JP6248919B2 - Braking force control device for vehicle - Google Patents

Description

  The present invention relates to a vehicle braking force control device that brakes a wheel by both a regenerative brake by a power generation action of a motor and a friction brake by applying mechanical frictional resistance.

  2. Description of the Related Art Conventionally, vehicles that generate driving force and braking force (called braking / driving force) on wheels by a motor are known. In such a vehicle, a friction braking force generated by bringing a brake pad into contact with a disk (or drum) by hydraulic pressure, and a regenerative system in which a motor driving a wheel acts as a generator to collect and generate generated power in a battery. Use both power to brake the wheels. In general, in order to exhibit the energy recovery effect by regenerative braking, regenerative braking is performed with priority over friction braking.

  A part of the braking / driving force of the wheel is converted into a vertical force of the vehicle body via the suspension. Therefore, in a vehicle equipped with a motor as a braking / driving force source for wheels, the braking / driving force of the motor can be controlled to control the motion state of the vehicle. For example, as proposed in Patent Document 1, in an in-wheel motor type vehicle in which motors are arranged in or near the front and rear wheels, the motor is controlled by powering control or regenerative control of each motor individually. It is possible to control the movement state. In the device proposed in Patent Document 1, the braking / driving force of the wheel is controlled so as to suppress the vertical vibration of the vehicle body.

  Here, the principle that a part of the braking / driving force of the wheel is converted into the vertical force of the vehicle body via the suspension will be described. Each wheel is suspended from the vehicle body by a suspension. In general, as shown in FIG. 2, the instantaneous rotation center Cf of the suspension that connects the front wheel 10f to the vehicle body B is located behind and above the front wheel 10f, and the instantaneous rotation center of the suspension that connects the rear wheel 10r to the vehicle body B. Cr is located in front of and above the rear wheel 10r. Therefore, as shown in FIG. 2A, when driving torque is applied to the front wheel 10f, a forward force Ff1 acts on the grounding point of the front wheel 10f with respect to the traveling direction of the vehicle, and the vehicle body B is directed downward by this force Ff1. A vertical force Fzf1 urging is generated at the ground contact point of the front wheel 10f. Therefore, driving the front wheel 10f causes a force in the direction of sinking the vehicle body B. On the contrary, as shown in FIG. 2B, when braking torque is applied to the front wheel 10f, a backward force Ff2 acts on the ground contact point of the front wheel 10f with respect to the traveling direction of the vehicle, and the vehicle body B is caused by this force Ff2. A vertical force Fzf2 that biases upward is generated at the ground contact point of the front wheel 10f. Therefore, a force in a direction to lift the vehicle body B acts by braking the front wheel 10f.

  On the other hand, with respect to the rear wheel 10r, the vertical force generation direction is opposite to the front wheel 10f. That is, as shown in FIG. 2A, when a driving torque is applied to the rear wheel 10r, a forward force Fr1 acts on the grounding point of the rear wheel 10r with respect to the traveling direction of the vehicle. A vertical force Fzr1 is applied to the grounding point of the rear wheel 10r. Therefore, driving the rear wheel 10r causes a force in a direction to lift the vehicle body B. On the other hand, as shown in FIG. 2B, when braking torque is applied to the rear wheel 10r, a rearward force Fr2 acts on the grounding point of the rear wheel 10r with respect to the traveling direction of the vehicle. A vertical force Fzr2 that urges B downward is generated at the ground contact point of the rear wheel 10r. Therefore, a force in the direction of sinking the vehicle body B acts by braking the rear wheel 10r.

  Therefore, by controlling the braking / driving force of each wheel, vehicle motion control (including vehicle body posture control, for example, suppression of roll motion, pitch motion, heave motion, etc.) can be performed.

JP 2009-173089 A

  By the way, when performing vehicle motion control while braking a wheel using the regenerative braking force of a motor, the problem that the motor of a specific wheel reaches the regenerative capacity limit earlier than the motors of other wheels. There is. Hereinafter, the reason will be described using the example shown in FIG.

  Assume that the angle between the line connecting the ground point of the front wheel 10f and the instantaneous rotation center Cf and the ground horizontal plane is θf, and the angle between the line connecting the ground point of the rear wheel 10r and the instantaneous rotational center Cr and the ground horizontal plane is θr. The magnitude of the vertical force is a value obtained by multiplying the braking / driving force Ff (Ff1 or Ff2) by tan (θf) on the front wheel 10f side, and the braking / driving force Fr (Fr1 or Fr2) on the rear wheel 10r side. A value obtained by multiplying (θr). This tan (θf) or tan (θr) is a conversion rate for converting the braking / driving force into the vertical force of the vehicle body B (referred to as a vertical force conversion rate). In a general vehicle, θr is larger than θf (θf <θr) because of the suspension structure. Therefore, the vertical force conversion rate of the suspension of the front wheel 10f is smaller than that of the rear wheel 10r. For this reason, the control range of the vertical force that can be generated by the regenerative braking force of the motor is narrower on the front wheel 10f than on the rear wheel 10r, and the above problem occurs.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to enable good vehicle motion control during braking of a wheel.

In order to achieve the above object, the features of the present invention are:
A motor (30) that transmits a driving torque and a regenerative braking torque of at least the front and rear wheels independently to the front and rear wheels to generate a braking / driving force on the wheels;
A friction brake device (40, 45) for applying a mechanical friction resistance of at least the front and rear wheels independently to the wheel to generate a braking force on the wheel;
A suspension (20) for connecting the wheel to the vehicle body and capable of converting the driving torque and regenerative braking torque of the motor into force in the vertical direction of the vehicle body;
A required braking force that distributes the total required braking force required for decelerating the vehicle independently to the required regenerative braking force generated by the motor and the required friction braking force generated by the friction brake device. Distribution means (53, S24);
Generated by the motor based on the required regenerative braking force distributed by the required braking force distribution means and the control braking / driving force necessary for vehicle motion control that requires the vertical force of the vehicle body. Motor control means (51, 52, S41) for calculating a target braking / driving force of the wheel and controlling the operation of the motor based on the target braking / driving force;
In a vehicle braking force control device comprising: friction brake control means (53, S28) for controlling the operation of the friction brake device based on the required friction braking force;
The suspension has a conversion rate (tan (θf), tan (θr)) for converting the braking / driving force of the wheel into the vertical force of the vehicle body on the front wheel (10f) side and the rear wheel (10r) side. Configured differently,
The required braking force distribution means is configured such that the wheel connected to the suspension having the smaller conversion rate has a smaller required regenerative braking force than the wheel connected to the suspension having the higher conversion rate. Further, the distribution of the required regenerative braking force and the required friction braking force for each of the front and rear wheels is set.

  The vehicle braking force control device according to the present invention includes a motor that generates a braking / driving force on a wheel by transmitting a driving torque and a regenerative braking torque of at least independent front and rear wheels to front and rear wheels, and at least front and rear wheels. And a friction brake device for generating a braking force on the wheel by applying a mechanical friction resistance having an independent wheel size. Therefore, the wheel can be braked by the regenerative braking force of the motor and the friction braking force of the friction brake device.

  The required braking force distribution means is configured such that the total required braking force required for decelerating the vehicle is divided into a required regenerative braking force generated by a motor and a required friction braking force generated by a friction brake device independently of the front and rear wheels. To distribute. That is, for example, the required braking force distribution means distributes the total required braking force to the front wheel required braking force and the rear wheel required braking force. Further, the required braking force distribution means distributes the front wheel required braking force to the front wheel required regenerative braking force and the front wheel required friction braking force, and the rear wheel required braking force is assigned to the rear wheel required regenerative braking force and the rear wheel required friction braking force. Distribute to power. Of course, the required braking force distribution means does not go through the procedure of distributing the total required braking force to the front wheel required braking force and the rear wheel required braking force, and the front wheel required regenerative braking force, the front wheel required friction braking force, and the rear wheel required regenerative braking force. You may distribute directly to a braking force and a rear-wheel request | requirement friction braking force.

