JP2023152293A - Brake control device - Google Patents

Abstract

To control a posture of a vehicle which is under braking, in a brake control device of a vehicle.SOLUTION: A brake control device 10 controls a brake force of a vehicle by operating a regeneration brake device and a friction brake device. The brake control device 10 comprises a posture target calculation part 12 for calculating a target of a pitching posture of the vehicle and a target of a sinking posture of the vehicle on the basis of a target of the deceleration of the vehicle. The brake control device 10 comprises a distribution ratio calculation part 13 for calculating a fore-and-aft distribution ratio and a friction regeneration ratio so as to make a posture of the vehicle follow a posture indicated by the target of the pitching posture and the target of the sinking posture. The brake control device 10 comprises an indication value calculation part for calculating an indication value for operating the friction brake device and the regeneration brake device on the basis of a requirement brake force being the target of the brake force of the vehicle, the fore-and-aft distribution ratio and the friction regeneration ratio.SELECTED DRAWING: Figure 4

Description

The present invention relates to a braking control device for a vehicle.

When braking a vehicle, the vehicle may pitch toward the nose dive side. In a vehicle, a force that acts in a direction that suppresses pitching motion is generated by applying a braking force. Specifically, if the braking force applied to the front wheels is the front wheel braking force and the braking force applied to the rear wheels is the rear wheel braking force, an anti-dive force corresponding to the front wheel braking force acts on the vehicle body, and the rear Anti-lift force is applied to the vehicle body according to the wheel braking force. When anti-dive force and anti-lift force are applied, even if the overall braking force of the vehicle is the same, if the distribution ratio between front wheel braking force and rear wheel braking force changes, the anti-dive force and anti-lift force acting on the vehicle body will change. The size of may change. This may change the pitching attitude of the vehicle.

The braking control device for a vehicle disclosed in Patent Document 1 is applied to a vehicle including a friction braking device and a regenerative braking device. In this braking control device, when changing the distribution ratio between the front wheel braking force and the rear wheel braking force while varying the regenerative braking force, a limit is set on the rate of change of the regenerative braking force. As a result, the distribution ratio between the front wheel braking force and the rear wheel braking force is gradually changed.

Japanese Patent Application Publication No. 2015-139293

When a frictional braking force is applied to a wheel, the braking force acts on the wheel, and when a regenerative braking force is applied to the wheel, the braking force acts on the wheel. Therefore, even if the magnitude of the braking force for the entire wheel is the same, the anti-dive force that acts on the vehicle body and the Lifting force is different.

For example, when the distribution of regenerative braking force is large, the speed at which the pitching attitude of the vehicle body changes in response to a change in braking force becomes faster. On the other hand, when the distribution of regenerative braking force is small, the speed at which the pitching attitude of the vehicle body changes relative to changes in braking force becomes slow. Furthermore, when the distribution of regenerative braking force applied to the rear wheels is large, the anti-lift force is reduced, and the vehicle sinks less.

The brake control device described in Patent Document 1, which does not take into consideration the relationship between the distribution of regenerative braking force and the attitude of the vehicle, has room for improvement in controlling the attitude of the vehicle.

A braking control device for solving the above problems includes a regenerative braking device that generates a regenerative braking force to be applied to at least one of a front wheel and a rear wheel among wheels in a vehicle, a friction braking force to be applied to the front wheel, and a A brake control device that is applied to a vehicle comprising a friction braking device that generates a frictional braking force to be applied to a rear wheel, and that controls the braking force of the vehicle by operating the regenerative braking device and the friction braking device. , based on the target deceleration of the vehicle, where the ratio of the frictional braking force applied to the wheel to the braking force applied to the wheel among the front wheels and the rear wheels to which regenerative braking force can be applied is defined as the friction regeneration ratio. an attitude target calculation unit that calculates a pitching attitude target of the vehicle and a sinking attitude target of the vehicle; and causing the attitude of the vehicle to follow the attitude indicated by the pitching attitude target and the sinking attitude target. a distribution ratio calculation unit that calculates the front-rear distribution ratio and the friction regeneration ratio; and a required braking force that is a target of the vehicle braking force, the friction braking device based on the front-rear distribution ratio and the friction regeneration ratio. and an instruction value calculation unit that calculates an instruction value for operating the regenerative braking device.

According to the above configuration, the frictional braking force and the regenerative braking force can be controlled according to the front-rear distribution ratio and the friction regeneration ratio calculated so that the attitude of the vehicle follows the target attitude corresponding to the target deceleration. This allows the pitching attitude and sinking attitude to be correlated with the deceleration target. By controlling the attitude of the vehicle in response to the deceleration, it is possible to suppress the deviation between the attitude of the vehicle estimated by the vehicle occupant from the deceleration and the actual attitude of the vehicle.

FIG. 1 is a block diagram showing a brake control device according to a first embodiment and a vehicle to be controlled by the brake control device. FIG. 2 is a diagram illustrating the distribution of braking force. FIG. 3 is a schematic diagram illustrating the force that acts on the vehicle due to braking force. FIG. 4 is a block diagram illustrating functions executed by the brake control device of the first embodiment. FIG. 5 is a flowchart showing the flow of processing executed by the brake control device of the first embodiment. FIG. 6 is a diagram showing an example of the front-rear distribution ratio and the friction regeneration ratio calculated by the brake control device of the first embodiment. FIG. 7 is a diagram illustrating the relationship between the pitch angle and bounce amount controlled by the brake control device of the first embodiment. FIG. 8 is a diagram showing an example of the front-rear distribution ratio and the friction regeneration ratio calculated by the brake control device of the modified example. FIG. 9 is a block diagram illustrating functions executed by the brake control device of the second embodiment. FIG. 10 is a diagram illustrating the ideal braking force distribution ratio of front wheel braking force and rear wheel braking force and explaining the concept of control in the brake control device of the second embodiment. FIG. 11 is a diagram showing the average rate of change in pitch angle controlled by the brake control device of the second embodiment. FIG. 12 is a diagram showing the average rate of change in the amount of bounce controlled by the brake control device of the second embodiment. FIG. 13 is a timing chart showing changes in pitch angular velocity, pitch angle, and braking force controlled by the brake control device of the second embodiment. FIG. 14 is a diagram illustrating a change in pitch rate when slip occurs in the wheels. FIG. 15 is a flowchart showing the flow of processing executed by the brake control device of the third embodiment. FIG. 16 is a diagram illustrating the friction regeneration ratio calculated by the brake control device of the third embodiment. FIG. 17 is a timing chart showing changes in braking force and pitch rate controlled by the braking control device of the third embodiment.

(First embodiment)
A first embodiment of the brake control device will be described below with reference to FIGS. 1 to 7.
FIG. 1 shows a brake control device 10 and a vehicle 90 on which the brake control device 10 is mounted.

<Vehicle>
The vehicle 90 is, for example, a four-wheeled vehicle having two front wheels and two rear wheels. Vehicle 90 includes a suspension device that suspends the wheels. The vehicle 90 includes front wheel suspension devices attached to the left front wheel and the right front wheel. The vehicle 90 includes a rear wheel suspension device attached to a left rear wheel and a right rear wheel.

As shown in FIG. 1, the vehicle 90 includes a friction braking device 70 and a regenerative braking device 80. The friction braking device 70 and the regenerative braking device 80 are braking devices that apply braking force to the wheels. The brake control device 10 has a function of operating the friction brake device 70. Vehicle 90 includes regeneration control device 20 that has a function of operating regenerative braking device 80 .

Vehicle 90 is equipped with an in-vehicle network. Vehicle 90 includes a plurality of processing circuits connected to an in-vehicle network. The brake control device 10 and the regeneration control device 20 are examples of processing circuits. Each processing circuit connected to the in-vehicle network can communicate with each other via the in-vehicle network.

Vehicle 90 includes a brake operation member 92. The brake operation member 92 is attached at a position where the driver of the vehicle 90 can operate it. The brake operation member 92 is, for example, a brake pedal.

Vehicle 90 is equipped with various sensors. FIG. 1 shows a brake sensor SE1 as an example of various sensors. Detection signals from various sensors are input to the brake control device 10 via an in-vehicle network.

The brake sensor SE1 can detect the operation amount Bp of the brake operation member 92. The operation amount Bp of the brake operation member 92 can be referenced when calculating the target value of the braking force to be applied to the vehicle 90. The brake sensor SE1 may be a sensor that detects pressure applied to the brake operation member 92 in order to operate the brake operation member 92.

<Brake device>
The friction braking device 70 can generate a friction braking force to be applied to the wheels. An example of the friction brake device 70 is a hydraulic brake device. The friction braking device 70 includes a braking mechanism corresponding to each wheel. The braking mechanism includes a rotating body that rotates integrally with the wheel, a friction material that can be pressed against the rotating body, and a wheel cylinder that presses the friction material against the rotating body in response to hydraulic pressure. An example of a braking mechanism is a disc brake. The braking mechanism may be a drum brake. Another example of the friction braking device 70 is an electric braking device that mechanically transmits the driving force of an electric motor to press a friction material against a rotating body.

The regenerative braking device 80 can generate regenerative braking force to be applied to the wheels. Regenerative braking device 80 is connected to a battery included in vehicle 90. An example of the regenerative braking device 80 is a motor generator. By making the motor generator function as a generator, regenerative braking force can be applied to the wheels. Another example of the regenerative braking device 80 is an in-wheel motor. The electric power generated as a result of applying the regenerative braking force is charged to the battery.

In the vehicle 90, the friction braking device 70 can separately adjust the front wheel friction braking force Fxfb, which is the friction braking force applied to the front wheels, and the rear wheel friction braking force Fxrb, which is the friction braking force applied to the rear wheels.

In the vehicle 90, the regenerative braking device 80 can separately adjust the front wheel regenerative braking force Fxfd, which is the regenerative braking force applied to the front wheels, and the rear wheel regenerative braking force Fxrd, which is the regenerative braking force applied to the rear wheels.

<Regeneration control device>
The regenerative control device 20 operates the regenerative braking device 80 based on the required value of regenerative braking force. Although details will be described later, the required value of the regenerative braking force is calculated by the brake control device 10 as the required regenerative braking force value FxdR. The regeneration control device 20 can transmit a regenerative braking force execution value Fxd representing the magnitude of the regenerative braking force actually applied to the vehicle 90 to the brake control device 10.

If the maximum value of the regenerative braking force that can be generated by the regenerative braking device 80 is smaller than the regenerative braking force request value FxdR, the regenerative braking force execution value Fxd may become smaller than the regenerative braking force request value FxdR. . For example, when the remaining capacity of the battery mounted on the vehicle 90 is greater than a threshold value, the regenerative braking force is set to the maximum level by the regenerative control device 20 in order to reduce the electric power generated when applying the regenerative braking force. The value may be limited to a small value.

