθ ＯＢＲ２ >tanθ ＩＢＲ２ , tanθ ＯＢＬ２ >tanθ ＩＢＬ２ Therefore, the regenerative braking torque T applied to the outer wheel (right rear wheel 22) is ＩＢＲ２ is large, and the friction braking torque T ＯＢＲ２ If becomes smaller, the rotational moment M ａｐ２ It can be seen that the regenerative braking torque T applied to the inner wheel (left rear wheel 22) becomes larger. ＩＢＬ２ is small, and the friction braking torque T ＯＢＬ２ If the rotational moment M ａｐ２ It can be seen that becomes larger.

[0062]

[0063] Therefore, the control device 16 adjusts the regenerative braking torque T applied to the outer wheel of the rear wheels 22 compared to before adjustment, as shown in Table 3 (the values ​​in parentheses are braking torques when turning left). ＩＢ２ and the friction braking torque T ＯＢ２In addition, the control device 16 performs a first rear-outer adjustment to reduce the regenerative braking torque T ＩＢ２ and the friction braking torque T ＯＢ２ Furthermore, the control device 16 performs the first front adjustment in the same manner as in the first embodiment. As a result, the load shift amount ΔW １ is reduced to reduce the lateral force Y acting on the front wheel 21. １ It is possible to suppress the US tendency of the vehicle 1 by increasing the value of the rotational speed.

[0064]

[0065] (Distribution ratio adjustment for OS tendency) In order to suppress OS tendency, the load shift amount ΔW ２ To reduce the rotational moment M ａｐ２ Therefore, from the equation (15), the regenerative braking torque T applied to the outer wheel (right rear wheel 22) is ＩＢＲ２ is small, and the friction braking torque T ＯＢＲ２ If the rotational moment M ａｐ２ It can be seen that the regenerative braking torque T applied to the inner wheel (left rear wheel 22) becomes smaller. ＩＢＬ２ is large, and the friction braking torque T ＯＢＬ２ If becomes smaller, the rotational moment M ａｐ２ It can be seen that becomes smaller.

[0066] Therefore, the control device 16 adjusts the regenerative braking torque T applied to the outer wheel of the rear wheels 22 compared to before adjustment, as shown in Table 4 (the values ​​in parentheses are braking torques when turning left). ＩＢ２ and reduce the friction braking torque T ＯＢ２ In addition, the control device 16 performs a second rear-outer adjustment to increase the regenerative braking torque T ＩＢ２ and the friction braking torque T ＯＢ２ Furthermore, the control device 16 performs the second front adjustment in the same manner as in the first embodiment. As a result, the load shift amount ΔW ２ is reduced to reduce the lateral force Y acting on the rear wheel 22. ２It is possible to suppress the OS tendency of the vehicle 1 by increasing the value of the rotational speed.

[0067]

[0068] As described above, the control device 16 of the second embodiment performs the first rear outer adjustment and the first rear inner adjustment when the vehicle behavior during cornering has a predetermined US tendency, and performs the second rear outer adjustment and the second rear inner adjustment when the vehicle behavior during cornering has a predetermined OS tendency. With this configuration, the load shift amount ΔW １ , ΔW ２ However, the control device 16 can adjust the load shift amount ΔW １ , ΔW ２ As long as it is possible to appropriately adjust the adjustment amount, at least one of the first front adjustment, the first rear outer adjustment, and the first rear inner adjustment, and at least one of the second rear adjustment, the second rear outer adjustment, and the second rear inner adjustment may be performed.

[0069] Although the description of the embodiment has been completed above, aspects of the present invention are not limited to these embodiments. For example, in the first and second embodiments, the regenerative braking device 20 is used as the first braking device, and the friction braking device 30 is used as the second braking device. However, the first braking device may be any device capable of appropriately applying a first braking torque to each front wheel 21 or each rear wheel 22, such as an internal combustion engine capable of applying engine brake torque as the first braking torque. Furthermore, the second braking device may be any device capable of applying a second braking torque to at least one of the front wheels 21 and the rear wheels 22 to which the first braking torque is applied from the first braking device, such as an electric in-wheel motor provided for each front wheel 21 or each rear wheel 22.