  The motor control means is generated by the motor based on the required regenerative braking force distributed by the required braking force distribution means and the control braking / driving force necessary for vehicle motion control that requires the vertical force of the vehicle body. The target braking / driving force of the wheel to be operated is calculated, and the operation of the motor is controlled based on the target braking / driving force. The friction brake control means controls the operation of the friction brake device based on the required friction braking force.

  Each wheel is connected to the vehicle body by a suspension. The suspension can convert the driving torque and regenerative braking torque of the motor into force in the vertical direction of the vehicle body. Therefore, the vehicle motion can be controlled by controlling the braking / driving torque of the motor. For example, at least one of a pitch motion, a roll motion, a heave motion, and the like of the vehicle can be controlled.

  This suspension is configured so that the conversion rate for converting the braking / driving force of the wheel into the vertical force of the vehicle body (referred to as vertical force) differs between the front wheel side and the rear wheel side. Therefore, in order to generate a vertical force of the same magnitude on the front wheels and the rear wheels, it is necessary to control the wheels connected to the suspension having a low conversion rate compared to the wheels connected to the suspension having a high conversion rate. It is necessary to increase the braking / driving force. For this reason, if the same vertical force is required for wheels having different conversion rates, when the required vertical force increases, the wheel connected to the suspension with the lower conversion rate is controlled. The driving motor reaches the limit of the regenerative capacity before the motor that brakes and drives the wheel connected to the suspension having the higher conversion rate. Such a situation remarkably occurs particularly when the required regenerative braking force for the wheel connected to the suspension having the smaller conversion rate is large.

  Therefore, in the present invention, the required braking force distribution means is such that the required regenerative braking force is smaller for the wheel connected to the suspension with the smaller conversion rate than for the wheel connected to the suspension with the smaller conversion rate. Thus, the distribution of the required regenerative braking force and the required friction braking force is set for each front and rear wheel. The front / rear distribution ratio of the total required braking force is maintained at a desired value by setting the required friction braking force for the front wheels and the required friction braking force for the rear wheels so as to maintain the relationship of the required regenerative power. obtain.

  Therefore, according to the present invention, as the braking / driving force for control required for vehicle motion control that requires the vertical force of the vehicle body increases, the wheel connected to the suspension with the smaller conversion rate is controlled. It is possible to reduce the possibility that the motor to be driven reaches the limit of the regenerative capacity before the motor that brakes and drives the wheel connected to the suspension with the higher conversion rate. As a result, the vehicle motion control capability can be improved.

A feature of one aspect of the present invention is that
The required braking force distribution means is configured such that a surplus force (Fzft, Fzrt) of a vertical force that can be additionally applied to the vehicle body via the suspension by the braking / driving force of the wheels is determined by the front wheel side and the rear wheel side. In other words, the distribution of the required regenerative braking force and the required friction braking force for each of the front and rear wheels is set.

  According to one aspect of the present invention, the surplus force of the vertical force that can be additionally applied to the vehicle body (the vertical force that can be further applied to the vehicle body from the present time) is the front wheel side and the rear wheel side. Is equivalent. Accordingly, the ability of the motor can be effectively used for vehicle motion control on the front wheel side and the rear wheel side, respectively. In other words, the front and rear wheel motors can be used in a balanced manner up to the capacity limit.

One aspect of the present invention is:
The required braking force distribution means distributes the required regenerative braking force only to the wheels connected to the suspension having the higher conversion rate when the total required braking force is less than a preset set value. In addition, the distribution of the required regenerative braking force and the required friction braking force for each of the front and rear wheels is set so that the required friction braking force is distributed only to the wheels connected to the suspension having the smaller conversion rate. There is to do.

  The amount of the vertical force that can be applied to the vehicle body via the suspension by the braking / driving force of the wheels is equalized between the front wheel side and the rear wheel side. When it becomes smaller, it becomes impossible. Therefore, in one aspect of the present invention, when the total required braking force is less than a preset set value, the required regenerative braking force is distributed only to the wheels connected to the suspension having the higher conversion rate. The required friction braking force is distributed only to the wheels connected to the suspension having the smaller conversion rate. Therefore, the remaining force of the vertical force that can be generated by the wheel connected to the suspension with the smaller conversion rate can be maximized. Thereby, when the total required braking force is small, the required regenerative braking force and the required friction braking force can be appropriately distributed for each front and rear wheel, and the vehicle motion control can be performed satisfactorily.

A feature of one aspect of the present invention is that
The motor is provided to drive the front, rear, left and right wheels independently,
The motor control means is configured to calculate a braking / driving force for control necessary for the vehicle motion control for each of the front, rear, left and right wheels.

  According to an aspect of the present invention, since braking / driving force can be generated independently for the left and right front and rear wheels, the vehicle roll motion, pitch motion and heave motion, and yaw motion can be controlled well. Can do.

  In the above description, in order to help the understanding of the invention, the reference numerals used in the embodiments are attached to the configuration of the invention corresponding to the embodiments in parentheses, but each constituent element of the invention is represented by the reference numerals. It is not intended to be limited to the embodiments specified.

1 is a schematic configuration diagram of a vehicle on which a vehicle braking force control device according to an embodiment is mounted. It is a figure showing the relationship between braking / driving force and vertical force. It is an image figure showing the component of required braking force in the case of controlling the yaw motion of vehicles, and a resultant force, (a) is a figure concerning a conventional example and (b) is a figure concerning this embodiment. It is a flowchart showing a drive control routine. It is a flowchart showing a main brake control routine. It is a flowchart showing a regenerative brake control routine. It is a graph showing braking force distribution of front and rear wheels. It is a graph showing the relationship between front wheel required regenerative braking force Fr_f and rear wheel required regenerative braking force Fr_r when equalizing the vertical force surplus force. When the vertical force surplus is equalized, the driver requested braking force Fbreq, the front wheel requested regenerative braking force Fr_f, the front wheel requested friction braking force Ff_f, the rear wheel requested regenerative braking force Fr_r, and the rear wheel requested friction braking force Ff_r It is a graph showing the relationship. It is a graph showing the relationship between front wheel total required braking force Fbf and rear wheel total required braking force Fbr. It is a figure for demonstrating a vehicle motion control range.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 schematically shows the configuration of a vehicle 1 on which the vehicle braking / driving force control device of this embodiment is mounted.

  The vehicle 1 includes a left front wheel 10fl, a right front wheel 10fr, a left rear wheel 10rl, and a right rear wheel 10rr. The left front wheel 10fl, the right front wheel 10fr, the left rear wheel 10rl, and the right rear wheel 10rr are suspended from the vehicle body B by independent suspensions 20fl, 20fr, 20rl, and 20rr, respectively.

  Suspensions 20fl, 20fr, 20rl, and 20rr are connecting mechanisms that connect the vehicle body B and the wheels 10fl, 10fr, 10rl, and 10rr, and include link mechanisms 21fl, 21fr, 21rl, and 21rr composed of suspension arms and the like in the vertical direction. Suspension springs 22fl, 22fr, 22rl, 22rr for supporting the load and shock absorbers 23fl, 23fr, 23rl, 23rr for attenuating vibrations on the springs (vehicle body B). As the suspensions 20fl, 20fr, 20rl, and 20rr, a known four-wheel independent suspension type suspension such as a wishbone type suspension or a strut type suspension can be adopted.