<Braking force>
Each braking force will be explained.
The sum of the front wheel frictional braking force Fxfb and the front wheel regenerative braking force Fxfd is referred to as the front wheel braking force Fxf. The sum of the rear wheel friction braking force Fxrb and the rear wheel regenerative braking force Fxrd is referred to as the rear wheel braking force Fxr. Vehicle braking force Fx, which is the braking force applied to vehicle 90, is the sum of front wheel braking force Fxf and rear wheel braking force Fxr. The regenerative braking force execution value Fxd corresponds to the sum of the front wheel regenerative braking force Fxfd and the rear wheel regenerative braking force Fxrd.

The front wheel braking force Fxf and the rear wheel braking force Fxr can be expressed using the vehicle braking force Fx and the front-rear distribution ratio n. The front wheel friction braking force Fxfb and the front wheel regenerative braking force Fxfd can be expressed using the front wheel braking force Fxf and the front wheel friction regeneration ratio nf. The rear wheel friction braking force Fxrb and the rear wheel regenerative braking force Fxrd can be expressed using the rear wheel braking force Fxr and the rear wheel friction regeneration ratio nr.

The front-rear distribution ratio n, the front wheel friction regeneration ratio nf, the rear wheel friction regeneration ratio nr, and the braking force applied to the wheels will be described using FIG. 2. FIG. 2 shows an example in which a front wheel friction braking force Fxfb, a front wheel regenerative braking force Fxfd, a rear wheel friction braking force Fxrb, and a rear wheel regenerative braking force Fxrd are applied. As shown in FIG. 2, the front-rear distribution ratio n is the sum of the front wheel braking force Fxf and the rear wheel braking force Fxr, that is, the ratio of the front wheel braking force Fxf to the vehicle braking force Fx. The front/rear distribution ratio n is a value of "0" or more and "1" or less. The front wheel friction regeneration ratio nf is the ratio of the front wheel friction braking force Fxfb to the front wheel braking force Fxf. The front wheel friction regeneration ratio nf has a value of "0" or more and "1" or less. The rear wheel friction regeneration ratio nr is the ratio of the rear wheel friction braking force Fxrb to the rear wheel braking force Fxr. The rear wheel friction regeneration ratio nr has a value of "0" or more and "1" or less.

As will be described in detail later, the brake control device 10 can calculate a front-rear distribution ratio n, a front wheel friction regeneration ratio nf, and a rear wheel friction regeneration ratio nr in order to adjust the braking force applied to each wheel. The brake control device 10 operates the friction braking device 70 and the regenerative braking device 80 so that the braking force distributed to the wheels is applied according to the calculated values of the front-rear distribution ratio n, the front wheel friction regeneration ratio nf, and the rear wheel friction regeneration ratio nr. can be done.

<Vehicle motion>
Using FIG. 3, the force that acts on the vehicle 90 when braking the vehicle 90 will be illustrated, and the sprung motion of the vehicle 90 will be explained.

FIG. 3 shows vehicle 90 seen from the side. FIG. 3 shows the left front wheel FL among the front wheels and the left rear wheel RL among the rear wheels. FIG. 3 shows the vehicle center of gravity GC of the vehicle 90.

Hereinafter, in the explanation with reference to FIG. 3, the left front wheel FL will be explained, and the explanation about the right front wheel, which is symmetrical with respect to the left front wheel FL, may be omitted. Similarly, the left rear wheel RL may be described, and the description regarding the right rear wheel symmetrical to the left rear wheel RL may be omitted.

In FIG. 3, the horizontal distance between the vehicle center of gravity GC and the front wheel axle in the longitudinal direction of the vehicle 90 is indicated as a first distance Lf. In FIG. 3, the horizontal distance between the vehicle center of gravity GC and the rear wheel axle in the longitudinal direction of the vehicle 90 is indicated as a second distance Lr. The sum of the first distance Lf and the second distance Lr corresponds to the wheelbase L of the vehicle 90.

FIG. 3 shows arrows illustrating the pitching moment M generated around the vehicle center of gravity GC when braking the vehicle 90. The pitching moment M can be calculated based on the inertial force acting on the vehicle center of gravity GC, the height from the road surface to the vehicle center of gravity GC, the first distance Lf, and the second distance Lr. When braking the vehicle 90, a forward inertial force acts on the vehicle center of gravity GC. Therefore, the pitching moment M becomes a force that displaces the front portion of the vehicle body 91, which is the portion of the vehicle body 91 on the front wheel side, downward. The pitching moment M is also a force that displaces the rear portion of the vehicle body 91, which is the portion of the vehicle body 91 on the rear wheel side, upward. That is, the pitching moment M is a force that causes the vehicle body 91 to tilt forward.

The degree to which the vehicle 90 leans forward is expressed as a pitch angle. In this embodiment, the pitch angle takes a larger value as the front of the vehicle is positioned lower than when the vehicle 90 is horizontal. That is, the larger the pitch angle is, the more the vehicle 90 is tilted forward. The closer the pitch angle is to "0", the smaller the degree of forward leaning. In other words, the closer the pitch angle is to "0", the more horizontal the vehicle 90 is.

The movement of moving the vehicle body 91 up and down is called a bouncing movement. In this embodiment, the amount by which the center of gravity GC of the vehicle sinks due to the bounce motion is referred to as the amount of bounce. In this embodiment, the bounce amount takes a value of "0" or more when the vehicle body 91 sinks. That is, the more the vehicle body 91 sinks, the larger the bounce amount becomes. In FIG. 3, an arrow indicating the direction in which the vehicle center of gravity GC sinks is shown as a bounce direction Z.

Frictional braking force acts at the point of contact between the wheels and the road surface. On the other hand, regenerative braking force acts at the point where the wheel is attached to the axle. FIG. 3 shows a first application point PA1 where the front wheel friction braking force Fxfb acts, a second application point PA2 where the front wheel regenerative braking force Fxfd acts, a third application point PA3 where the rear wheel friction braking force Fxrb acts, and the rear wheel rotation. A fourth point of application PA4 on which the raw braking force Fxrd acts is shown.

FIG. 3 shows the instantaneous center of rotation of the wheel. The instantaneous rotation center of the left front wheel FL when braking the vehicle 90 is indicated as a front wheel rotation center Cf. The angle formed by the road surface and the straight line connecting the first point of action PA1 and the front wheel rotation center Cf is indicated as a first angle θfb. The angle formed by the road surface and the straight line connecting the second point of action PA2 and the front wheel rotation center Cf is indicated as a second angle θfd. From the positional relationship between the first point of action PA1 and the second point of action PA2 with respect to the front wheel rotation center Cf, the first angle θfb is larger than the second angle θfd. Further, the instantaneous rotation center of the left rear wheel RL when braking the vehicle 90 is indicated as the rear wheel rotation center Cr. The angle formed by the road surface and the straight line connecting the third point of action PA3 and the rear wheel rotation center Cr is indicated as a third angle θrb. The angle formed by the road surface and the straight line connecting the fourth point of action PA4 and the rear wheel rotation center Cr is indicated as a fourth angle θrd. From the positional relationship between the third point of action PA3 and the fourth point of action PA4 with respect to the rear wheel rotation center Cr, the third angle θrb is larger than the fourth angle θrd.

Note that the position of each momentary center of rotation is determined by the characteristics of the suspension device. The positions of the instantaneous rotation centers shown in FIG. 3 are merely examples, and do not represent the actual positions of the instantaneous rotation centers. Therefore, the sizes of the first angle θfb, the second angle θfd, the third angle θrb, and the fourth angle θrd do not indicate the actual angle sizes.

The force that changes the attitude of the vehicle 90 will be explained using FIG. 3. In FIG. 3, the anti-dive force FAD is indicated by a white arrow as a force acting on the vehicle 90 by the front wheel suspension device. In FIG. 3, the anti-lift force FAL is indicated by a white arrow as a force acting on the vehicle 90 by the suspension device for the rear wheels. Note that the white arrows indicate the direction of the force and do not indicate the actual magnitude of the force.

Anti-dive force FAD will be explained. The anti-dive force FAD is a force that acts when braking force is applied to the front wheels. The anti-dive force FAD is a force that suppresses the front part of the vehicle body from sinking. The direction in which the anti-dive force FAD acts is the direction in which the front portion of the vehicle is displaced away from the road surface.

The anti-lift force FAL will be explained. The anti-lift force FAL is a force that acts when braking force is applied to the rear wheels. The anti-lift force FAL is a force that suppresses lifting of the rear part of the vehicle body. The direction in which the anti-lift force FAL acts is the direction in which the rear of the vehicle is displaced closer to the road surface.

The anti-dive force FAD can be expressed as the following relational expression (Formula 1). The anti-lift force FAL can be expressed as the following relational expression (Formula 2).

As shown in the relational expression (Equation 1), when the front-rear distribution ratio n is the same, the anti-dive force FAD becomes larger as the vehicle braking force Fx becomes larger. When the vehicle braking force Fx is the same, the anti-dive force FAD becomes larger as the front-rear distribution ratio n becomes larger. That is, the anti-dive force FAD becomes larger as the front wheel braking force Fxf becomes larger.

As shown in FIG. 3, since the first angle θfb is larger than the second angle θfd, the front wheel friction braking force Fxfb has a larger contribution to the anti-dive force FAD than the front wheel regenerative braking force Fxfd. In other words, when the proportion of the front wheel frictional braking force Fxfb in the front wheel braking force Fxf is made larger than the proportion of the front wheel regenerative braking force Fxfd in the front wheel braking force Fxf, in other words, when the front wheel friction regeneration ratio nf is made larger, Anti-dive force FAD increases. On the other hand, when the proportion of the front wheel regenerative braking force Fxfd in the front wheel braking force Fxf is made larger than the proportion of the front wheel friction braking force Fxfb in the front wheel braking force Fxf, in other words, when the front wheel friction regeneration ratio nf is made smaller, Anti-dive force FAD becomes smaller.

As shown in the relational expression (Equation 2), when the front-rear distribution ratio n is the same, the greater the vehicle braking force Fx, the greater the anti-lift force FAL becomes. When the vehicle braking force Fx is the same, the anti-lift force FAL becomes larger as the front-rear distribution ratio n becomes smaller. That is, the anti-lift force FAL becomes larger as the rear wheel braking force Fxr becomes larger.