[0070] In the first and second embodiments, the yaw rate deviation Δγ is used to determine whether the vehicle behavior has a predetermined US tendency or OS tendency, and the larger the yaw rate deviation Δγ, the larger the allocation amount for the allocation adjustment. However, instead of the yaw rate deviation Δγ, the steering angle of the vehicle 1, wheel speed difference, lateral acceleration, or the like may be used. Furthermore, the wheel speed may be used to determine whether the inner wheel is locked during cornering braking, and if the inner wheel is locked, it may be determined that the vehicle is exhibiting a predetermined US tendency or OS tendency.

[0071] 1, 10 Vehicle 11 Suspension device 16 Control device 20 Regenerative braking device (first braking device) 21 Front wheel 22 Rear wheel 30 Friction braking device (second braking device) T ＩＢ１ , T ＩＢ２ , T ＩＢＬ２ , T ＩＢＲ２ Regenerative braking torque (first braking torque) T ＯＢ１ , T ＯＢ２ , T ＯＢＬ２ , T ＯＢＲ２ Friction braking torque (second braking torque)

Claims

1. A vehicle comprising: a first braking device mounted above a suspension device and applying a first braking torque to at least one of the front wheels and rear wheels; a second braking device mounted below the suspension device and applying a second braking torque to at least one of the front wheels and the rear wheels to which the first braking torque is applied from the first braking device; and a control device that controls the first braking device and the second braking device so that they coordinate to output required braking torques required for braking, wherein the control device adjusts the distribution ratio between the first braking torque and the second braking torque so that the amount of load transfer between the left and right front wheels decreases when the vehicle behavior during a turn has a predetermined tendency toward understeer, and adjusts the distribution ratio between the first braking torque and the second braking torque so that the amount of load transfer between the left and right rear wheels decreases when the vehicle behavior during a turn has a predetermined tendency toward oversteer.

2. The vehicle described in claim 1, characterized in that the first braking device applies the first braking torque to at least the front wheels, the second braking device applies the second braking torque to at least the front wheels, and the control device performs a first front adjustment to reduce the first braking torque applied to the front wheels and increase the second braking torque when the vehicle behavior during cornering has the predetermined understeer tendency.

3. The vehicle described in claim 1, characterized in that the first braking device applies the first braking torque to at least the rear wheels, the second braking device applies the second braking torque to at least the rear wheels, and the control device performs a first rear adjustment to increase the first braking torque applied to the rear wheels and decrease the second braking torque when the vehicle behavior during cornering has the predetermined oversteer tendency.

4. The vehicle described in claim 1, wherein the first braking device applies the first braking torque to the front wheels and the rear wheels, the second braking device applies the second braking torque to the front wheels and the rear wheels, and the control device, when the vehicle behavior during cornering has the predetermined tendency toward understeer, performs at least one of a first front adjustment that reduces the first braking torque applied to the front wheels and increases the second braking torque, and a first rear adjustment that reduces the first braking torque applied to the rear wheels and increases the second braking torque, and when the vehicle behavior during cornering has the predetermined tendency toward oversteer, performs at least one of a second front adjustment that increases the first braking torque applied to the front wheels and decreases the second braking torque, and a second rear adjustment that increases the first braking torque applied to the rear wheels and decreases the second braking torque.

5. The vehicle described in claim 1, wherein the first braking device applies the first braking torque separately to the left and right rear wheels, the second braking device applies the second braking torque separately to the left and right rear wheels, and the control device, when the vehicle behavior during cornering has the predetermined tendency toward understeer, performs at least one of a first outer rear adjustment that increases the first braking torque applied to the outer rear wheel and decreases the second braking torque, and a first inner rear adjustment that decreases the first braking torque applied to the inner rear wheel and increases the second braking torque, and when the vehicle behavior during cornering has the predetermined tendency toward oversteer, performs at least one of a second outer rear adjustment that decreases the first braking torque applied to the outer rear wheel and increases the second braking torque, and a second inner rear adjustment that increases the first braking torque applied to the inner rear wheel and decreases the second braking torque.

6. A vehicle as claimed in any one of claims 1 to 5, characterized in that the first braking device is a regenerative braking device that generates regenerative braking torque, and the second braking device is a friction braking device that generates friction braking torque.

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