  Motors 30fl, 30fr, 30rl and 30rr are incorporated in the left front wheel 10fl, right front wheel 10fr, left rear wheel 10rl and right rear wheel 10rr, respectively. The motors 30fl, 30fr, 30rl, and 30rr are so-called in-wheel motors, which are arranged under the spring of the vehicle 1 together with the left front wheel 10fl, the right front wheel 10fr, the left rear wheel 10rl, and the right rear wheel 10rr, respectively, and the motor torque is left. The front wheel 10fl, the right front wheel 10fr, the left rear wheel 10rl, and the right rear wheel 10rr are communicably connected. In the vehicle 1, by independently controlling the rotation of each motor 30fl, 30fr, 30rl, 30rr, the driving force generated on the left front wheel 10fl, the right front wheel 10fr, the left rear wheel 10rl, and the right rear wheel 10rr and The braking force can be controlled independently.

  The left front wheel 10fl, the right front wheel 10fr, the left rear wheel 10rl, and the right rear wheel 10rr are provided with friction brake mechanisms 40fl, 40fr, 40rl, 40rr. The friction brake mechanisms 40fl, 40fr, 40rl, and 40rr include a brake disc rotor 41fl, 41fr, 41rl, and 41rr that rotates together with the left front wheel 10fl, the right front wheel 10fr, the left rear wheel 10rl, and the right rear wheel 10rr, and a wheel cylinder (not shown) by hydraulic pressure. Is operated, and brake calipers 42fl, 42fr, 42rl, 42rr for pressing the brake pads against the brake disc rotors 41fl, 41fr, 41rl, 41rr are provided.

  Regarding the configuration provided for each wheel, the sign of the left front wheel is fl, the left front wheel is fr, the left rear wheel is rr, and the right rear wheel is rl. In the explanation of, the last symbol is attached only when it is necessary to specify the wheel position. Further, when it is necessary to specify the front wheel and the rear wheel, “f” is attached to the end of the code and “r” is attached to the rear wheel. In the drawing, a code for specifying a wheel position is attached to the end.

  In the configuration (geometry) of the suspension 20 of the present embodiment, as shown in FIG. 2, the angle (smaller angle) formed by the line connecting the ground contact point of the front wheel 10f and the instantaneous rotation center Cf and the ground horizontal plane is θf. When the angle (smaller angle) formed by the line connecting the grounding point of the rear wheel 10r and the instantaneous rotation center Cr and the ground horizontal plane is θr, θr is larger than θf (θf < θr). Therefore, the vertical force conversion rate of the suspension 20f of the front wheel 10f is smaller than the vertical force conversion rate of the suspension 20r of the rear wheel 10r. Hereinafter, θf and θr are referred to as instantaneous rotation center angles.

  As shown in FIG. 2, the magnitude of the vertical force acting on the vehicle body B is a value obtained by multiplying the braking / driving force Ff1 (or Ff2) by tan (θf) on the front wheel 10f side and braking / driving on the rear wheel 10r side. The force Fr1 (or Fr2) is multiplied by tan (θr). The vertical force conversion rate for converting the braking / driving force into the vertical force of the vehicle body B is represented by tan (θf) and tan (θr). The vertical force conversion rate is determined by the positions of the instantaneous rotation centers Cf and Cr. The instantaneous rotation centers Cf and Cr are determined by the suspension 20 (mainly the link mechanism 21).

  Each motor 30 is, for example, a brushless motor. Each motor 30 is connected to a motor driver 35. The motor driver 35 is, for example, an inverter, and four sets are provided so as to correspond to each motor 30. The motor driver 35 converts the DC power supplied from the battery 70 into AC power, and the AC power is independent of each motor 30. And supply. Accordingly, each motor 30 is independently driven and controlled to generate torque, and apply driving force to each wheel 10. Thus, supplying electric power to the motor 30 to generate driving torque is referred to as power running.

  Each motor 30 also functions as a generator, and can generate electric power by the rotational energy of each wheel 10 and regenerate the generated power to the battery 70 via the motor driver 35. The braking torque generated by the power generation of the motor 30 gives a braking force to the wheel 10. Hereinafter, when it is not necessary to distinguish between the driving force and the braking force, they are referred to as braking / driving force, and when it is necessary to specify the driving force, the driving force and the braking force. When it is necessary to specify this, it is called a braking force.

  Each friction brake mechanism 40 is connected to a brake actuator 45. The brake actuator 45 is an actuator that adjusts the hydraulic pressure supplied to the wheel cylinder built in the friction brake mechanism 40. Since such a brake actuator 45 is well-known and will not be described in detail, for example, a hydraulic circuit that supplies hydraulic pressure to the wheel cylinder of the friction brake mechanism 40, a master cylinder that pressurizes hydraulic oil by the depression force of the brake pedal, and a booster pump Power hydraulic pressure generator that generates high-pressure hydraulic pressure regardless of the brake pedal depression force, a linear control valve that adjusts the hydraulic pressure output from the power hydraulic pressure generator to control the target hydraulic pressure, and the wheel cylinder of each wheel independently. An open / close control valve for opening and closing a hydraulic circuit for supplying hydraulic pressure, a hydraulic sensor for detecting the hydraulic pressure of the hydraulic circuit, and the like.

  By providing such a configuration, the brake actuator 45 is configured to be able to independently control the friction brake mechanism 40f of the front wheel 10f and the friction brake mechanism 40r of the rear wheel 10r. That is, the front and rear wheels 10f and 10r are configured to be able to generate independent friction braking forces. As such a brake actuator 45, for example, a type having a linear control valve capable of independently controlling the wheel cylinder pressure of the left and right front and rear wheels 10 (Japanese Patent Laid-Open No. 2014-19247) can be applied.

  The motor driver 35 and the brake actuator 45 are connected to the integrated electronic control unit 50. The integrated electronic control unit 50 (hereinafter referred to as an integrated ECU 50) includes a power management ECU 51, a motor ECU 52, and a brake ECU 53. The power management ECU 51 (hereinafter referred to as the power ECU 51) is connected to the motor ECU 52 and the brake ECU 53 so as to communicate with each other. The integrated ECU 50 (power ECU 51, motor ECU 52, and brake ECU 53) includes a microcomputer including a CPU, a ROM, a RAM, and the like as a main part, and executes various programs to control the operation of the motor 30 and the friction brake mechanism 40. To do.

  The integrated ECU 50 connects an operation state detection device 60 that detects an operation state operated by the driver to drive the vehicle, and a motion state detection device 65 that detects the motion state of the vehicle, and detects these detection devices 60 and 65. The detection signal output from is input.

  The operation state detection device 60 is an accelerator sensor that detects the driver's accelerator operation amount from the accelerator pedal depression amount (or angle, pressure, etc.), and the driver's brake operation from the brake pedal depression amount (or angle, pressure, etc.). It includes a brake sensor that detects the amount, a steering angle sensor that detects a steering operation amount by which the driver has operated the steering handle, a shift position sensor that detects a shift position, and the like. The motion state detection device 65 is a wheel speed sensor that detects a wheel speed that is the rotational speed of each wheel 10, and a vehicle speed sensor that calculates and detects a vehicle speed that is the traveling speed of the vehicle body B based on the wheel speeds of the four wheels. A yaw rate sensor that detects the yaw rate of the vehicle body B, a sprung acceleration sensor that detects vertical acceleration of the vehicle body B (on the spring) at each wheel position, a lateral acceleration sensor that detects lateral acceleration of the vehicle body B in the left-right direction, and the vehicle body B A pitch rate sensor for detecting the pitch rate of the vehicle body B, a roll rate sensor for detecting the roll rate of the vehicle body B, a stroke sensor for detecting the stroke amount of each suspension 20, and a spring for detecting the vertical acceleration in the vertical direction below the spring of each wheel 10. Includes a bottom acceleration sensor. In addition, about the sensor value containing a direction element, a direction is identified by the code | symbol. When discussing the magnitude of the sensor value, the absolute value of the sensor value is used.