As shown in FIG. 3, since the third angle θrb is larger than the fourth angle θrd, the rear wheel friction braking force Fxrb has a larger contribution to the anti-lift force FAL than the rear wheel regenerative braking force Fxrd. In other words, when the proportion of the rear wheel frictional braking force Fxrb in the rear wheel braking force Fxr is made larger than the proportion of the rear wheel regenerative braking force Fxrd in the rear wheel braking force Fxr, in other words, the rear wheel friction regeneration ratio nr is made larger. In this case, the anti-lift force FAL becomes large. On the other hand, when the proportion of the rear wheel regenerative braking force Fxrd in the rear wheel braking force Fxr is made larger than the proportion of the rear wheel friction braking force Fxrb in the rear wheel braking force Fxr, in other words, the rear wheel friction regeneration ratio nr is made smaller. In this case, the anti-lift force FAL becomes small.

<Brake control device>
The brake control device 10 is composed of a processing circuit that controls the vehicle 90. Brake control device 10 controls the braking force of vehicle 90 by operating regenerative braking device 80 and friction braking device 70 according to a target deceleration of vehicle 90 .

The brake control device 10 is composed of a plurality of functional units that perform various types of control. FIG. 1 shows a target deceleration calculation unit 11, a posture target calculation unit 12, a distribution ratio calculation unit 13, an instruction value calculation unit 14, and a friction control unit 15 as examples of functional units. Each functional unit included in the brake control device 10 is capable of transmitting and receiving information to and from each other.

<Target deceleration calculation section>
The target deceleration calculation unit 11 can calculate a target deceleration DVT as a target deceleration of the vehicle 90. The deceleration indicates the rate of change in the speed of the vehicle 90. In this embodiment, the deceleration takes a positive value when the vehicle 90 is decelerating. The deceleration takes a larger value as the speed of the vehicle 90 changes more greatly in the deceleration direction.

The target deceleration calculation unit 11 calculates the target deceleration DVT based on the manipulated variable Bp. The target deceleration calculation unit 11 calculates a larger target deceleration DVT as the manipulated variable Bp becomes larger.
Further, the target deceleration calculation unit 11 can also calculate the required braking force FxR based on the operation amount Bp as a target of the vehicle braking force Fx for causing the deceleration of the vehicle 90 to follow the target deceleration DVT.

<Posture target calculation section>
Posture target calculation unit 12 calculates a pitching attitude target of vehicle 90 and a sinking attitude target of vehicle 90 based on target deceleration DVT. As a pitching posture target, for example, a pitch angle target value can be mentioned. The pitching attitude target may be a pitch moment target value that achieves the pitch angle target value. An example of the target for the sinking posture is a target value for the amount of bounce. The target of the sinking posture may be a target value of the bounce force that achieves the target value of the bounce amount.

The functions of the posture target calculation unit 12 will be explained in detail using FIG. 4.
Posture target calculation unit 12 obtains target deceleration DVT calculated by target deceleration calculation unit 11. The posture target calculation unit 12 calculates a target pitch angle Θreq as a target value of the pitch angle. The posture target calculation unit 12 calculates a target pitch moment Mreq for achieving the target pitch angle Θreq. Here, the moment in the backward rotation direction generated by the action of the front wheel anti-dive force FAD and the rear wheel anti-lift force FAL is defined as a controllable moment Ma. The controllable moment Ma is a moment that acts in a direction to suppress the pitching moment M. The target pitch moment Mreq can be said to be a target value of a moment obtained by suppressing the pitching moment M by the controllable moment Ma. The posture target calculation unit 12 calculates a target bounce amount DZreq as a target value of the bounce amount. The posture target calculation unit 12 calculates a target bounce force Zreq for achieving the target bounce amount DZreq.

Posture target calculation unit 12 calculates target pitch angle Θreq such that the pitching motion of vehicle 90 increases as target deceleration DVT increases. Posture target calculation unit 12 calculates target pitch moment Mreq based on target pitch angle Θreq so that it increases as target deceleration DVT increases. Posture target calculation unit 12 calculates target bounce amount DZreq such that the larger the target deceleration DVT is, the larger the bounce motion of vehicle 90 is. Posture target calculation unit 12 calculates target bounce force Zreq based on target bounce amount DZreq so that it increases as target deceleration DVT increases.

Note that the attitude target calculation unit 12 calculates the target pitch moment Mreq using the target deceleration DVT as input, using a function corresponding to the target deceleration DVT based on the relationship between the target pitch angle Θreq and the target pitch moment Mreq. It's okay. Similarly, the posture target calculation unit 12 uses a function corresponding to the target deceleration DVT based on the relationship between the target bounce amount DZreq and the target bounce force Zreq, and calculates the target bounce force Zreq using the target deceleration DVT as input. You may.

An example of a manner of calculating the target pitch moment Mreq and the target bounce force Zreq will be described. For example, the posture target calculation unit 12 stores a calculation map 12a for calculating a target pitch moment Mreq and a target bounce force Zreq corresponding to the target deceleration DVT. In the calculation map 12a, a relationship calculated in advance through experiments or the like is set as the relationship between the target deceleration DVT, the target pitch moment Mreq, and the target bounce force Zreq. FIG. 4 illustrates the relationship between the target deceleration DVT, the target pitch moment Mreq, and the target bounce force Zreq indicated by the calculation map 12a.

The posture target calculation unit 12 can calculate the target pitch moment Mreq to be larger as the target deceleration DVT is larger, based on the calculation map 12a. FIG. 4 shows an example of the relationship between the target deceleration DVT and the target pitch moment Mreq in which the target pitch moment Mreq increases linearly as the target deceleration DVT increases. The relationship between the target deceleration DVT and the target pitch moment Mreq is not limited to the example shown in FIG. 4.

The posture target calculation unit 12 can calculate the target bounce force Zreq to be larger as the target deceleration DVT is larger, based on the calculation map 12a. FIG. 4 shows an example of the relationship between the target deceleration DVT and the target bounce force Zreq in which the target bounce force Zreq increases linearly as the target deceleration DVT increases. The relationship between the target deceleration DVT and the target bounce force Zreq is not limited to the example shown in FIG. 4.

<Allocation ratio calculation section>
The allocation ratio calculation unit 13 executes allocation ratio calculation processing. In the distribution ratio calculation process, the distribution ratio calculation unit 13 calculates the front and rear distribution ratio n, the front wheel friction regeneration ratio nf, and the rear wheel so that the posture of the vehicle 90 follows the posture indicated by the pitching posture target and the sinking posture target. Calculate the friction regeneration ratio nr. That is, the distribution ratio calculation unit 13 adjusts the front and rear distribution ratio n and the front wheel friction regeneration ratio nf so that the pitch angle of the vehicle 90 follows the target pitch angle Θreq and the bounce amount of the vehicle 90 follows the target bounce amount DZreq. and calculate the rear wheel friction regeneration ratio nr. Details of the processing executed by the allocation ratio calculation unit 13 will be described later.

<Instruction value calculation section and friction control section>
The instruction value calculation unit 14 obtains the required braking force FxR, the front-rear distribution ratio n, the front wheel friction regeneration ratio nf, and the rear wheel friction regeneration ratio nr. The instruction value calculation unit 14 calculates an instruction value for operating the friction braking device 70 and the regenerative braking device 80 based on the required braking force FxR, the front-rear distribution ratio n, the front wheel friction regeneration ratio nf, and the rear wheel friction regeneration ratio nr. .

The instruction value calculation unit 14 calculates a friction braking force request value FxbR as an instruction value for operating the friction braking device. The friction braking force request value FxbR includes an instruction value corresponding to the front wheel friction braking force Fxfb and an instruction value corresponding to the rear wheel friction braking force Fxrb. The friction control unit 15 operates the friction braking device 70 according to the friction braking force request value FxbR.

The instruction value calculation unit 14 calculates a regenerative braking force request value FxdR as an instruction value for operating the regenerative braking device. The regenerative braking force request value FxdR includes an instruction value corresponding to the front wheel regenerative braking force Fxfd and an instruction value corresponding to the rear wheel regenerative braking force Fxrd. The regenerative braking force request value FxdR is transmitted to the regeneration control device 20. The regenerative braking device 80 is operated by the regenerative control device 20 in accordance with the regenerative braking force request value FxdR.

<Allocation ratio calculation process>
An example of a manner in which the distribution ratio calculation unit 13 calculates the front-rear distribution ratio n, the front wheel friction regeneration ratio nf, and the rear wheel friction regeneration ratio nr will be described.

FIG. 5 shows the flow of processing when the allocation ratio calculation unit 13 executes the allocation ratio calculation process. This processing routine is repeatedly executed at predetermined intervals while the vehicle 90 is braking.
When this processing routine is started, first in step S101, the distribution ratio calculation unit 13 obtains a target pitch moment Mreq corresponding to the target pitch angle Θreq and a target bounce force Zreq corresponding to the target bounce amount DZreq. The distribution ratio calculation unit 13 calculates a front-rear distribution ratio n, a front wheel friction regeneration ratio nf, and a rear wheel friction regeneration ratio nr based on the target pitch moment Mreq and the target bounce force Zreq calculated by the posture target calculation unit 12.

An example of the process performed by the allocation ratio calculation unit 13 in step S101 will be described.
The front wheel friction regeneration ratio nf can be expressed as the following relational expression (Equation 3) based on the equation of motion of the vehicle 90. The rear wheel friction regeneration ratio nr can be expressed as the following relational expression (Equation 4) based on the equation of motion of the vehicle 90.

In the relational expression (Equation 3) and the relational expression (Equation 4), "M'" is a value obtained by dividing the target pitch moment Mreq by the required braking force FxR as shown in the following relational expression (Equation 5). In the relational expression (Formula 3) and the relational expression (Formula 4), "Z'" is a value obtained by dividing the target bounce force Zreq by the required braking force FxR as shown in the following relational expression (Formula 6). In the relational expression (Formula 3) and the relational expression (Formula 4), "a", "b", "c", and "d" are, in order, the following relational expression (Formula 7), relational expression (Formula 8), This is as shown in the relational expression (Formula 9) and the relational expression (Formula 10). That is, "a", "b", "c", and "d" are, in order, the tangent of the first angle θfb, the tangent of the second angle θfd, the tangent of the third angle θrb, and the tangent of the fourth angle θrd. .

The distribution ratio calculation unit 13 calculates the front-rear distribution ratio n, the front wheel friction regeneration ratio nf, and the rear wheel friction regeneration ratio nr as solutions to the simultaneous equations of the relational expression (Formula 3) and the relational expression (Formula 4). An example will be explained using FIG. 6.

FIG. 6 shows an orthogonal coordinate system in which the horizontal axis represents the front-rear distribution ratio n as the first axis, and the front wheel friction regeneration ratio nf and the rear wheel friction regeneration ratio nr as the second axis, the vertical axis. In FIG. 6, the function of the relational expression (Formula 3) is shown by a solid line. In FIG. 6, the function of the relational expression (Equation 4) is shown by a broken line. The distribution ratio calculation unit 13 obtains a solution by setting the front wheel friction regeneration ratio nf and the rear wheel friction regeneration ratio nr to equal values. That is, the horizontal axis coordinate value "X" of the intersection (X, Y) between the solid line and the broken line shown in FIG. Calculated as wheel friction regeneration ratio nr.