  The power ECU 51 mainly monitors the processing for calculating the target control amount of each motor 30, the state of charge (SOC) of the battery 70, the terminal voltage of the battery, the current flowing through the battery, the temperature of the battery, and the like. Responsible for processing. The target control amount of each motor 30 is limited according to the state of the battery 70. The power ECU 51 transmits the calculated target control amount of each motor 30 to the motor ECU 52.

  The motor ECU 52 is in charge of processing for controlling energization of each motor 30 based on the target control amount of each wheel 10 transmitted from the power ECU 51.

  The brake ECU 53 transmits the target control amount for the braking force applied to each wheel 10 separately to the regenerative control amount by regenerative braking and the friction control amount by friction braking, and transmits the target control amount for regenerative braking to the power ECU 51. And processing for controlling the operation of the brake actuator 45 based on the target control amount related to friction braking.

  Next, processing of the power ECU 51 at the time of accelerator operation will be described. FIG. 4 is a flowchart showing a drive control routine executed by the power ECU 51. When the power ECU 51 has not received a regenerative braking request from the brake ECU 53, the power ECU 51 repeatedly executes the drive control routine at a predetermined calculation cycle.

  When this routine is started, the power ECU 51 detects a driver operation state and a vehicle motion state in step S11. In this case, the power ECU 51 acquires the accelerator operation amount and the steering operation amount obtained from the sensor value of the operation state detection device 60, the vehicle speed obtained from the sensor value detected by the motion state detection device 65, and the vehicle body B. The motion state quantity representing the degree of the motion state (yaw motion, roll motion, pitch motion, heave motion) is acquired.

  Subsequently, in step S12, the power ECU 51 calculates a driver request driving force Fareq based on the accelerator operation amount. The driver-requested driving force Fareq is a driving force in the vehicle front-rear direction that should be generated by the entire vehicle requested by the driver, that is, a driving force for driving (a force that increases the rotational speed of the wheels 10). The power ECU 51 stores association data such as a map for deriving the driver requested driving force Fareq from the accelerator operation amount, and calculates the driver requested driving force Fareq using this association data. For example, the driver required driving force Fareq is set to a value that increases as the accelerator operation amount (accelerator opening degree or the like) increases.

  Subsequently, in step S13, the power ECU 51 controls the control braking / driving force Fcfl for the left front wheel 10fl, the control braking / driving force Fcfr for the right front wheel 10fr, and the left rear wheel, which are control amounts necessary for performing vehicle motion control. The control braking / driving force Fcrl for 10 rl and the control braking / driving force Fcrr for the right rear wheel 10 rr are calculated. Hereinafter, the control braking / driving forces Fcfl, Fcfr, Fcrl, and Fcrr for the four wheels are collectively referred to as the control braking / driving force Fcx when it is not necessary to distinguish the corresponding wheels 10.

  In vehicle motion control, when the deviation between the ideal yaw rate and the actual yaw rate detected by the yaw rate sensor exceeds the allowable value, or at least one of the roll state amount, the pitch state amount, and the heave state amount exceeds the allowable value. It is executed in the case where Therefore, when it is not necessary to execute vehicle motion control, the control braking / driving force Fcx is set to zero.

  For example, the control braking / driving force Fcx of each wheel 10 includes a target roll moment Mx that suppresses the roll motion of the vehicle body B around the longitudinal axis (roll axis) passing through the center of gravity Cg of the vehicle, and the left and right passing through the center of gravity Cg of the vehicle. A target pitch moment My that suppresses the pitch motion of the vehicle body B around the direction axis (pitch axis), a target yaw moment Mz that turns the vehicle about the vertical axis (yaw axis) passing through the center of gravity Cg of the vehicle, and the center of gravity of the vehicle The calculation is performed using the target heave force Fz that suppresses the heave motion (bouncing) that is the vertical motion at the Cg position. For the calculation of these target values, various known calculation methods can be employed.

  For example, the power ECU 51 detects the position, speed, and acceleration in the vertical direction at the four-wheel position from the sensor values detected by the stroke sensor and the sprung vertical acceleration sensor, and determines the roll state amount, the pitch state amount, and the heave state amount. The target roll moment Mx, the target pitch moment My, and the target heave force Fz, which have a predetermined relationship with the detected state quantity, are calculated so as to cancel these movements. Further, the power ECU 51 calculates a target yaw moment Mz set so as to eliminate the deviation based on the deviation between the ideal yaw rate set based on the steering angle and the vehicle speed and the actual yaw rate detected by the yaw rate sensor. .

ここで、ｔfは、左右前輪１０fのトレッド幅、ｔrは、左右後輪１０rのトレッド幅を表す。Ｌfは、車両の重心Ｃｇと左右前輪１０fの中心との間の前後方向水平距離、Ｌrは、車両の重心Ｃｇと左右後輪１０rの中心との間の前後方向水平距離を表す。 For example, the power ECU 51 calculates the control braking / driving forces Fcfl, Fcfr, Fcrl, and Fcrr by the following equations.

Here, tf represents the tread width of the left and right front wheels 10f, and tr represents the tread width of the left and right rear wheels 10r. Lf represents the front-rear horizontal distance between the center of gravity Cg of the vehicle and the center of the left and right front wheels 10f, and Lr represents the front-rear direction horizontal distance between the center of gravity Cg of the vehicle and the center of the left and right rear wheels 10r.

  In this case, the motor ECU 52 selects three of the target roll moment Mx, the target pitch moment My, the target yaw moment Mz, and the target heave force Fz to calculate the control braking / driving forces Fcfl, Fcfr, Fcrl, Fcrr. . This is because the braking / driving force to be finally generated on each wheel 10 is determined by the driver requested driving force Fareq, that is, the restriction that the total value of the control braking / driving forces Fcfl, Fcfr, Fcrl, Fcrr is zero. This is because the calculation cannot be performed using four target values at the same time. In this case, when the yaw motion control is required, the motor ECU 52 preferentially selects the target yaw moment Mz and the target roll moment Mx, the two target values Mz and Mx, and the remaining target pitch moment My. The control braking / driving forces Fcfl, Fcfr, Fcrl, Fcrr are calculated using any one of the target values of the target heave force Fz.

Subsequently, in step S14, the power ECU 51 sets the target braking / driving force Ffl of the left front wheel 10fl, the target braking / driving force Ffr of the right front wheel 10fr, the target braking / driving force Frl of the left rear wheel 10rl, and the target braking / driving of the right rear wheel 10rr. The force Frr is calculated by the following equation.
Ffl = αf · Freq + Fcfl
Ffr = αf · Fareq + Fcfr
Frl = αr · Freq + Fcrl
Frr = αr · Freq + Fcrr
Here, αf represents a distribution ratio in which the driver required driving force Fareq is distributed to one wheel of the front wheel 10f, and αr represents a distribution ratio in which the driver required driving force Fareq is distributed to one wheel of the rear wheel 10r ( 2αf + 2αr = 1). The front and rear wheel distribution ratios αf and αr may be set to the same value (= 1/4) for both the front and rear wheels 10f and 10r, or may be set to be different between the front wheel 10f and the rear wheel 10r. Hereinafter, the four-wheel target braking / driving forces Ffl, Ffr, Frl, and Frr are collectively referred to as the target braking / driving force Fx when it is not necessary to distinguish the corresponding wheels 10.

  Subsequently, in step S15, the power ECU 51 converts the target braking / driving force Fx for each wheel 10 into a target motor torque Tx for driving the motor 30, and generates a braking / driving command signal representing the target motor torque Tx as a motor ECU 52. Send to. Thus, the motor ECU 52 outputs a control signal (for example, a PWM control signal) generated so that the motor 30 generates the target torque in accordance with the target motor torque Tx to the motor driver 35. Thus, the duty ratio of the switching element of the motor driver 35 is controlled, a current corresponding to the target torque flows to the motor 30, and braking / driving force is generated on the wheel 10.

  When the target motor torque Tx represents the drive torque, the motor 30 is power-running and a current flows from the motor driver 35 to the motor 30. When the target motor torque Tx represents the braking torque, the motor 30 is regeneratively controlled and a current flows from the motor 30 to the battery 70 via the motor driver 35. Thus, a braking / driving force equivalent to the target braking / driving force Fx is generated on each wheel 10. The total braking / driving force of each wheel 10 is a value corresponding to the driver-requested driving force Fareq.

  When the power ECU 51 transmits a braking / driving command signal to the motor ECU 52, the power ECU 51 once ends the drive control routine. Then, the drive control routine is repeated at a predetermined short cycle.

  Next, processing during brake operation will be described. FIG. 5 is a flowchart showing a main brake control routine executed by the brake ECU 53, and FIG. 6 is a flowchart showing a regenerative brake control routine executed by the power ECU 51. The brake ECU 53 repeatedly executes the main brake control routine at a predetermined calculation cycle while the brake pedal operation is being performed. Further, the power ECU 51 repeatedly executes the regenerative brake control routine at a predetermined calculation cycle while receiving the regenerative braking request from the brake ECU 53.

  When the main brake control routine is activated, the brake ECU 53 detects the driver operation state and the vehicle motion state in step S21. In this case, the brake ECU 53 acquires the brake operation amount obtained from the sensor value of the operation state detection device 60 and the vehicle speed and wheel speed obtained from the sensor value of the motion state detection device 65.

  Subsequently, in step S22, the brake ECU 53 calculates a target deceleration of the vehicle based on the brake operation amount. The brake ECU 53 stores association data for deriving the target deceleration from the brake operation amount, and calculates the target deceleration based on the association data. Subsequently, in step S23, the brake ECU 53 calculates a driver-requested braking force Fbreq of the wheel 10 necessary for decelerating the vehicle at the target deceleration. The driver required braking force Fbreq corresponds to the total required braking force of the present invention.

  Subsequently, in step S24, the brake ECU 53 distributes the driver requested braking force Fbreq to the regenerative braking force and the friction braking force for each of the front and rear wheels, the front wheel requested regenerative braking force Fr_f, the front wheel requested friction braking force Ff_f, and the rear wheel. The required regenerative braking force Fr_r and the rear wheel required friction braking force Ff_r are calculated. These front wheel required regenerative braking force Fr_f, front wheel required regenerative braking force Ff_f, rear wheel required regenerative braking force Fr_r, and rear wheel required regenerative braking force Ff_r are set to values for two left and right wheels, respectively. (The left and right side wheels are half the value.) The symbol “r” following the symbol F represents the initial of regenerative, and the symbol “f” represents the initial of friction. Further, the symbol “f” that follows these symbols represents the initial of front, and the symbol “r” represents the initial of rear.

  Since the arithmetic processing in step S24 relates to the characteristic part of the present invention, it will be described in detail after the entire description of this routine.

  In step S24, the brake ECU 53 calculates the front wheel required regenerative braking force Fr_f, the front wheel required regenerative braking force Ff_f, the rear wheel required regenerative braking force Fr_r, and the rear wheel required regenerative braking force Ff_r. The power Fr_f and the rear wheel required regenerative braking force Fr_r are transmitted to the power ECU 51. When receiving the front wheel required regenerative braking force Fr_f and the rear wheel required regenerative braking force Fr_r, the power ECU 51 executes a regenerative brake control routine shown in FIG.

When the regenerative brake control routine is activated, the power ECU 51 calculates the target braking / driving force Fx of the left and right front and rear wheels in step S41. The power ECU 51 uses the front wheel required regenerative braking force Fr_f, the rear wheel required regenerative braking force Fr_r, and the control braking / driving force Fcx to target the target braking / driving force Ffl of the left front wheel 10fl and the target braking / driving force Ffr of the right front wheel 10fr. , The target braking / driving force Frl of the left rear wheel 10rl and the target braking / driving force Frr of the right rear wheel 10rr are calculated by the following equations. In this case, the front wheel required regenerative braking force Fr_f and the rear wheel required regenerative braking force Fr_r are equally divided between the left and right wheels. In step S41, the power ECU 51 calculates the control braking / driving force Fcx as described above (S13).
Ffl = Fcfl−Fr_f / 2
Ffr = Fcfr−Fr_f / 2
Frl = Fcrl−Fr_r / 2
Frr = Fcrr−Fr_r / 2

  Subsequently, in step S42, the power ECU 51 converts the target braking / driving force Fx for each wheel 10 into a target motor torque Tx for driving the motor 30, and generates a braking / driving command signal representing the target motor torque Tx as a motor ECU 52. Send to. Thereby, the motor ECU 52 outputs a drive signal to the motor driver 35 in accordance with the target motor torque Tx. When the target motor torque Tx represents the drive torque, the motor 30 is power-running and a current flows from the motor driver 35 to the motor 30. When the target motor torque Tx represents the braking torque, the motor 30 is regeneratively controlled and a current flows from the motor 30 to the battery 70 via the motor driver 35. Thus, a braking / driving force equivalent to the target braking / driving force Fx is generated on each wheel 10.

  Subsequently, in step S43, the power ECU 51 executes the effective regenerative braking force that is actually generated in the four wheels (the left front wheel effective regenerative braking force Fr_fl_real, the right front wheel effective regenerative braking force Fr_fr_real, the left rear wheel effective regenerative regeneration). The braking force Fr_rl_real and the right rear wheel execution regenerative braking force Fr_rr_real) are transmitted to the brake ECU 53, and the regenerative brake control routine is temporarily terminated. The power ECU 51 repeatedly executes the regenerative brake control routine while receiving the regenerative braking request from the brake ECU 53.