Returning to FIG. 5, in the process of step S101, as illustrated above, the distribution ratio calculation unit 13 calculates the front and rear distribution ratio n, the front wheel friction regeneration ratio nf, and the rear wheel friction regeneration ratio nr. As a result, the instruction value calculation unit 14 calculates the friction braking force request value FxbR and the regenerative braking force request value FxdR. The friction braking device 70 is operated by the friction control unit 15 based on the friction braking force request value FxbR. Further, the regenerative braking device 80 is operated by the regenerative control device 20 based on the regenerative braking force request value FxdR.

After calculating the front-rear distribution ratio n, the front wheel friction regeneration ratio nf, and the rear wheel friction regeneration ratio nr in the process of step S101, the distribution ratio calculation unit 13 moves the process to step S102.
In step S102, the distribution ratio calculation unit 13 obtains the regenerative braking force execution value Fxd. When the distribution ratio calculation unit 13 acquires the regenerative braking force execution value Fxd from the regeneration control device 20, the process proceeds to step S103.

In step S103, the distribution ratio calculation unit 13 recalculates the front-rear distribution ratio n, the front wheel friction regeneration ratio nf, and the rear wheel friction regeneration ratio nr. For example, the distribution ratio calculation unit 13 solves the simultaneous equations of the relational expression (Equation 3) and the relational expression (Equation 4) so that the regenerative braking force request value FxdR becomes a value equal to or less than the regenerative braking force execution value Fxd. The distribution ratio calculation unit 13 updates the front-rear distribution ratio n, the front wheel friction regeneration ratio nf, and the rear wheel friction regeneration ratio nr using the calculated values again. As a result, the instruction value calculation unit 14 calculates the frictional braking force request value FxbR and the regenerative braking force request value FxdR based on the recalculated values. After recalculating the front-rear distribution ratio n, the front wheel friction regeneration ratio nf, and the rear wheel friction regeneration ratio nr in the process of step S103, the distribution ratio calculation unit 13 ends this processing routine.

<Actions and effects of the first embodiment>
The operation and effect of the first embodiment will be explained.
The anti-dive force FAD and the anti-lift force FAL are values that change depending on the front-rear distribution ratio n, the front wheel friction regeneration ratio nf, and the rear wheel friction regeneration ratio nr, as shown in the above relational expressions (Formula 1) and (Formula 2). It is. By adjusting the front-rear distribution ratio n, the front wheel friction regeneration ratio nf, and the rear wheel friction regeneration ratio nr, the anti-dive force FAD and anti-lift force FAL generated in the vehicle 90 can be adjusted. That is, the attitude of the vehicle 90 can be controlled by setting the front-rear distribution ratio n, the front wheel friction regeneration ratio nf, and the rear wheel friction regeneration ratio nr.

Through a test drive of the vehicle 90 controlled by the brake control device 10, the following was confirmed. The pitch angle could be varied according to the deceleration. The amount of bounce could be varied depending on the deceleration. It was possible to create a predetermined regular relationship between the pitch angle and the amount of bounce. The actual deceleration, pitch angle, bounce amount, etc. of the vehicle 90 can be detected by using sensors such as an acceleration sensor and a gyro sensor. An example will be explained using FIG. 7.

FIG. 7 illustrates, as a solid line, the relationship between the pitch angle and the amount of bounce when the brake control device 10 of the first embodiment is applied. In FIG. 7, as a comparative example, an example in which the control of this embodiment based on the target pitch moment Mreq and the target bounce force Zreq is not performed is shown by a two-dot chain line.

In the case of the comparative example, as shown by the two-dot chain line in FIG. 7, the bounce amount may vary irregularly with respect to the pitch angle. For example, even if the pitch angle increases, the amount of bounce may decrease.

On the other hand, according to the brake control device 10, the pitch angle can be varied in proportion to the deceleration. The bounce amount can be varied in proportion to the deceleration. Thereby, as shown by the solid line in FIG. 7, a proportional relationship can be established between the pitch angle and the amount of bounce.

According to the brake control device 10, the front-rear distribution ratio n, the front wheel friction regeneration ratio nf, and the rear wheel friction regeneration ratio are adjusted so that the attitude of the vehicle 90 follows the target pitch angle Θreq and the target bounce amount DZreq according to the target deceleration DVT. nr is calculated. The front-rear distribution ratio n, the front wheel friction regeneration ratio nf, and the rear wheel friction regeneration ratio nr are calculated based on the target pitch moment Mreq and the target bounce force Zreq. The friction braking force and the regenerative braking force can be controlled according to the calculated front-rear distribution ratio n, front wheel friction regeneration ratio nf, and rear wheel friction regeneration ratio nr. This allows the pitch angle and bounce amount to be correlated with the target deceleration DVT. By controlling the attitude of the vehicle 90 in response to the deceleration, it is possible to suppress the deviation between the attitude of the vehicle 90 estimated by the occupant of the vehicle 90 based on the deceleration and the actual attitude of the vehicle 90.

In the brake control device 10, the target pitch angle Θreq, the target pitch moment Mreq, the target bounce amount DZreq, and the target bounce force Zreq are calculated based on the target deceleration DVT. The target deceleration DVT is calculated based on the manipulated variable Bp. Therefore, according to the brake control device 10, it is possible to improve the followability of the attitude of the vehicle 90 to the operation performed by the driver of the vehicle 90. This can prevent the driver from feeling uncomfortable with the behavior of the vehicle 90 as a result of the driver's operations.

(Second embodiment)
A brake control device according to the second embodiment will be explained with reference to FIGS. 9 to 13.
The brake control device of the second embodiment includes an attitude target calculation unit 112 in place of the attitude target calculation unit 12 of the first embodiment. That is, the second embodiment differs from the first embodiment in that the posture target calculation unit 112 calculates the target pitch moment Mreq and the target bounce force Zreq. Other configurations in the second embodiment are common to the first embodiment. Descriptions of configurations common to the first embodiment will be omitted as appropriate.

The second embodiment aims to control the attitude of the vehicle 90 so that the driver of the vehicle 90 can easily feel the deceleration of the vehicle 90. Specifically, at the beginning of braking, the pitch angular velocity is increased by increasing the pitch angular acceleration. The pitch angular velocity is gradually decreased in response to an increase in deceleration during braking. Also, the change in pitch angle is reduced in accordance with the increase in deceleration. Further, the amount of bounce is increased in accordance with an increase in deceleration during braking.

As shown in FIG. 9, the posture target calculation section 112 includes a pitching gain calculation section 112a and a sinking gain calculation section 112b.
Posture target calculation unit 112 obtains target deceleration DVT calculated by target deceleration calculation unit 11. The target deceleration DVT is input to the pitching gain calculation section 112a and the sinking gain calculation section 112b.

The pitching gain calculation unit 112a calculates the pitch angle gain KtΘ based on the target deceleration DVT. Posture target calculation unit 112 calculates target pitch angle Θreq by multiplying pitch angle gain KtΘ and pitch angle base Θbase.

The pitch angle gain KtΘ is a value for adjusting the target pitch angle Θreq according to the target deceleration DVT.
The pitch angle base Θbase serves as a reference for calculating the target pitch angle Θreq. The pitch angle base Θbase can be said to be the relationship between the target pitch angle Θreq and the target deceleration DVT when the pitch angle gain KtΘ is "1". The pitch angle base Θbase is stored in the posture target calculation unit 112 as a pre-calculated value. For example, the pitch angle base Θbase can be the relationship between the pitch angle and the deceleration when braking force is generated in the vehicle 90 with equal pressure distribution in the front and rear. Generating braking force with equal pressure distribution front and rear means setting the front wheel regenerative braking force Fxfd and the rear wheel regenerative braking force Fxrd to "0" and making the hydraulic pressure in each wheel cylinder of the front wheel and rear wheel equal. This means generating a front wheel frictional braking force Fxfb and a rear wheel frictional braking force Fxrb. The hydraulic pressure in the wheel cylinder of the front wheel is an example of a pressing force that corresponds to the magnitude of the frictional braking force applied to the front wheel. The hydraulic pressure in the wheel cylinder of the rear wheel is an example of a pressing force that corresponds to the magnitude of the frictional braking force applied to the rear wheel.

The sinking gain calculation unit 112b calculates the bounce amount gain KtZ based on the target deceleration DVT. The posture target calculation unit 112 calculates the target bounce amount DZreq by multiplying the bounce amount gain KtZ and the bounce amount base DZbase.

The bounce amount gain KtZ is a value for adjusting the target bounce amount DZreq according to the target deceleration DVT.
The bounce amount base DZbase is a reference for calculating the target bounce amount DZreq. The bounce amount base DZbase can be said to be the relationship between the target bounce amount DZreq and the target deceleration DVT when the bounce amount gain KtZ is "1". The bounce amount base DZbase is stored in the posture target calculation unit 112 as a pre-calculated value. For example, the bounce amount base DZbase can be a relationship between the bounce amount and the deceleration when braking force is generated in the vehicle 90 with equal pressure distribution in the front and rear.

Posture target calculation unit 112 calculates target pitch moment Mreq based on target pitch angle Θreq. Posture target calculation unit 112 calculates target bounce force Zreq based on target bounce amount DZreq.

The functions of the posture target calculation unit 112 will be explained in detail using FIG. 9.
Posture target calculation unit 112 calculates the target pitch angle Θreq so that the pitch increase rate when the target deceleration DVT is small is larger than the pitch increase rate when the target deceleration DVT is large. Here, the pitch increase rate refers to the rate at which the target pitch angle Θreq changes in the direction in which the pitching motion of the vehicle 90 increases relative to the increase in the target deceleration DVT. In other words, when the deceleration of the vehicle 90 increases at the same speed, the rate of pitch angle change is high in areas where the deceleration is small, and the rate of change in the pitch angle is low in areas where the deceleration is large.

More specifically, the posture target calculation unit 112 calculates the target pitch angle Θreq so that the pitch increase rate is larger than the reference pitch rate when the target deceleration DVT is small. On the other hand, when the target deceleration DVT is large, the posture target calculation unit 112 calculates the target pitch angle Θreq so that the pitch increase rate is equal to or less than the reference pitch rate. Here, the above reference pitch ratio is the rate at which the pitch angle changes in the direction in which the pitching motion of the vehicle 90 increases with respect to an increase in deceleration when a braking force is generated in the vehicle 90 with equal pressure distribution in the front and rear. say.

Posture target calculation unit 112 calculates the target bounce amount DZreq so that the bounce increase rate when the target deceleration DVT is small is smaller than the bounce increase rate when the target deceleration DVT is large. Here, the above-mentioned bounce increase rate refers to the rate at which the target bounce amount DZreq changes in a direction in which the bounce motion of the vehicle 90 increases with respect to an increase in the target deceleration DVT.

More specifically, the posture target calculation unit 112 calculates the target bounce amount DZreq so that the bounce increase rate is smaller than the reference bounce rate when the target deceleration DVT is small. On the other hand, when the target deceleration DVT is large, the posture target calculation unit 112 calculates the target bounce amount DZreq so that the bounce increase rate is equal to or higher than the reference bounce rate. Here, the above-mentioned reference bounce ratio is the rate at which the bounce amount changes in the direction in which the bounce motion of the vehicle 90 increases with respect to an increase in deceleration when braking force is generated in the vehicle 90 with equal front and rear pressure distribution. say.

<Pitch angle gain>
An example of a manner in which the pitching gain calculation unit 112a calculates the pitch angle gain KtΘ will be described. For example, the pitching gain calculation unit 112a stores a calculation map for calculating the pitch angle gain KtΘ corresponding to the target deceleration DVT. A relationship calculated in advance through experiments or the like is set in the calculation map as the relationship between the target deceleration DVT and the pitch angle gain KtΘ. FIG. 9 illustrates the relationship between the target deceleration DVT and the pitch angle gain KtΘ shown by the calculation map.

The relationship between the target deceleration DVT and the pitch angle gain KtΘ illustrated in FIG. 9 will be explained.
In a range where the target deceleration DVT is smaller than the first deceleration dv1, the pitch angle gain KtΘ is a constant value greater than "1".

In a range where the target deceleration DVT is greater than or equal to the first deceleration dv1, the pitch angle gain KtΘ decreases as the target deceleration DVT increases.
Specifically, in a range where the target deceleration DVT is greater than or equal to the first deceleration dv1 and less than the second deceleration dv2, the pitch angle gain KtΘ decreases at a constant slope. The pitch angle gain KtΘ corresponding to the second deceleration dv2 is smaller than "1". In a range where the target deceleration DVT is equal to or higher than the second deceleration dv2, the pitch angle gain KtΘ decreases at a smaller rate with respect to an increase in the target deceleration DVT than the above-mentioned predetermined slope. It is decreasing. That is, with the second deceleration dv2 as a boundary, the target deceleration DVT increases between a range where the target deceleration DVT is smaller than the second deceleration dv2 and a range where the target deceleration DVT is greater than or equal to the second deceleration dv2. The rate at which the pitch angle gain KtΘ decreases relative to the pitch angle gain KtΘ is changed.

Note that the first deceleration dv1 is a value smaller than the second deceleration dv2, for example, a value slightly larger than "0". The second deceleration dv2 will be described later.
The relationship between the target deceleration DVT and the pitch angle gain KtΘ is not limited to the example shown in FIG. 9 . For example, the pitch angle gain KtΘ may be decreased at a predetermined gradient in the range from the target deceleration DVT "0" to the second deceleration dv2.

Attitude control realized by the target pitch angle Θreq calculated by the attitude target calculation unit 112 will be described using FIG. 11. FIG. 11 shows the relationship between the average rate of change in pitch angle (ΔΘ/ΔDV) and target deceleration DVT. The solid line in FIG. 11 shows the relationship when the braking force is generated so that the attitude of the vehicle 90 follows the target pitch angle Θreq calculated by the attitude target calculation unit 112. The two-dot chain line in FIG. 11 shows, as a comparative example, the relationship when braking force is generated in the vehicle 90 with equal front and rear pressure distribution. The average rate of change in pitch angle corresponds to the pitch increase rate. The average rate of change in pitch angle indicated by the two-dot chain line corresponds to the reference pitch ratio.

As shown by the solid line in FIG. 11, in the range where the target deceleration DVT is smaller than the first deceleration dv1, the attitude target calculation unit 112 calculates that the average rate of change in the pitch angle is higher than in the comparative example shown by the two-dot chain line. The target pitch angle Θreq is calculated so as to greatly increase the pitch angle Θreq. In a range where the target deceleration DVT is greater than or equal to the first deceleration dv1 and less than the second deceleration dv2, the posture target calculation unit 112 calculates the target pitch angle Θreq so as to gradually reduce the average rate of change of the pitch angle. do. As a result, in a range where the target deceleration DVT is large, the pitch increase rate shown by the solid line is equal to or less than the reference pitch rate shown by the two-dot chain line. In a range where the target deceleration DVT is equal to or greater than the second deceleration dv2, the posture target calculation unit 112 calculates the target pitch angle Θreq so that the average rate of change of the pitch angle is constant. In other words, the pitch angle gain KtΘ is calculated so that the average change rate of the pitch angle stops changing in a range where the target deceleration DVT is equal to or higher than the second deceleration dv2.

The concept of setting the second deceleration dv2 will be explained using FIG. 10.
In FIG. 10, the front-rear distribution ratio in which the front wheels and rear wheels are simultaneously locked during braking is illustrated as an ideal braking force distribution ratio by a broken line. Furthermore, the gradient that reduces the pitch angle gain KtΘ in the range where the target deceleration DVT is greater than or equal to the first deceleration dv1 and smaller than the second deceleration dv2 shown in FIG. The transition of the braking force in each case is illustrated by a solid line.

Here, in the vehicle 90, the anti-dive coefficient Ad due to the frictional braking force can be expressed as the following relational expression (Equation 11). The anti-lift coefficient Al due to the friction braking force can be expressed as the following relational expression (Equation 12). Further, the anti-dive coefficient Adr due to the regenerative braking force can be expressed as the following relational expression (Equation 13). The anti-lift coefficient Alr due to the regenerative braking force can be expressed as the following relational expression (Equation 14).

In the second embodiment, the vehicle 90 is a vehicle in which the anti-lift coefficient Al is greater than or equal to the anti-dive coefficient Ad. Therefore, in order to increase the braking force so as to control the change in the pitch angle of the vehicle 90 to be small, the proportion of the rear wheel braking force increases as the braking force increases. According to this tendency, based on the ideal braking force distribution ratio shown in FIG. It can be said that this increase does not contribute to the attitude control of the vehicle. In other words, in a range where the braking force is greater than the intersection of the solid line and the broken line, it is not possible to reduce the change in pitch angle even if the braking force is actively increased. Therefore, in the second embodiment, the target pitch angle Θreq is calculated so as not to deliberately reduce the change in pitch angle in a range where the braking force is larger than the intersection of the solid line and the broken line. In the second embodiment, the target deceleration DVT corresponding to the braking force at the intersection corresponds to the second deceleration dv2.

<Bounce amount gain>
Returning to FIG. 9, an example of how the sinking gain calculation unit 112b calculates the bounce amount gain KtZ will be described. For example, the sinking gain calculation unit 112b stores a calculation map for calculating the bounce amount gain KtZ corresponding to the target deceleration DVT. In the calculation map, a relationship calculated in advance through experiments or the like is set as the relationship between the target deceleration DVT and the bounce amount gain KtZ. FIG. 9 illustrates the relationship between the target deceleration DVT and the bounce amount gain KtZ shown by the calculation map.

The relationship between the target deceleration DVT and the bounce amount gain KtZ illustrated in FIG. 9 will be explained.
In a range where the target deceleration DVT is smaller than the first deceleration dv1, the bounce amount gain KtZ is a constant value smaller than "1".

In a range where the target deceleration DVT is greater than or equal to the first deceleration dv1, the bounce amount gain KtZ increases as the target deceleration DVT increases.
Specifically, in a range where the target deceleration DVT is greater than or equal to the first deceleration dv1 and less than the second deceleration dv2, the bounce amount gain KtZ increases at a constant slope. The bounce amount gain KtZ corresponding to the second deceleration dv2 is larger than "1". In a range where the target deceleration DVT is equal to or higher than the second deceleration dv2, the bounce amount gain KtZ increases at a smaller rate with respect to an increase in the target deceleration DVT than the above-mentioned predetermined slope. It is increasing. That is, with the second deceleration dv2 as a boundary, the target deceleration DVT increases between a range where the target deceleration DVT is smaller than the second deceleration dv2 and a range where the target deceleration DVT is greater than or equal to the second deceleration dv2. The rate at which the bounce amount gain KtZ increases relative to that is changed.

The relationship between the target deceleration DVT and the bounce amount gain KtZ is not limited to the example shown in FIG. 9 . For example, the bounce amount gain KtZ may increase at a predetermined slope in the range from the target deceleration DVT "0" to the second deceleration dv2.

Posture control realized by the target bounce amount DZreq calculated by the posture target calculation unit 112 will be described using FIG. 12. FIG. 12 shows the relationship between the average change rate of the bounce amount (ΔDZ/ΔDV) and the target deceleration DVT. The solid line in FIG. 12 shows the relationship when the braking force is generated so that the attitude of the vehicle 90 follows the target bounce amount DZreq calculated by the attitude target calculation unit 112. The two-dot chain line in FIG. 12 shows, as a comparative example, the relationship when braking force is generated in the vehicle 90 with equal front and rear pressure distribution. The average rate of change in the amount of bounces corresponds to the rate of increase in bounces. The average rate of change in the bounce amount indicated by the two-dot chain line corresponds to the reference bounce rate.

As shown by the solid line in FIG. 12, the attitude target calculation unit 112 calculates the target bounce so that the average rate of change in the amount of bounce is smaller than in the comparative example shown by the two-dot chain line in the range where the target deceleration DVT is small. Calculate the quantity DZreq. The attitude target calculation unit 112 calculates that in a range where the target deceleration DVT is smaller than the first deceleration dv1, the bounce amount changes in a direction that decreases from "0", that is, the bounce amount changes in a direction in which the vehicle 90 rises. is allowed to do so. In a range where the target deceleration DVT is greater than or equal to the first deceleration dv1 and smaller than the second deceleration dv2, the posture target calculation unit 112 calculates the target bounce amount DZreq so as to gradually increase the average rate of change of the bounce amount. do. As a result, in a range where the target deceleration DVT is large, the bounce increase rate shown by the solid line is equal to or higher than the reference bounce rate shown by the two-dot chain line. In a range where the target deceleration DVT is equal to or greater than the second deceleration dv2, the posture target calculation unit 112 calculates the target bounce amount DZreq so that the average rate of change in the bounce amount is constant. In other words, the bounce amount gain KtZ is calculated such that the average change rate of the bounce amount stops changing in a range where the target deceleration DVT is equal to or higher than the second deceleration dv2.