Referring to FIG. 5 again, in step S26, the brake ECU 53 performs the execution regenerative braking force (left front wheel execution regenerative braking force Fr_fl_real, right front wheel execution regenerative braking force Fr_fr_real, left rear wheel execution regenerative control) transmitted from the power ECU 51 in step S26. Power Fr_rl_real, right rear wheel execution regenerative braking force Fr_rr_real) are received. Subsequently, in step S27, the brake ECU 53 determines the difference ΔFr between the required regenerative braking force and the effective regenerative braking force for each of the four wheels (Fr_f / 2−Fr_fl_real, Fr_f / 2−Fr_fr_real, Fr_r / 2−Fr_rl_real, Fr_r / 2). -Fr_rr_real) is calculated. Then, using this difference ΔFr as a correction value, this correction value is calculated based on the required friction braking force of each wheel (left front wheel required friction braking force Ff_f / 2, right front wheel required friction braking force Ff_f / 2, left rear wheel required friction damping). Power Ff_r / 2, right rear wheel required friction braking force Ff_r / 2), corrected left front wheel required friction braking force Ff_fl *, corrected right front wheel required friction braking force Ff_fr *, corrected left rear wheel required friction The braking force Ff_rl * and the corrected right rear wheel required friction braking force Ff_rr * are calculated.
Ff_fl * = Ff_f / 2 + (Fr_f / 2−Fr_fl_real)
Ff_fr * = Ff_f / 2 + (Fr_f / 2−Fr_fr_real)
Ff_rl * = Ff_r / 2 + (Fr_r / 2−Fr_rl_real)
Ff_rr * = Ff_r / 2 + (Fr_r / 2−Fr_rr_real)

  Subsequently, in step S28, the brake ECU 53 corrects the left front wheel required friction braking force Ff_fl *, the corrected right front wheel required friction braking force Ff_fr *, the corrected left rear wheel required friction braking force Ff_rl *, and the corrected right rear wheel. Based on the required friction braking force Ff_rr *, the operation of the brake actuator 45 is controlled. The brake ECU 53 stores association data for setting the relationship between the control hydraulic pressure of the hydraulic circuit and the friction braking force, and using this association data, the corrected left front wheel required friction braking force Ff_fl *, the corrected right front wheel request A target control hydraulic pressure for each of the four wheels necessary to generate the friction braking force Ff_fr *, the corrected left rear wheel required friction braking force Ff_rl *, and the corrected right rear wheel required friction braking force Ff_rr * is set. The brake ECU 53 controls energization of the linear control valve so that the wheel cylinder pressure of the left and right front and rear wheels 10 detected by the hydraulic sensor follows the target control hydraulic pressure. As a result, the friction brake mechanism 40 is actuated to brake each wheel 10 with a frictional force.

  The brake ECU 53 once ends the main brake control routine when executing the process of step S28. The brake ECU 53 repeats the main brake control routine at a predetermined calculation cycle.

  Thereby, the wheel 10 is braked by the regenerative braking force generated by the power recovery of the motor 30 and the friction braking force generated by the frictional resistance of the friction brake mechanism 40.

  Next, the calculation process in step S24 will be described. Step S24 distributes the driver required braking force Fbreq to the regenerative braking force and the friction braking force for each of the front and rear wheels, the front wheel required regenerative braking force Fr_f, the front wheel required friction braking force Ff_f, the rear wheel required regenerative braking force Fr_r, and the rear This is a process of calculating the wheel required friction braking force Ff_r. As described above, the instantaneous rotation center angles θf and θr are different between the suspension 20f of the front wheel 10f and the suspension 20r of the rear wheel 10r (θf <θr). For this reason, the vertical force conversion rate of the suspension 20f of the front wheel 10f is smaller than that of the suspension 20r of the rear wheel 10r (tan (θf) <tan (θr)). Therefore, if the vertical force required for the front wheel 10f and the rear wheel 10r is equal to each other and the required vertical force increases, the front wheel connected to the suspension 20f on the side with the smaller vertical conversion rate. The motor 30f for braking / driving 10f reaches the limit of the regenerative capacity earlier than the motor 30r for driving the rear wheel 10r connected to the suspension 20r on the side with the higher vertical conversion rate.

  Therefore, in step S24, when the driver required braking force Fbreq is distributed to the required friction braking force and the required regenerative braking force, the wheel 10 (in this embodiment, the front wheel) connected to the suspension 20f on the side with the smaller vertical force conversion rate. 10f), the required regenerative braking force is set to be smaller than that of the wheel 10 (rear wheel 10r in the present embodiment) connected to the suspension 20r on the side with the larger vertical force conversion rate. In the present embodiment, the remaining force of the vertical force (vertical force) that can be additionally applied to the vehicle body B via the suspension 20 by the braking / driving force of the wheel 10 is the same for the front wheel 10f and the rear wheel 10r. Then, the distribution of the required friction braking force and the required regenerative braking force is determined.

Here, the sign used for the calculation is defined as follows. In the following, the symbols already described are also defined again. The front wheel braking force and the rear wheel braking force will be described as the total braking force of both the left and right wheels (two wheels). It should be noted that the braking force of the front wheels and the braking force of the rear wheels are the same when considered as the values of the left and right side wheels (one wheel). In this case, the following driver required braking force is Fbreq / 2. Become.
Required regenerative braking force for front wheels: Fr_f
Required friction braking force for front wheels: Ff_f
Required regenerative braking force of rear wheel: Fr_r
Required friction braking force of rear wheel: Ff_r
Total required braking force of front wheels: Fbf (= Fr_f + Ff_f)
Rear wheel total required braking force: Fbr (= Fr_r + Ff_r)
Distribution ratio between the required regenerative braking force and the required friction braking force at the front wheels: (Kr_f: Kf_f)
(Kr_f + Kf_f = 1)
Distribution ratio between required regenerative braking force and required friction braking force at the rear wheel: (Kr_r: Kf_r)
(Kr_r + Kf_r = 1)
Brake force distribution ratio in front and rear wheels: (front wheel side K_f: rear wheel side K_r)
(K_f + K_r = 1)
Driver required braking force: Fbreq (= Fbf + Fbr)

The required regenerative braking force at the front wheel 10f is calculated by the following equation.
Fr_f = Fbreq × K_f × Kr_f
The required regenerative braking force at the rear wheel 10r is calculated by the following equation.
Fr_r = Fbreq × K_r × Kr_r
The required friction braking force at the front wheel 10f is calculated by the following equation.
Ff_f = Fbreq × K_f × Kf_f
The required friction braking force at the rear wheel 10r is calculated by the following equation.
Ff_r = Fbreq × K_r × Kf_r

  The braking force distribution ratio (K_f: K_r) in the front and rear wheels is set according to the magnitude of the driver required braking force Fbreq, for example, as shown in FIG. FIG. 7B shows a relationship between the front wheel total required braking force Fbf and the rear wheel total required braking force Fbr. As can be seen from this figure, the braking force distribution ratio characteristics of the front and rear wheels are set such that the front wheel braking force distribution ratio K_f increases and the rear wheel braking force distribution ratio K_r decreases as the driver required braking force Fbreq increases. Has been.

1. Assuming that the maximum regenerative braking force that can be generated by the front wheel 10f and the rear wheel 10r is Fmmax, assuming that the maximum generated torques of the motor 30f of the front wheel 10f and the motor 30r of the rear wheel 10r are equal, the front wheel 10f additionally The vertical force remaining force Fzft that can be applied to the vehicle body and the vertical force remaining force Fzrt that can be additionally applied to the vehicle body by the rear wheel 10r can be expressed by the following equations.
Fzft = (Fmmax−Fr_f) · tan (θf)
Fzrt = (Fmmax−Fr_r) · tan (θr)
In this case, since Fr_f and Fr_r are handled as braking forces for two left and right wheels, Fmmax is also set for two left and right wheels.