<Actions and effects of the second embodiment>
The operation and effect of the second embodiment will be explained using FIG. 13.
In the example shown in FIG. 13, braking is started at timing t11. That is, the attitude of the vehicle 90 is controlled based on the target pitch moment Mreq and the target bounce amount DZreq calculated by the attitude target calculation unit 112 from timing t11.

In (a) and (b) of FIG. 13, an example in which the control in the second embodiment is applied is shown by a solid line. In FIGS. 13A and 13B, as a comparative example, an example in which the attitude control of the vehicle 90 is not performed is shown by a two-dot chain line.

In FIG. 13(c), the vehicle braking force Fx is shown by a broken line. The regenerative braking force execution value Fxd is shown by a solid line. The regenerative braking force execution value Fxd as a comparative example is shown by a two-dot chain line.
As shown by the broken line in FIG. 13(c), the vehicle braking force Fx gradually increases from timing t11. That is, the target deceleration DVT is increasing.

At the beginning of braking when the target deceleration DVT is relatively small, as shown in FIG. 13(a), the pitch angular acceleration is large, so the pitch angular velocity becomes large from an earlier stage compared to the comparative example. Therefore, as shown in FIG. 13(b), the pitch angle becomes large from an earlier stage. As described above, according to the second embodiment, the pitch angular velocity is increased from the initial stage of braking, that is, from the timing when the driver of the vehicle 90 starts operating the brake operation member 92. Then, the pitch angle is increased.

As shown in FIG. 13(a), the pitch angular velocity, which is increased at the initial stage of braking, is gradually decreased. Therefore, as shown in FIG. 13(b), the amount of change in the pitch angle gradually decreases. As described above, according to the second embodiment, during the middle period of braking, that is, while the target deceleration DVT is gradually increasing, the pitch angular velocity is decreased in accordance with the increase in the target deceleration DVT.

According to the second embodiment, especially after timing t12 in FIG. 13(c), the proportion occupied by the frictional braking force execution value Fxb is increased and the proportion occupied by the regenerative braking force execution value Fxd is decreased. . As a result, the anti-dive force FAD and the anti-lift force FAL generated in the vehicle 90 are adjusted to realize attitude control as shown in FIGS. 13(a) and 13(b).

By controlling the vehicle 90 to follow the target value calculated by the posture target calculation unit 112 of the second embodiment, the driver of the vehicle 90 is provided with the following sensations during the initial and middle stages of braking. can be provided.

At the initial stage of braking, the pitch angle of the vehicle 90 changes significantly, which changes the information visible to the driver of the vehicle 90. For example, the dashboard of vehicle 90 appears to move downward. The driver can feel the deceleration of the vehicle 90 by changing the information obtained visually. Further, as the pitch angle of the vehicle 90 changes greatly, the upper body of the driver is pushed by the seat, which can encourage the driver's upper body to lean forward.

In the middle period of braking, the pitch angular velocity of the vehicle 90 gradually decreases, thereby suppressing the swinging of the driver's head. For example, the stimulation to the otolith organs can be reduced. This can prevent the driver's sense of balance from being disturbed. Therefore, it is possible to prevent the driver from misunderstanding the deceleration of the vehicle 90. Furthermore, by gradually decreasing the pitch angular velocity of the vehicle 90, the acceleration that causes the driver's upper body to lean forward due to the seat can be decreased. This allows the driver to feel a sense of unity with the seat of the vehicle 90. Furthermore, since the amount of bounce of the vehicle 90 increases in accordance with the increase in deceleration, the driver can feel that the deceleration is increasing from the sinking of the vehicle body 91. Furthermore, the driver can feel a sense of stability from the sinking of the vehicle body 91.

(Third embodiment)
During braking of a vehicle, the braking force actually acting on the wheels may be limited. For example, if a control with a high priority is being executed, the braking force may not be able to be adjusted by other controls. Examples of high-priority control include anti-lock brake control and braking force distribution control. Anti-lock brake control, so-called ABS control, is control that adjusts braking force to suppress wheel locking. Braking force distribution control, so-called EBD control, is a control that limits the braking force of one of the front wheels and rear wheels in order to prevent one wheel from locking in advance. For example, the brake control device 10 shown in FIG. 1 has a function of executing ABS control. For example, the brake control device 10 has a function of executing EBD control.

If the braking force acting on the wheels is limited, the attitude of the vehicle 90 may not be able to follow the attitude indicated by the target pitching attitude and the target sinking attitude. An example will be explained using FIG. 14.

FIG. 14 shows an example in which execution of ABS control and EBD control is started for the rear wheels at timing t21. Before timing t21, the attitude of vehicle 90 is controlled so that the pitch rate, which indicates the rate of change in pitch angle per unit time, gradually decreases. However, after timing t21, the degree of freedom of the front-rear distribution ratio n is lost, so it is not possible to reduce the pitch rate, and the pitch rate increases excessively.

Therefore, in the third embodiment, when the braking force is limited in one of the front wheels and the rear wheels, and the braking force is not limited in the other wheel, the distribution ratio calculation unit 13 performs the restriction. This embodiment differs from each of the above embodiments in that it further includes a function to execute time recalculation processing. The purpose of the limit recalculation process is to control the attitude of the vehicle 90 by controlling the braking force of wheels whose braking force is not limited. The limit time recalculation process may be applied to the first embodiment or the second embodiment. In the following description, descriptions of configurations common to the first embodiment or the second embodiment will be omitted as appropriate.

By the way, when ABS control is started, application of regenerative braking force to the wheels targeted for ABS control may be terminated. In such a case, for example, by acquiring the regenerative braking force execution value Fxd in the process of step S102 described using FIG. It is also possible to recalculate the regeneration ratio as "1".

<Limit recalculation process>
FIG. 15 shows the flow of processing when the allocation ratio calculation unit 13 executes the time limit recalculation processing. This processing routine is repeatedly executed at predetermined intervals when the front-rear distribution ratio n, the front wheel friction regeneration ratio nf, and the rear wheel friction regeneration ratio nr have been calculated by the process shown in FIG. 5, for example.

When this processing routine is started, first in step S201, the distribution ratio calculation unit 13 determines whether there is a limit on the rear wheel braking force.
An example in which it is determined that there is a limit to the rear wheel braking force will be described. If ABS control and EBD control are being performed on the rear wheels, the distribution ratio calculation unit 13 can determine that there is a limit to the rear wheel braking force. If the rear wheels are slipping, the distribution ratio calculation unit 13 can determine that there is a restriction on the rear wheels. If the difference between the wheel speed of the rear wheels and the vehicle body speed is larger than a prescribed slip determination value, the distribution ratio calculation unit 13 can determine that there is a restriction on the rear wheels. When the ratio of the rear wheel braking force is larger than the ideal braking force distribution ratio, the distribution ratio calculation unit 13 can determine that there is a restriction on the rear wheels. The distribution ratio calculation unit 13 includes information indicating whether ABS control is being executed, information indicating whether EBD control is being executed, information indicating a wheel in which slip has occurred, wheel speed, and vehicle body. Elements such as speed can be obtained.

In step S201, if there is a limit on the rear wheel braking force (S201: YES), the distribution ratio calculation unit 13 shifts the process to step S202. In step S202, the distribution ratio calculation unit 13 determines whether there is a limit on the front wheel braking force.

An example in which it is determined that there is a limit to the front wheel braking force will be described. If ABS control and EBD control are being performed on the front wheels, the distribution ratio calculation unit 13 can determine that there is a limit to the front wheel braking force. If slipping occurs in the front wheels, the distribution ratio calculation unit 13 can determine that there is a restriction on the front wheels. When the difference between the wheel speed of the front wheels and the vehicle body speed is larger than a prescribed slip determination value, the distribution ratio calculation unit 13 can determine that there is a restriction on the front wheels.

In step S202, if there is a limit on the front wheel braking force (S202: YES), the distribution ratio calculation unit 13 temporarily ends this processing routine. That is, if there is a limit on both the front wheel braking force and the rear wheel braking force, the distribution ratio calculation unit 13 ends this processing routine.

On the other hand, if there is no limit to the front wheel braking force (S202: NO), the distribution ratio calculation unit 13 shifts the process to step S203. That is, if there is a limit on the rear wheel braking force while there is no limit on the front wheel braking force, the distribution ratio calculation unit 13 shifts the process to step S203.

In step S203, the distribution ratio calculation unit 13 recalculates the front wheel friction regeneration ratio nf and the front-rear distribution ratio n. For example, the distribution ratio calculation unit 13 calculates the front wheel friction regeneration ratio nf and the front-rear distribution ratio n so that the posture of the vehicle 90 follows the target pitching posture by suppressing an increase in the front wheel braking force Fxf. Details of this process will be described later. After the distribution ratio calculation unit 13 recalculates the front wheel friction regeneration ratio nf and the front-rear distribution ratio n, it ends this processing routine.

In step S201, if there is no limit to the rear wheel braking force (S201: NO), the distribution ratio calculation unit 13 moves the process to step S204. In step S204, the distribution ratio calculation unit 13 determines whether there is a limit on the front wheel braking force.

In step S204, if there is no limit to the front wheel braking force (S204: NO), the distribution ratio calculation unit 13 temporarily ends this processing routine. That is, if there is no limit to both the front wheel braking force and the rear wheel braking force, the distribution ratio calculation unit 13 ends this processing routine.

On the other hand, if there is a limit on the front wheel braking force (S204: YES), the distribution ratio calculation unit 13 shifts the process to step S205. That is, if there is a limit on the front wheel braking force while there is no limit on the rear wheel braking force, the distribution ratio calculation unit 13 shifts the process to step S205.

In step S205, the distribution ratio calculation unit 13 recalculates the rear wheel friction regeneration ratio nr and the front and rear distribution ratio n. For example, the distribution ratio calculation unit 13 calculates the rear wheel friction regeneration ratio nr and the front-rear distribution ratio n so that the posture of the vehicle 90 follows the target pitching posture by suppressing an increase in the rear wheel braking force Fxr. Details of this process will be described later. After recalculating the rear wheel friction regeneration ratio nr and the front-rear distribution ratio n, the distribution ratio calculation unit 13 ends this processing routine.

<Details of S203 and S205>
An example of the process in step S203 and the process in step S205 will be described. Note that the process in step S203 and the process in step S205 correspond to the limit time recalculation process.

The purpose of the process in step S203 is to adjust the braking force gradient ΔFxf of the front wheels to make the attitude of the vehicle 90 follow the target pitching attitude. The purpose of the process in step S205 is to adjust the braking force gradient ΔFxr of the rear wheels to make the attitude of the vehicle 90 follow the target pitching attitude. Here, regarding the target pitching posture, the amount of change in the target pitch moment Mreq is defined as the amount of change in the target pitch moment ΔM.

The front wheel braking force gradient ΔFxf and the rear wheel braking force gradient ΔFxr can be expressed as the following relational expression (Equation 15). In the relational expression (Formula 15), "*" corresponds to "f" or "r". Accordingly, "n*" corresponds to "nf" or "nr". In the relational expression (Formula 15), "A**" corresponds to "Ad" when "*" is "f". "A**" corresponds to "Al" when "*" is "r". "*" and "A**" shown below also have the same meanings as above. In the relational expression (Equation 15), "h" indicates the height of the center of gravity, which is the distance from the road surface to the vehicle center of gravity GC shown in FIG. The center of gravity height h corresponds to a moment arm with respect to the pitching motion of the vehicle 90.

FIG. 16 shows a solution of "n*" and "ΔFx*" to achieve the target pitch moment change amount ΔM for the relational expression (Equation 15). The dashed-dotted line shown in FIG. 16 corresponds to the asymptote in the solution of the relational expression (Equation 15) shown by the solid line. The asymptote can be expressed as the above relational expression (Equation 16), with the horizontal axis coordinate value of the asymptote being "n*ay".

In the following, cases [A] and [B] will be explained depending on the relationship between the center of gravity height h and the anti-dive coefficient Ad or the relationship between the center of gravity height h and the anti-lift coefficient Al.
[A] When the center of gravity height h is greater than or equal to the anti-dive coefficient Ad, or when the center of gravity height h is greater than or equal to the anti-lift coefficient Al (h≧A**).

In this case, based on the relational expression (Equation 16), "n*ay" becomes "1" or more (n*ay≧1). That is, the minimum value of "n*ay" is "1".
Therefore, in the process of step S203, the front wheel friction regeneration ratio nf can be recalculated as "1". As a result of the process in step S203, the front wheel regenerative braking force Fxfd is set to "0" (Fxfd=(1-nf)Fxf), and only the front wheel friction braking force Fxfb acts on the front wheels. That is, the target pitch moment change amount ΔM is achieved by controlling the front wheel braking force gradient ΔFxf by adjusting the front wheel friction braking force Fxfb.

On the other hand, in the process of step S205, the rear wheel friction regeneration ratio nr can be recalculated as "1". As a result of the process in step S205, the rear wheel regenerative braking force Fxrd is set to "0" (Fxrd=(1-nr)Fxr), and only the rear wheel frictional braking force Fxrb acts on the rear wheels. That is, the target pitch moment change amount ΔM is achieved by controlling the rear wheel braking force gradient ΔFxr by adjusting the rear wheel friction braking force Fxrb.

The front wheel braking force gradient ΔFxf and the rear wheel braking force gradient ΔFxr in the case of “n*=1” can be expressed as the above relational expression (Formula 17) from the above relational expression (Formula 15).

Next, the flow of recalculating the front/rear distribution ratio n will be explained.
The front and rear distribution ratio n is defined as the braking force gradient ΔFxf of the front wheels after the time when the braking force of either the front or rear system wheels is limited, and the braking force Fxflim of the front wheels at the time when the braking force of either the front or rear system wheels is limited. It can be expressed by The following relational expression (Formula 18) can be derived by transforming the expression expressing the front-to-rear distribution ratio n based on the relational expression (Formula 15). Note that the braking force gradient ΔFxf of the front wheels in the relational expression (Equation 18) represents the amount of increase in the braking force of the front wheels after the time when the braking force of either the front or rear system wheels is limited. In addition, the front-rear distribution ratio n is determined by the braking force gradient ΔFxr of the rear wheels after the time when the braking force of either the front or rear system wheels is limited, and the braking force gradient of the rear wheels at the time when the braking force of either the front or rear system wheels is limited. It can be expressed by the braking force Fxrlim. By modifying the equation representing the front-to-rear distribution ratio n, the following relational equation (Equation 19) can be derived. Note that the braking force gradient ΔFxr of the rear wheels in the relational expression (Equation 19) represents the amount of increase in the braking force of the rear wheels after the time when the braking force of either the front or rear system wheels is limited.

In the process of step S203, the front and rear distribution ratio n can be calculated based on the relational expression (Equation 18). Specifically, the front-rear distribution ratio n can be calculated based on the target pitch moment change amount ΔM, the front wheel friction regeneration ratio nf, the center of gravity height h, and the anti-dive coefficients Ad and Adr.

In the process of step S205, the front and rear distribution ratio n can be calculated based on the relational expression (Formula 19). Specifically, the front-rear distribution ratio n can be calculated based on the target pitch moment change amount ΔM, the rear wheel friction regeneration ratio nr, the center of gravity height h, and the anti-lift coefficients Al and Alr.

[B] When the center of gravity height h is smaller than the anti-dive coefficient Ad, or when the center of gravity height h is smaller than the anti-lift coefficient Al (h<A**).
In this case, based on the relational expression (Equation 16), "n*ay" becomes smaller than "1"(n*ay<1). That is, in order to achieve the target pitch moment change amount ΔM, it is not enough to just adjust the braking force gradient ΔFx*, but it is necessary to generate regenerative braking force by adjusting the friction regeneration ratio n*.

Therefore, in the processing of steps S203 and S205, the friction regeneration ratio n* is set as a value as close to the asymptote as possible. The braking force gradient ΔFx* is adjusted based on the above relational expression (Equation 15) by setting "n*" to as large a value as possible within the range of "n*ay" or less.

The front-rear distribution ratio n can be recalculated in the same manner as in the case of [A] above. That is, in the process of step S203, the front-to-back distribution ratio n can be calculated based on the relational expression (Formula 18). In the process of step S205, the front and rear distribution ratio n can be calculated based on the relational expression (Formula 19).

<Actions and effects of the third embodiment>
The operation and effect of the third embodiment will be explained using FIG. 17.
FIG. 17 shows an example where there is a limit on the rear wheel braking force and there is no limit on the front wheel braking force. In the example shown in FIG. 17, the front wheel friction regeneration ratio nf is "1".

In the example shown in FIG. 17, braking is started at timing t31. After timing t32, an example is shown in which the rear wheel braking force is limited. For example, this is the case where the rear wheels slip at timing t32.

In FIG. 17(a), the front wheel frictional braking force Fxfb is shown by a solid line. The rear wheel friction braking force Fxrb is shown by a broken line.
FIG. 17(b) shows the change in pitch rate. FIG. 17 shows an example in which the attitude of the vehicle 90 is controlled according to the pitching attitude target calculated by the attitude target calculation unit 112 of the second embodiment.

As shown by the broken line in FIG. 17(a), after timing t32, the rear wheel frictional braking force Fxrb is limited, and the degree of freedom of the front-rear distribution ratio n is lost. At this time, according to the third embodiment, the front wheel friction regeneration ratio nf and the front-rear distribution ratio n are recalculated by executing the limit time recalculation process (S203). As a result, as shown by the solid line in FIG. 17(a), an increase in the front wheel frictional braking force Fxfb is suppressed after timing t32. As a result, the pitch rate can be kept low even after timing t32, as shown in FIG. 17(b). As described above, according to the third embodiment, even if the braking force is limited in one of the front wheels and the rear wheels, it is possible to suppress the pitch rate from increasing excessively.

According to the third embodiment, even if the braking force is limited at either the front wheels or the rear wheels, the attitude of the vehicle 90 can be changed to the pitching attitude by adjusting the braking force gradient of the other wheel. It can be made to follow the target.

(Example of change)
Each of the above embodiments can be modified and implemented as follows. The above embodiments and the following modifications can be implemented in combination with each other within a technically consistent range.

- In each of the above embodiments, the brake control device 10 is applied to a vehicle 90 that includes a regenerative braking device 80 that generates regenerative braking force to be applied to front wheels and rear wheels among wheels. The vehicle may include a regenerative braking device that generates regenerative braking force to be applied to at least one of the front wheels and the rear wheels. Note that "at least one of the front wheel and the rear wheel" means "only the front wheel", "only the rear wheel", or "both the front wheel and the rear wheel".

For example, the brake control device 10 can be applied to a vehicle equipped with a regenerative braking device that generates regenerative braking force to be applied to the rear wheel. An example in which the distribution ratio calculation unit 13 calculates the front-rear distribution ratio n, the front wheel friction regeneration ratio nf, and the rear wheel friction regeneration ratio nr in this case will be described with reference to FIG.

FIG. 8 shows an orthogonal coordinate system in which the horizontal axis represents the front-rear distribution ratio n as the first axis, and the front wheel friction regeneration ratio nf and the rear wheel friction regeneration ratio nr as the second axis, the vertical axis. In FIG. 8, the function of the relational expression (Formula 3) is shown by a solid line. In FIG. 8, the function of the relational expression (Formula 4) is shown by a broken line. Here, since the vehicle is not equipped with a regenerative braking device that generates regenerative braking force to be applied to the front wheels, the front wheel braking force Fxf is equal to the front wheel frictional braking force Fxfb. That is, the front wheel friction regeneration ratio nf is "1". The distribution ratio calculation unit 13 calculates the front-rear distribution ratio n by setting the front wheel friction regeneration ratio nf to "1". That is, the horizontal axis coordinate value "X" of the coordinate (X, 1) on the solid line shown in FIG. 8 is calculated as the front-rear distribution ratio n. The distribution ratio calculation unit 13 calculates a rear wheel friction regeneration ratio nr based on the calculated front-rear distribution ratio n.

As described above, the brake control device 10 can also be applied to a vehicle equipped with a regenerative braking device that generates regenerative braking force to be applied to one of the front wheels and the rear wheel. In this case as well, the pitch angle and bounce amount of the vehicle can be controlled based on the target deceleration DVT, as in the above embodiment. The effect of controlling the attitude of the vehicle in response to deceleration can be obtained.

- In each of the above embodiments, as the distribution ratio calculation process by the distribution ratio calculation unit 13, the regenerative braking force execution value Fxd is acquired and the front and rear distribution ratio n, the front wheel friction regeneration ratio nf, and the rear wheel friction regeneration ratio nr are recalculated. An example was given. If there is no deviation between the regenerative braking force execution value Fxd and the regenerative braking force request value FxdR, the distribution ratio calculation unit 13 recalculates the front and rear distribution ratio n, the front wheel friction regeneration ratio nf, and the rear wheel friction regeneration ratio nr. You may choose not to do so. If the deviation width between the regenerative braking force execution value Fxd and the regenerative braking force request value FxdR is smaller than the prescribed judgment value, the distribution ratio calculation unit 13 calculates the front and rear distribution ratio n, the front wheel friction regeneration ratio nf, and the rear wheel friction The regeneration ratio nr may not be recalculated.