2. Equalization of vertical force surplus force If the front wheel side vertical force surplus force Fzft is equal to the rear wheel side vertical force surplus force Fzrt, it is specified in vehicle motion control (vehicle roll motion, pitch motion and heave motion) that requires vertical force. Only the wheel 10 (the front wheel 10f in this embodiment) can be prevented from reaching the regenerative braking limit (the maximum value of the force that can be generated by the motor) first. Therefore, it is defined as:
Fzft = Fzrt
From this equation, the relationship between the front wheel required regenerative braking force Fr_f and the rear wheel required regenerative braking force Fr_r is derived. Here, tan (θr) / tan (θf) is Θ.
(Fmmax−Fr_f) · tan (θf) = (Fmmax−Fr_r) · tan (θr)
Fmmax−Fr_f = (Fmmax−Fr_r) · Θ
When this equation is solved, the rear wheel required regenerative braking force Fr_r can be expressed as a linear function of the front wheel required regenerative braking force Fr_f as in the following equation (1).
Fr_r = {(Θ−1) / Θ} · Fmmax + (1 / Θ) · Fr_f (1)

3. Specific Distribution FIG. 8 is a graph showing the above formula (1). The rear wheel required regenerative braking force Fr_r at point A can be expressed by the following equation.
Fr_r = {(Θ−1) / Θ} · Fmmax = Fbreq · K_r
Accordingly, when the required regenerative braking force is distributed to the front wheels 10f and the rear wheels 10r, if the driver required braking force Fbreq is smaller than (1 / K_r) · {(Θ−1) / Θ} · Fmmax, the front wheels The side vertical force residual force Fzft and the rear wheel side vertical force residual force Fzrt cannot be made equal. In this case, if the distribution characteristic of moving on a line connecting point A from point 0 in FIG. 8 is set, the front wheel side vertical force residual force Fzft and the rear wheel side vertical force residual force Fzrt are closest to each other. It becomes.

Therefore, when the driver-requested braking force Fbreq is smaller than (1 / K_r) · {(Θ-1) / Θ} · Fmmax, the brake ECU 53 determines the friction braking forces Ff_f and Ff_r for the front and rear wheels as follows. Regenerative braking forces Fr_f and Fr_r are set.
Front wheel required regenerative braking force Fr_f = 0
Front wheel required friction braking force Ff_f = Fbreq · K_f
Rear wheel required regenerative braking force Fr_r = Fbreq · K_r
Rear wheel required friction braking force Ff_r = 0

  Accordingly, when the driver-requested braking force Fbreq is smaller than (1 / K_r) · {(Θ−1) / Θ} · Fmmax, the braking force is generated only by the friction braking force for the front wheel 10f, and the rear wheel 10r. With respect to, the regenerative / friction braking force distribution is set so that the braking force is generated only by the regenerative braking force.

  Further, when the driver required braking force Fbreq is equal to or greater than (1 / K_r) · {(Θ−1) / Θ} · Fmmax, the front wheel side vertical force residual force Fzft and the rear wheel side vertical force residual force Fzrt are made equal. be able to. In this case, the front wheel required regenerative braking force Fr_f and the rear wheel required regenerative braking force Fr_r may be set so as to satisfy the relational expression expressed by the above formula (1). The front wheel required friction braking force Ff_f is set to a value obtained by subtracting the front wheel required regenerative braking force Fr_f from the front wheel total required braking force Fbf (= Fbreq · K_f), and the rear wheel required friction braking force Ff_r is set to the rear wheel total required braking force Ff_r. A value obtained by subtracting the rear wheel required regenerative braking force Fr_r from the braking force Fbr (= Fbreq · K_r) may be set.

  FIG. 9 shows the driver required braking force Fbreq, the front wheel required regenerative braking force Fr_f, the front wheel required friction braking force Ff_f, the rear wheel required regenerative braking force Fr_r, and the rear wheel required friction braking force Ff_r obtained by the above calculation. Represents the relationship. The brake ECU 53 stores the relational expression shown in FIG. 9 or data such as a map. In step S24, the brake ECU 53 uses the data to request the front wheel required regenerative braking force Fr_f, the front wheel required friction braking force Ff_f, The rear wheel required regenerative braking force Fr_r and the rear wheel required friction braking force Ff_r are calculated. In this case, as shown in FIG. 10, the front wheel total required braking force Fbf and the rear wheel total required braking force Fbr are maintained in the distribution characteristic (K_f: K_r).

  According to the vehicle braking control apparatus of the present embodiment described above, the required regenerative braking force in the driver required braking force has a vertical conversion rate higher than that of the rear wheel 10r connected to the suspension 20r on the side where the vertical conversion rate is large. The distribution of the required regenerative braking force and the required friction braking force for each of the front and rear wheels is set so that the front wheel 10f connected to the smaller suspension 20f is smaller. Accordingly, as the control braking / driving force Fcx required for the vehicle motion control that requires the vertical force of the vehicle body increases, the motor 30f of the front wheel 10f has a regenerative capacity before the motor 30r of the rear wheel 10r. The possibility of reaching the limit can be reduced.

  For example, as shown in FIG. 11, the front wheel 10f with the smaller up / down conversion rate is braked with a friction braking force, and the rear wheel 10r with the larger up / down conversion rate is braked with a regenerative braking force. The control braking / driving force Fcx can be generated within a range where the maximum braking / driving force Fmmax of 30f can be fully used. Therefore, the vehicle motion control capability can be improved. Here, the maximum braking / driving force Fmmax represents the maximum braking force that can be generated by the regenerative torque of the motor 30, and the driving force having the same magnitude (absolute value) as the maximum braking force.

  Further, in the present embodiment, the required friction braking force and the required regenerative braking force are distributed so that the remaining force of the vertical force that can be generated in the vehicle body B is equal between the front wheel 10f and the rear wheel 10r. To decide. Therefore, the ability of the motor 30 can be effectively used for vehicle motion control that requires the vertical force of the vehicle body on the front wheel 10f side and the rear wheel 10r side, respectively. That is, the motor 30 of the specific wheel 10 can be reduced from reaching the capacity limit first, and the motors 30 of the front, rear, left and right wheels 10 can be used up to the capacity limit with good balance.

  Further, when the remaining force of the vertical force that can be generated in the vehicle body B cannot be made equal between the front wheel 10f and the rear wheel 10r, that is, the driver requested braking force Fbreq is a set value ((1 / K_r)) · { (Θ-1) / Θ} · Fmmax), the total required braking force distributed to the front wheels 10f is set as the friction braking force. Therefore, the remaining force of the vertical force that can be generated on the front wheel 10f side can be maximized. As a result, even when the driver-requested braking force Fbreq is small, vehicle motion control that requires a force in the vertical direction of the vehicle body can be satisfactorily performed.

  Now consider yaw motion control. For example, as shown in FIG. 3A, consider a case where the vehicle body is caused to yaw in the counterclockwise direction while the vehicle is being braked by the regenerative braking force. In this case, the required regenerative braking force (-Fr_fl, -Fr_fr, -Fr_rl, -Fr_rr) is generated evenly on the front, rear, left and right wheels, and the braking force for yaw control (-Fc_yaw) is applied to the left front wheel 10fl. The yaw control driving force (+ Fc_yaw) in the direction opposite to the yaw control braking force (−Fc_yaw) is applied to the right front wheel 10fr.

  When the yaw motion is controlled in this way, the vehicle body rolls. Therefore, at the time of yaw motion control, it is necessary to generate a roll moment in the opposite direction to the roll moment generated on the front wheel 10f side on the rear wheel 10r side. In this case, the roll control braking force (−Fc_roll) is applied to the left rear wheel 10rl and the right rear wheel 10rl is applied so that the roll moment generated on the front wheel 10f side is canceled, that is, the roll moment is zero for the entire vehicle. A roll control driving force (+ Fc_roll) in the direction opposite to the roll control braking force (−Fc_roll) may be applied.