- The distribution ratio calculation unit 13 may acquire the maximum value of the regenerative braking force. The distribution ratio calculation unit 13 uses the maximum value of the regenerative braking force to calculate the front and rear distribution ratio n, the front wheel friction regeneration ratio nf, and the rear wheel friction so that the regenerative braking force request value FxdR is equal to or less than the maximum value of the regenerative braking force. It is also possible to calculate the regeneration ratio nr.

- The posture target calculation unit 12 may have a plurality of calculation maps having different characteristics. The attitude target calculation unit 12 may change the relationship between the deceleration, the pitching attitude, and the sinking attitude by switching the calculation map to be used.

As an example, a case where the first mode and the second mode can be switched will be described. The calculation map in the first mode is the calculation map 12a in the above embodiment illustrated in FIG.

The second mode calculation map has, for example, a smaller slope of the target pitch moment Mreq than the calculation map 12a. That is, the amount of change in the target pitch moment Mreq with respect to the target deceleration DVT is reduced. Furthermore, the second mode calculation map has a smaller slope of the target bounce force Zreq than, for example, the calculation map 12a. That is, the amount of change in the target bounce force Zreq with respect to the target deceleration DVT is increased.

In other words, the calculation map of the first mode is set so as to obtain a larger amount of power generation due to application of regenerative braking force, compared to the calculation map of the second mode. By switching from the first mode to the second mode, for example, the driver can feel the enjoyment of operating the vehicle 90. Preferably, switching between the first mode and the second mode can be selected by the driver.

- The relationship between the deceleration, the pitching attitude, and the sinking attitude may be set so that more regenerative energy can be recovered as the vehicle is braked, as in the first mode. The relationship between the deceleration, the pitching attitude, and the sinking attitude may be set so that the behavior of the vehicle is the one preferred by the driver, as in the second mode.

- The pitching gain calculation unit 112a in the second embodiment may have a plurality of calculation maps having different characteristics. The pitching gain calculation unit 112a may change the relationship between the pitch angle gain KtΘ and the target deceleration DVT by switching the calculation map to be used. Similarly, the sinking gain calculation unit 112b may have a plurality of calculation maps with different characteristics. The sinking gain calculation unit 112b may change the relationship between the bounce amount gain KtZ and the target deceleration DVT by switching the calculation map to be used.

- In each of the embodiments described above, the attitude target calculation units 12 and 112 are configured to calculate a target pitch angle Θreq as a target pitching attitude of the vehicle 90 and a target pitch moment Mreq for achieving the target pitch angle Θreq. The pitching posture target is not limited to the target pitch angle Θreq and the target pitch moment Mreq. For example, a pitch angular velocity target may be employed as the pitching posture target. A pitch angular acceleration target can also be adopted as a pitching posture target. Pitch angular velocity is the rate of change of pitch angle per unit time. Pitch angular acceleration is the rate of change in pitch angular velocity per unit time.

- In each of the above embodiments, the posture target calculation units 12 and 112 are configured to calculate a target bounce amount DZreq as a target for the sinking posture of the vehicle 90 and a target bounce force Zreq for achieving the target bounce amount DZreq. . The target of the sinking posture is not limited to the target bounce amount DZreq and the target bounce force Zreq. For example, a bounce speed target may be adopted as a sinking attitude target. A bounce acceleration target can also be adopted as a sinking attitude target. The bounce speed is the rate of change in the amount of bounces per unit time. Bounce acceleration is the rate of change in bounce speed per unit time.

- The brake control device 10 and the regeneration control device 20, which are the processing circuits in each of the above embodiments, may have any of the configurations [a] to [c] below. [a] A circuit that includes one or more processors that execute various processes according to a computer program. The processor includes a processing device. Examples of processing devices are CPUs, DSPs, GPUs, and the like. The processor includes memory. Examples of memory are RAM, ROM, flash memory, and the like. The memory stores program code or instructions configured to cause the processing device to perform operations. Memory or computer-readable media includes any media that can be accessed by a general purpose or special purpose computer. [b] A circuit that includes one or more hardware circuits that perform various processes. Examples of hardware circuits include ASIC (Application Specific Integrated Circuit), CPLD (Complex Programmable Logic Device), and FPGA (Field Programmable Gate Array). [c] A circuit that includes a processor that executes a part of various processes according to a computer program, and a hardware circuit that executes the remaining processes among the various processes.

- A part or all of the functions realized by the regeneration control device 20 may be realized by the brake control device 10.
- Some of the functions realized by the brake control device 10 may be realized by another processing circuit connected to the brake control device 10.

- In the third embodiment, when the braking force of one of the front wheels and the rear wheels is limited, by adjusting the braking force gradient of the other wheel where the braking force is not limited. An example configured to control the attitude of the vehicle 90 has been shown. Instead of the configuration of the third embodiment, the attitude of the vehicle 90 may be controlled as follows.

For example, when the vehicle 90 is equipped with an active suspension, the attitude of the vehicle 90 is controlled by operating the active suspension when the braking force of either the front wheels or the rear wheels is limited. You can do it like this. In this case, the control for adjusting the front-rear distribution ratio n and the friction regeneration ratio n* based on the attitude target calculated by the attitude target calculation unit may be ended.

DESCRIPTION OF SYMBOLS 10... Brake control device 12, 112... Attitude target calculation part 12a... Calculation map 13... Distribution ratio calculation part 14... Instruction value calculation part 20... Regeneration control device 70... Friction braking device 80... Regenerative braking device 90... Vehicle 91... Vehicle body

Claims (6)

A regenerative braking device that generates a regenerative braking force to be applied to at least one of a front wheel and a rear wheel among the wheels of a vehicle, and a friction that generates a frictional braking force to be applied to the front wheel and a frictional braking force to be applied to the rear wheel. Applicable to vehicles equipped with a braking device,
A brake control device that controls the braking force of the vehicle by operating the regenerative braking device and the friction braking device,
The sum of the braking force applied to the front wheels and the braking force applied to the rear wheels is the vehicle braking force, and the ratio of the braking force applied to the front wheels to the vehicle braking force is the front-rear distribution ratio. For wheels to which regenerative braking force can be applied, the ratio of the frictional braking force applied to the wheel to the braking force applied to the wheel is defined as the friction regeneration ratio,
an attitude target calculation unit that calculates a target pitching attitude of the vehicle and a target sinking attitude of the vehicle based on a target deceleration of the vehicle;
a distribution ratio calculation unit that calculates the longitudinal distribution ratio and the friction regeneration ratio so that the vehicle posture follows the posture indicated by the pitching posture target and the sinking posture target;
an instruction value calculation unit that calculates an instruction value for operating the friction braking device and the regenerative braking device based on the required braking force that is a target of the vehicle braking force, the front-rear distribution ratio, and the friction regeneration ratio. Braking control device. The attitude target calculation unit calculates the pitching attitude target such that the larger the deceleration target is in the direction of decelerating the vehicle, the greater the pitching movement of the vehicle is, and The braking control device according to claim 1, wherein the target of the sinking posture is calculated such that the bouncing motion of the vehicle increases as the vehicle is decelerated. Applied to a vehicle in which the regenerative braking device generates a regenerative braking force to be applied to the front wheels and a regenerative braking force to be applied to the rear wheels,
The friction regeneration ratio is a front wheel friction regeneration ratio as a ratio of the friction braking force applied to the front wheel to the braking force applied to the front wheel,
The ratio of the frictional braking force applied to the rear wheel to the braking force applied to the rear wheel is defined as the rear wheel friction regeneration ratio,
The instruction value calculation unit instructs the operation of the friction braking device and the regenerative braking device based on the required braking force, the front-rear distribution ratio, the front wheel friction regeneration ratio, and the rear wheel friction regeneration ratio. ,
The allocation ratio calculation unit includes:
As a solution of the function indicating the front wheel friction regeneration ratio based on the equation of motion regarding the posture of the vehicle and the function indicating the rear wheel friction regeneration ratio based on the equation of motion, the front and rear distribution ratio, the front wheel friction regeneration ratio, and the It calculates the rear wheel friction regeneration ratio,
A function indicating the front wheel friction regeneration ratio and a function indicating the rear wheel friction regeneration ratio are shown in an orthogonal coordinate system in which the front and rear distribution ratio is set on the first axis and the front wheel friction regeneration ratio and the rear wheel friction regeneration ratio are set on the second axis. The brake control device according to claim 1 or 2, wherein a first axis coordinate value at an intersection with a function is calculated as the front-rear distribution ratio. A pitch increase rate is defined as a rate at which the pitching attitude target changes in a direction in which the pitching motion of the vehicle increases with respect to an increase in the deceleration target in a direction in which the vehicle is decelerated;
A bounce increase rate is defined as a rate at which the target of the sinking posture changes in a direction where the bounce motion of the vehicle increases with respect to an increase in the target deceleration in a direction that decelerates the vehicle;
The posture target calculation unit includes:
The pitching posture target is calculated so that the pitch increase rate when the deceleration target is small is larger than the pitch increase rate when the deceleration target is large;
The braking according to claim 1, wherein the target of the sunken posture is calculated so that the bounce increase rate when the deceleration target is small is smaller than the bounce increase rate when the deceleration target is large. Control device. A frictional braking force is generated in the vehicle by equalizing a pressing force corresponding to the magnitude of the frictional braking force applied to the front wheels and a pressing force corresponding to the magnitude of the frictional braking force applied to the rear wheels. In this case, the rate at which the pitching attitude changes in the direction in which the pitching motion of the vehicle increases with respect to the increase in the deceleration in the direction in which the vehicle is decelerated is defined as a reference pitch rate,
A frictional braking force is generated in the vehicle by equalizing a pressing force corresponding to the magnitude of the frictional braking force applied to the front wheels and a pressing force corresponding to the magnitude of the frictional braking force applied to the rear wheels. In this case, the rate at which the sinking attitude changes in the direction in which the bounce motion of the vehicle increases with respect to the increase in the deceleration in the direction in which the vehicle is decelerated is set as a reference bounce rate,
The posture target calculation unit includes:
When the deceleration target is small, the pitch increase rate is made larger than the reference pitch rate, while when the deceleration target is large, the pitch increase rate is set to be less than or equal to the reference pitch rate. , which calculates the target pitching posture;
When the deceleration target is small, the bounce increase rate is made smaller than the standard bounce rate, while when the deceleration target is large, the bounce increase rate is made equal to or higher than the standard bounce rate. The braking control device according to claim 4, further comprising: calculating a target of the sunken attitude. If one of the front wheels and the rear wheels is slipping, and the other wheel is not slipping,
The brake control device according to claim 1, wherein the gradient of the braking force applied to the other wheel is adjusted so that the attitude of the vehicle follows the attitude indicated by the target pitching attitude.

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