  However, since the vertical force conversion rate is different between the front wheel 10f side and the rear wheel 10r side, when comparing the combined braking / driving force (required regenerative braking force + control braking / driving force) of the front and rear wheels in the turning direction, The combined braking / driving force Ffl of the front wheel 10fl is larger than the combined braking / driving force Frl of the rear wheel 10rl. For this reason, the motor 30fl of the left front wheel 10fl reaches the capacity limit earlier than the motors 30fr, 30rl, 30rr of the other wheels 10fr, 10rl, 10rr. Therefore, there is a possibility that good vehicle motion control cannot be performed.

  On the other hand, in the present embodiment, as shown in FIG. 3B, the required regenerative braking force (−Fr_fl, −Fr_fr) on the front wheel 10f side is changed to the required regenerative braking force (−Fr_rl) on the rear wheel 10r side. , -Fr_rr) (the required friction braking force is applied to the front wheel 10f side). For this reason, the combined braking / driving force Ffl of the left front wheel 10fl and the combined braking / driving force Frl of the rear wheel 10rl can be made substantially equal. Therefore, the vehicle motion control can be performed by fully utilizing the capabilities of the motors 30f and 30r of the front and rear wheels 10f and 10r. For this reason, vehicle motion control can be implemented satisfactorily.

  The vehicular braking force control apparatus according to the present embodiment has been described above, but the present invention is not limited to the above embodiment, and various modifications can be made without departing from the object of the present invention.

<Modification 1: Vertical force conversion rate>
For example, the present embodiment is applied to a vehicle in which the suspension 20r of the rear wheel 10r has a higher vertical force conversion rate than the suspension 20f of the front wheel 10f, but the reverse, that is, the suspension 20f of the front wheel 10f is used as the rear wheel. The present invention can also be applied to a vehicle having a higher vertical force conversion rate than the 10r suspension 20r. In that case, the distribution ratio of the required regenerative braking force in the driver required braking force may be larger on the rear wheel 10r side than on the front wheel 10f side.

<Modification 2: Vehicle type>
In the present embodiment, the in-wheel motor 30 is provided in each of the front, rear, left and right wheels 10 and the vehicle braking force control device applied to a vehicle that independently controls and drives the front, rear, left and right wheels 10 has been described. The vehicular braking force control apparatus is not limited to application to this type of vehicle. For example, the present invention can also be applied to a vehicle in which four motors are provided on the vehicle body B side and transmit independent driving torque and braking torque to the front, rear, left and right wheels 10.

  Further, for example, the present invention can be applied to a front and rear wheel independent drive type vehicle in which the left and right front wheels 10f are driven by a common motor and the left and right rear wheels 10r are commonly driven by other motors. In the case of driving the left and right wheels with a common motor, it is not possible to generate braking / driving forces of different magnitudes on the left and right wheels, so that the roll motion around the longitudinal axis passing through the center of gravity Cg of the vehicle, the center of gravity Cg of the vehicle It is not possible to control the yaw movement around the vertical axis passing through. However, for the pitch motion around the left-right axis passing through the center of gravity Cg of the vehicle and the heave motion that is the vertical motion at the position of the center of gravity Cg of the vehicle, the required regenerative braking forces Fr_f and Fr_r are equal to each other on the left and right wheels. Control can be performed by adding the driving force Fcx.

<Modification 3: Total required braking / driving force>
In the present embodiment, the driver requested braking force generated by operating the brake pedal is distributed to the requested regenerative braking force and the requested friction braking force, but is not necessarily limited to when the brake pedal is operated. For example, the required braking force generated during automatic braking during automatic driving, braking by performing traction control (TRC), braking by performing side-slip suppression control that suppresses vehicle side-slip, etc. (total requirement of the present invention) (Corresponding to the braking force) can be distributed to the required regenerative braking force and the required friction braking force for each front and rear wheel as in the above embodiment. Therefore, the total required braking force in the present invention is not limited to the driver required braking force, and may be a required braking force generated during automatic traveling operation or the like.

<Modification 4: Distribution of regenerative braking force>
Further, for example, in the present embodiment, the required regenerative braking force for each front and rear wheel is set so that the remaining force of the vertical force that can be generated in the vehicle body B is equal between the front wheel 10f and the rear wheel 10r. Although the distribution with the required friction braking force is set, it is not always necessary to set such distribution, and any configuration may be used as long as the front wheel required regenerative braking force is set smaller than the rear wheel required regenerative braking force.

  DESCRIPTION OF SYMBOLS 1 ... Vehicle, 10 ... Wheel, 10f ... Front wheel, 10r ... Rear wheel, 20 ... Suspension, 21 ... Link mechanism, 30 ... Motor, 35 ... Motor driver, 40 ... Friction brake mechanism, 45 ... Brake actuator, 50 ... Integrated ECU , 51 ... Power management ECU, 52 ... Motor ECU, 53 ... Brake ECU, 60 ... Operation state detection device, 65 ... Motion state detection device, 70 ... Battery, B ... Vehicle body, Cf, Cr ... Instantaneous rotation center, Freq ... Driver Required driving force, Fbreq: Driver required braking force, Fcx: Control braking / driving force, Ff_f: Front wheel required friction braking force, Fr_f: Front wheel required regenerative braking force, Ff_r: Rear wheel required friction braking force, Fr_r: Rear wheel required regeneration Braking force.

Claims (4)

A motor that transmits driving torque and regenerative braking torque of at least the front and rear wheels independently to the front and rear wheels to generate braking and driving force on the wheels; and
A friction brake device that generates a braking force on the wheel by applying mechanical friction resistance of at least the front and rear wheels independently to the wheel; and
A suspension capable of connecting the wheel to the vehicle body and converting the driving torque and regenerative braking torque of the motor into a force in the vertical direction of the vehicle body,
A required braking force that distributes the total required braking force required for decelerating the vehicle independently to the required regenerative braking force generated by the motor and the required friction braking force generated by the friction brake device. Distribution means,
Generated by the motor based on the required regenerative braking force distributed by the required braking force distribution means and the control braking / driving force necessary for vehicle motion control that requires the vertical force of the vehicle body. Motor control means for calculating a target braking / driving force of the wheel and controlling the operation of the motor based on the target braking / driving force;
A braking force control device for a vehicle, comprising: friction brake control means for controlling the operation of the friction brake device based on the required friction braking force;
The suspension is configured such that the conversion rate for converting the braking / driving force of the wheel into the force in the vertical direction of the vehicle body is different between the front wheel side and the rear wheel side,
The required braking force distribution means is configured such that the wheel connected to the suspension having the smaller conversion rate has a smaller required regenerative braking force than the wheel connected to the suspension having the higher conversion rate. And a braking force control device for a vehicle that sets a distribution of the required regenerative braking force and the required friction braking force for each of the front and rear wheels. The braking force control device for a vehicle according to claim 1,
The required braking force distribution means is configured such that the remaining force of the vertical force that can be additionally applied to the vehicle body via the suspension by the braking / driving force of the wheels is equal on the front wheel side and the rear wheel side. And a braking force control device for a vehicle that sets a distribution of the required regenerative braking force and the required friction braking force for each of the front and rear wheels. The vehicle braking force control device according to claim 2,
The required braking force distribution means distributes the required regenerative braking force only to the wheels connected to the suspension having the higher conversion rate when the total required braking force is less than a preset set value. In addition, the distribution of the required regenerative braking force and the required friction braking force for each of the front and rear wheels is set so that the required friction braking force is distributed only to the wheels connected to the suspension having the smaller conversion rate. A braking force control device for a vehicle. The vehicle braking force control device according to any one of claims 1 to 3,
The motor is provided to drive the front, rear, left and right wheels independently,
The motor control means is a vehicular braking force control device configured to calculate a braking / driving force for control necessary for the vehicle motion control for each of front, rear, left and right wheels.

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